Patent Application
20110128541
This application claims priority from German Patent Application No. 102009046831.5, which was filed on Nov. 18, 2009, and is incorporated herein in its entirety by reference.
The present invention relates to devices for generating electromagnetic radiation having adjustable spectral composition.
In optical spectral analysis, the composition, the condition or other properties of the object to be examined are examined by means of the interaction of electromagnetic radiation with the surface and at the volume of said object. In this context, the wavelength-dependent reflection, transmission, absorption and scattering properties of materials are exploited.
Various variants of arrangements for performing spectroanalytical examinations have been known.
A first variant illuminates the sample with the entire polychrome spectrum of a light source, for example a halogen lamp or a thermal radiator. The light that has started to interact with the sample is then broken up into its spectral constituents within a monochromator, and detected by means of a radiation detector or photodetector. To this end, what may be used is either a mechanically movable dispersive element (grating, prism) or an arrangement of several radiation detectors. What is disadvantageous in the first possibility is utilization of a movable element, which results in increased overhead for the overall system. On the other hand, use of an arrangement of several detectors entails a relatively large amount of effort and is relatively expensive, particularly in the infrared wavelength range. In addition, due to the high optical power, the sample is heated and, thus, the measurement is influenced. A further disadvantage is the limited miniaturizability of the overall system. It is restricted, among other things, by the sizes of the radiation sources.
In a second variant, the light of a light source is broken up into its spectral constituents before starting to interact with the sample. For this purpose, a monochromator may be used as well, which, in turn, contains mechanically movable parts. Following the interaction with the sample, the light is detected using an individual detector. The sample is exposed to a comparatively small radiation intensity. The architecture is comparatively costly and mechanically delicate. In addition, in this case, too, the radiation source restricts the miniaturization of the overall system on the basis of system integration.
In a third variant, the electromagnetic radiation is generated within a very small spectral range only. For this method, one predominately uses such lasers whose wavelengths may be changed by tunable resonators are predominately used. What is advantageous is the high intensity within a very small wavelength interval. What is disadvantageous is the limitation to specific wavelength ranges with corresponding laser activity, increased effort devoted to the system due to the high levels of mounting accuracy, and the high price resulting therefrom. In addition, mechanically movable elements, such as gratings, are sometimes used, which entails sensitivity toward mechanical environmental influences. Also, when irradiating rough surfaces, the high spatial coherence leads to interference effects, so-called speckles, which may result in measurement errors in the detection.
In a fourth variant for a wide-range near-infrared spectral analysis, an electron cyclotron (storage ring) may be used, for example, which due to its size cannot be configured to be portable.
According to an embodiment, a radiation generation device for generating resulting electromagnetic radiation having an adjustable spectral composition may have: a multitude of radiation elements configured to generate a radiation element specific electromagnetic radiation, respectively, upon being activated, a first radiation element of the multitude of radiation elements being activatable independently of a second radiation element of the multitude of radiation elements; a dispersive optical element; and an optical opening; the dispersive optical element being configured to deflect each radiation element specific electromagnetic radiation, in dependence on its wavelength and on a position of the radiation element generating the respective radiation element specific electromagnetic radiation, such that a particular spectral range of each of the radiation element specific electromagnetic radiations may exit through the optical opening, so that the spectral composition of the resulting electromagnetic radiation exiting through the optical opening is adjustable by selectively activating the multitude of radiation elements.
According to another embodiment, a spectral analysis device may have: a radiation generation device for generating resulting electromagnetic radiation having an adjustable spectral composition, which radiation generation device may have: a multitude of radiation elements configured to generate a radiation element specific electromagnetic radiation, respectively, upon being activated, a first radiation element of the multitude of radiation elements being activatable independently of a second radiation element of the multitude of radiation elements; a dispersive optical element; and an optical opening; the dispersive optical element being configured to deflect each radiation element specific electromagnetic radiation, in dependence on its wavelength and on a position of the radiation element generating the respective radiation element specific electromagnetic radiation, such that a particular spectral range of each of the radiation element specific electromagnetic radiations may exit through the optical opening, so that the spectral composition of the resulting electromagnetic radiation exiting through the optical opening is adjustable by selectively activating the multitude of radiation elements; a radiation detector configured to receive the resulting electromagnetic radiation or an electromagnetic radiation generated by means of the resulting electromagnetic radiation; and an evaluation unit configured to perform a spectral analysis on the basis of the received electromagnetic radiation.
According to another embodiment, a method of producing a radiation generation device may have the steps of: providing or generating a multitude of radiation elements configured to generate a radiation element specific electromagnetic radiation, respectively, upon being activated, a first radiation element of the multitude of radiation elements being activatable independently of a second radiation element of the multitude of radiation elements; providing or generating an optical opening; providing or generating a dispersive optical element, connecting the dispersive optical element to the multitude of radiation elements and to the optical opening, the dispersive optical element being arranged and configured, in relation to the multitude of radiation elements and the optical opening, to deflect the radiation element specific electromagnetic radiations in dependence on their wavelengths and on a position of the radiation element generating the respective radiation element specific electromagnetic radiation such that a limited spectral range of each of the radiation element specific electromagnetic radiations may exit through the optical opening, so that the spectral composition of the resulting electromagnetic radiation exiting through the optical opening is adjustable by selectively activating the multitude of radiation elements.
