Optical system for optical inspection of test sample

Abstract

An optical system includes a front optical film and a rear reflector defining a light recirculation optical cavity therebetween. The light recycling optical cavity is configured to receive a test sample. The optical system includes a light source disposed on a front optical film side of the light recirculation optical cavity and configured to emit first and second light having respective intensities I1b and I1g and respective first and second wavelengths toward the light recirculation optical cavity, when a test sample is disposed in the light recirculation optical cavity and the emitted first and second light are at least partially absorbed by the test sample while being recirculated in the light recirculation optical cavity, the test sample is recirculated in the light recirculation optical cavity. At least a portion of the recirculated emitted first and second light exits the light recirculation optical cavity through the front optical film as respective exit first and exit second light, the respective exit first and exit second light having respective light intensities I2b and I2g. I2g / I1g is at least 10% greater than I2b / I1b.

Description

Technical Field

[0001] This specification generally relates to optical systems that can be used to optically inspect test samples. Background Art

[0002] An optical cavity may be defined between the spaced-apart reflectors. Summary of the Invention

[0003] In some aspects, the present disclosure provides an optical system for optical inspection of a test sample having a first optical absorption that is relatively high at a first wavelength and a second optical absorption that is relatively low at a second wavelength. The optical system includes a front optical film and a back reflector defining a light recycling optical cavity therebetween. The light recycling optical cavity is configured to receive the test sample such that, for substantially normally incident light, for at least one polarization state, and for at least one wavelength within a wavelength range extending from about 250 nm to about 1500 nm, the front optical film transmits at least 20% of the incident light and reflects at least 20% of the incident light, and the back reflector reflects at least 60% of the incident light. The optical system includes a light source disposed on a front optical film side of a light recycling optical cavity and configured to emit first and second lights having respective intensities I1b and I1g and respective first and second wavelengths toward the light recycling optical cavity, such that when a test sample is disposed in the light recycling optical cavity and the emitted first and second lights are at least partially absorbed by the test sample while being recycled in the light recycling optical cavity, at least portions of the recycled emitted first and second lights exit the light recycling optical cavity through the front optical film as respective exiting first and second lights, the respective exiting first and second lights having respective light intensities I2b and I2g and respective first and second wavelengths. I2g / I1g may be at least 10% greater than I2b / I1b.

[0004] In some aspects, the present disclosure provides an optical system comprising a front optical film and a back reflector defining a light recycling optical cavity therebetween. The light recycling optical cavity is configured to receive a test sample configured to convert at least a portion of incident first light having a first wavelength and intensity I1b into converted second light having at least a second wavelength different from the first wavelength and an intensity I1g. The front optical film includes a plurality of layers counting at least 4 in total, wherein each of the layers has an average thickness of less than about 500 nm, such that for substantially normally incident light and for at least one polarization state: for a first wavelength, the front optical film reflects at least 50% of the incident light for a first angle of incidence less than about 20 degrees and transmits at least 50% of the incident light for a second angle of incidence greater than about 30 degrees; for a second wavelength and each of the first and second angles of incidence, the front optical film transmits at least 50% of the incident light; and for each of the first and second wavelengths and each of the first and second angles of incidence, the back reflector reflects at least 60% of the incident light. The optical system includes a light source disposed on the front optical film side of the light recycling optical cavity and configured to emit emitted first light having a first wavelength and an intensity I1b toward the light recycling optical cavity. When a test sample is disposed in the light recycling optical cavity and the emitted first light is at least partially absorbed by the test sample while being recycled in the light recycling optical cavity, at least a portion of the recycled emitted first light is converted by the test sample into recycled second light, which exits the light recycling optical cavity through the front optical film as outgoing second light having a second wavelength and light intensity I2g. I2g may be at least 10% greater than I1g.

