Patent Application
20250216660
The project leading to this application has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 101035014 and No 863203.
The present disclosure concerns an assembly of optical elements for the adaptation or control of light, particularly for adapting or controlling light arriving from a light source. Particular preferred embodiments of the present disclosure concerns such an assembly for microscopy and a microscope comprising said assembly. The present disclosure further concerns a related method for controlling light, particularly for microscopy, and a computer implemented method and a corresponding computer program. The assembly of optical elements may particularly be a tunable single objective or illumination lens with standard coupling to a microscope body and configured to provide an adaptive illumination modulator capable of modulating both the amplitude and the phase profile of the microscope's input beam or of the light produced by the microscope's light source. The assembly may be particularly suitable to be used for converting a microscope into a super-resolved microscopy system. The assembly may also be any of: an optical fiber driver, a device for use in a secure communications system, a device for use in an optical physical unclonable function system, a laser lithography beam modifier, a device for use in vehicle's headlight.
For centuries optical microscopy constitutes one of the most fundamental paradigms in biological and medical imaging. Microscopes are the primary instrumentation in use to inspect micrometer detail with the use of light as a probe. While the plethora of variations and applicability of microscopes is a non-trivial task to catalogue, the basic elements of a microscope are the illumination source and the imaging part. The sample is set in the working distance of the imaging system, and it is illuminated most commonly either in transmission or reflection mode. The imaging part usually refers to an objective lens, a composite element that collects the light from the sample and is sent to an eyepiece or digital camera. The area that the imaging system can collect sufficiently signal is defined by the depth of field (DOF) and field of view (FOV). Typically, the magnification of conventional microscopes relies on the magnification capabilities of the objective lens as their ability to collect light from the effective zone defined by DOF and FOV.
One family of microscopy techniques is fluorescence microscopy, where fluorescent agents are embedded in the study sample. In this case, most commonly, illumination is used as the excitation method of those agents. Fluorescent light in different wavelength bands compared to the excitation light can be isolated in the imaging part and record only the fluorescent halo.
Another family of microscopy techniques is light sheet fluorescent microscopy (LSFM), a technique with an advantage in imaging mesoscale and microscale fluorescent samples. Although the imaging part of an LSFM is the same as conventional microscopy, the illumination method differs. The source of illumination is designed and composed with optical elements that create a light distribution that resemblances a plane or a sheet of light. Usually, this is achieved using cylindrical lenses that provide a light sheet of finite width and intensity uniformity. Such a light distribution is used to illuminate the subject of study, while the angle of the imaging path is vertical to the light sheet plane. The desired dimensions of the light sheet are to match or exceed the field of view of the imaging lens. In contrast, the width of the light sheet plane should be kept as thin as possible compared to the depth of view. The imaging system then can capture a thin layer of the sample of the study. A necessity for the technique is that the sample has fluorescent agents within its body. The signal of interest is the fluorescent light that is emitted after it has been excited by the light sheet. A filter is positioned in the imaging system to select only the fluorescent light. This configuration reduces the photodamage of fluorescence molecules from unnecessary exposure compared to conventional and confocal microscopy. The sample can be rotated with the axis of rotation in the middle of the illumination plane. A camera is recording the fluorescent signal at specific angles. The whole process of rotation and image recoding is controlled most commonly with a computer. Such a rotational scan will allow a volumetric observation of the sample. Each slice is recorded and then saved on the computer's memory. When the scan is finished, the recorded slices are digitally processed to provide a 3D reconstruction of the sample in question.
In LSFM, the sample preparation and positioning are complicated and customized processes. However, the most frequent methods to attach a sample are hanging, embedding, or enclosing. An LSFM operation requires the user to place the sample. The light sheet will be illuminating a thin slice vertically into the DOF of the imaging system. The sample is moved onto the light sheet region, and the fluorescence response is recorded. A stage assists on the rotation of the sample, and in periodic angular spacings, the optical response is recorded. After the scan is complete, the recorded data are digitally processed, and the user can inspect the volumetric representation of the sample.
