Wave front sensor using polarization imaging

Abstract

Methods, devices and systems are described enable the detection of an unknown wave front by measurement of the polarization properties of the wave front. One example method for measuring a wave front of an optical beam includes receiving the optical beam at a plate, where the plate is configured to modify polarization of the optical beam to allow light with particular polarization characteristics to traverse therethrough in a direction of an object. The method further includes receiving the light with the particular polarization characteristics at the object, where the object has known polarization parameters. A polarization sensitive detector is used to measure light after reflection from, or transmission though, the object, and the propagation vector of the wave front is determined based on at least partial or full Stokes parameters obtained from measurements of the polarization sensitive detector.

Description

PCT Patent Application 044974.8132.WO00 (UA24-255) WAVE FRONT SENSOR USING POLARIZATION IMAGING CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to the provisional application with serial number 63 / 649,827 titled “WAVEFRONT SENSOR USING POLARIZATION IMAGING,” filed May 20, 2024. The entire contents of the above noted provisional application are incorporated by reference as part of the disclosure of this document. TECHNICAL FIELD

[0002] The technology described in this patent document relates to methods and systems for wave front sensing that utilize polarization principles. BACKGROUND

[0003] Wave front of an electromagnetic wave is a surface where the phase of the wave is constant, having the same optical path length from the source. Example wave fronts include plane wave fronts and spherical wave fronts, where the surfaces are a plane and a sphere, respectively. Aberration is often defined as a deviation from a reference surface such as a plane or a sphere. Generally, the wave front in most situations is a complex surface of both space and time.

[0004] Wave front sensing has several applications in metrology, remote sensing and laser beam characterization and others. It is therefore important to develop improved systems and methods for measuring wave fronts. SUMMARY

[0005] The disclosed embodiments relate to methods and systems, that among other features and benefits, enable the detection of an unknown wave front by measurement of the polarization properties of the wave front.

[0006] One example wave front sensor includes a plate positioned to receive an incoming optical beam having a wave front. The plate is configured to modify polarization of the incoming optical beam and to produce light with particular polarization characteristics. The wave front sensor configured to accommodate an object in a position to receive the light with the particular polarization characteristics, wherein the object hasPCT Patent Application 044974.8132.WO00 (UA24-255) known polarization parameters. The wave front sensor further includes a polarization sensitive detector positioned to receive light that is reflected from, or transmitted though, the object, and a processor and a memory including instructions stored thereon, wherein the instructions when executed by the processor configure the processor to determine a propagation vector of the wave front based on at least partial or full Stokes parameters obtained from measurements of the polarization sensitive detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 illustrates a configuration of an example Shack-Hartmann wave front sensor (SHWS).

[0008] FIG.2 illustrates a configuration of an example polarization imaging system.

[0009] FIG. 3 illustrates a wave front sensor configuration in accordance with an example embodiment.

[0010] FIG.4 illustrates a wave front sensor configuration in accordance with another example embodiment.

[0011] FIG.5 illustrates a wave front sensor configuration in accordance with another example embodiment.

[0012] FIG.6 illustrates a wave front sensor configuration in accordance with another example embodiment.

[0013] FIG.7 illustrates a coordinate system showing propagation, transmission and reflection vectors and associated angles to facilitate the description of the disclosed embodiments.

[0014] FIG.8 illustrates reflection from a plate and associated angles and vectors to facilitate the description of the disclosed embodiments.

[0015] FIG. 9 illustrates example ray tracing results conducted using a collimated beam for the configuration of FIG.3.

[0016] FIG. 10 illustrates example ray tracing results conducted using a collimated beam for the configuration of FIG.3.PCT Patent Application 044974.8132.WO00 (UA24-255)

[0017] FIG. 11 illustrates example results representing the degree of circular polarization (DoCP) and polarization major axis orientation (AoLP) as a function of incident and azimuthal angles.

