1. Field of the Invention
The present invention relates to an optical device, and more particularly relates to a miniature spectrometer.
2. Description of Related Art
Spectrometers are a type of non-destructive detection instruments, and are typically used in applications of identification of composition and characteristics of substances. A beam of light is projected onto a substance and, due to the principle of reflection of light and the reflection, absorption or penetration of light by the substance's compositional structure of different wavelengths, a spectrometer shows corresponding spectrum after receiving the reflected light from the substance. As different substances show different characteristics of the spectrum, the composition and characteristics of a substance can thus be identified.
To achieve the aforementioned effect, the positioning of various components of the spectrometer needs to be precise. If any component is shifted, rotated or damaged, performance of the spectrometer would be affected. Therefore, a goal of the industry is to provide a technique to precisely and rapidly dispose the various components of a spectrometer at respective positions.
An objective of the present invention is to provide a miniature spectrometer. It can be convenient and not difficult for the miniature spectrometer to adjust and to affix a grating without undermining the grating.
A so-called miniature spectrometer is a miniaturized spectrometer having a grating that is a miniature diffraction grating. The miniature diffraction grating is generally fabricated by micro-electro-mechanical system (MEMS), semiconductor fabrication process, lithography, electroplating and molding (Lighographie GaVanoformung Abformung, LIGA) or other manufacturing processes. The height of the miniature diffraction grating is typically in a range from approximately tens of microns to hundreds of microns. As the thickness of the miniature diffraction grating is limited, and as the materials used in fabricating the miniature diffraction grating are usually brittle, the assembly and positioning of the miniature diffraction grating are not easy.
According to one aspect of the present invention, a miniature spectrometer may comprise an input port, an image capture unit, a miniature diffraction grating, a grating accommodation slot, a cushion and an affixing plate. The input port is configured to receive an optical signal. The miniature diffraction grating is configured to separate the optical signal into a plurality of spectral components that are projected onto the image capture unit. The cushion is disposed above the miniature diffraction grating, and the cushion and the miniature diffraction grating are disposed in the grating accommodation slot. The affixing plate applies a compressive force on the cushion to affix the miniature diffraction grating in the grating accommodation slot.
According to another aspect of the present invention, a method of fabricating a miniature spectrometer may comprise: providing a waveguide device in which an optical signal is transmitted, wherein the waveguide device includes a grating accommodation slot; disposing an input port at a starting point of a transmission path of the optical signal so that the input port receives the optical signal; disposing an image capture unit at an end point of the transmission path of the optical signal; providing a miniature diffraction grating and a cushion with the cushion disposed above the miniature diffraction grating, wherein by moving the cushion the miniature diffraction grating is disposed in the grating accommodation slot such that the miniature diffraction grating is in the transmission path to separate the optical signal into a plurality of spectral components that are projected onto the image capture unit; and providing an affixing plate that is disposed on the waveguide device to cover the grating accommodation slot, the affixing plate compressing on the cushion such that the miniature diffraction grating is affixed in the grating accommodation slot.
Detailed description of select embodiments of the present invention is provided below with reference to the attached figures to aid better understanding of the present invention.
In order to further the understanding regarding the present invention, the following embodiments are provided along with illustrations to facilitate the disclosure of the present invention.
Detailed description of various embodiments is provided below. The disclosed embodiments are example illustrations, and do not limit the protective of the present invention. Additionally, non-critical components may be omitted in the drawings of the embodiments in order to clearly illustrate the technical characteristics of the present invention.
The description below refers to
The miniature spectrometer 100 comprises an input port 200, an image capture unit 400, a miniature diffraction grating 500, a grating accommodation slot 310, a cushion 600 and an affixing plate 700. Preferably, the miniature spectrometer 100 further comprises a waveguide device 300.
In the miniature spectrometer 100 described above, the waveguide device 300 (as shown in
Preferably, as shown in
In one embodiment, the grating accommodation slot 310 is located at a space defined by the opening 331 of the waveguide device 300. In some embodiments, the grating accommodation slot may selectively be located on a chassis of the miniature spectrometer 100 (not shown), the protective plate 800, or elsewhere between the input port 200 and the image capture unit 400 that is suitable for the miniature diffraction grating 500 to be placed. The input port 200 is utilized to receive an optical signal 500. The waveguide device 300 is utilized to transmit the optical signal 50 therein. In one embodiment, the waveguide device 300 includes a grating accommodation slot 310 for receiving the miniature diffraction grating 500. In one embodiment, the grating accommodation slot 310 is a rectangular region and has two adjacent sidewalls to form a positioning line 311 for the miniature diffraction grating 500, whereas the other two adjacent sidewalls of the rectangular region provide no particular function (to be described in detail below).