Another family of microscopy techniques is the super resolution microscopy and specifically the structure illumination microscopy (SR-SIM). Structure detail that a microscope can capture is defined by the ability of the imaging lens to collect light from the optical response of the sample of the study. Each imaging objective has a finite capacity to collect light defined by the numerical aperture. A sample optical response varies given the k-vector of the illumination beam. In structure illumination microscopy, one predetermines the illumination profile with specific k-vectors defined by a light modulator, three in total or more, and records the response. One needs to repeat the recording for different positioning of the sample compared to the illumination modulator and illumination modulation profile orientation onto the sample. The accumulated result of those two positionings with digital processing maximizes the capacity to capture detail on the final image by the imaging objective in terms of resolution by 2-fold. In conclusion, the SR-SIM advantages are the sum of the ability to modulate the light beam profile in phase and amplitude with a combination of digital processing over a number of recorded images.
While structure illumination microscopy is a technique which generally offers high resolution imaging, it is limited by the small working distance that is generally related to this technique. Likewise, while light sheet fluorescence microscopy (LSFM) is a technique which offers long working distance, it is limited by the low resolution it offers. Hence, there is an important need for methods and systems for microscopy combining long working distance and high-resolution imaging, particularly for the purpose of imaging of in-vivo dynamics of organisms or live specimens, where high-level details of specimen function at a cellular level are required while holding intact the information of the whole specimen. Moreover, for several applications of interest, particularly the ones described further below, there is a need for methods and systems for controlling or adapting light, e.g. light received by a light source, wherein said methods and systems can offer a long working distance and/or the ability to create precise illumination patterns as may be required by the specific application of interest.
The present invention intends to fill a space between optical techniques of high resolution and small working distance such as structure illumination microscopy with those of low resolution and high working distance such as light sheet fluorescence microscopy. The device disclosed advantageously can offer high resolution and long working distance, and is particularly intended for microscopy imaging of in-vivo dynamics of organisms or live specimens, where high-level details of specimen function at a cellular level are required while holding the information of the whole specimen body intact. More generally, the present invention allows to adapting light and/or creating precise illumination patterns as may be required for specific applications of interest such as any of: microscopy, driving an optical fiber, implementing secure optical communications, implementing an optical physical unclonable functions, oPUF, protocol for authentication, lithography, smart adaptive lighting, headlights of vehicles.
The present invention in a first aspect concerns an assembly of optical elements for the control of light, said assembly comprising in order from a first side of it: a light modulator configured to actively modulate a wavefront of light passing though the assembly, the light modulator comprising an electronic interface; a first polarization element configured to define a polarization of the light received from the light modulator; an optical element that has a region across which a value of a refractive index of the optical element varies for passively modulating the wavefront of the light received from the first polarization element; a second polarization element configured to define the polarization of the light received from the optical element, thereby second polarization outputting an adapted light. It can be understood that the adapted light is the optical output of the assembly i.e. the result of the assembly transforming the light that passes through it. Exemplary embodiment of the first aspect of the invention concern application of the invention in microscopy, hence, in relation to these exemplary embodiments the invention in its first aspect can also be considered as being an assembly of optical elements for microscopy.
The assembly can achieve high resolution and long working distance, because there is used the optical element, which preferably may comprise one or more photonic structures, in combination with active light wavefront control. The modulation offered by the optical element may enhance the production of light k-vectors and wavefront control in combination with the light wavefront modulator. Hence, an important advantage of this arrangement, is that it gives the ability to image at larger depths within biological tissue or complex media in a more general sense, since light diffusion can be proactively compensated within the assembly that may be the microscope objective. Shaping the incident wavefront with the modulator which may act as a spatial light modulator (SLM), can create a near diffraction limit, with high signal-to-noise ratio (SNR), circular spot at a long working distance behind the optical element which passively modulates the wavefront of the light. The system, i.e. the assembly according to the invention, can achieve all optical manipulation of the incident light with the light wave controllers, allowing scanning and focusing without mechanical movements, and increasing speed and stability of image acquisition and fidelity. The system can advantageously operate in variable working distances and wavelengths while maintaining the quality of the wavefront, allowing the inspection of small live specimens such as cells up to mesoscopic samples, in one non-limiting example such a sample being Danio rerio zebrafish. Additionally, the preferred use of complex wavefronts of multiple focal points advantageously permits image reconstruction of the sample using structure illumination microscopy and doubling the resolution compared to a conventional microscope. Moreover, the two polarization elements in combination can define whether the optical output from the assembly comprises ballistic or scattered light or both. Hence, when the two polarization elements have respective polarization planes which are parallel to each other, i.e. when the respective polarization angles of the two polarization elements are the same, then the optical output from the assembly may predominantly or exclusively comprise ballistic light i.e. light propagating ballistically through the assembly. However, when said polarization planes are not parallel to each other, and particularly when they are normal to each other, i.e. when the respective polarization angles differ by 90 degrees, said optical output may predominantly or exclusively comprise scattered light i.e. light scattered by the assembly's scattering parts between the two polarizers. Choosing between ballistic or scattered light or both can be beneficial depending on the intended application of the assembly. Hence, optionally and preferably the respective polarization angle or plane of the first and/or second polarization elements is adjustable. This can for example be done by any or both of the polarization elements being configured to rotate.