One embodiment of the present invention provides a radiation generation device for generating resulting electromagnetic radiation having an adjustable spectral composition, comprising: a multitude of radiation elements configured to generate a radiation element specific electromagnetic radiation, respectively, upon being activated, a first radiation element of the multitude of radiation elements being activatable independently of a second radiation element of the multitude of radiation elements; a dispersive optical element; and an optical opening; the dispersive optical element being configured to deflect each radiation element specific electromagnetic radiation, in dependence on its wavelength and on a position of the radiation element generating the respective radiation element specific electromagnetic radiation, such that a limited spectral range of each of the radiation element specific electromagnetic radiations may exit through the optical opening, so that the spectral composition of the resulting electromagnetic radiation exiting through the optical opening is adjustable by selectively activating the multitude of radiation elements.
A further embodiment of the present invention provides a radiation generation device for generating resulting electromagnetic radiation having an adjustable spectral composition, comprising: a multitude of radiation elements configured to generate a radiation element specific electromagnetic radiation, respectively, upon being activated, each radiation element of the multitude of radiation elements being activatable independently of other radiation elements of the multitude of radiation elements; a dispersive optical element configured to split up each of the radiation element specific electromagnetic radiations into a multitude of spectral constituents, respectively; and an optical opening; the dispersive optical element and the optical opening being arranged and configured such that one of the spectral constituents of each radiation element specific electromagnetic radiation may pass through the optical opening, so that the spectral composition of the resulting electromagnetic radiation passing through the optical opening is adjustable by selectively activating the multitude of radiation elements.
The radiation elements may be configured to generate monochrome radiation element-specific electromagnetic radiations and/or polychrome radiation element specific electromagnetic radiations, it being possible for the polychrome radiation element specific electromagnetic radiations to be narrow-band or wide-band.
Embodiments of the radiation generation device may, therefore, comprise several monochrome light emitting diodes or laser diodes generating radiation element specific electromagnetic radiation of different wavelengths in each case, so that by selectively activating said radiation elements, a resulting electromagnetic radiation is generated which comprises one or more of said monochrome spectra.
Further embodiments may comprise thermal radiation elements, radiation elements in accordance with the halogen lamp principle or white light emitting diodes or other radiation elements configured to generate polychrome radiation element specific electromagnetic radiation. The dispersive optical element may be configured such that a particular or a limited spectral range of each of said radiation element specific electromagnetic radiations may exit through the optical opening, for example a spectral range smaller than the original spectral range generated by the radiation element, so that the resulting electromagnetic radiation comprises a spectral composition defined from one or more of the particular or limited spectral ranges.
In certain embodiments, the dispersive optical element and the optical opening may be configured such that of at least one or of each of said radiation element specific electromagnetic radiations, only a spectral range that is limited as compared to the original spectrum of the radiation element specific electromagnetic radiation may exit through the optical opening. In other words, such embodiments may be configured to filter the original radiation element specific electromagnetic radiation, it being possible, depending on the implementation of the optical dispersive element and the optical opening, for an original radiation element specific electromagnetic radiation to be filtered onto a narrow-band or, as seen in relation to the original spectrum, narrower-band spectrum or onto a monochrome spectrum. Such embodiments enable flexibly selecting, from the entire original wide-band or narrow-band spectrum of the polychrome radiation elements, particular spectral components, e.g. narrow-band, narrower-band or monochrome spectral constituents, and to select and/or superimpose them for generating the spectrum of the resulting electromagnetic radiation.
Further embodiments may comprise one or more polychrome radiation elements and, in addition, one or more monochrome radiation elements. In such embodiments, the dispersive optical element may further be configured such that of each of the polychrome radiation element specific electromagnetic radiations, a particular or limited spectral range may exit through the optical opening, for example a spectral range that is smaller than the original spectral range generated by the radiation element, and may further be configured to deflect the wavelength or the spectral range of each monochrome radiation element such that the monochrome radiation element specific electromagnetic radiation may exit through the optical opening. Such embodiments enable filtering out certain spectral components, e.g. narrow-band or monochrome spectral constituents, from wide-band polychrome radiation elements in a flexible manner, for example, and to superimpose them, for generating the resulting electromagnetic radiation spectrum, with monochrome radiation element specific electromagnetic radiations of the monochrome radiation sources, it being possible for the intensity of the monochrome radiation to be higher, for example, than an intensity of the spectra generated by means of filtering, or for the monochrome radiation to be within a spectral range not covered by the original spectrum of the polychrome radiation elements.
Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:
a shows an embodiment of an arrangement of thermal radiation elements, so-called filaments.
b shows an embodiment of an arrangement of light emitting diodes as radiation elements.
a shows a schematic cross section of a first embodiment of a radiation generation device for generating a resulting electromagnetic radiation with a multitude of similar thermal radiation elements,
b shows the schematic cross section of the first embodiment of
c shows the schematic cross section of the first embodiment of
Before the present invention will be explained in more detail below with reference to the accompanying figures, it shall be noted that the drawings are not realized to scale for better comprehensibility. In addition, identical reference numerals are used for objects and functional units having identical or similar functional properties, repeated descriptions of said objects and functional units being dispensed with. It shall further be noted in this context that on the one hand, sections referring to objects having similar or identical functional properties are exchangeable between the descriptions of the different embodiments unless explicitly stated otherwise. On the other hand, it shall be noted that shared utilization of a reference numeral for an object occurring in more than one embodiment does not indicate that said objects have identical features and properties in the different embodiments or in the embodiment concerned. Shared or similar reference numerals, thus, do not represent any statement regarding the specific configuration and positioning.
