Optical Systems for Noise Mitigation

Abstract

To mitigate coherent noise of a photonics assembly.SOLUTION: A photonics assembly may include a set of light sources, an optical subsystem that may include a set of optical elements, and a diffusing element. The light emitted by the set of light sources may have different wavelengths, and the light may be de-cohered by a phase shifter before being received by the set of optical elements. The diffusing element may be movable and may be capable of repeating the same positions or set of positions for each beam of light emitted by the set of light sources. By combining coherent noise mitigation techniques of the movable diffusing element and the de-cohered light, a photonics system may provide an illumination profile with specific spatial and angular profiles on a sample that allows reliable measurement of the sample and coherent noise mitigation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This PCT (Patent Cooperation Treaty) patent application claims priority to U.S. Provisional Patent Application No. 63 / 076,249, filed September 9, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002] The present disclosure relates generally to systems and methods for coherent noise mitigation, and more particularly to systems having multiple light sources and optical elements that generate decohered light forming an asymmetric emission beam. [Background technology]

[0003] Generally, noise in various types of imaging systems can cause undesired signal modifications. Noise can degrade images in systems such as medical ultrasound systems, radar systems, projection systems, or any coherent imaging system. Noise can cause graininess, grain patterns, or intensity patterns in measurement signals or images. In some instances, noise can significantly interfere with the detection of optical signals, and therefore, lighting conditions can be designed to mitigate noise while maintaining other specifications of the optical system, such as the operating speed and size of the optical device or system. Summary of the Invention

[0004] Embodiments of the systems, devices, methods, and devices described herein relate to optical systems for mitigating coherent noise. Systems, devices, methods, and apparatuses directed to providing decohered light that generates an asymmetric launch beam are also described. The optical system may include multiple light sources that provide decohered light via phase shift, frequency difference, etc. The optical subsystem can receive light from the light sources and substantially collimate the light to generate a desired intensity profile of the launch beam. The launch beam can include light in the form of light beams from the light sources, each light beam incident on the launch beam at a different angle relative to one another. The optical system can also include a movable diffuser to help mitigate coherent noise.

[0005] In some examples, the present disclosure describes a photonics assembly. The photonics assembly may include a set of semiconductor light sources, each emitting light; a set of output couplers receiving light from the set of semiconductor light sources; an optical subsystem positioned to receive and shape the light from the set of output couplers; and a diffuser configured to provide light having a coherent noise state on a sample, the diffuser operable to repeatedly move between at least a first position and a second position, and by repeatedly moving between at least the first position and the second position, the diffuser mitigates the coherent noise. In some examples, the photonics assembly may include a set of phase shifters positioned to transmit light to each output coupler of the set of output couplers, generating decohered light, wherein the beam divergence of the light emitted by the set of semiconductor light sources upon exiting the set of semiconductor light sources is between 1 and 5 microns in at least one dimension, and the beam divergence exiting the diffuser upon entering the sample is in the range of 2 to 4 mm in at least one dimension. In some examples, the beam divergence exiting the diffuser may be approximately 0.5 mm by 2-4 mm.

[0006] In some examples, the optical subsystem may include a collimating array positioned to receive light from the set of output couplers and a polarizing prism array positioned to receive light from the collimating array. In some examples, the optical subsystem may include a collimating array positioned to receive light from the set of output couplers and a diverging array positioned to receive light from the collimating array. In some examples, the optical subsystem may include an off-centered toroidal lens array positioned to receive light from the set of output couplers. In some examples, the optical subsystem may include a cylinder lens array positioned to receive light from the set of output couplers and a crossed cylinder lens array positioned to receive light from the cylinder lens array. In some examples, the diffuser is configured to provide an 8 degree by 8 degree divergent light beam to the sample.

[0007] In some examples, the present disclosure describes an optical system. The optical system may include a set of semiconductor light sources for emitting light having multiple light beams, a set of output couplers for receiving light from the set of semiconductor light sources, and a movable diffusing element configured to receive light from the set of optical couplers and move to a set of positions relative to each output coupler of the set of output couplers to provide a set of different coherent noise states corresponding to each output coupler of the set of output couplers and define an illumination profile incident on the sample. In some examples, the optical system may include an optical subsystem configured to receive light from the set of output couplers and a set of phase shifters for decohering the light, wherein each light beam of the multiple light beams received by the set of output couplers is decohered by a corresponding phase shifter of the set of phase shifters, and each of the sets of positions is repeatable. In some examples, the optical system may include a frequency modulator for decohering the light provided by the set of output couplers. In some examples, the movable diffusing element is a circular diffuser. In some examples, the illumination profile is based at least in part on an angular spacing of the light received from the optical subsystem. In some examples, the illumination profile is based at least in part on the range of angles of light incident on the diffuser. In some examples, the light emitted by each light source in the set of solid-state light sources is at a different wavelength.