[0018] FIG.12 illustrates a set of operations that can be carried out to measure a wave front of an optical beam in accordance with an example embodiment. DETAILED DESCRIPTION

[0019] Applications of wave front sensors, among others, include optical testing, fiber optics alignment, metrology, ophthalmic diagnostic imaging, remote sensing and laser beam characterization. In addition, wave front sensor is a key component of adaptive optics system which is used in astronomy, vision science, microscopy, laser and microelectronics manufacturing and free space optical communications.

[0020] A wave front sensor measures both the phase and the intensity of a wave front. A common wave front sensor is the Shack-Hartmann wave front sensor (SHWS). FIG.1 shows one version of a SHWS 100 with incoming wave front 110, which includes a sensor array 101 such as a CMOS, CCD, PMT, SPAD array sensor and one or combination of a lenslet array 102. The sensor is located at the focal plane of the lenslet array. For each lenslet, the displacement of the intensity centroid relative to a predefined reference spot provides the propagation angles of the wave front. The wave front is approximated by a discrete array of propagation angles, with the lateral resolution of the SHWS given by the size of the lenslet array. In such a way, each propagation angle defines a plane which closely matches a local part of a wave front. In a SHWS, the wave front can be constructed by measurement of the intensity profile using a sensor array.

[0021] The disclosed embodiments, among other features and benefits, detect an unknown wave front by measurement of the polarization properties of the wave front. In conventional polarization imaging as shown in FIG. 2, incoming wave front 202 with a polarization state defined by a two component Jones vector ^^^and propagation vector, ^^^, is incident on an object 201. The incident light is reflected by the surface with a normal vector, ^^, and an outgoing wave front 203 has a polarization state defined by Jones vector, ^^^and propagation vector, ^^^. By carefully controlling and calibrating the incidentPCT Patent Application 044974.8132.WO00 (UA24-255) wave front 202, ^^^and ^^^, and measuring the outgoing wave front 203, ^^^and ^^^, the properties of object 201, such as the normal vector, ^^, shape, refractive indices, polarization bidirectional reflectance distribution function (pBRDF), Jones matrix and Mueller matrix can be precisely measured.

[0022] The same configuration in FIG. 2 can be used to describe the process of polarization and wave front conversion. In this case, the shape and Mueller matrix of object 201 is designed and engineered to convert a known wave front 202 with polarization state defined by Jones vector, ^^^, and propagation vector, ^^^, to a desired output wave front 203 with polarization state defined by Jones vector, ^^^, and propagation vector, ^^^. Finally, the configuration in FIG.2 also applies to the disclosed embodiments where the incoming wave front 202 is unknown. Notably, the properties of object 201, such as shape and refractive index distribution, are known. The polarization state of the incoming wave front 202 is also known (or can be modified / controlled to produce a known polarization), which allows the polarization state of the outgoing wave front 203 to be measured. The disclosed embodiments solve the inverse problem of determining the incoming wave front 202 based on known properties of object 201 and outgoing wave front 203.

[0023] FIG. 3 illustrates one example configuration of a wave front sensor in accordance with some embodiments. Incoming unknown wave front 310 passes through a spectral filter and / or polarization filter 303 and is reflected from a plate 302 to a polarization camera 301. The polarization camera 301 is focused to the front of the plate 302 and measures the full or partial Stokes parameters of the wave front 310 as a function of position. In one embodiment, the orientation of the polarizer 303 is fixed, and at least one image is taken using the camera 301. In other embodiments, the orientation of the polarizer 303 is changed, and at least one image is taken using the camera 301 at each polarizer orientation.

[0024] FIG. 4 illustrates another example configuration of a wave front sensor in accordance with some embodiments. Incoming wave front 410 passes through a spectral filter and / or polarization filter 403 and is transmitted through a plate 402 to a polarizationPCT Patent Application 044974.8132.WO00 (UA24-255) camera 401. The polarization camera 401 is focused to the back of the plate 402 and measures the full or partial Stokes parameters of the wave front 410 as a function of position. In one embodiment, the orientation of the polarizer 403 is fixed, and at least one image is taken using the camera 401. In other embodiments, the orientation of the polarizer 403 is changed, and at least one image is taken using the camera 401 at each polarizer orientation.