The optical element is configured to modulate the wavefront so that the latter preferably has the form of a speckle pattern, more preferably an elongated speckle pattern. In an embodiment, such an elongated speckle pattern is achieved by means of the optical element being a photonic structure with anisotropic modulation of the refractive index along one dimension. When the photonic structure is configured to cause such an anisotropic modulation along one direction, its use can advantageously create different wavelength sub-micrometer light-sheet structures at a user-defined position with high axial resolution at long working distances in the order of centimeters. From the above it is understood that preferably the optical element is configured to scatter light. More preferably the optical element is configured to anisotropically scatter or diffuse light. Likewise, optionally along at least one desired direction there is (i.e., the optical element has) a stripe-shaped variation (i.e. modulation) of the value of the refractive index of the optical element. When the modulation has a stripe shape that is aligned across at least one direction it may cause the formation of the aforementioned elongated speckle pattern.
Overall, the optical element which may act as a scattering medium, combined with the assembly's first and second polarization elements and the light modulation can be mounted altogether to create new state-of-the-art microscope objective. It is noted that the assembly's light modulator which can actively modulate the wavefront, may be a transmission or reflection mode light wave shaper. Hence, the light modulator may be or comprise a reflection or a transmission spatial light modulator.
In an exemplary embodiment the light modulator's configuration allows for advantageously making the assembly particularly compact and easily integratable within a microscope. In said exemplary embodiment, the light modulator comprises in order along an optical path: a beam splitter which is configured to direct about half of an intensity of the light towards a modulator screen which is reflective, the beam splitter being also configured to allow light being reflected by the modulator screen to pass through the beam splitter and reach a dovetail prism; the modulator screen which is connected to (or alternatively comprises) the electronic interface and is configured to operate on a reflection mode for reflecting the light and for actively modulating the wavefront of said light; the dovetail prism which is configured to direct towards a right-angle prism the light received from the modulator screen; the right-angle prism which is configured to receive the light received from the dovetail prism and direct said light to propagate towards the first polarization modulator. Optionally, said beam splitter is at the first side. An embodiment that is according to the aforementioned exemplary embodiment, further comprises a cup or support for mounting and fixing the modulator screen within the assembly. Optionally, the assembly may further comprise and imaging element, e.g. a lens, located between the first polarization element and the aforementioned right-angle prism, wherein said imaging element is configured to image the modulator screen onto the surface of the scattering medium. Therefore, said optional imaging element or imaging lens may be used (i.e. be configured to) to focus the modulated light (i.e. the light modulated by the modulator screen) onto an area close to the surface of the scattering medium.
The assembly of optical elements according to the invention, may be a microscope lens system. Advantageously a lens system according to the invention offers adaptable operational characteristics based on altering the properties of the incident light wave. Moreover, the optical assembly (device) according to the invention may act as an adaptive illumination modulator of a light source e.g. for modulating both the amplitude and the phase profile of a microscope's input beam. The device overall can provide for versatility of operations in conventional microscopes.