In this context, the term “spectrum” is used for generally describing the wavelength-related composition of electromagnetic radiation, the terms “spectral range” and “wavelength range” being used synonymously and describing a range of wavelengths defined by a lower limit or minimum wavelength and by an upper limit or maximum wavelength. Two spectral ranges or wavelength ranges are the same, or identical, if they have the same minimum and the same maximum wavelengths. Two spectral ranges or wavelength ranges are different if they differ either in terms of the minimum length and/or in terms of the maximum wavelength. In addition, two spectral ranges or wavelength ranges are referred to as being non-overlapping if the maximum wavelength of one spectral range is smaller than the minimum wavelength of the other spectral range.
In addition, the term “monochrome spectrum” is used when the spectrum essentially, i.e. while neglecting a scattering of the wavelength, comprises only one wavelength, and the term “polychrome spectrum” is used when the spectrum comprises more than one wavelength, while neglecting the scattering. A spectrum is referred to as a discrete spectrum if it comprises only one or more monochrome spectra, and is referred to as a continuous spectrum if it comprises, between a first cut-off wavelength and a second wavelength, all of the wavelengths contained within this range. A narrow-band spectrum generally designates a spectrum comprising a discrete or a continuous spectrum of a smaller bandwidth, i.e. of a smaller wavelength range, than a wide-band spectrum.
Before the individual embodiments of the figures are addressed, general aspects of embodiments of the radiation generation device for generating a resulting electromagnetic radiation having an adjustable spectral composition shall first be described. Embodiments of the radiation generation device comprise individual ranges emitting electromagnetic radiation, which will also be referred to as elements, radiation elements, radiation emitters or light emitters below. The radiation generation of the radiation elements may be based on various physical principles. The elements for generating the radiation may be manufactured by means of technologies known from semiconductor and microsystems technologies, such as lithography, etching and coating processes. By means of said methods, radiation generation devices may be generated which have thermal radiators as radiation elements in the form of thin beams that may be used like an incandescent filament in “incandescent lamps” by means of heat for emitting electromagnetic radiation. These embodiments of the radiation elements are particularly advantageous in infrared spectral ranges.
In addition, organic light emitting diodes (OLEDs), inorganic light emitting diodes (LEDs) or semiconductor lasers or laser diodes may be laterally structured as radiation elements that may be manufactured such that they are adapted to different wavelength ranges. In organic light emitting diodes, one single electrode may be generated and laterally structured instead of a multitude of individual organic light emitting diodes and, in this manner, a large-area diode may be locally excited, e.g. in a strip-shape, to emit radiation.
Depending on the implementation, embodiments may therefore cover large spectral ranges, but also relatively small ranges within a wide electromagnetic spectrum. Due to the combination with an optical means for spectral decomposition of the emitted radiation and an aperture or opening, embodiments of the radiation generation device enable a spectrally modulatable light source that may be generated without any costly adaptations or implementations of the radiation elements. In particular, “tuning” of radiation sources, which is known from other conventional approaches, such as with lasers by performing mechanical adaptations of the laser cavity, or rotation of a diffraction grating within a monochromator is avoided. Thus, embodiments of the present radiation generation device enable a marked improvement of the stability of the radiation source as compared to conventional technology. Instead of tuning, the embodiments of the radiation generation device comprise exploiting the lateral structuring, i.e. the several radiation elements that are controllable independently of one another, in order to change or adjust the wavelength composition of the spectral constituents unified within the aperture.
Due to the production-related possibility of integration and direct utilization of the radiation elements, high energy efficiency can be achieved.
The wavelength ranges that may be used for the resulting electromagnetic radiation may be changed within the emission spectrum of the radiation elements by adapting a few system parameters, for example the implementation and properties of the means for spectrally splitting up the radiation, also referred to as a dispersive optical element, and of the aperture, also referred to as an optical opening. Thus, different embodiments of the radiation sources or radiation generation device for generating resulting electromagnetic radiation comprising adjustable spectral composition may be created by means of few adaptations.
The architecture of the inventive radiation generation devices enables production of the entire spectrally modulatable light source in microtechnology or while using molding and injection molding technologies. The small sizes of the individual radiation elements enable relatively high temporal modulation frequencies, whereby embodiments of the radiation generation device for measurement principles may be enabled using the lock-in method (modulation of the source and demodulation upon receipt of the detected signal; TDM—time-division multiplexing), so that an improved signal-to-noise ratio (SNR) can be achieved. In addition, embodiments of the radiation generation device for generating a resulting electromagnetic radiation comprising an adjustable spectral composition enable wave modulation, for example in communication engineering, that may be used for an improved signal-to-noise ratio and for increasing the data transmission rate (WDM—wavelength-division multiplexing). The radiation generation device, which may also be referred to and used as a modulatable light source, comprises no mechanically movable parts and may be designed in a robust manner, which is advantageous, among other things, for employing portable devices.
a shows a schematic view of an arrangement of a multitude of radiation elements 1 arranged on a substrate 6. Below, reference numeral 1 will be generally used for the radiation elements, and reference numerals 1a, 1b, 1c, etc. will be used for designating individual radiation elements (see
The radiation elements, in particular the filaments, 1a to 1n may have a height (dimension perpendicular to the substrate plane) ranging from 100 nm to 100 μm or 500 nm to 10 μm, a width (a dimension within the substrate plane) from 1 to 200 μm or 5 to 100 μm, or a length (perpendicular to the other dimension within the substrate plane) ranging from 10 μm to 100 mm or 100 μm to 1 mm.