[0008] In some examples, the present disclosure describes a method for mitigating coherent noise. The method may include emitting decohered light from a set of light sources, receiving the decohered light in an optical subsystem that generates a desired illumination profile, and diffusing the desired illumination profile of the decohered light using a movable diffuser with a coherent-noise-specific diffuser state for each light beam received from each light source of the set of light sources. In some examples, the illumination profile is based at least in part on an angular spacing of the light received from the optical subsystem, and the coherent-noise-specific diffuser state for each light beam may be repeatable, with the full range of angles of the light incident on the diffuser. In some examples, emitting the decohered light may include generating a beam divergence that is less than 4 microns upon exiting the set of light sources. In some examples, diffusing the decohered light may include generating a beam divergence of less than 3.2 mm upon incident on a sample. In some examples, emitting the decohered light may include phase-shifting the decohered light. In some examples, each light source in the set of light sources is at a different wavelength from the others, and diffusing the decohered light may include generating a set of coherent noise views, where the same coherent noise view is generated for each wavelength.

[0009] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following descriptions. [Brief explanation of the drawings]

[0010] [Figure 1] 1 illustrates an exemplary photonics assembly embodiment. [Figure 2A] 1 shows an optical system. [Figure 2B] 1 shows an optical system. [Figure 2C] A representation of a lighting profile. [Figure 2D]A representation of a lighting profile. [Figure 3A] 1 illustrates an exemplary optical subsystem within an optical system. [Figure 3B] 1 illustrates an exemplary optical system without a diffuser and the corresponding far-field angular separation of the light. [Figure 3C] 1 illustrates an exemplary optical system without a diffuser and the corresponding far-field angular separation of the light. [Figure 3D] 1 illustrates an exemplary optical system having a diffuser and corresponding far-field angular separation of non-overlapping light. [Figure 3E] 1 illustrates an exemplary optical system having a diffuser and corresponding far-field angular separation of non-overlapping light. [Figure 3F] 1 illustrates an exemplary optical system having a diffuser and corresponding far-field angular separation of overlapping light. [Figure 3G] 1 illustrates an exemplary optical system having a diffuser and corresponding far-field angular separation of overlapping light. [Figure 4] 1 illustrates an exemplary optical subsystem of an optical system. [Figure 5] 1 illustrates an exemplary optical subsystem of an optical system. [Figure 6] 1 illustrates an exemplary optical subsystem of an optical system. [Figure 7] 1 illustrates an exemplary optical subsystem of an optical system. [Figure 8] 1 illustrates an exemplary optical subsystem of an optical system. [Figure 9] 1 shows an exemplary block diagram of an optical system.

[0011] It should be understood that the proportions and dimensions (relative or absolute) of the various features and elements (and their collections and groupings), as well as the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate understanding of the various embodiments described herein, and as such may not necessarily be presented or drawn to scale, and are not intended to imply any preference or requirement for the illustrated embodiments, excluding the embodiments described with reference to those figures. DETAILED DESCRIPTION OF THE INVENTION

[0012] Reference will now be made in detail to exemplary embodiments as illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit these embodiments to any single preferred embodiment. On the contrary, the following description is intended to cover alternatives, modifications, and equivalents, as may be included within the spirit and scope of the described embodiments as defined by the appended claims.

[0013] In general, noise, such as random noise or semi-random noise, may be present in various types of imaging systems and may cause undesired signal modifications. In some examples, the noise in an imaging system may be coherent noise. The noise may degrade an image by causing graininess, grain patterns, or intensity patterns in the image in systems such as medical ultrasound systems, radar systems, projection systems, or any coherent imaging system. Some systems may generate signals with so much noise that it may be difficult to determine the measured signal. In some examples, coherent multipath interference may be a noise source, one example of which may be speckle noise.

[0014] In some examples, coherent noise can significantly interfere with the detection of optical signals, and therefore, illumination conditions may be designed to mitigate coherent noise while maintaining other specifications of the optical system, such as the operating speed and size of the optical device or system. Various factors may be considered when mitigating or reducing coherent noise, including, but not limited to, the illumination conditions within the geometric specifications of the system, such as the intensity profile of the light, the angular distribution or beam divergence angle of the light, and reducing the number of moving parts in the optical system.