For facilitating the transport and robustness of the assembly, and for facilitating the integration or the attachment of the assembly in other systems such as existing microscopes, in a preferred embodiment the assembly further comprises a housing that encapsulates the light modulator and the first and second polarization elements and the optical element, and said housing has an access for accessing the electronic interface. Preferably, said optical housing is configured to lodge the light modulator and the first and second polarization elements and the optical element at respective positions along a symmetry axis of the housing, said symmetry axis preferably coinciding with a propagation axis of the light. More preferably the housing is elongated and comprises a proximal end at the first side of the assembly and a distal end which is opposite to the proximal end. For advantageously being able to screw the assembly on a microscope, further preferably the aforementioned optional housing is threaded at the proximal end and/or at the distal end. In the latter case the threaded part of the connector may act as a connector for connecting the assembly to a microscope. More generally, the assembly may comprise a connector for connecting the assembly to a microscope or other optical instrument or apparatus, said connector preferably being at the first side.
In an embodiment, the assembly's first polarization element is a first polarizer, and/or the second polarization element is a second polarizer. Any or both of said first and second polarizers may optionally be linear polarizer(s) and/or polarizing beam splitter(s).
In an embodiment, the assembly comprises adjustment means for rotating and/or displacing the assembly or any part thereof in relation to a propagation axis of the light. Being able to rotate and/or displace the assembly or parts thereof, for example rotating the polarization elements, allows for optical aligning and can advantageously permit adapting the assembly to an apparatus or particular optical source used in combination with the assembly
In preferred embodiments the optical element is removably attachable or insertable to/in the assembly, preferably as a removable cassette. This may advantageously allow using different optical elements with different optical properties (e.g. different scattering and/or transparency profiles) for different types of samples, microscopes, wavelengths or other working parameters (e.g. working distance). Likewise, having cassettes may prevent damaging the respective optical elements.
In some embodiments, a surface of the optical element comprises a pattern, e.g. the surface comprises recesses and/or protrusions forming a pattern, and at the same time, despite having said pattern surface, the optical element is substantially transparent to an optical frequency or a range of optical frequencies of the light passing through the assembly during the latter's operation, so that the brightness at the assembly's optical output is high for illuminating sufficiently a sample that is tested using the assembly. Preferably, the optical element, a material comprised by the optical element, or a material from which the optical element is made of is more that 80% or 90% transparent at said frequency or range of frequencies. The aforementioned optional pattern on a surface of the optical element may be the primary cause of the modulation of the wavefront by the optical element. However, there also contemplated similar embodiment where a pattern is embedded within the volume of the optical element.
In a particularly preferred embodiment of the invention, the optical element comprises or is made of a material which has a refractive index of more than 1.3; a surface of the optical element comprises a pattern etched or engraved on the surface; said surface is made of the material; the material is more than 80% transparent to an optical frequency or to a range of optical frequencies of the light passing through the assembly. Preferably, said frequency or range of optical frequencies is in the visible spectrum. Also preferably, the material is a polymer.
Considering that the value of the refractive index of the optical element affects how the optical element passively modulates the wavefront of the light, in some embodiments said value is adjusted to further optimize the wavefront modulation. Hence, in an embodiment the optical element has a refractive index of between 1.3 and 1.8. Preferably, the optical element is made of a plastic that has a refractive index of between 1.3 and 1.8. More generally, the optical element preferably comprises or is made of materials, such as crystals or polymers or glasses or ceramics or others, preferably having a refractive index in the 1.3-1.8 range. A non-limiting list of such materials from which the optical element may be made of is the following wherein within parenthesis the corresponding refracting index that each of said materials typically (but not always) have is also provided: N-BK7 (n=1.52), Fused silica (n=1.46), N-SF11 (n=1.79), CaF2 (n=1.43), MgF2 (n=1.41), BaF2 (n=1.47), ZnSe (n=2.7), ZnTe (n=3.1), Germanium (n=4.67). Hence, in some embodiments the optical element comprises (or is made of) any of: poly (methyl methacrylate), polyethylene terephthalate, Polycarbonate, Amorphous copolyesters, Fluorinated ethylene propylene, ABS thermoplastic, MABS thermoplastic, polymethylpentene, polyvinyl chloride, General Purpose Polystyrene, Styrene Methyl Methacrylate, fused silica amorphous silicon oxide, crystalline silicon oxide, sapphire, amorphous aluminum oxide, calcium fluoride, zinc selenide, zinc telluride, germanium, barium fluoride, magnesium fluoride, gallium phosphide, a crystalline or amorphous material (crystals, glasses, ceramics), or a combination thereof, or a material that offers transmission above 80% for the visible frequencies.