As their materials, the filaments may comprise, for example, a metal, a metal alloy or an electrically conductive metal/non-metal compound or a semiconductor material or a conductive material, e.g. graphite-type carbon, or compounds of non-metals. In addition, the filaments 1a to 1n may consist of a stack of different materials, which combine, e.g., the functions of an electrical conductor, a barrier or a diffuse barrier and a material having a high emission rate.
In accordance with an embodiment as is shown in
The radiation elements 1 or 1a to 1n may be controlled independently of one another and, thus, be excited to emit the radiation element specific electromagnetic radiation.
The controller 100 may be configured to successively activate individual, or combinations of individual, radiation elements to perform, e.g., a spectral analysis or wavelength modulation or to temporally change intensities of the respective radiation element specific electromagnetic radiations so as to perform an amplitude modulation, for example.
b shows a schematic top view of another embodiment of an arrangement of radiation elements 1 or 1a to 1n. Like in
The carrier substrate 6 on which the radiation elements are arranged may be implemented as a silicon or glass substrate. As in
a shows a schematic cross section of a first embodiment of a radiation generation device comprising a first carrier substrate 62, a diaphragm layer or functional layer 61, a second carrier substrate 9, and an encapsulation substrate 8. The second carrier substrate 9 has a first surface 206 and a surface 204 opposite said first surface. The second carrier substrate 9 further has a one-sided recess or cavity 202 that is upwardly opened, in the orientation of
In the embodiment of
In alternative embodiments of the radiation generation device, further layers or substrates may be arranged between the second carrier substrate 9 and the functional layer 61, between the functional layer 61 and the first carrier substrate 62, and between the first carrier substrate 62 and the encapsulation substrate 8, respectively. It is also possible for further embodiments to comprise no encapsulation substrate 8. The dispersive optical element 2 may further comprise the same material as the second carrier substrate 9, for example it may be made of same during manufacturing, or it may be made of a different material, which is deposited onto or into the recess 202 of the second carrier substrate 9 and structured.
The mode of operation of the radiation generation device will be described below with reference to
Specifically,
b shows the same embodiment of the radiation generation device of
c, in turn, shows the first and further radiation element specific electromagnetic radiation 4a and 4n generated by activating the first radiation element 1a and the nth radiation element 4n. Unlike
In other words, embodiments of the radiation generation device may comprise a multitude of radiation elements 1, 1a-1n that are configured to generate radiation element specific electromagnetic radiation 4a-4n, respectively, when they are activated, each radiation element of the multitude of radiation elements being activatable independently of other radiation elements of the multitude of radiation elements, and comprise a dispersive optical element 2 and an optical opening 3, a first radiation element 1a of the multitude of radiation elements being configured to generate a first radiation element specific electromagnetic radiation 4a, and a second radiation element 4n of the multitude of radiation elements being configured to generate a second radiation element specific electromagnetic radiation 4n, a spectral range of the second radiation element specific electromagnetic radiation 4n being identical with a spectral range of the first radiation element specific electromagnetic radiation 4a, and the dispersive optical element 2 being configured to deflect the radiation element specific electromagnetic radiations 4a-4n, in dependence on their angles of incidence and their wavelengths, in such a manner, or to split up the radiation element specific electromagnetic radiations 4a-4n in such a manner that a first spectral constituent of the first radiation element specific electromagnetic radiation 4a may exit through the optical opening 3, and a first spectral constituent of the second radiation element specific electromagnetic radiation 4n cannot exit through the optical opening 3, the first spectral constituent of the first radiation element specific electromagnetic radiation and the first spectral constituent of the second radiation element specific electromagnetic radiation being identical.
Embodiments may further comprise a dispersive optical element 2 configured to deflect the radiation element specific electromagnetic radiations 4a-4n, in dependence on their angles of incidence and their wavelengths, or to split up the radiation element specific electromagnetic radiations 4a-4n, such that a first spectral constituent of the first radiation element specific electromagnetic radiation 4a and a second spectral constituent of the second radiation element specific electromagnetic radiation 4n may exit through the optical opening 3, the first spectral constituent of the first radiation element specific electromagnetic radiation being different from the second constituent 5n2 of the second radiation element specific electromagnetic radiation.
In further embodiments, the radiation elements may be configured to generate radiation element specific radiations of different spectra, and the spectral constituents into which the radiation element specific radiations are split up may be different. In addition, in some embodiments, the spectral constituents, e.g. the first spectral constituent 5a1 and the second spectral constituent 5n2, may overlap irrespective of whether said radiation elements are identical or different, whereas in other embodiments, both spectral constituents are adjacent to each other, or are free from overlap.