[0005] In some aspects, the present specification provides an optical system comprising a front optical film and a back reflector defining a light recycling optical cavity therebetween; and a biological test sample disposed in the light recycling optical cavity and having a first optical absorption that is higher at a first wavelength and a second optical absorption that is lower at a second wavelength. For substantially normally incident light, for at least one polarization state, and for at least one wavelength within a wavelength range extending from about 250 nm to about 1500 nm, the front optical film transmits at least 20% of the incident light and reflects at least 20% of the incident light, and the back reflector reflects at least 60% of the incident light, such that when a light source is disposed on the front optical film side of the light recycling optical cavity and emits first light and second light having respective intensities I1b and I1g and respective first and second wavelengths toward the light recycling optical cavity, wherein I1b and I1g differ by within 10% of each other, the emitted first light and second light are at least partially absorbed by the biological test sample while being recycled in the light recycling optical cavity, and at least a portion of the recycled emitted first light and second light exits the light recycling optical cavity through the front optical film as respective exiting first light and exiting second light, the respective exiting first light and the respective exiting second light having respective light intensities I2b and I2g and respective first and second wavelengths. I2g / I1g may be at least 10% greater than I2b / I1b.

[0006] In some aspects, the present specification provides an optical system comprising a front optical film and a back reflector defining a light recycling optical cavity therebetween; and a biological test sample disposed in the light recycling optical cavity. The biological test sample is configured to convert at least a portion of incident first light having a first wavelength and intensity I1b into converted second light having at least a second wavelength different from the first wavelength and an intensity I1g. Each of the first wavelength and the second wavelength is within a wavelength range extending from approximately 250 nm to approximately 1500 nm. The front optical film includes a plurality of layers, counted in total as at least 4, wherein each of the layers may have an average thickness of less than about 500 nm, such that for substantially normally incident light and for at least one polarization state: for a first wavelength, the front optical film reflects at least 50% of the incident light for a first incident angle less than about 20 degrees, and transmits at least 50% of the incident light for a second incident angle greater than about 30 degrees; for a second wavelength and each of the first and second incident angles, the front optical film transmits at least 50% of the incident light; and for each of the first and second wavelengths and each of the first and second incident angles, the back reflector reflects at least 60% of the incident light. When a light source is disposed on the front optical film side of the light recycling optical cavity and emits emitted first light having a first wavelength and intensity I1b toward the light recycling optical cavity such that the emitted first light is incident on the front optical film at a second angle of incidence, the emitted first light is at least partially absorbed by the biological test sample while being recycled in the light recycling optical cavity, and at least a portion of the recycled emitted first light is converted by the biological test sample into recycled second light, which exits the light recycling optical cavity through the front optical film as exiting second light having a second wavelength and light intensity I2g. I2g may be at least 10% greater than I1g.

[0007] These and other aspects will become apparent from the detailed description that follows.This brief summary, however, should not be construed in any way as limiting the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figures 1 to 2 is a schematic cross-sectional view of an optical system according to some embodiments.

[0009] Figure 3 is a schematic cross-sectional view of a mobile device according to some embodiments.

[0010] Figures 4A to 4C are schematic cross-sectional views of light substantially normally incident on a back reflector, a front optical film, and a test sample, respectively, according to some embodiments.

[0011] Figure 5is a schematic graph of optical absorption versus wavelength for test samples according to some embodiments.

[0012] Figure 6 is a schematic cross-sectional view of an optical film according to some embodiments.

[0013] Figure 7 is a graph of transmittance and reflectance versus wavelength for exemplary optical films according to some embodiments.

[0014] Figure 8 is a graph of normalized output power versus wavelength for various optical systems according to some embodiments. DETAILED DESCRIPTION

[0015] In the following description, reference is made to the accompanying drawings, which form a part of this disclosure and in which various embodiments are shown by way of illustration. The drawings are not necessarily drawn to scale. It should be understood that other embodiments may be envisioned and implemented without departing from the scope or spirit of this description. Therefore, the following detailed description should not be construed in a limiting sense.

[0016] Diagnostic enhancement systems have previously utilized bottom-illuminated, top-reading architectures and typically involve backlights or light guides to introduce light into the system. According to some embodiments of the present specification, an optical system utilizing a top-illuminated, top-reading architecture is provided that can avoid the use of a backlight and can provide a simpler diagnostic system than conventional systems. The optical system may include an optical cavity defined between a front optical film and a rear reflector. The front optical film may be a transflector through which light may be injected to optically inspect a test sample disposed in the optical cavity. For example, light exiting the front optical film from the optical cavity may be detected to determine the presence of a material in the test sample. For example, the test sample may be a biological test sample, such as an enzyme-linked immunosorbent assay (ELISA) test sample. The front optical film may be, for example, a metallic transflector or a polymeric multilayer optical film. For a first wavelength, the multilayer optical film may be substantially reflective for a smaller first angle of incidence and substantially transmissive for a larger second angle of incidence. The optical system may include a light source configured to inject light having a first wavelength into the optical cavity at a second incident angle, and a light detector configured to detect light having a second wavelength different from the first wavelength and exiting the optical cavity along a direction defined by the first incident angle.