In an embodiment the assembly is a microscope lens system. In another embodiment the assembly is an objective lens. In another embodiment the assembly is an illumination lens.
In an embodiment the assembly further comprises an electronic controller which is connectable with the electronic interface and is configured to control the light modulator. The electronic controller may be a computer or be connected or be part of a computer. Also, the electronic computer may be connectable to the electronic interface via a wired or wireless connection.
The present invention in a further aspect concerns a microscope that comprises the assembly according to the invention. Said microscope preferably is any of a fluorescence microscope, a super-resolved microscopy system, a photoacoustic microscopy system, a light sheet fluorescence microscope or a structure illumination microscopy system. Further aspects of the invention concern other types of devices or systems comprising the herein disclosed assembly, said devices or systems being any of: an optical fiber driver, a device for use in a secure communications system, a device for use in an optical physical unclonable function system, a laser lithography beam modifier, a device for use in vehicle's headlight.
The invention in a further aspect concerns the use of the assembly of the first aspect in (for) microscopy, fluorescence microscopy, a super-resolved microscopy, photoacoustic microscopy, light sheet fluorescence microscopy or structure illumination microscopy. Moreover, the disclosed assembly may also be used in any of the following applications: driving an optical fiber, implementing a secure optical communication protocol, implementing an optical physical unclonable functions, oPUF, protocol for authentication, lithography, smart adaptive lighting, in a light, e.g. a headlight, of a vehicle.
The invention in a forth aspect concerns a method for controlling light, the method comprising the consecutive steps of: receiving a wavefront of light; actively modulating the wavefront of light, thereby transforming said light into an actively modulated light; determining a polarization of the actively modulated light, thereby transforming the latter into a polarized light; passively modulating the wavefront of the polarized light, thereby transforming the latter into a passively modulated light; determining the polarization of the passively modulated light, thereby transforming the latter into an adapted light. The method according to the invention can be implemented by using the assembly of the first aspect of the invention. Exemplary embodiments of the method according to the fourth aspect of the invention are related to application of the method in microscopy. Hence, for these exemplary embodiments, the method according to the fourth aspect of the invention can also be considered as being a method for adapting light for microscopy.
In an embodiment the adapted light is a light sheet. The adapted light may be considered as the optical output resulting from applying the method on the optical input which is the light received by the first polarization element.
An exemplary embodiment of the method for microscopy according to the invention is executed by means of a microscope which is according to the invention, the microscope further comprising a feedback sensor or camera that is configured to receive the adapted light, the microscope further comprising a computer which comprises a memory, wherein the computer is connected to the feedback sensor or camera and is also connected to and is configured to control via the electronic interface the light modulator of the assembly, the method for microscopy further comprising the additional steps of: loading on the memory or computing with the computer a set of current parameters which correspond to operational parameters of the assembly's light modulator; controlling the light modulator according to the current parameters; detecting with the feedback sensor or camera the wavefront of the adapted light, and transferring to the computer information which is related to the detected wavefront; with the computer using the information and determining whether the detected wavefront differs from a desired wavefront, and/or determining a difference or similarity between the detected wavefront and the desired wavefront, wherein said desired wavefront is loaded or stored on the memory or is computed with the computer; if the detected wavefront differs from the desired wavefront, and/or if the difference is more than a condition difference, then repeat the above additional steps wherein in the first one of the additional steps a new set of current parameters is being loaded on the memory or is being computed with the computer by means of an optimization algorithm, until the detected light's wavefront is substantially the same with the desired wavefront, or until the difference is equal to or less than the condition difference. The exemplary embodiment of the method allows for accurately compensating for the diffusion of light that may take place within a sample being examined with the microscope, and hence, allows for imaging with high resolution. Using the exemplary embodiment may be combined with operating the microscope as a conventional LFSM microscope, where the method further comprises with the microscope examining a sample and recording digital images of the fluorescence of the sample for different positions of the sample, and digitally processing the digital images for preferentially providing a volumetric representation of the sample's fluorescence. The sample may be brought to different positions by means of a motorized stage, e.g. an xy or xyz stage, of the microscope.