In further embodiments of
On the reverse side, the SOI substrate 61 may be encapsulated with a further substrate, which is also referred to as an encapsulation substrate 8, for example a glass substrate. On the front side, the SOI substrate 61, 62 may be directly connected to a further substrate 9, which is also referred to as a second carrier substrate 9 and has a dispersive optical element 2 located thereon or therein. The second carrier substrate 9 may be manufactured from a glass or metal material, and in the embodiment of
Diffraction gratings, also concave diffraction gratings, may be manufactured, for example, using methods of ultra-precision cutting or corresponding molding and embossing processes. Both the substrate 9 and the diffraction grating 2 may share a manufacturing step, e.g. molding, or be manufactured separately. For example, the diffraction grating 2 may be created, by holographic methods, on the second carrier substrate 2, which has been previously manufactured and provided with a polymer layer. In addition, the diffraction grating 2 may consist of structures optimized within a specific wavelength range, such diffraction gratings also being referred to as blazed gratings.
The functional layer 61 has an opening 3 located therein for coupling out the electromagnetic radiation 5 generated by the filaments 1, which radiation 5 spectrally limits, in combination with the dispersive optical element 2, the spectral range that may be contributed by each of the radiation elements for the spectral composition of the resulting electromagnetic radiation.
The optical opening 3 may be selected, for example, as a rectangular slit etched into the functional layer 61. By the slit 3, spectral filtering of the radiation 5 is achieved, which radiation 5 originates from the individual elements, filaments or, generally, radiation elements, and is spectrally split up by the diffraction grating 2. The encapsulation substrate 8 may be configured to be transparent at least above the second recess 214 so as to enable the radiation 220, which passes through the slit, from the overall system, i.e. from the radiation generation device.
Connection of the substrates 61, 62, 8 and 9 may be effected by customary joining processes of semiconductor and microsystems technology, such as gluing or bonding. For example, the encapsulation substrate 8 may be connected to the first carrier substrate 62 by anodic or adhesive bonding. In addition, soldering processes, in particular laser soldering, are suited to yield a connection of the substrates 61, 62, 8 and 9. Connection of the substrates 8, 61, 62 and 9 may be effected both in a wafer bond arrangement and with singulating components.
Mutual hermetic connection of the individual substrates 8, 61, 62 and 9, which may be achieved by the above-mentioned technologies, offers the possibility of operating the filaments 1 within a vacuum or within a suitable filling gas. The filling gas may be a protective gas or an active gas, for example, such as in commercial halogen lamps. The filling gas may be advantageously configured to be gas-chemical, which, by increasing the pressure, minimizes evaporation of the filaments, changes the precipitation of the evaporated filament material on the surrounding surfaces, and supports or enables, by a corresponding reaction, recirculation of the filament material. Gas mixtures may also be employed in this context. Said gas mixtures may consist, for example, of an element of the group of halogens, such as iodine, of oxygen, or of an element of the group of noble gases, such as argon, xenon or krypton.
In addition, the filaments 1 may be connected to the carrier substrate 61 by a holder suitably implemented to compensate for thermal expansion, e.g. by flexible elements or spring structures.
As was explained above,
In other words,
In
In other words,
The first carrier substrate may be encapsulated, on the front side (on the side of the OLED) with an encapsulation substrate 8, e.g. a glass substrate 8. The dispersive optical element 2 used is, again, a concave diffraction grating 2, which is integrated into the second carrier substrate 9 on the reverse side, i.e. on the first surface 206 of the second carrier substrate 9, as already depicted in
In other words,
The first carrier substrate 63 is arranged above the encapsulation substrate 8, i.e. on the second surface of the encapsulation substrate 8. The radiation elements are arranged on the bottom side of the first carrier substrate 63, i.e. on the first surface of the first carrier substrate 63, which faces the encapsulation substrate 8. The recess 814 of the encapsulation substrate 8 is arranged below the radiation elements and comprises an opening in the direction of same. The encapsulation substrate 8 may be configured, for example, to hermetically seal a cavity formed from the recess 814. The second surface 204 of the second carrier substrate 9 has the non-transparent layer 30 arranged thereon in a lateral manner, i.e. adjacently to the encapsulation substrate 8, and said non-transparent layer 30 has the optical opening 3 in the form of a continuous recess extending from a first surface of the layer 30, which faces the second carrier substrate, to a second surface of the layer 30, which is arranged opposite the first surface.
In
Instead of the organic light emitting diodes, further embodiments comprise inorganic light emitting diodes or laser diodes or a combination of said three or further types of diodes.
In other words,
In other words,
In further embodiments of
The dispersive optical elements 2 of
Even though the above discussion was mainly about embodiments comprising thermal radiation elements, further embodiments may comprise, instead of the thermal radiation elements, such radiation elements that are based on a different physical principle, and vice versa. In addition, in the embodiments of
In addition, embodiments of
Even though the description has sometimes differentiated between layers, diaphragms and substrates, the substrates or diaphragms described in
Embodiments of the radiation generation device may be employed in any fields wherein radiation sources (or light sources) comprising modulatable or changeable spectral emission may be used. As was explained above, one application is, for example, in optical spectral analysis, wherein a statement is to be made about the composition, the condition or other properties by means of the interaction of electromagnetic radiation with the surface or the volume of an object, a liquid, or a gas. The wavelength-dependent reflection, transmission, absorption, and scattering properties are dependent on the material that may be employed for its identification. Several basically different variants are used. One variant of applying the inventive solution is as follows. Using the light source represented, a measurement object that is to be spectrally analyzed is transluminated. By sequentially changing the emission spectrum, the spectrum to be determined in accordance with the measurement principle may be captured by a single detector. From this spectrum, the material composition or concentration of specific substances may be inferred. Solid, liquid or gaseous substances may be analyzed in this manner. In the application, spectra of a high number down to two measurement values are captured for identification. The validity and reliability of the measurement will change in dependence thereon. Embodiments of the radiation generation device enable adaptation to different wavelength ranges and to the widths and number of the spectral intervals within which the spectrum is varied.