[0017] Figures 1 to 2Schematic cross-sectional views of optical systems 300 and 310, respectively, according to some embodiments. The optical systems 300, 310 can be configured for optical inspection of a test sample 10. The optical systems 300, 310 include a front optical film 20 and a back reflector 30, with a light recycling optical cavity 40 defined therebetween. The light recycling optical cavity 40 is configured to receive the test sample 10. The optical systems 300, 310 can include a light source 50 and / or at least one detector 70b, 70c. The electro-optical device, which can be a mobile device such as a cellular phone, can include the light source 50 and / or the at least one detector 70b, 70c. Figure 3 is a schematic cross-sectional view of a mobile device 56 according to some embodiments. The mobile device 56 includes a lamp 53 that can correspond to the light source 50 and a camera 54 that can correspond to at least one detector 70b, 70c. For example, the mobile device 56 can be or include a cellular phone. The test sample 10 can be a biological test sample. The biological test sample can be or include, for example, an enzyme-linked immunosorbent assay (ELISA) test sample. The front optical film 20, the back reflector 30, and the (e.g., biological) test sample 10 can define an optical system (e.g., a subsystem of the optical systems 300, 310) and / or an optical stack.

[0018] The optical systems 300, 310 may include a light source 50 disposed on a front optical film side of the light recycling optical cavity and configured to emit first light 50b and second light 50g having respective intensities I1b and I1g and respective first and second wavelengths Lb and Lg toward the light recycling optical cavity (see, e.g., Figure 1), such that when the test sample 10 is disposed in the light recycling optical cavity 40 and the emitted first and second lights are at least partially absorbed by the test sample 10 while being recycled in the light recycling optical cavity 40 (recycled light 51b, 51g), at least a portion of the recycled emitted first and second lights exit the light recycling optical cavity through the front optical film 20 as respective outgoing first and second lights 52b and 52g, respectively, having respective light intensities I2b and I2g and respective first and second wavelengths, wherein I2g / I1g may be at least 10%, 15%, 20%, 25%, or 30% greater than I2b / I1b. For example, I2b / I1b can be reduced by the test sample 10 absorbing light having the first wavelength Lb. In some embodiments, the light source 50 is configured to emit substantially collimated light (e.g., having a divergence / convergence angle of less than 30 degrees, 20 degrees, or 10 degrees) for at least each of the first wavelength and the second wavelength toward the light recycling optical cavity. In some embodiments, I1b and I1g are within about 50%, 40%, 30%, 20%, 10%, or 5% of each other. In some embodiments, the light source 50 comprises a lamp 53 of a mobile device 56 (e.g., see FIG. Figure 3 ).

[0019] For example, the first wavelength and the second wavelength can differ by at least about 10 nm, 20 nm, or 30 nm. In some embodiments, the first wavelength Lb is, for example, in the range of about 250 nm to about 600 nm, or about 300 nm to about 500 nm. In some embodiments, the first wavelength Lb is, for example, a blue wavelength in the range of about 400 nm to about 480 nm or about 420 nm to about 460 nm. In some embodiments, the second wavelength Lg is, for example, a green wavelength in the range of about 500 nm to about 600 nm or about 520 nm to about 580 nm.