[0015] When mitigating noise in an optical system, coherent noise can be reduced without exacerbating other noise sources in the optical system, such as detector noise and laser noise. In some examples, coherent noise can be reduced by combining the functions of multiple elements in the optical system, such as a moving diffuser and a phase shifter in an integrated optical system. In addition, coherent noise can be mitigated by decohering multiple optical outputs from one another through several time-varying phase relationships. These phase relationships may be from phase shifters, frequency modulators, and / or chirp and group delay, any combination thereof, etc. In some examples, coherent noise can be mitigated by each output receiving a slightly different wavelength. By using these elements in conjunction with observing other specifications of the optical system, coherent noise can be mitigated or reduced so that optical signals can be more effectively measured by the optical system.

[0016] Disclosed herein are optical systems, devices, and methods for using a moving diffuser and decohered light together to mitigate coherent noise and generate a predetermined illumination profile incident on a sample. The photonics assembly may include a photonics die that emits multiple wavelengths. Additionally, the photonics assembly may include photonics die(s), an outcoupler, optical components that receive light from the photonics die(s), free-space optics, etc., but does not include a sample. The photonics assembly is described in more detail below with reference to FIG. 1. The light emitted by the photonics die(s) may be decohered using a phase shifter, which may be part of or external to the photonics die. The light may be received by an optical subsystem that shapes the light and directs it to a diffusing element. The optical subsystem may include one or more optical components as needed to achieve a desired shape and beam angle incident on the diffusing element. In some examples, the optical subsystem may shape the light by collimating the light. In general, shaping light may include directing light, focusing light, collimating light, other suitable shaping functions, and / or any combination thereof.

[0017] In some examples, the diffusing element can move in one or more dimensions with the decohered light beam to generate a unique coherent noise view or coherent noise state, and the position of the diffusing element can also be repeatable. The coherent noise can cause graininess, grain patterns, or intensity patterns in the measurement signal or image. In some examples, a first light can experience coherent multipath interference that generates coherent noise, and the first coherent noise can exhibit a first intensity pattern that can be a first coherent noise view or coherent noise state. Further to this example, a second light can experience coherent multipath interference that generates coherent noise, and the second coherent noise can exhibit a second intensity pattern that can be a second coherent noise view or coherent noise state. What qualifies as a unique coherent noise view or a unique (e.g., different) coherent noise state depends largely on the precision constraints for a given system design and intended sample characteristics, but for purposes of this application, two or more spectroscopic measurements of a sample have a unique noise view or a unique coherent noise state if they have a correlation coefficient r between 0 and 0.5 (e.g., noise views between 0 and 0.5 are decohered from one another). However, it should be understood that some systems may be designed with different precision constraints (e.g., r between 0 and 0.4 or r between 0 and 0.3). The correlation coefficient may be based at least in part on a mapping of intensity values ​​in the image, where bright regions may correspond to high correlation and dark regions may correspond to low correlation.

[0018] As described herein, a position or set of positions of a diffusing element is discussed as repeatable, but the position or set of positions may be nearly repeatable and vary within about 10 percent of the actual position. In some examples, the diffuser may repeatedly move between a predetermined set of positions over the course of a measurement. The predetermined set of positions may be a repeating sequence (e.g., 1-2-3-4-1-2-3-4 or 1-2-3-4-4-3-2-1) or a pseudo-random sequence (e.g., 1-2-4-1-2-3-1-4), and the diffuser may spend equal time at each position. Additionally, there may be some inaccuracy between the target and actual positions of the diffuser when performing measurements. Tolerances may depend on the individual system and may vary from system to system. In some examples, the predetermined set of positions may be selected to be sufficiently distant so that they can provide a unique coherent noise view or condition, even when tolerances are taken into account.