[0025] Discussion of plates 302 and 402

[0026] Plate 302 operates in reflection and can be made of dielectric or metallic material. The refractive index of the plate must be uniform and known a priori and can be used in the calculation of the Fresnel reflection coefficients dictating the polarization state change. Additionally, the surface of plate 302 must be optically flat, as to not change the wave front distribution. Plate 402 operates in transmission and can be made of dielectric and thin metallic material. The refractive index of the plate and potentially thickness of metallic material must be uniform and known a priori and can be used in the calculation of the Fresnel transmission coefficients dictating the polarization state change. Additionally, the surface of plate 402 must be optically flat, as to not account for any defocus and spherical aberration transmission through a plane parallel plate might introduce.

[0027] One challenge of the plate 302 is that the higher order reflections and transmissions may interfere at the detector, creating error in measurement of the Stokes parameters. These higher order reflections 304 and transmission 305 are shown in a separate diagram (dashed box) in FIG.3.

[0028] These artifacts caused by higher order reflection and transmission can be avoided some embodiments by adding an antireflection coating on the back side of plate 302 to eliminate or greatly reduce the reflections. Alternatively, as shown, for example, in FIG. 5, in some embodiments, the plate 302 is replaced by a prism 502. Incoming unknown wave front 510 passes through a spectral filter and / or polarization filter 503 and is reflected from one side of the prism 502 to a polarization camera 501. The polarization camera 501 is focused to the bottom side of the prism 502 and measures the full or partialPCT Patent Application 044974.8132.WO00 (UA24-255) Stokes parameters of the wave front 510 as a function of position. The incident angle is normal to the prism surface. In this case, the measured polarization parameters are a function of the Jones matrix transmission from air to prism, the Jones matrix for propagation, the Jones matrix of total internal reflection inside the prism, and the Jones matrix transmission from prism to air. This embodiment avoids the higher order reflections but requires that all surfaces of the prism to be optically flat.

[0029] FIG. 6 illustrates another example configuration of a wave front sensor in accordance with some embodiments. Incoming wave front 610 passes through a spectral filter and / or polarization filter 603 and is reflected from a curved surface 602 to a polarization camera 601. The polarization camera 601 is focused to the front of the surface 602 and measures the full or partial Stokes parameters of the reflected wave front 610 as a function of position. The shape and Jones matrix of the curved surface is known. The usage of a curved surface 602 instead of a flat plate 302 can in some cases increase the angular measurement range of the wave front 610. For example, if the incoming wave front 610 has a known curvature, and we are interested in measuring the deviation of the wave front from this known curvature, then the surface 602 is chosen to offset the known curvature, so that only the deviation from the known curvature is measured.

[0030] Discussion of elements 303, 403, 503 and 603

[0031] Plates 303, 403, 503 and 603 can be a combination of a spectral filter, a polarizer and, in some embodiments, a waveplate, allowing for polarization of the input wave front to be known and controlled. Of key importance is the a priori knowledge of the polarization state across the incident wave front (wave front incident on the known object). That is, the transmission axis or eigenpolarizations are known, thus allowing for calculation of the wave front after transmission through, or reflection from, the object with known polarization characteristics (with known Jones or Mueller matrices). The polarizer operates at a wide range of angles by introducing a uniform and well-defined polarization state to an incoming unknown wave front.

[0032] In some embodiments, the plates 303, 403, 503 and 603 may be omitted, if the wavelength and polarization states of the unknown wave front is known a priori. In onePCT Patent Application 044974.8132.WO00 (UA24-255) example, the unknown wave front is the polarized output of a single mode laser. In another example, the polarization state of the unknown wave front has been independently measured as a function of position.