The miniature diffraction grating 500 is utilized to separate the optical signal 50 transmitted in the waveguide device 300 into numerous spectral components 51 and cause the spectral components 51 to be projected onto the image capture unit 400. The cushion 600 is disposed above the miniature diffraction grating 500, and the cushion 600 together with the miniature diffraction grating 500 are disposed in the grating accommodation slot 310. In one embodiment, the affixing plate 700 is disposed on the waveguide device 300 and applies a compressive force on the cushion 600 to affix the miniature diffraction grating 500 in the grating accommodation slot 310. Regarding design choices, the affixing plate 700 may be locked on the chassis of the miniature spectrometer 100 (not shown), or the protective plate 800 may be expanded beyond the waveguide device 300 so that the affixing plate 700 may be locked on the protective plate 800 so long as a compressive force is applied on the cushion 600. Thus, the affixing plate 700 may be a part of the chassis of the miniature spectrometer 100 or may be substituted with a circuit board of the miniature spectrometer 100 (not shown) as it is not required to be an independent component and there is no particular limitation on the location thereof.
Moreover, in one embodiment, the image capture unit 400 of the miniature spectrometer 100 is disposed on the protective plate 800, and the image capture unit 400 comprises, for example, a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS). Furthermore, in one embodiment, the input port 200 is disposed on the protective plate 800, for example.
In one embodiment, the waveguide device 300 of the miniature spectrometer 100 has a dart-type structure. In one embodiment the dart-type structure includes a turning point 70 from which two plate-like protrusions extend out and form an angle θ that is, for example, between 90 and 180 degrees. Additionally, distal edges of the two plate-like protrusions away from the turning point 70 comprise endpoints 60 and 61. In one embodiment, the input port 200 is disposed at the endpoint 61, the image capture unit 400 is disposed at the endpoint 60, and the grating accommodation slot 310 is disposed at the turning point 70. In one embodiment, the structure of the protective plate 800 corresponds to the dart-type structure of the waveguide device 300, yet this by no means limits the spirit and scope of the present invention. The protective plate 800 may have, for example, a rectangular shape or other shapes. The size of the waveguide device 300 can be reduced appropriately so that it covers the path of the optical signal 50. The size of the protective plate 800 can be expanded beyond the scope of the waveguide device 300 conspicuously, and the grating accommodation slot 310 can be designed to be on the protective plate 800 near the turning point 70 such that the miniature diffraction grating can properly receive the optical signal 50 from the input port 200 for spectrophotometry.
Next, detailed description of a relationship between the positions of the miniature diffraction grating 500 and the cushion 600 of the miniature spectrometer 100 is provided. In
In one embodiment, the miniature diffraction grating 500 is cut into a wafer having a substantially rectangular contour, and can be moved during assembly within the region provided by the grating accommodation slot 310 which is the rectangular region shown in
More specifically, two adjacent edges on the second waveguide plate 330 form the two adjacent sidewalls of the opening 331, and the miniature diffraction grating 500 abuts the two adjacent sidewalls which are not coplanar. The other two adjacent sidewalls of the grating accommodation slot 310 are defined by the side plates 340 (these two adjacent sidewalls play no specific role in terms of positioning, as described below). The cushion 600 is disposed above the miniature diffraction grating 500 and, in one embodiment, the cushion 600 is stacked over the miniature diffraction grating 500 with adhesive substance. In terms of design choices the stacking can be achieved without using adhesive substance. Operation of the cushion 600 may include, for example, exerting an external force to toggle the cushion 600 to move the miniature diffraction grating 500 forward. Thus, by exerting an external force on the cushion 600 to cause it to move toward the front left side of the opening 331 of the second waveguide plate 330 near the path of the optical signal 50 (which is the front left side of the grating accommodation slot 310), the miniature diffraction grating 500 also moves toward the front left side of the opening 331 of the second waveguide plate 330 (which is the front left side of the grating accommodation slot 310) until it touches the front left two adjacent sidewalls of the opening 331 of the second waveguide plate 330. At such time the miniature diffraction grating 500 is up against the front left two adjacent sidewalls of the opening 331 of the second waveguide plate 330 and thereby sets the position of the miniature diffraction grating 500. The front left two adjacent sidewalls of the rectangular region of the grating accommodation slot, which are the front left two adjacent sidewalls of the opening 331 of the second waveguide plate 330, form an angle α to provide the positioning line 311 for proper positioning of the miniature diffraction grating 500 in the optical path(s) in the overall spectrometer. The location of the positioning line 311 is predetermined during the design of the entire spectrometer. When the miniature diffraction grating 500 abuts the positioning line 311, the miniature diffraction grating 500 is properly positioned in the predefined optical path(s) where grating should be. Through the operation of the cushion 600, the miniature diffraction grating 500 can be precisely positioned into the proper position. In one embodiment, the angle α is a rectangular angle and may be abutted by the miniature diffraction grating 500 as shown in