[0020] For example, when it is desired that the test sample being tested convert at least a portion of the received light into emitted light having a different wavelength, the light source 50 may alternatively be configured to emit light 50b instead of light 50g. In some embodiments, the light source 50 is disposed on the front optical film side of the optical cavity 40 and is configured to emit the emitted first light 50b having a first wavelength Lb and an intensity I1b toward the optical cavity 40. In some embodiments, the test sample 10 is configured to convert at least a portion of the incident first light 63 having the first wavelength Lb and the intensity I1b into converted second light 64 having at least a second wavelength Lg and an intensity I1g different from the first wavelength (see, for example, FIG. 1 ). Figure 4CIn some embodiments, when the test sample is disposed in a light recycling optical cavity and the emitted first light is at least partially absorbed by the test sample 10 while being recycled in the light recycling optical cavity 40 (recycled light 51 b), at least a portion of the recycled emitted first light is converted by the test sample 10 into recycled second light 51 g, which exits the light recycling optical cavity through the front optical film 20 as outgoing second light 52 g having a second wavelength and light intensity I2 g (see, e.g., FIG. 2 ). Figure 2 ). I2g may be at least 10%, 15%, 20%, 25%, or 30% greater than I1g. For example, due to constructive interference of light reflected from the front optical film 20 and the back reflector 30 in the optical cavity, the intensity of light having the second wavelength in the optical cavity may be enhanced, and this may cause I2g to increase compared to I1g.

[0021] In some embodiments, the optical system 300, 310 includes a sensor 70c configured to detect the outgoing second light 52g and / or includes a sensor 70b configured to detect the outgoing first light 52b. In some embodiments, the outgoing first light 52b and the outgoing second light 52g are detected by at least one sensor 70a, 70b, 70c (see, e.g., Figure 1 ) detection. In some embodiments, at least one sensor includes a viewer's eye 70a (e.g., see Figures 1 to 2 ). For example, the optical systems 300, 310 can be configured so that the outgoing first light 52b and the outgoing second light 52g can be detected by inspection without the need for an electronic detector. In some embodiments, at least one sensor includes at least one electronic detector 70b, 70c. In some embodiments, the optical systems 300, 310 include at least one electronic detector 70b, 70c. In some embodiments, the at least one electronic detector includes a first electronic detector 70b and a second electronic detector 70c configured to detect the corresponding outgoing first light 52b and the outgoing second light 52g. Available light sources and detectors include those described in, for example, U.S. Patent Application Publication Nos. 2015 / 0131948 (Selli et al.), 2014 / 0211822 (Fattal et al.), and 2005 / 0019973 (Chua). In some embodiments, the at least one electron detector 70b, 70c comprises a photodiode or photodiode array, a charge coupled device (CCD), a charge injection device (CID), a photodiode, an organic photodiode, a complementary metal oxide semiconductor (CMOS), and a thin film transistor (TFT). In some embodiments, the at least one electron detector 70b, 70c comprises a camera 54 of a mobile device 56 (e.g., see Figure 3 ).

[0022] In some embodiments, detector 70c is configured to detect light exiting optical cavity 40 at an angle θ1 of less than about 20 degrees, 15 degrees, 10 degrees, or 5 degrees from a normal to optical film 20. In some embodiments, light source 50 is configured such that incident light 50b and / or 50g defines an angle of incidence θ2 of greater than about 30 degrees, 35 degrees, 40 degrees, or 45 degrees. In some embodiments, detector 70b is configured to detect light exiting optical cavity 40 at an angle θ2 from a normal to optical film 20.

[0023] Figures 4A to 4C 61, 60, and 63 are schematic cross-sectional views of light 61, 60, and 63 incident substantially normally (e.g., within 30 degrees, 20 degrees, 10 degrees, or 5 degrees of the normal) on the back reflector 30, the front optical film 20, and the test sample 10, respectively, according to some embodiments. The front optical film 20, the back reflector 30, and / or the test sample 10 can have the optical properties described elsewhere herein (e.g., transmittance and / or reflectance and / or absorbance for substantially normally incident light 61, 60, 63).

[0024] Figure 5 6 is a schematic graph of optical absorption versus wavelength of a test sample 10 according to some embodiments. Optical absorption may be for substantially vertical incident light 63. In some embodiments, the optical systems 300, 310 are configured to optically inspect a test sample 10 having different optical absorptions at different wavelengths. In some embodiments, the test sample 10 has a higher first light absorption Ab at a first wavelength Lb and a lower second light absorption Ag at a second wavelength Lg. In some embodiments, for example, Ab / Ag is greater than about 1.5, 2, 3, 5, 7, or 10. Optical absorption may have a peak at a blue wavelength (e.g., Lb and / or about 450 nm). In some embodiments, the test sample 10 includes one or more of a fluorophore, a fluorescent dye, and quantum dots. In some embodiments, the test sample 10 is a biological test sample including a chromogenic substrate such as 3,3',5,5'-tetramethylbenzidine (TMB).