[0019] Each photonics die may emit a respective light beam that may enter the diffusing element with a predetermined beam divergence after passing through the optical elements of the system. Additionally, each light beam may have a different angle relative to the diffusing element due to the spacing between the photonics die and the optical elements of the system. A light beam may be understood to be a portion of light having one or more rays. The diffusing element may be moved to a repeatable set of positions for each light beam so that each light beam may pass through the same or similar set of diffusing element positions as each of the other light beams. The diffusing element may be moved to a set of positions for each light beam to provide a corresponding set of coherent noise views or coherent noise states for that light beam incident on the sample. The diffusing element may then be moved to the same or similar set of positions for the light beam at the next spatial location to provide a corresponding set of coherent noise views or coherent noise states for that light beam, and so on. While light beams at a first position and a next spatial location are sometimes discussed, it may be understood that the diffuser may change the coherent noise views for all of the light beams simultaneously. By providing repeatable positions for each light beam, signals measured from different light beams can be averaged together so that the signals approach, or even converge to, an accurate measurement signal and coherent noise is reduced. In other embodiments, each diffuser position may be visited only once per overall measurement, and wavelengths may be used multiple times, once per diffuser position. Stated differently, in some embodiments, diffuser positions may be nested within wavelengths, and in other embodiments, wavelengths may be nested within diffuser positions.

[0020] In some examples, each wavelength may experience the same diffuser position, but because the wavelengths are different, the coherent noise state for each wavelength at a given diffuser position may be different. When mitigating coherent noise, the same or similar coherent noise view or coherent noise state may be available for all wavelengths or wavelength ranges emitted by the photonics die. By examining light at various angles of the individual light beams, each signal may contain some coherent noise. Signals at different angles of light are averaged together, and the coherent noise may approach zero mean, as long as the signal can approach or converge to an accurate signal or measurement signal without coherent noise. The terms "coherent noise view" and "coherent noise state" may be used interchangeably herein.

[0021] Although a diffusing element or a phase shifter, even when employed individually, may generate unique coherent noise views at a rate sufficient for coherent noise mitigation in a photonics assembly, each component used individually and without the other may occupy too much space and require too much operating power, so a combination of a diffusing element and a phase shifter may better comply with photonics assembly specifications for space and power considerations. Although the diffusing element and the phase shifter can each generate unique views, this combination can increase the number of coherent noise views in a small form factor device and / or system.

[0022] These and other embodiments are described below with reference to Figures 1-8. However, those skilled in the art will readily appreciate that the detailed description provided herein with reference to these figures is for illustrative purposes only and should not be construed as limiting.

[0023] Directional terms, such as "top," "bottom," "upper," "lower," "above," "below," "beneath," "front," "back," "over," "under," "left," "right," etc., are used with reference to some of the orientations of components in some of the figures described below. Because components in various embodiments may be positioned in many different orientations, the directional terms are used for illustrative purposes only and are not limiting in any way. The directional terms are intended to be broadly interpreted and therefore should not be construed to exclude components that are positioned in a different manner.

[0024] As used throughout this specification, a reference number without an alphabetic character following the reference number can refer to one or more corresponding references, a group of all references, or some of the references. For example, "215" can refer to any one of photonics dies 215 (e.g., photonics die 215A, photonics die 215B, etc.), or all of photonics dies 215, or some of the photonics dies (e.g., both photonics die 215A and photonics die 215B), depending on the context in which it is used.

[0025] Representative applications of the methods and apparatus according to the present disclosure are described in this section. These examples are provided solely to add context and aid in understanding the described examples. Therefore, it will be apparent to one skilled in the art that the described examples can be practiced without some or all of the specific details. Other applications are possible, and therefore the following examples should not be construed as limiting.

[0026] FIG. 1 illustrates an exemplary photonics assembly 100 that may include an interface 180, a light emitter 110, a detector 130, and a controller 140. The interface 180 may include an exterior surface of a device that may accommodate the transmission of light therethrough. It may be understood that the interface 180 may accommodate the transmission of light at an operating wavelength. In some examples, the operating wavelength may be a wavelength of light used to measure a sample property. Additionally, in some examples, the interface 180 may be opaque to visible light, as visible wavelengths of light may not be used to measure a sample property. In some examples, the photonics assembly 100 may include an aperture structure 160 that includes regions that provide different functions. In some examples, the regions of the aperture structure 160 may include one or more of a transparent region 170, an opaque region, a semi-transparent region, a reflective region, a region having a refractive index different from the surrounding material, any combination thereof, etc. The aperture structure 160 may direct and / or control the location of the emission of light into the measurement sample volume 120 and the collection of the returned light from the measurement sample volume 120. By controlling the position and / or angle of light entering measurement sample volume 120, the light entering and / or exiting measurement sample volume 120 can be selectively configured. As shown in FIG. 1 , aperture structure 160 may be a single interface with multiple apertures, or the interface may be divided into different windows, such as an emission window and one or more collection windows. In some examples, a photonics assembly may include photonics die(s), an outcoupler, optical components that receive light from the photonics die(s), free-space optics, etc., but does not include a sample. Although shown in FIG. 1 , measurement sample volume 120 is not included in photonics assembly 100. The terms “photonics assembly” and “photonics system” may be used interchangeably herein.