That range of the electromagnetic spectrum that excites characteristic molecular vibrations or their overtones, or combination vibrations, is particularly suitable for numerous examinations of objects made of organic materials. These ranges are referred to as medium infrared (MIR: wavelengths from 2,500 nm to 25 μm) or near infrared (NIR: wavelengths between 780 nm and 2,500 nm). Other substances and compounds, too, may have characteristic absorption bands within this range. However, visible light (380 nm . . . 780 nm), the ultraviolet spectrum (wavelengths below 380 nm) as well as far infrared (FIR) above 25 μm may also be taken into account for the examinations.
In other words, embodiments of the radiation generation device may be employed, for example, in the field of spectral analysis or spectroscopy, i.e. in fields wherein light of a selected wavelength interacts with matter, and wherein the characteristic of the interaction is interpreted by changes in intensity, possibly in dependence on the wavelength. Various approaches are applied here, for example measurements in reflection, transmission, absorption, transflection, fluorescence, excitation of processes, induced emission, or evaluation of so-called RAMAN signals. The measurements may be effected, inter alia, on the surface or the volume of solid matters, in liquids, gasses or plasmas, the objects may be present and be analyzed at normal pressure, in a reduced atmosphere, or at increased pressure. Furthermore, the objects may be present in a basic state or in an excited form.
An advantageous variant for such measurements comprises narrow-band, with regard to the wavelength, illumination of an object using a source for a tunable spectrum, and detection by means of a simple light-sensitive detector.
A further application comprises measuring the spectral sensitivity of radiation detectors or photodetectors. Both individual detectors and detector arrays may be measured. The inventive solution provides a light source with which the detector(s) is/are irradiated with radiation (light) of different known wavelength compositions. In this manner, it is possible to determine the spectral sensitivity.
Embodiments of the radiation generation device may be additionally used for measuring the color of an object. In this context, the modulatable light source is configured such that this light is emitted within the visible wavelength range, the surface to be analyzed is irradiated, and the light that is reflected back is detected by an individual detector. Usually, the corresponding light source is configured such that the emitted wavelength ranges in combination with the wide-band sensitivity of the individual detector are adapted to the eye's spectral sensitivity (red, green, blue). For detecting so-called “methame” colors, measurement of the spectrum may be effected with increased spectral resolution and number of measurements.
Embodiments of the radiation generation device have no movable elements and may therefore be potentially employed in portable devices. By means of system integration, implementations of the invention enable a miniaturized, low-cost, spectrally tunable radiation source. The invention enables integration of radiation sources with different emission principles. In this context, both thermal radiation elements and non-thermal radiation elements, e.g. luminescent radiation elements, organic or inorganic light emitting diodes (LEDs, OLEDs) may be integrated.
The spectral composition of the radiation emitted by the radiation generation device or source may be influenced by the selection of the emission principle, by the implementation (e.g. the geometry), by the number of radiation emitting elements and their control, by the implementation of the dispersive element as well as by the position and the configuration of the optical opening.
Embodiments of the radiation generation device comprise individual or a multitude of radiation emitting areas or elements. By using micro- and lithographic technologies, these filaments may be manufactured on the basis of the various physical emission principles. For example, self-supporting beams of a high-melting metal or metal alloy may be structured on a silicon or SOI substrate (silicon/silicon dioxide/silicon). They are individually controllable. By combination with an optical system and a dispersive element, the radiation is split up, in a wavelength-dependent manner, within an aperture plane. Only part of the spectrum may exit from the source through an aperture, such as an aperture slot, for example. Depending on the position of the element, the split-up spectrum is offset within the aperture plane, which is why, for each element, a different part of the spectrum may pass through the aperture. Due to the superposition of the spatially offset spectra of different elements, a spectrum thus forms again, behind the aperture, the composition of which depends on the control of the elements.
By controlling the individual filaments, the spectrum of the radiation generation device may be changed or modulated. Due to the size of the individual radiation emitting areas, a high level of temporal modulation may be achieved, which may also be used for a high level of temporal wavelength modulation. Depending on the wavelength range that may be used, it is also possible to structure organic light emitting diodes (OLEDs), light emitting diodes (LEDs), or similar emitters. In addition, it is possible to generate a mixture of light from different wavelength intervals by simultaneously controlling several filaments or, generally, several radiation elements.
For spectrally limiting the spectrum and for suppressing relatively high-order diffractions in the use of gratings, absorption or interference filters may be additionally integrated into the optical path. For controlling the light source, or as a current source or current supply, an electronic circuit 100, or a micro-electronic circuit, may be part of the overall system of the modulatable light source. It is also possible for radiation detectors to be integrated, which monitor the total performance or the spectral composition and may be used for closed-loop control.