[0033] Discussion of polarization camera 301, 401, 501 and 601

[0034] The polarization camera 301, 401, 501 and 601 can be a polarization sensitive camera, including a partial or full Stokes camera. One example of partial Stokes camera is the Lucid PHX050S1-P / Q camera made by Lucid Vision Labs which utilizes the Sony IMX264MZR CMOS sensor. One example of full Stokes camera is described in a paper by X. Tu, S. McEldowney, Y. Zou, M. Smith, C. Guido, N. Brock, S. Miller, L. Jiang and S. Pau, “Division of focal plane RGB full-Stokes imaging polarimeter,” Applied Optics 59, 22, p.G33-G40, 2020, which is incorporated by reference herein. The polarization camera obtains images of Stokes parameters which represent the polarization state of light. The Stokes parameters are mathematically described using Mueller calculus and can be related to Jones vector which is mathematically described using Jones calculus.

[0035] A wave front can be approximated as a discrete array of propagation angles defined by a propagation vector, ^^^. As shown in FIG.7, the vector ^^^is defined by two angles, ^^^and ^^^. The wave front can be calculated by measurement of either the propagation vector, ^^௧, or the reflected propagation vector, ^^^, after refraction or reflection from a surface plane 701. The vector, ^^^, describes a local wave front with a polarization state defined by the plane 702. The polarization state changes after transmission and reflection and is measured by a polarization camera. The values of the two angles, ^^^and ^^^, can be estimated if we know both the polarization states of the incoming and the outgoing light.

[0036] The mathematical relationship between the incoming electric field and outgoing electric field can be described in some embodiments using Jones calculus. In FIG.8, the incident light with propagation vector, ^^^^^^,^^^, undergoes the following transformation in reflection. ^^^ ൌ ^^^ ∙ ^^^ ^1^PCT Patent Application 044974.8132.WO00 (UA24-255)

[0037] In Eq. (1), ^^^is the reflected Jones vector, ^^^is the Jones matrix of the reflected light path from a surface, for example plate 302, and ^^^is the incident Jones vector. The reflected light has a propagation vector, ^^^^^^,^^^. And ^^^is the Jones matrix structured with the Fresnel amplitude and phase coefficients as: ^^ ^^^ ^^ ^^^ 0^ ൌ ^ 0 ^^ ^ ^^^^^^^൨ 2

[0038] The Fresnel^^^ cos^^ െ ^^ cos^^^^^^^^^^ ൌ ^ ௧ ௧^^ cos^^ ^ ^^ cos^3^ ^^ ^^^

[0039] In the above are of incidence to the surface for the incident electric field. In general, ^^^and ^^^are complex valued. The refracted angle of incidence, ^^௧, can be calculated through Snell’s Law, incident refractive index ^^^, and transmitted refractive index ^^௧.

[0040] Eq. (1) can be extended to capture the three-dimensional electric field through the use of polarization raytracing calculus, which is known in the art, and can be found, for example, in Chapter 9 of the book published as: R. A. Chipman, W.T. Lam, and G. Young, Polarized Light and Optical Systems (CRC, 2019), which is incorporated by reference herein. Eq. (1) now becomes: ^^′^ ൌ ^^^ ∙ ^^′^ ^5^

[0041] In Eq. (5), ^^′^are and ^^′^are three component electric field vector and ^^^can be expressed as: ^^^,௫^^^,௬^^^,௭ ^^^ 0 0^^^,௫^^ଶ,௫^^^,௫^

[0042] In, corresponding to ^^′^, ^^^is the k-vector of the reflected electric field corresponding to ^^′^,PCT Patent Application 044974.8132.WO00 (UA24-255) ^^^is global coordinates of the local s-polarization, ^^^is global coordinates of the incident light’s p-polarization, and, ^^ଶis global coordinates of the reflected light’s p-polarization. We note that the electric field can then be referenced in the local coordinate system of the polarization field and transformed into power units or Stokes parameters.