[0027] During operation of the photonics assembly 100, the measurement sample volume 120 may be positioned in proximity to or in contact with at least a portion of the photonics assembly 100, such as the photonics system interface 180. The one or more light emitters 110 may be coupled to a controller 140. The controller 140 may send a signal (e.g., a current or voltage waveform) to control the light emitters 110, which may emit light. The one or more light emitters 110 may be included in one or more photonics dies 115, which are described in detail herein. Although discussion herein may refer to the photonics die(s) 115 as emitting light, it may be one or more light emitters 110 that are part of the photonics die 115 that may generate light. Thus, discussion of a photonics die that emits light is understood to encompass a light emitter that generates light, so long as the light emitter is part of the photonics die.

[0028] In some examples, the photonics die 115 may emit light, which may be reflected by an outcoupler or mirror 150 included in the photonics die 115, and the light may be received by the lens 190. The lens 190 may be a free-space lens and is referred to as a single lens, but in some examples, the lens 190 may be multiple lenses. Additionally, the lens 190 may be a single lens that performs multiple functions, or multiple lenses that each perform a function, such as collimating the light and / or beam steering or beam shaping the light received from the photonics die 115. The lens 190 is described in more detail herein with reference to FIGS. 2A-8. The light from the lens 190 may be directed to the diffusing element 135. The diffusing element 135 may move in one or more dimensions, and the movement of the diffusing element 135 may be discrete or continuous. In some examples, discrete diffusing elements 135 can advance between different positions, while continuous diffusing elements can oscillate or otherwise move continuously without stopping at a specific position. In further examples, diffusing elements 135 can be movable to any target position within a desired range, or can only physically move between a few fixed positions. Diffusing elements 135 can generate an illumination profile of light based at least in part on the angular spacing of light received from lens 190 and the full range of angles of light incident on the diffuser. Diffusing elements are described in further detail with reference to FIGS. 2A-8.

[0029] Depending on the properties of the measurement sample volume 120, the light can penetrate into the measurement sample volume 120, reach one or more scattering sites, and return (e.g., be reflected and / or scattered back) toward the photonics assembly 100 over a controlled path length. The returning light returning to the photonics assembly 100 may be directed, collimated, focused, and / or expanded. The returning light may be directed toward the detector 130. The detector 130 may detect the returning light and send an electrical signal to the controller 140 indicative of the amount of light detected. In some examples, the detector 130 may include optical elements for directing, collimating, focusing, expanding, or otherwise shaping the returning light from the sample.

[0030] Additionally or alternatively, the light emitter 110 can optionally emit light toward a reference object (not shown in FIG. 1 ). The reference object can include, but is not limited to, mirrors, lenses, and / or filters to redirect the light toward an optical system, and may redirect the light toward a sample with known optical properties. The optical system can direct, collimate, focus, expand, or otherwise shape the returning light toward the detector 130. The detector 130 can measure the light reflected from the reference object and generate an electrical signal indicative of this reflected light for quality purposes. As shown in FIG. 1 , the light emitter 110 emits light toward an outcoupler or mirror 150. In some examples, the detector 130 may not have unique and / or individual corresponding pixels for each of the sample and reference signals. In some examples, the optical system can direct the reference light onto the same pixel(s), and measurements can be time-multiplexed. Additionally, in some examples, detector 130 may include one or more pixels, each of which may output an individual signal based on the light collected or returned by that pixel. Thus, any individual signal generated by detector 130 may represent a signal or a reference depending on which part of the system the light striking or returned by that pixel is coming from.

[0031] The controller 140 can be configured to receive one or more electrical signals from the detector 130, and the controller 140 (or another processor) can determine characteristics of the sample from the received electrical signals. In some examples, the detector 130 can generate a signal in response to receiving and / or absorbing the returning light, and in some examples, can generate at least two electrical signals, one electrical signal indicative of the returning light that may be reflected and / or scattered from the measurement sample volume 120 and another electrical signal indicative of the light reflected / scattered from the reference object. Additionally, the detector 130 can be configured to send the electrical signals to the controller 140. In some examples, each of the different electrical signals can be time-multiplexed signals. For example, each of the different electrical signals for the measurement sample volume and the reference object can alternate with each other at different times. Further to this example, the signal during a first period can represent the reference object, and the signal during a second period can represent the sample. In other cases, two or more electrical signals can be received simultaneously by different detector pixels, and each of the electrical signals can include information indicative of different light information, such as wavelength and intensity.