The following applications shall be mentioned as examples of application: gas analysis (CO2 measurement, CO measurement, sensors for fire detectors, checking of the fuel gas composition and monitoring of waste gas treatment), analysis of liquids (on-line water analysis, analysis of alcohol, and monitoring of fuel quality), analysis of solids (water content of foodstuffs, on-line checking of the main components of foodstuffs, sorting of plastics and monitoring of the compositions of pharmaceutical products), telecommunications (wavelength-modulated signal transmission), and measurement technology (on-line color check and calibration of photodetectors and detector arrays). Applications may therefore be found, for example, in environmental measurement technology, agriculture, production of foodstuffs, pharmaceutics, dermatology, medicine, biotechnology, chemistry, petrochemistry, recycling, automobile manufacture, aviation, and air-conditioning technology.
Embodiments of the present invention provide a radiation generation device that may emit light within a narrow, but freely selectable wavelength range, is tunable, particularly in the near-infrared to medium-infrared spectral ranges, may be manufactured in large batches, may be realized to be small-sized and light-weight, consumes little energy, and is sufficiently robust for mobile applications.
The high level of integration enables low-cost production in large numbers of pieces. In addition, embodiments of the radiation generation device have no movable parts, so that the radiation generation device is particularly robust and, additionally, easy to control electrically. Moreover, radiation generation devices may also be configured to be small-sized, light-weight and energy-efficient.
Embodiments enable optional access to the wavelength intervals, fast response, tailor-made spectra by means of corresponding selection from an m-of-n ensemble.
Embodiments of the radiation generation device comprise several means for thermal generation of electromagnetic radiation, so-called filaments, the filaments being spatially arranged such that they directly or indirectly illuminate a diffractive structure, for example a reflection grating. Due to the diffractive structure, the radiation is split up, in a solid angle dependent manner, into the various wavelengths. By means of at least one corresponding means, for example an exit slit, only a certain part of the wavelength range is coupled out. The location of the wavelength range may be controlled by the selection of filament.
Further embodiments of the radiation generation device comprise filaments that have, as their material, monocrystalline silicon, which is conductive due to sufficiently high doping levels. Alternatively, the filaments may be configured in metal thin layers or conductive ceramics. The filaments may be manufactured, for example, from so-called SOI substrates by etching. Depending on the selection of the configuration substrate, the filaments have thicknesses of several 100 nm to several μm. The exit slit, or the optical opening, may be realized within the same chip, and its position is precisely definable due to the high precision of micro-system technique technology. This chip may be mounted, by means of vacuum packaging technology, onto a pressed plastic body or substrate containing a holographic grating, for example with a blazed structure. In the other spatial direction, the system is also hermetically sealed, so that the filaments are entirely within a vacuum. Alternatively, a protective gas or an active gas may be employed, as with commercial halogen lamps. Embodiments of the radiation generation device comprise, e.g., 128 or 256 filaments per chip, which have widths of about 5 μm and lengths of about 250 μm. For compensating for the thermal expansion (a change in length of 6 μm with an Si filament of 250 μm at an operation of 1,200° C.), the embodiments may further comprise a holder that is specifically designed on one side and comprises a flexible element.
Yet another embodiment of the present invention provides a radiation generation device comprising several radiation elements for emitting electromagnetic radiation that may be controlled by generating a high temperature of the element, said radiation generation device further comprising a wavelength-selective element, which deflects, for each radiation element, a certain wavelength range to a certain solid-angle element, said radiation generation device further comprising an element for limiting a solid-angle range through which the electromagnetic radiation exits the radiation generation device, it being possible for the location of the wavelength interval to be influenced by the selection of the one or more emitting elements, and that a spectrum which has a measurable intensity only within a certain wavelength interval may exit the light source.
In other embodiments, the functional layer 61 and/or the non-transparent layer 30 may have, instead of a slit or a continuous recess, a transparent area within the functional layer 61 or the non-transparent layer 30 so as to form the optical opening 3.
Embodiments of the present invention may be configured such that the multitude of radiation elements, the dispersive optical element, and the optical opening are mutually mechanically secured, that is, they are unmovably arranged within the radiation generation device, i.e. none of the above-mentioned elements is displaceable or rotatable, for example.
Further embodiments provide a radiation generation device for generating electromagnetic radiation, said radiation generation device comprising several elements 1, or 1a to 1n, for generating electromagnetic radiation, and it being possible to control the elements independently of one another, wherein the radiation generation device comprises at least one dispersive optical element 2 for spectrally splitting up the radiation emanating from the elements, the radiation generation device comprising an optical device 3 for coupling out the electromagnetic radiation, the opening 3 being configured and arranged such that it limits the spectral bandwidth of the radiation emitted by each individual element 1a to 1n and split up by the dispersive element, and it being possible for the spectral composition of the radiation 220 passing through the optical opening to be influenced by controlling the radiation generating element(s) in a targeted manner.