Referring to
The description above pertains to how the position of the miniature diffraction grating 500 is determined and how the miniature diffraction grating 500 is precisely positioned. The following description refers to
Furthermore, with the trend of miniaturization of the miniature spectrometer 100, fabrication of the miniature diffraction grating 500 becomes ever smaller and more precise. In order to conform with the trend of miniaturization, the miniature diffraction grating 500 may be manufactured using semiconductor technology. Accordingly, the material of the miniature diffraction grating 500 may be, for example, silicon, a III-V semiconductor material or a single-crystal material. Given the trend of manufacturing the miniature diffraction grating 500 using a semiconductor-related material, such as silicon, a III-V semiconductor material or a single-crystal material, the miniature diffraction grating 500 tends to be brittle under excessive external force. Thus, with the employment of the cushion 600 of an elastic material, not only the miniature diffraction grating 500 can be affixed but also there is no risk of damaging the miniature diffraction grating 500 due to excessive external force.
On the other hand, the present invention also provides a method of assembly of the miniature spectrometer 100 with reference to
Another method of assembling the miniature spectrometer 100 is shown in
The miniature spectrometer disposed according to various embodiments of the present invention utilizes a technique of disposing a cushion on the miniature diffraction grating to achieve precise positioning of the miniature diffraction grating and preventing the grating from being damaged due to excessive external force. As the miniature diffracting grating is a small component, movement or rotation thereof is not easy let alone precise positioning to a predefined position. Moreover, given the modernization of the miniaturization of spectrometers, spectrometers are ever smaller and the demand for precision of internal optical components is greatly increased. As the miniature diffraction grating is the most important component of a miniature spectrometer, any slight deviation in positioning or any damage thereof would reduce the precision and performance of the miniature spectrometer.
With respect to the movement and rotation of the grating, conventional technology only controls the grating itself. Miniaturization of the diffraction grating requires a higher precision of the positioning and movement of the grating device. In the embodiments of the present invention, a design of having a cushion disposed above the miniature diffraction grating is employed. By moving the cushion the miniature diffraction grating can be indirectly moved.
Further, the positioning of the miniature diffraction grating can be determined by defining the position of the grating device of the miniature spectrometer. Moreover, by covering the cushion with the affixing plate, the restoration force of the cushion helps affix the miniature diffraction grating in the grating accommodation slot. By employing a cushion of an elastic material, not only there is no risk of damaging the miniature diffraction grating due to excessive external force but also there is no risk of the miniature diffraction grating becoming loose due to insufficient external force. On the other hand, methods of assembling the miniature spectrometer as provided by the present invention are simple and do not require complicated procedure to assemble the miniature spectrometer.
Overall, embodiments of the present invention address issues associated with the difficulty in disposing a miniature diffraction grating in a miniature spectrometer, and further provide a technique that avoids damaging the miniature diffraction grating during the positioning thereof Specifically, when brittle material such as semiconductor material is used, the disclosed technique is key to the precision and safety in assembly of the miniature diffraction grating. Moreover, methods of assembling the miniature spectrometer in accordance with embodiments of the present invention are simple and not complicated, thus enhancing the convenience and precision of the manufacturing of the miniature spectrometer.
From the foregoing it would be appreciated that, although specific embodiments of the present invention have been described for purpose of illustration, by no means they are to be interpreted as limiting the scope of the present invention. Various modifications may be made without departing from the spirit and scope of the present invention. The descriptions illustrated supra set forth simply the preferred embodiments of the present invention; however, the characteristics of the present invention are by no means restricted thereto. All changes, alternations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the present invention delineated by the following claims.
This application is a continuation application of U.S. patent application Ser. No. 13/642,312, filed on Oct. 19, 2012, which is the national phase application of international application number PCT/CN2010/072278, filed on Apr. 29, 2010.
Number | Date | Country | |
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Parent | 13642312 | Oct 2012 | US |
Child | 14940114 | US |