[0043] The explicit form of these are: ^^^ ൌ ^sin^^^ sin^^^ , sin^^^ cos^^^ , cos ^^^^ ^7^^^^ ൈ ^^^^^ൌ ^8^ ^ൈ^^ଶ ൌ ^^^ ൈ ^^^ ^10^^^^ ൌ ^^^ െ 2^^^^ ∙ ^^^^^ ^11^^^ ൌ ^0, sin ^^ ,െcos ^^^ ^12^

[0044] In the above equations, ^^ is the vector defining the surface normal of the plate and ^^ describes the tilt of the plate in FIG. 8. With these quantities and Eq. (6), the polarization state reflected from a dielectric and metallic surface can be described as a function of wavelength and the two defining angles of ^^^, namely, ^^^and ^^^.

[0045] The explicit form of ^^^is given by ^^^^ 0 0^^16^

[0047] The incident and reflected electric fields are known based on the input statesPCT Patent Application 044974.8132.WO00 (UA24-255) and measurement of the Stokes parameters. The values for ^^^and ^^^can be calculated from the explicit form of ^^^.

[0048] To visualize the variation of ^^^and ^^^for a simple optical system described in the configuration in FIG. 3, polarization ray tracing was conducted using commercial Polaris-M software (Airy Optics, Tucson, Arizona, USA). The raytracing calculation shows two wave fronts reflected off a flat plate of refractive index 1.5 at a wavelength of 500 nm. The input light rays have left-hand circular polarization state. The first wave front is collimated and shows a uniform reflected polarization state across the beam and is presented in FIG. 9. The left-hand side of FIG.9 illustrates a side view of the collimated rays traced through the configuration of FIG.3. The right-hand side of FIG.9 shows a top view, with ellipses on the detection plane being representations of polarizations at the corresponding points.

[0049] FIG.10 shows a similar ray tracing illustration as in FIG.9 but for an incident converging beam with a numerical aperture of 0.1. The input light rays have left-hand circular polarization. The reflected beam shows a non-uniform polarization state due to the ^^^and ^^^difference for each of the rays.

[0050] FIG.11 shows the degree of circular polarization (DoCP) and polarization major axis orientation (AoLP) as a function of ^^^and ^^^. DoCP is calculated from the Stokes parameters below as: ^^ ^^^^^^^^ ൌ ଷ^^^17^

[0051] And the AoLP can betanି^^^^ଶൗ ^^^ ^

[0052] Referencing the two^^^can be calculated from measurement of DoCP and AoLP, allowing for wave front sensing through measurement of the image of Stokes parameters. Other parameters which can be used include orientation of major axis of elliptical polarization, orientation ofPCT Patent Application 044974.8132.WO00 (UA24-255) minor axis of elliptical polarization, ellipticity of elliptical polarization, eccentricity of elliptical polarization, degree of linear polarization (DoLP) and degree of polarization (DoP).

[0053] In some embodiments, the measurement of the Stokes image may include utilizing a lens in front of elements 302, 402, 502 and 602 and another lens in front of the camera 301, 401, 501 and 601 in order to defocus the image of the light source of the wave front on the polarization camera. This configuration can be used where there is a bright light source which interferes with the accurate measurement of the polarization image. These lenses are not shown in FIGs.3, 4, 5 and 6. The effect of the lenses on the unknown wave front can be calculated from the locations, focal lengths and sizes of the lenses and are taken into account in the measurement of the wave front by using polarization raytracing technique as done in the aforementioned example.

[0054] Advantages of the disclosed technology include high speed, high accuracy, broad spectral range, applicability to both coherent and incoherent light and high dynamic range. For example, as compared to SHWS sensor of FIG. 1, the lenslet array is removed, thereby reducing the cost, and the sampling of the wave front is effectuated at a higher resolution since it is not limited by the lenslet array but is based on the spatial resolution of the polarization sensitive detector. In one example, the spatial resolution is improved by 1000X. Additionally, wave front sensing in accordance with the disclosed technology is not limited to, and is not required to have, a coherent source unlike some prior art techniques.