[0032] In general, photonics systems can be used to sense and process light in electronic systems and devices. Some photonics assemblies can be used to transmit light and can be included in electronic devices such as mobile devices, tablets, smartphones, etc., which can be used for various purposes, such as optical communication, environmental sensing, and / or biometric sensing. Mobile electronic devices are becoming increasingly popular, and these devices are often small enough to be portable and / or handheld. The architecture of these mobile devices can include various components, including photonics circuitry, which can affect the size of the device in which it is incorporated.

[0033] With the increasing emphasis on smaller and more compact electronic devices, the size and thickness of components within an electronic device may be limited. In some examples, a specific size of the electronic device is targeted, and each component within the electronic device is given a maximum form factor or area that the component(s) may occupy within the electronic device. Thus, the physical configuration of individual components, such as optical elements, light emitters, detectors, and integrated circuits, such as photonics integrated circuits and / or photonics assemblies, may become increasingly important to the form factor of the device. In some examples, the photonics assembly 100 may be included in various handheld or portable electronic devices, such as mobile devices, and wearable devices, such as smartphones, tablets, watches, or any type of device that may be worn by a user, such as a cuff or bracelet.

[0034] FIG. 2A illustrates an optical system. The optical system 200 is rotated approximately 90 degrees from the view of the photonics assembly in FIG. 1. The optical system 200 may include multiple photonics dies 215 and an output coupler 250. The photonics dies may include multiple photonics dies 215, and each individual photonics die may be referenced with a separate element number, such as 215a, 215b, 215c, etc. Although eight photonics dies 215 are shown in FIG. 2A, any suitable number of photonics dies 215 may be included in the optical system 200. Similarly, each individual output coupler 250 may be referenced with a separate element number, etc.

[0035] In some examples, each of the photonics dies 215 may include multiple lasers, each of which may emit over a different wavelength range, with the lasers of the corresponding photonics die 215 emitting at unique wavelengths within the wavelength range of the photonics die 215. The photonics dies 215 may be integrated into a photonics system that can combine all emitted light across all wavelength ranges into a single waveguide via an optical multiplexer. In some examples, this light can be split into multiple output waveguides, with each waveguide reaching the output coupler 250. In some examples, when a single laser produces a single wavelength, that single wavelength of light from the single laser can be routed to all of the output couplers 250. Thus, when a single wavelength of light from a single laser reaches free space, there may be multiple simultaneous light beams that all came from the same single laser on the same photonics die. When different single lasers on different photonics dies emit light of different wavelengths, the light of the different wavelengths can all pass through the same output coupler and thus through the same free-space optical system. It will be appreciated that the number of photonics dies 215 and the number of output couplers 250 may differ from one another (e.g., there may be more photonics dies 215 than output couplers 250, or there may be more output couplers 250 than photonics dies 215, or both).

[0036] Optical system 200 can generate a predetermined illumination profile, which can include both controlling the spatial profile of the light beam and providing a predetermined range of light angles at diffusing element 235, as will be described in further detail with reference to Figures 2B-2D and 3-8. The range of beam angles incident on diffusing element 235 can be a wide range of beam angles such that optical system 200 can reduce noise and therefore adjust accordingly.

[0037] As shown in FIG. 2A , the optical system 200 can include a photonics die 215 that can provide light to the optical subsystem 290 via output couplers 250. In some examples, all of the light emitted by the photonics die 215 can be coupled into a single waveguide. This single waveguide can provide light to each of the output couplers 250. In some examples, the light received by the optical subsystem 290 from the output couplers 250 can be collimated, directed, and / or deflected at various angles by the optical subsystem 290 toward a measurement sample volume (not shown in FIG. 2A ). The optical subsystem can include one or more elements to achieve the desired functionality. In some examples, the optical subsystem can include a collimation lens array 292 and a deflection prism array 294. In some examples, the output couplers 250 can provide light to the collimation lens array 292 of the optical subsystem 290. Collimation lens array 292 collimates the light and may direct the light to a deflecting prism array 294, also in optical subsystem 290. Deflecting prism array 294 may deflect the light at various angles depending on which output coupler 250 the light was received from. The deflected light from deflecting prism array 294 may be directed to a diffusing element 235 and then to a measurement sample volume.