Considering the above, it is contemplated that a preferred embodiment of the method according to the invention, comprises adapting light according to the invention by means of a microscope which is also according to the invention, said microscope comprising a motorized stage which supports a sample that is illuminated with the adapted light received from the assembly's second polarization element, the microscope further comprising an imaging sensor or camera that is configured to acquire an optical readout by receiving light from the sample, the microscope further comprising a computer which comprises a memory, wherein the computer is connectable to the imaging sensor or camera and is also connected to and is configured to control via the electronic interface the light modulator of the assembly, the computer further being connectable to and configured to control the motorized stage, the method for microscopy further comprising the steps of: calculating, by means of the computer, a set of positions; controlling, by means of the computer, the motorized stage to move at or about said positions; with the feedback sensor or camera acquiring a corresponding optical measurement for each one of the set of positions at or about which the motorized stage moves; transferring to the computer information which is related to the optical measurements. Another embodiment is according to the previous preferred one, and further comprises: for each of said positions determining and setting with the computer (i.e. by means of the computer) corresponding operational parameters for the light modulator. Hence, the additional steps of the exemplary embodiment of the method according the invention as described further above, said additional steps being preferably executed using the microscope's computer, may be repeated by for each of the different positions of the sample. Preferably, the method further comprises placing the stage at a resting position after acquiring the optical measurements corresponding to the set of positions. Also preferably, the method further comprises with the computer analyzing or processing the information related to the optical readouts.
Considering that a significant number of the steps of various embodiments of the method according to the invention can be executed by means of a computer, a further aspect of the invention concerns a computer implemented method executed by means of a microscope which is according to the invention, the microscope further comprising a feedback sensor or camera that is configured to receive the adapted light, the microscope further comprising or being connected to a computer which comprises a memory, wherein the computer is connected to the feedback sensor or camera and is also connected to and is configured to control via the electronic interface the light modulator of the assembly, and the computer performing the steps of: loading on the memory or computing a set of current parameters which correspond to operational parameters of the assembly's light modulator; controlling the light modulator according to the current parameters; detecting with the feedback sensor or camera the wavefront of the adapted light, and transferring to the computer information which is related to the detected wavefront; using the information and determining whether the detected wavefront differs from a desired wavefront, and/or determining a difference or similarity between the detected wavefront and the desired wavefront, wherein said desired wavefront is loaded or stored on the memory or is computed with the computer; if the detected wavefront differs from the desired wavefront, and/or if the difference is more than a condition difference, then repeat the above additional steps wherein in the first one of the additional steps a new set of current parameters is being loaded on the memory or is being computed by means of an optimization algorithm, until the detected light's wavefront is substantially the same with the desired wavefront, or until the difference is equal to or less than the condition difference.
In an embodiment of said computer implemented method, the microscope further comprises a motorized stage which supports a sample illuminated with the adapted light received from the assembly's second polarization element, the microscope further comprising an imaging sensor or camera that is configured to acquire an optical readout by receiving light from the sample, wherein the computer is connected to the feedback sensor or camera and is also connected to and is configured to control via the electronic interface the light modulator of the assembly, the computer further being connected to and configured to control the motorized stage, the computer implemented method further comprising the steps of: calculating, by means of the computer, a set of positions; controlling, by means of the computer, the motorized stage to move at or about said positions; with the feedback sensor or camera acquiring a corresponding optical measurement for each one of the set of positions at or about which the motorized stage moves; transferring to the computer information which is related to the optical measurements.
In an embodiment the computer implemented method (CII) further comprises for each of said positions determining and setting with the computer corresponding operational parameters for the light modulator. This allows for compensating for the light diffusion by the sample for each of the different sample positions. Preferably, the CII further comprises placing the stage at a resting position after acquiring the optical measurements corresponding to the set of positions. Also, the CII preferably further comprises analyzing the information related to the optical readouts, by means of the computer.
It is noted that the computer which may be part of the microscope and be used for executing several of the aforementioned embodiments, may not necessarily be an integral part of the microscope, but rather be a separate computer or sets of computers which is/are connectable to the microscope. Said computer or sets of computers, may be local or at a remote location with respect to the microscope, and may for example be connected to the microscope via a network or the internet.