[0025] The front optical film 20 can be partially reflective and partially transmissive for at least one wavelength. In some embodiments, the front optical film 20 is or includes a metal. For example, the front optical film 20 can be a metal transflector (e.g., a half-silvered mirror). In some embodiments, the front optical film 20 is or includes a multilayer (e.g., polymer) optical film. For example, the multilayer optical film can have a reflection band that shifts with the angle of incidence such that the wavelength Lb is substantially reflected at substantially normal incidence, but not reflected at an angle of incidence of about 45 degrees (see, e.g., FIG. 1 ). Figure 7). In some embodiments, the back reflector 30 comprises a metal. For example, the back reflector 30 can be a metal reflector. In some embodiments, the back reflector 30 is or comprises a multilayer (e.g., polymer) optical film. The back reflector may comprise a broadband mirror film, such as those available from 3M under the trade name ESR. Suitable metals for the front optical film 20 and / or the back reflector 30 include silver, aluminum, steel, or other suitable reflective metals or metal alloys. The metal used for the front optical film 20 can be suitably thin to give the desired transmittance. The metal used for the back reflector can be suitably thick to give the desired reflectivity.

[0026] Figure 6 is a schematic cross-sectional view of a multilayer optical film 125 according to some embodiments. As is known in the art, multilayer optical films comprising alternating polymer layers can be used to provide desired reflection and transmission over a desired wavelength range by appropriately selecting layer thicknesses and refractive index differences. Multilayer optical films and methods of making multilayer optical films are described, for example, in U.S. Patent No. 5,882,774 (Jonza et al.); U.S. Patent No. 6,783,349 (Neavin et al.); U.S. Patent No. 6,949,212 (Merrill et al.); U.S. Patent No. 6,967,778 (Wheatley et al.); and U.S. Patent No. 9,162,406 (Neavin et al.). The multilayer optical film 125 may correspond to the front optical film 20 and / or the back reflector 30. In some embodiments, the front optical film 20 and / or the back reflector 30 include a plurality of layers 21, 22 counting a total of at least 4 layers, wherein each layer has an average thickness of less than about 500 nm. For example, the plurality of layers 21, 22 may be counted in total to be at least 10, 25, 50, or 100. For example, the plurality of layers 21, 22 may be counted up to 1500, 1200, 1000, 800, 600, or 400. Each of the layers 21, 22 may have an average thickness of less than about 450 nm, 400 nm, 350 nm, 300 nm, 250 nm, or 200 nm. The average thickness of each of the layers 21, 22 may be, for example, at least about 10 nm, 25 nm, or 50 nm. In some embodiments, the front optical film 20 includes a plurality of layers 21, 22, and the back reflector 30 includes a plurality of second layers 21, 22. The front optical film 20 and / or the back reflector 30 may further include at least one surface layer 23, 24 having an average thickness greater than about 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1500 nm, or 2000 nm. The surface layer may have an average thickness of, for example, up to about 20 microns, 15 microns, or 10 microns.

[0027] Figure 7is a graph of transmittance (T) and reflectance (R) versus wavelength for normal incidence (θ=0 degrees) and 45 degree angle of incidence (θ=45 degrees) of an exemplary optical film according to some embodiments. Figure 7 The optical film of the spectrum can be a multilayer optical film and can correspond to the front optical film 20. As will be understood by those skilled in the art, the multilayer optical film can include alternating first and second layers having optical properties selected to produce Figure 7 The thickness distribution of the reflection bands is shown. The first and second layers can comprise, for example, polyethylene terephthalate (PET) and copolymethyl methacrylate (coPMMA), respectively, or other polymers described in the multilayer optical film references provided elsewhere herein.

[0028] In some embodiments, for substantially vertically incident light 60, 61, for at least one polarization state (e.g., polarization along the x-axis or y-axis, see e.g., Figure 6 ), and for at least one wavelength 62 within a wavelength range extending from about 250 nm to about 1500 nm, the front optical film 20 transmits at least 20% of the incident light and reflects at least 20% of the incident light, and the back reflector reflects at least 60%, or 70%, or 80%, or 90%, or 95% of the incident light. The front optical film 20 may transmit at least 25%, 30%, 35%, 40%, 45%, or 50% of the incident light. The front optical film 20 may reflect at least 25%, 30%, 35%, 40%, 45%, or 50% of the incident light. For example, the front optical film 20 may transmit at least 30% of the incident light and reflect at least 30% of the incident light, or may transmit at least 40% of the incident light and reflect at least 40% of the incident light. At least one polarization state can include orthogonal first and second polarization states (e.g., a mirror or partial mirror), or can include a single polarization state (e.g., a reflective polarizer). At least one at least one wavelength 62 can be, for example, at least about 250 nm, 300 nm, or 350 nm. At least one at least one wavelength 62 can be, for example, up to about 1500 nm, 1200 nm, 1000 nm, 800 nm, or 600 nm.