[0055] FIG.12 illustrates a set of operations that can be carried out to measure a wave front of an optical beam in accordance with an example embodiment. At 1202, the optical beam is received at a plate, wherein the plate is configured to modify polarization of the optical beam to allow light with particular polarization characteristics to traverse therethrough in the direction of an object. At 1204, the light with the particular polarization characteristics is received at the object, wherein the object has known polarization parameters. At 1206, a polarization sensitive detector is used to measure light after reflection from, or transmission though, the object. At 1208, a propagation vector of thePCT Patent Application 044974.8132.WO00 (UA24-255) wave front is determined based on at least partial or full Stokes parameters obtained from measurements of the polarization sensitive detector.

[0056] In one example embodiment, the particular polarization characteristics of the light that is incident on the object include a known polarization state. In another example embodiment, the particular polarization characteristics of the light that is incident on the object include a polarization state that is defined by a Jones vector and a propagation vector for the light that exits the plate. In yet another example embodiment, the plate is one of, or a combination of, a spectral filter, a polarizer or a waveplate. In still another example embodiment, the known polarization parameters of the object include a known Jones matrix or a known Mueller matrix.

[0057] According to another example embodiment, the object is a parallel plate, and is positioned to receive the light with the particular polarization characteristics at a non- zero angle. In another example embodiment, the parallel plate is configured to reflect the light that is incident thereon in a direction of the polarization sensitive detector. In yet another example embodiment, the parallel plate is configured to transmit the light that is incident thereon to allow the transmitted light to reach the polarization sensitive detector. In one example embodiment, the object is a prism, and is positioned to allow the light with the particular polarization characteristics to enter the prism through a first facet, internally reflect from a second facet, and exit the prism through a third facet. In another example embodiment, the object includes a curved surface and is positioned to reflect the light with the particular polarization characteristics that is incident thereon in a direction of the polarization sensitive detector. The curved surface can be combination of concave, convex, and spatial varying surfaces with well-defined shape and orientation.

[0058] In another example embodiment, determining the propagation vector includes determining two angles in a polar coordinate system associated with the propagation vector. In one example embodiment, determining the propagation vector includes determining one or more degrees of polarization based on the at least partial or full Stokes parameters, and using the one or more degrees of polarization to determine the two angles. In still another example embodiment, the one or more degrees of polarizationPCT Patent Application 044974.8132.WO00 (UA24-255) include a degree of circular polarization and a degree of linear polarization. In still another example embodiment, the above noted method further includes using one or more lenses with known polarization characteristics to defocus light incident on the object or received at the polarization sensitive detector.

[0059] Another aspect of the disclosed embodiments relates to a wave front sensor that includes a plate positioned to receive an incoming optical beam having a wave front, wherein the plate is configured to modify polarization of the incoming optical beam and to produce light with particular polarization characteristics. The wave front sensor also includes an object positioned to receive the light with the particular polarization characteristics, wherein the object has known polarization parameters, and a polarization sensitive detector positioned to receive light that is reflected from, or transmitted though, the object. The wave front sensor further includes a processor and a memory including instructions stored thereon, wherein the instructions when executed by the processor configure the processor to determine a propagation vector of the wave front based on at least partial or full Stokes parameters obtained from measurements of the polarization sensitive detector.

[0060] In one example embodiment related to wave front sensor, the particular polarization characteristics include a known polarization state. In another example embodiment, the particular polarization characteristics is defined by a Jones vector and a propagation vector for the light that exits the plate. In yet another example embodiment, the plate is one of, or a combination of, a spectral filter, a polarizer or a waveplate. In still another example embodiment, the known polarization parameters of the object include a known Jones matrix or a known Mueller matrix. In still another example embodiment, the object is a parallel plate, and is positioned to receive the light with the particular polarization characteristics at a non-zero angle. In one example embodiment, the parallel plate is positioned to reflect the light that is incident thereon in a direction of the polarization sensitive detector. In another example embodiment, the parallel plate is configured to transmit the light with the particular polarization characteristics that is incident thereon to allow the transmitted light to reach the polarization sensitive detector.PCT Patent Application 044974.8132.WO00 (UA24-255)