Further developments of the embodiments provide, for example, a radiation generation device wherein the elements for generating the electromagnetic radiation are configured to be strip-shaped and are arranged in a regular manner or at variable distances from one another.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the elements for generating the electromagnetic radiation have different geometries in each case.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the elements for generating the electromagnetic radiation are formed from heatable structures, so-called filaments, or inorganic or organic light emitting diodes (LEDs, OLEDs), or laser diodes.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the filaments consist of a metal or a metal alloy or an electrically conductive metal/non-metal compound or a semiconductor material such as silicon, or a conductive non-metal such as graphite-like carbon, or compounds of non-metals.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the filaments consist of a (lateral) stack of different materials.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the dispersive optical element is a diffraction grating or a prism or a combination of same.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the optical opening for coupling out electromagnetic radiation is configured as an aperture having a rectangular or oval cross section, or is configured from a structure having a plurality of openings.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the optical opening for coupling out electromagnetic radiation consists of a material that is transparent to the radiation and is partly coated with a material not transparent to the radiation, or a stack of layers.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the optical opening for coupling out electromagnetic radiation are arranged on or in a shared substrate or a shared diaphragm or are arranged in a self-supporting manner, mechanically secured by a shared substrate.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the dispersive optical element or the opening for coupling out the radiation is arranged in or on a substrate.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the elements for generating the electromagnetic radiation and the dispersive optical element or the opening for coupling out the radiation, or both, are arranged on or in a shared substrate or a shared diaphragm.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the dispersive element and the opening for coupling out the radiation are arranged on or in a shared substrate.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the substrate having arranged the elements for generating electromagnetic radiation arranged thereon or therein is indirectly or directly connected to the substrate, which has the dispersive optical element arranged thereon or therein, or to the substrate which has the opening for coupling out the radiation arranged thereon or therein.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the substrates are connected to one another in a stacked manner.
Further developments of the embodiments provide, e.g., a radiation generation device wherein there is a spacer substrate between the substrate having the elements for generating electromagnetic radiation arranged thereon or therein and the substrate having the dispersive optical element arranged thereon or therein, or the substrate having the opening for coupling out the radiation arranged thereon or therein.
Further developments of the embodiments provide, e.g., a radiation generation device wherein one of the substrates comprises further optical functional elements.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the substrates are indirectly or directly connected to one another.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the shared substrate of the elements for generating electromagnetic radiation is a silicon-on-insulator substrate (SOI) or a silicon substrate or a glass substrate or a ceramic substrate.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the substrate having the dispersive element or the optical opening located thereon or therein comprises one of the material groups of glass, ceramics, plastic, metal, or a semiconductor material.
Further developments of the embodiments provide, e.g., a radiation generation device wherein at least one detector is present for measuring the power of electromagnetic radiation.
Further developments of the embodiments provide, e.g., a radiation generation device wherein at least one measuring means is present for detecting the spectral composition.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the radiation emitted by the source is within the ultraviolet or visible or infrared spectral range, or a combination of same.
Further developments of the embodiments provide, e.g., a radiation generation device wherein the spectral composition of the radiation output by the source may be varied in time by sequentially controlling one or more radiation emitting elements.
Further developments of the embodiments provide, e.g., a radiation generation device wherein a mixture of electromagnetic radiation is generated in a targeted manner by simultaneously operating several radiation emitting elements.
Yet further developments may comprise reflection gratings or holographic gratings as dispersive optical elements, may comprise silicon monocrystal, doped semiconductor substrates, SOI substrates, high-melting metals, high-melting and conductive compounds such as TaC, HfC, TaHfC, which comprise thermal stress compensation, as filament materials, may comprise monitor diodes as radiation elements, may comprise electrical excitation, pulsed excitation or non-electrical excitation, may comprise gratings that have been manufactured in molding processes, are pressed or deep-drawn, may comprise gratings within the chip, and mirrors.
Embodiments of the present invention also provide a spectral analysis device having a radiation generation device as was described above, a radiation detector configured to receive the resulting electromagnetic radiation or electromagnetic radiation generated by means of the resulting electromagnetic radiation, and an evaluation unit configured to perform a spectral analysis on the basis of the electromagnetic radiation received.
Embodiments of the spectral analysis device may comprise only one single radiation detector that is arranged in a spatially unvariable manner in relation to the radiation generation device, or is configured to perform a spectral analysis without changing a position of the radiation detector or a spatial arrangement of the radiation generation device in relation to the radiation detector.
Embodiments of the present invention also provide a method of producing a radiation generation device, comprising the following steps.
Providing or generating a multitude of radiation elements configured to generate a radiation element specific electromagnetic radiation, respectively, upon being activated, a first radiation element of the multitude of radiation elements being activatable independently of other radiation elements of the multitude of radiation elements. Providing or generating an optical opening. Providing or generating a dispersive optical element. Connecting the dispersive optical element to the multitude of radiation elements and to the optical opening, the dispersive optical element being arranged and configured, in relation to the multitude of radiation elements and the optical opening, to deflect the radiation element specific electromagnetic radiations in dependence on their angles of incidence and their wavelengths such that a limited spectral range of each of the radiation element specific electromagnetic radiations may exit through the optical opening, so that the spectral composition of the resulting electromagnetic radiation exiting through the optical opening is adjustable by selectively activating the multitude of radiation elements.
Depending on the production technologies, the aforementioned steps may be performed in a different order and/or at least partially simultaneously. Embodiments of the manufacturing method of manufacturing a radiation generation device may be configured such that the step of generating the radiation elements, the dispersive element and/or the optical opening, the step of connecting the substrates and layers (e.g., of
While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations and equivalents as fall within the true spirit and scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 046831.5 | Nov 2009 | DE | national |