A further aspect of the invention concerns a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the computer implemented method according to the invention.
In a preferred embodiment, the manufacturing process for making the aforementioned scattering pattern of the optical element relies on controlled etching using a rough and stiff surface to engrave a material of the optical element. The type of the etching process can lead to different types of light scattering structures. For example, 1-D controlled etching creates a photonic structure with anisotropic modulation of the refractive index along one dimension. The resulted optical response will be an elongated speckle pattern. Using this media type can create different wavelength sub-micrometer light-sheet structures at a user-defined position with high axial resolution at long working distances (centimeters).
The scattering photonic structure (i.e. the scattering medium) may be formed on the optical element by random direction-controlled etching which generally creates a completely anisotropic structure that leads to a typical speckle pattern. Other manufacturing methods for the fabricating the scattering medium may be lithography, chemical etching, mechanical etching, 3d printing, machining, patterned (e.g. using a deposition mask) deposition (e.g. by print transfer, thermal evaporation, scattering etc.) or other.
As mentioned further above the optical element is preferably made or comprises one or more polymers which more preferably are selected from the following list: i) Poly (methyl methacrylate) (PMMA), also known as acrylic, acrylic glass, or plexiglass. PMMA transmits up to 92% of visible light (3 mm thickness), and gives a specular reflection of about 4% from each of its surfaces due to its refractive index mismatch (1.490); ii) Polyethylene terephthalate (sometimes written poly(ethylene terephthalate)), commonly abbreviated PET, PETE. Its refractive index is 1.575; iii) Polycarbonate (PC) which is a high-performance amorphous and transparent thermoplastic polymer that offers high impact strength, dimensional stability, good mechanical properties, etc. It can transmit over 90% light, and its refractive index is 1.585; iv) Amorphous copolyesters (PETG) combine excellent clarity and toughness with outstanding heat and chemical resistance. PETG transmits up to 92% of visible light, and its refractive index is 1.55; v) Fluorinated ethylene propylene (FEP) is chemically a copolymer of hexafluoropropylene and tetrafluoroethylene. This polymer transmits a high percentage of ultraviolet and visible light. The visible transmission of FEP is approximately 96%, and its refractive index is about 1.55; vi) Acrylonitrile butadiene styrene (ABS) is an impact-resistant thermoplastic composed of three monomers: acrylonitrile, butadiene, and styrene. The manufacturing process converts it into a highly transparent ABS resin called MABS (Methyl Methacrylate Acrylonitrile Butadiene Styrene). Its optical transmissivity is about 86% for the visible light, and its refractive index is about 1.52; vii) Polymethylpentene (PMP), is a thermoplastic polyolefin with high thermal stability, excellent dielectric characteristics, and a high chemical resistance. Its optical transmission value is more than 90%, and its refractive index 1.463; viii) Polyvinyl chloride (PVC) is one of the most widely produced synthetic plastic polymers. Its light transmissivity is more than 85%, and its refractive index is about 1.531; viiii) General Purpose Polystyrene (GPPS), also known as crystal-clear polystyrene. Its light transmissivity is more than 88%, and its refractive index is about 1.6; x) Styrene Methyl Methacrylate (SMMA) is a high clarity styrene-acrylic copolymer with a glossy surface. Its light transmissivity is more than 90%, and its refractive index is about 1.59.
A goniometer may be used for characterizing the light intensity distribution of the scattering medium (photonic structure) of the corresponding optical element of an embodiment of the assembly. The sample is mounted onto a base fixed on an arm that can be rotated freely. The arm in an example has a radius in the order of 15 cm. The length of the arm allows sufficient distance from the sample to capture intensity patterns in the far-field. The scattering sample is placed in the center of a goniometer and is then illuminated using a laser source of appropriate wavelength at a normal incidence angle. Angular measurements are recorded on the other side of the sample using an optical power meter mounted on the rotating arm. The rotating arm can be rotated by 180° around the illuminated sample. The laser is mounted behind the scattering medium, arranged so that the collimated beam is normally incident at the sample. The output angle is defined in relation to the original optical axis when the diffuser is not within the light path, while the signal is sampled every 1° and then plotted as normalized intensity versus output angle.