[0061] According to another example embodiment related to the wavefront sensor, the object is a prism, and is positioned to allow the light with the particular polarization characteristics to enter the prism through a first facet, internally reflect from a second facet, and exit the prism through a third facet. In still another example embodiment, the object includes a curved surface and is positioned to reflect the light with the particular polarization characteristics that is incident thereon in a direction of the polarization sensitive detector. In yet another example embodiment, the instructions when executed by the processor configure the processor to determine the propagation vector by determining two angles in a polar coordinate system associated with the propagation vector.

[0062] In another example embodiment, the instructions when executed by the processor configure the processor to determine the propagation vector by determining one or more degrees of polarization based on the at least partial or full Stokes parameters, and use the one or more degrees of polarization to determine the two angles. In another example embodiment, the one or more degrees of polarization include a degree of circular polarization and a degree of linear polarization.

[0063] In still another example embodiment, the wave front sensor further includes a first lens positioned in a path of the light with the particular polarization characteristics before the object, and a second lens positioned in an optical path between the object and the polarization sensitive detector, wherein the first or the second lens cause a defocused image of a light source corresponding to the wave front to be produced on at the polarization sensitive detector.

[0064] Various components may be controlled or various operations may be performed via implementations using a processor / controller that is configured to include, or be coupled to, a memory that stores processor executable code that causes the processor / controller carry out various computations and processing of information. The processor / controller can further generate and transmit / receive suitable information to / from the various system components, as well as suitable input / output (IO) capabilities (e.g., wired or wireless) to transmit and receive commands and / or data. ThePCT Patent Application 044974.8132.WO00 (UA24-255) processor / controller may, for example, provide signals to control the operation of various components such as light sources, power supplies and detectors that are disclosed herein.

[0065] Various information and data processing operations described herein may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), cloud storage, etc. Therefore, the computer-readable media that is described in the present application comprises non-transitory storage media. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes. Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

Claims

PCT Patent Application 044974.8132.WO00 (UA24-255) CLAIMS I / We Claim:

1. A method for measuring a wave front of an optical beam, comprising: receiving the optical beam at a plate, wherein the plate is configured to modify polarization of the optical beam to allow light with particular polarization characteristics to traverse therethrough in a direction of an object; receiving the light with the particular polarization characteristics at the object, wherein the object has known polarization parameters; using a polarization sensitive detector to measure light after reflection from, or transmission though, the object; and determining a propagation vector of the wave front based on at least partial or full Stokes parameters obtained from measurements of the polarization sensitive detector.

2. The method of claim 1, wherein the particular polarization characteristics of the light that is incident on the object include a known polarization state.

3. The method of claim 1, wherein the particular polarization characteristics of the light that is incident on the object include a polarization state that is defined by a Jones vector and a propagation vector for the light that exits the plate.

4. The method of claim 1, wherein the plate is one of, or a combination of, a spectral filter, a polarizer or a waveplate.

5. The method of claim 1, wherein the known polarization parameters of the object include a known Jones matrix or a known Mueller matrix.

6. The method of claim 1, wherein the object is a parallel plate, and is positioned to receive the light with the particular polarization characteristics at a non-zero angle.

7. The method of claim 6, wherein the parallel plate is configured to reflect the lightPCT Patent Application 044974.8132.WO00 (UA24-255) that is incident thereon in a direction of the polarization sensitive detector.

8. The method of claim 6, wherein the parallel plate is configured to transmit the light that is incident thereon to allow the transmitted light to reach the polarization sensitive detector.

9. The method of claim 1, wherein the object is a prism, and is positioned to allow the light with the particular polarization characteristics to enter the prism through a first facet, internally reflect from a second facet, and exit the prism through a third facet.

10. The method of claim 1, wherein the object includes a curved surface and is positioned to reflect the light with the particular polarization characteristics that is incident thereon in a direction of the polarization sensitive detector.