[0029] In some embodiments, for substantially normally incident light 60, 61 and for at least one polarization state: for a first wavelength Lb, the front optical film 20 reflects [Rb(θ1), which may be about 100% - Tb(θ1)] at least 50% for a first incident angle of less than about 20 degrees (e.g., corresponding to Figures 1 to 2 1) and transmits [Tb(θ2)] at least 50% of a second incident angle greater than about 30 degrees (e.g., corresponding to Figures 1 to 22); and for each of the first and second angles of incidence, Lg, and the second wavelength, Lg, the front optical film transmits [Tg(θ1), Tg(θ2)] at least 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, or 85%, or 90% of the incident light. The first angle of incidence may be less than about 5 degrees, 10 degrees, or 5 degrees. The second angle of incidence may be greater than about 35 degrees, 40 degrees, or 45 degrees. In some embodiments, for substantially vertically incident light, for at least one polarization state, and for the first wavelength, Lb, the front optical film 20 reflects at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% of the incident light at the first angle of incidence. In some embodiments, for substantially normal incident light, for at least one polarization state, and for the first wavelength Lb, the front optical film 20 transmits at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% of the incident light at the second angle of incidence. In some embodiments, for substantially normal incident light, for at least one polarization state, and for each of the first and second wavelengths Lg and the first and second angles of incidence, the front optical film transmits at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% of the incident light. In some embodiments, for substantially normal incident light 60, 61, for at least one polarization state, and for each of the first and second wavelengths and each of the first and second angles of incidence, the back reflector reflects at least 60%, 70%, 80%, 90%, or 95% of the incident light.

[0030] Example

[0031] For example Figures 1 to 2 The system generally shown in FIG is modeled. Model setup A utilizes a non-absorbing transflector as the front optical film 20 that is 50% reflective and 50% transmissive. Setup B uses an absorptive transflector with 50% reflection, 20% absorption, and 30% transmission. Setups C and D utilize a non-absorbing transflector with Figure 7 A multilayer optical film (MOF) with a spectrum of 100 nm is used as the front optical film. In settings AC, light is incident perpendicularly on the front optical film 20. In setting D, light is incident on the MOF at an angle of incidence of approximately 45 degrees. In each setting, the outgoing light (e.g., by the light source) is detected in a direction substantially perpendicular to the front optical film 20. Figure 1Detector 70c shown). In each case, the back reflector 30 is modeled as a Lambertian reflector with 100% reflectivity. The test sample is modeled as 3,3',5,5'-tetramethylbenzidine (TMB), which has an absorption peak at a wavelength of about 450nm. The spectrum of the detected light is normalized by averaging the spectrum between 580nm and 780nm and normalizing it to one. This wavelength range is selected because the absorption of TMB is low here, so that the light detected in this range represents a background signal. Any deviation from this signal from 400nm to 500nm represents absorption from the test sample. Deviations below 400nm are due to lower inputs from the source and from absorption.

[0032] Figure 8 Figure 2 shows a plot of normalized output power versus wavelength for various modeled systems. Setup A shows a 15% drop in signal at 450 nm, where TMB has its absorption peak, while Setup B shows a 7% drop at 450 nm. For Setup C, where light is incident perpendicularly on the MOF, an increase in power is seen between 420 nm and 450 nm, which is expected behavior, as the MOF is designed to reflect perpendicularly incident light in this band. For Setup D, where light is incident obliquely on the MOF, an approximately 40% drop in signal is observed at 450 nm, demonstrating that Setup D provides an effective recycling cavity for detecting the absorbing material of Test Sample 10.