In one non-limiting example the resulting diffused pattern was distributed mostly in one dimension (horizontal). Using ten different scatterers made by 0.6 mm thick Poly (methyl methacrylate) (PMMA) and taking the mean value for the intensity distribution for each angle, the result is that 50% of maximum intensity is detected ±10° relative to the optical axis.
With reference to
Hence, it can be understood that
In
The embodiment shown in
Also as shown in
Hence, it can be understood that the embodiment shown in
In an embodiment the optical assembly, which may be also called wavelens system, is used for microscopy as shown in
An embodiment of the method according to the invention comprises the steps indicated in the flow diagram of
The method according to the invention may be performed by means of the assembly according to the invention where at step 1001 the input light reaches (i.e. is received by) the light modulator 1. Subsequently steps 1002, 1003, 1004 and 1005 successively occur respectively be means of the first polarization element 3, the optical element 4 and the second polarization element via which the light successively passes travelling though the assembly. The optical output, i.e. the adapted light after the application of step 1005, preferably has the form of a light sheet, and some of the possible ways of achieving this is by having an optical element which has a one-dimensional (1D) scattering pattern on it, and/or by controlling the shape of the optical input of the assembly.
In a preferred embodiment, the method is executed/performed by means of a microscope which comprises an assembly of optical elements according to the invention, and also comprises: a feedback sensor or camera that is configured to receive the adapted light; a motorized stage which supports a sample that is illuminated with the adapted light received from the assembly's second polarization element; an imaging sensor or camera that is configured to acquire an optical readout by receiving light from the sample. The microscope further comprises or is connected to a computer which comprises a memory, wherein the computer is communicatively connected to the feedback sensor or camera and to the imaging sensor or camera, and the computer is also connected to and is configured to control via the electronic interface the light modulator of the assembly. The computer is also communicatively connected and configured to control the motorized stage. As shown in
In step 1006 loading on the memory or computing with the computer a set of current parameters which correspond to operational parameters of the assembly's light modulator.
In step 1007 controlling the light modulator according to the current parameters.
In step 1008 detecting with the feedback sensor or camera the wavefront of the adapted light. In step 1009 receiving at (or transferring to) the computer information which is related to the detected wavefront.
In step 1010 with the computer (i.e. by means of the computer) using the information and determining whether the detected wavefront differs from a desired wavefront, and/or determining a difference or similarity between the detected wavefront and the desired wavefront, wherein said desired wavefront is loaded or stored on the memory or is computed with the computer. Hence, it can be considered that in step 1010 the detected wavefront is compared with the desired wavefront.
If the detected wavefront differs from the desired wavefront, and/or if the difference is more than a condition difference, then repeat the above additional steps wherein in step 1006 a new set of current parameters is being loaded on the memory or is being computed with the computer by means of an optimization algorithm applied in step 1011. When the detected light's wavefront is substantially the same with the desired wavefront, or when the difference is equal to or less than the condition difference, then a next step may be applied such as the step 1012.
In step 1012 with (by means of) the imaging sensor or camera acquiring an optical readout.
In step 1013 calculating, by means of the computer, a set of positions. This step may also be executed before any of the previous steps.
In step 1014 controlling, by means of the computer, the motorized stage to move at or about each one the positions of said set of positions.
For each of said positions at which the sample is moved, repeating the aforementioned steps 1006-1010, 1012 and where needed step 1011, this is to say performing the following:
In step 1016 processing, by means of the computer, the information related to the optical readouts.
Optionally in step 1017, placing the stage at a resting position after acquiring the optical measurements corresponding to the set of positions.
The set of steps 1006-1017 of the aforementioned embodiment, or any subset of set steps can constitute a corresponding embodiment of the computer implement method according to the invention. An embodiment of the computer implemented method according to the invention, may be executed by means of a software which comprises instructions for executing any or all of the aforementioned steps.
Those skilled in the art will understand that the embodiments disclosed here are non-limitative examples, and other embodiments are possible within the scope or the claims, for example but not limited to, different sequences of the method steps or different combinations of technical features.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22164624.3 | Mar 2022 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/086594 | 12/19/2022 | WO |