11. The method of claim 1, wherein determining the propagation vector includes determining two angles in a polar coordinate system associated with the propagation vector.

12. The method of claim 11, wherein determining the propagation vector includes determining one or more degrees of polarization based on the at least partial or full Stokes parameters, and using the one or more degrees of polarization to determine the two angles.

13. The method of claim 12, wherein the one or more degrees of polarization include a degree of circular polarization and a degree of linear polarization.

14. The method of claim 1, further comprising using one or more lenses with known polarization characteristics to defocus light incident on the object or received at the polarization sensitive detector.PCT Patent Application 044974.8132.WO00 (UA24-255) 15. A method for measuring a wave front of an optical beam, comprising: receiving the optical beam with known polarization states and unknown wave front at an object, wherein the object has known polarization parameters; using a polarization sensitive detector to measure light after reflection from, or transmission though, the object; and determining a propagation vector of the wave front based on at least partial or full Stokes parameters obtained from measurements of the polarization sensitive detector.

16. A wave front sensor, comprising: a plate positioned to receive an incoming optical beam having a wave front, wherein the plate is configured to modify polarization of the incoming optical beam and to produce light with particular polarization characteristics; the wavefront sensor configured to accommodate an object in a position to receive the light with the particular polarization characteristics, wherein the object has known polarization parameters; a polarization sensitive detector positioned to receive light that is reflected from, or transmitted though, the object; and a processor and a memory including instructions stored thereon, wherein the instructions when executed by the processor configure the processor to determine a propagation vector of the wave front based on at least partial or full Stokes parameters obtained from measurements of the polarization sensitive detector.

17. The wave front sensor of claim 16, wherein the particular polarization characteristics include a known polarization state.

18. The wave front sensor of claim 16, wherein the particular polarization characteristics is defined by a Jones vector and a propagation vector for the light that exits the plate.

19. The wave front sensor of claim 16, wherein the plate is one of, or a combinationPCT Patent Application 044974.8132.WO00 (UA24-255) of, a spectral filter, a polarizer or a waveplate.

20. The wave front sensor of claim 16, wherein the known polarization parameters of the object include a known Jones matrix or a known Mueller matrix.

21. The wave front sensor of claim 16, wherein the object is a parallel plate, and is positioned to receive the light with the particular polarization characteristics at a non-zero angle.

22. The wave front sensor of claim 21, wherein the parallel plate is positioned to reflect the light that is incident thereon in a direction of the polarization sensitive detector.

23. The wave front sensor of claim 21, wherein the parallel plate is configured to transmit the light with the particular polarization characteristics that is incident thereon to allow the transmitted light to reach the polarization sensitive detector.

24. The wave front sensor of claim 16, wherein the object is a prism, and is positioned to allow the light with the particular polarization characteristics to enter the prism through a first facet, internally reflect from a second facet, and exit the prism through a third facet.

25. The wave front sensor of claim 16, wherein the object includes a curved surface and is positioned to reflect the light with the particular polarization characteristics that is incident thereon in a direction of the polarization sensitive detector.

26. The wave front sensor of claim 16, wherein the instructions when executed by the processor configure the processor to determine the propagation vector by determining two angles in a polar coordinate system associated with the propagation vector.

27. The wave front sensor of claim 26, wherein the instructions when executed by the processor configure the processor to determine the propagation vector by determiningPCT Patent Application 044974.8132.WO00 (UA24-255) one or more degrees of polarization based on the at least partial or full Stokes parameters, and use the one or more degrees of polarization to determine the two angles.

28. The wave front sensor of claim 27, wherein the one or more degrees of polarization include a degree of circular polarization and a degree of linear polarization.

29. The wave front sensor of claim 16, further comprising: a first lens positioned in a path of the light with the particular polarization characteristics before the object; and a second lens positioned in an optical path between the object and the polarization sensitive detector, wherein the first or the second lens cause a defocused image of a light source corresponding to the wave front to be produced on at the polarization sensitive detector.

Images