[0033] Terms such as "about" will be understood by one of ordinary skill in the art in the context of their use and description in this specification. If it is not clear to one of ordinary skill in the art in the context of their use and description in this specification that "about" should be used to express quantities of feature sizes, quantities, and physical properties, then "about" will be understood to mean within 10% of the specified value. A quantity given as about a specified value may be exactly the specified value. For example, if it is not clear to one of ordinary skill in the art in the context of their use and description in this specification, a quantity having a value of about 1 means that the quantity has a value between 0.9 and 1.1, and that the value may be 1.

[0034] Those of ordinary skill in the art will understand terms such as "substantially" in the context of use and description in this specification. If the use of "substantially" with respect to a property or characteristic in the context of use and description in this specification is not clear to those of ordinary skill in the art, and when the opposite meaning of the property or characteristic is clear to those of ordinary skill in the art, the term "substantially" will be understood to mean that the property or characteristic is exhibited to a greater extent than the opposite meaning of the property or characteristic.

[0035] All references, patents, and patent applications cited above are hereby incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or conflicts between an incorporated reference portion and this application, the information in the foregoing description shall prevail.

[0036] Unless otherwise indicated, descriptions of elements in the accompanying drawings should be understood to apply equally to corresponding elements in other drawings. Although specific embodiments have been illustrated and described herein, those skilled in the art will appreciate that a variety of alternative and / or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any modifications, variations, or combinations of the specific embodiments discussed herein. Therefore, the present disclosure is intended to be limited only by the claims and their equivalents.

Claims

1. An optical system for optical inspection of a test sample having a first optical absorption that is relatively high at a first wavelength and a second optical absorption that is relatively low at a second wavelength, the optical system comprising: a front optical film and a back reflector defining a light recycling optical cavity therebetween, the front optical film and the back reflector being configured to receive the test sample such that, for substantially normally incident light, for at least one polarization state, and for at least one wavelength within a wavelength range extending from about 250 nm to about 1500 nm, the front optical film transmits at least 20% of the incident light and reflects at least 20% of the incident light, and the back reflector reflects at least 60% of the incident light; and a light source disposed on a front optical film side of the light recycling optical cavity and configured to emit first light and second light having respective intensities I1b and I1g and respective first wavelengths and second wavelengths toward the light recycling optical cavity, such that when the test sample is disposed in the light recycling optical cavity and the emitted first light and second light are at least partially absorbed by the test sample while being recycled in the light recycling optical cavity, at least portions of the recycled emitted first light and second light exit the light recycling optical cavity through the front optical film as respective exiting first light and exiting second light, the respective exiting first light and the respective exiting second light having respective light intensities I2b and I2g and respective first wavelengths and second wavelengths, I2g / I1g being at least 10% greater than I2b / I1b.

2. The optical system of claim 1, wherein the front optical film comprises metal.

3. The optical system of claim 1 , wherein the front optical film comprises a plurality of layers counting at least 4 in total, each of the layers having an average thickness of less than about 500 nm, such that for substantially normally incident light and for at least one polarization state: For the first wavelength, the front optical film reflects at least 50% of the incident light for a first incident angle less than about 20 degrees and transmits at least 50% of the incident light for a second incident angle greater than about 30 degrees; and For the second wavelength and each of the first and second angles of incidence, the front optical film transmits at least 50% of the incident light.

4. The optical system of claim 3, wherein the light source is configured to emit substantially collimated light for at least each of the first wavelength and the second wavelength toward the light recycling optical cavity. The optical system of claim 1 , wherein the light source comprises a light of a mobile device. The optical system according to claim 1 , wherein the outgoing first light and the outgoing second light are detected by at least one sensor.

7. The optical system of claim 6, wherein the at least one sensor comprises at least one electronic detector.

8. The optical system of claim 7, wherein the at least one electron detector comprises a first electron detector and a second electron detector configured to detect the respective outgoing first light and the outgoing second light.