[0038] In some examples of FIG. 2A, the diffusing element 235 may be positioned within a range of approximately 500 microns to 3 millimeters from the measured sampling interface. The diffusing element 235 may be positioned sufficiently close to the measurement sample volume so that the path length can be controlled. Additionally, the distance between the output coupler 250 and the diffusing element 235 may be approximately 2.5 to 5 millimeters. As the light leaves the photonics die 215, the light beam may continue to diverge as it passes through each element of the optical system 200. In some examples, the beam divergence of the focused beam in its widest dimension may be 1 to 5 microns or less as the light exits the photonics die 215, and then the beam divergence of the focused beam in its widest dimension may be approximately 100 to 300 microns as it enters the collimation lens array 292. The beam divergence of the focused beam may expand to approximately 2.5 mm in its widest dimension when it enters the diffuser, and then expand to approximately 3.0 mm or a range of approximately 2 mm to 4 mm in its widest dimension when it enters the measurement sample volume. The corresponding angular range also changes as the focused beam expands as it passes through optical system 200. The angular range and beam size at the measurement sample volume are discussed in further detail with reference to Figures 2C and 2D.

[0039] In some examples, a photonics assembly can be used to measure signal strength from the measurement sample volume of Figure 1. It can be understood that all spatial locations can receive all wavelengths. When probing with one angle of launch light and one signal is present on the detector, coherent noise can be high for any single launch angle, but multiple uncorrelated measurements can be used to help distinguish the signal. One way to determine signal strength in the presence of coherent noise is by acquiring multiple uncorrelated measurements with the same nominal underlying signal but with different uncorrelated coherent noise views. In some examples, the uncorrelated coherent noise views can be provided by decohered light. Decohered light is light that does not interfere to provide coherent noise. Providing a desired number of unique coherent noise views can be achieved by using a phase shifter and a diffusive element together in the photonics assembly. For example, a phase shifter can provide light to an output coupler, resulting in decohered light. There are various ways to change the coherent noise pattern on the detector, such as by changing the wavelength of the light source or by changing the polarization of the light. Another way to change the coherent noise pattern on the detector can depend on how the light is launched onto the sample, which is described in more detail below with reference to Figures 2B-2D and 3-8.

[0040] In one example, two different angles of returning light may have the same path length when the light is reflected by the measurement sample volume and two signals are measured at a detector (not shown in FIG. 2A). The two signals may have different coherent noise patterns, and therefore, even if all other factors are held constant, the two signals will have different intensities because both signals are the related signal plus some amount of coherent noise. By examining various angles, each of which contains some coherent noise, when the signals from different angles of light are averaged together, the coherent noise can approach zero mean, and the signals can converge to an accurate signal or measurement signal free of coherent noise. In some examples, there may be deviations in the path length signals along different paths (e.g., in a system that may be designed to pick up a single scattering event, many returning photons may encounter multiple scattering events). In some examples, multiple signals with nearly similar signal characteristics (e.g., similar path lengths and similar sample characteristics) but with angles that are different enough to create different noise views, and the signals may be averaged, which may serve to reduce the effects of noise.

[0041] In FIG. 2A , the optical system may include eight output couplers. Eight output couplers are shown for illustrative purposes only, and it can be understood that any number of output couplers can be used. By using multiple output couplers 250, the optical system 200 does not rely on the diffusing element 235 to generate the coherent noise view. For example, if the optical system used only one output coupler, the diffusing element would have to be much larger to diffuse the light into the desired angular range, and it would be difficult to control the movement of the diffusing element and the repeatability of the diffusing element position or set of positions. While this type of diffusing element could be used in an optical system with a single photonics die, the movement of the diffusing element is very sensitive to any change in position—even a small change would generate a new coherent noise view—thus making it difficult to revisit the same coherent noise view from the same position due to sensitivity. Because the optical system 200 uses multiple output couplers 250, the number of positions to which the diffusing element 235 can move may be reduced compared to a system with a single output coupler. In some embodiments, the positions to which diffusing element 235 can move may be a short distance apart from one another, and thus diffusing element 235 has a shorter total distance to move than in other embodiments where the distance between positions is greater. In some embodiments, using a greater number of output couplers 250 to achieve a greater number of coherent noise views may result in fewer positions visited by diffusing element 235. In this example, diffusing element 235 can be smaller because it can move to fewer positions.