9. The optical system of claim 7, wherein the at least one electronic detector comprises a camera of a mobile device.

10. An optical system, comprising: a front optical film and a back reflector defining a light recycling optical cavity therebetween, the light recycling optical cavity being configured to receive a test sample, the test sample being configured to convert at least a portion of incident first light having a first wavelength and intensity I1b into converted second light having at least a second wavelength different from the first wavelength and intensity I1g, the front optical film comprising a plurality of layers counting at least 4 in total, each of the layers having an average thickness of less than about 500 nm, such that for substantially normally incident light and for at least one polarization state: For the first wavelength, the front optical film reflects at least 50% of the incident light for a first incident angle less than about 20 degrees and transmits at least 50% of the incident light for a second incident angle greater than about 30 degrees; for the second wavelength and each of the first and second angles of incidence, the front optical film transmits at least 50% of the incident light; and for each of the first wavelength and the second wavelength and each of the first angle of incidence and the second angle of incidence, the back reflector reflects at least 60% of the incident light; and a light source disposed on a front optical film side of the light recycling optical cavity and configured to emit emitted first light having the first wavelength and the intensity I1b toward the light recycling optical cavity, wherein when the test sample is disposed in the light recycling optical cavity and the emitted first light is at least partially absorbed by the test sample while being recycled in the light recycling optical cavity, at least a portion of the recycled emitted first light is converted by the test sample into recycled second light, and the recycled second light exits the light recycling optical cavity through the front optical film as outgoing second light having the second wavelength and light intensity I2g, where I2g is at least 10% greater than I1g. The optical system of claim 10 , wherein the back reflector comprises metal.

12. The optical system of claim 10, wherein the back reflector comprises a plurality of second layers counting a total of at least 4, each of the second layers having an average thickness of less than about 500 nm. 13 . The optical system according to claim 10 , further comprising a sensor configured to detect the outgoing second light.

14. An optical system, comprising: a front optical film and a back reflector, wherein a light recycling optical cavity is defined between the front optical film and the back reflector; and a biological test sample disposed in the light recycling optical cavity and having a first optical absorption that is higher at a first wavelength and a second optical absorption that is lower at a second wavelength, wherein for substantially normally incident light, for at least one polarization state, and for at least one wavelength within a wavelength range extending from about 250 nm to about 1500 nm, the front optical film transmits at least 20% of the incident light and reflects at least 20% of the incident light, and the back reflector reflects at least 60% of the incident light, such that when a light source is disposed on the front optical film side of the light recycling optical cavity and emits first light and second light having respective intensities I1b and I1g and respective first and second wavelengths toward the light recycling optical cavity, I 1b and I1g are within 10% of each other, the emitted first light and the second light are at least partially absorbed by the biological test sample while being recycled in the light recycling optical cavity, at least a portion of the recycled emitted first light and the second light exit the light recycling optical cavity through the front optical film as corresponding exiting first light and exiting second light, the corresponding exiting first light and the exiting second light having corresponding light intensities I2b and I2g and corresponding first wavelengths and second wavelengths, I2g / I1g being at least 10% greater than I2b / I1b.

15. An optical system, comprising: a front optical film and a back reflector, wherein a light recycling optical cavity is defined between the front optical film and the back reflector; and a biological test sample disposed in the light recycling optical cavity, the biological test sample configured to convert at least a portion of incident first light having a first wavelength and intensity I1b into converted second light having at least a second wavelength different from the first wavelength and an intensity I1g, each of the first wavelength and the second wavelength being within a wavelength range extending from about 250 nm to about 1500 nm, the front optical film comprising a plurality of layers counting a total of at least 4 layers, each of the layers having an average thickness of less than about 500 nm, such that for substantially normally incident light and for at least one polarization state: For the first wavelength, the front optical film reflects at least 50% of the incident light for a first incident angle less than about 20 degrees and transmits at least 50% of the incident light for a second incident angle greater than about 30 degrees; for the second wavelength and each of the first and second angles of incidence, the front optical film transmits at least 50% of the incident light; and for each of the first wavelength and the second wavelength and each of the first angle of incidence and the second angle of incidence, the back reflector reflects at least 60% of the incident light, wherein, when a light source is disposed on the front optical film side of the light recycling optical cavity and emits emitted first light having the first wavelength and the intensity I1b toward the light recycling optical cavity so that the emitted first light is incident on the front optical film at the second incident angle, the emitted first light is at least partially absorbed by the biological test sample while being recycled in the light recycling optical cavity, and at least a portion of the recycled emitted first light is converted by the biological test sample into recycled second light, and the recycled second light exits the light recycling optical cavity through the front optical film as outgoing second light having the second wavelength and light intensity I2g, I2g being at least 10% greater than I1g.

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