[0042] In some embodiments, the diffusing element 235 may move between positions faster than the wavelength of light changes. For example, the diffusing element 235 may move to or pass through more than one position in the same amount of time it takes the emitter to output light of a single wavelength. Thus, to the extent that the diffusing element 235 occupies multiple such positions while light of a particular wavelength is being emitted, the positions can be said to be "nested" within the particular wavelength.

[0043] In other embodiments, the wavelength of light may change faster than the position of the diffusing element 235 changes. That is, the diffusing element 235 may be positioned at a first position for the same length of time as the emitter outputs multiple wavelengths. Because the wavelength may change while the diffusing element 235 may remain in the same position, the wavelength may be said to be "nested" within the position of the diffusing element 235. In this embodiment, each diffuser position may be visited only once per overall measurement, and multiple wavelengths may be used once per diffuser position. Generally, in some embodiments, diffuser positions may be nested within wavelengths, and in other embodiments, wavelengths may be nested within diffuser positions.

[0044] In some examples, each of the output couplers 250 may be coupled with a phase shifter (not shown in FIG. 2A ), which may be included in the photonics die 215 or may be external to the photonics die 215. The phase shifter may generate a unique coherent noise view very rapidly, for example, on the order of every 100 picoseconds. While a phase shifter may be capable of generating a unique coherent noise view at a rate sufficient for coherent noise mitigation of the optical system, the phase shifter may occupy too much space and require too much operating power, so a combination of the diffusing element 235 and the phase shifter may better meet photonics assembly specifications due to space and power considerations.

[0045] In some examples, light emitted by the photonics die 215A may provide light to at least the output coupler 250A, which reflects the light to the optical subsystem 290. The optical subsystem 290 may include two optical components: a collimation lens array 292 and a deflecting prism array 294. In some examples, the functions of the collimation lens array 292 and the deflecting prism array 294 may be combined into a single optical subsystem 290. In some examples, the collimation lens array 292 may collimate the light received from the output coupler 250 and direct the light to the deflecting prism array 294. The deflecting prism array 294 may direct the light at a different angle to the diffusing element 235. Prisms are generally used to redirect light through refraction or internal reflection. In some examples, the amount a light beam is bent depends on the apex angle of the prism and the refractive index of the prism material. The angle of incidence of the light may also be used to adjust the apex angle of the prism.

[0046] 2A , output coupler 250A provides light to collimation lens array 292, which can collimate the light and direct it to deflecting prism array 294. Deflecting prism array 294 can then predictably deflect the collimated light toward diffusing element 235 at a predetermined angle. The angle at which light exits deflecting prism array 294 depends on the position in output coupler 250 at which the light is received. For example, light received from output coupler 250A may be directed toward diffusing element 235 at a different angle than light received from output coupler 250D, or light received from output coupler 250A may be at a steeper angle to deflecting prism array 294 than light received from output coupler 250D. Deflecting prism array 294 may be designed to direct each light beam to a predetermined position and angle at which it enters diffusing element 235. Continuing with this example, the turning prism array 294 can direct the light to the diffusing element 235. The diffusing element can provide an illumination profile 245, which is shown in far-field angle space and represents the beam angle of the light provided by the diffusing element 235. In some examples of the optical system 200, the illumination profile 245 can have a wide dimension and a narrow dimension. The illumination profile 245 in FIG. 2A shows the wide dimension. The illumination profile 245 is described in further detail with respect to FIGS. 2B and 2C.

[0047] In general, the diffusing element 235 may be capable of generating multiple coherent noise views by moving to multiple positions. However, the more the diffusing element 235 moves, the less reliable and repeatable each position becomes. Therefore, even though the diffusing element 235, like a phase shifter, can sufficiently generate sufficient coherent noise views for the photonics assembly by changing its position, the combination of the diffusing element 235 and a phase shifter in the photonics assembly provides a more reliable means of mitigating coherent noise while staying within the specifications of the photonics assembly, such as system power, size, and number of available electrical connections. Furthermore, the ability to control the beam spread and angular range of light between the output coupler to the optical subsystem 290 and between the optical subsystem 290 and the diffusing element 235 allows the optical system 200 to reliably generate a predetermined illumination profile of light.

[0048] In some examples, the diffusing element 235 can receive light having a certain input angle and diffuse that light to a larger output angular spread. In the example of FIG. 2A , because the diffusing element 235 receives eight light beams from eight output couplers 250, the diffusing element 235 can output eight light beams with eight angular spreads. Additionally, the diffusing element 235 can be moved to multiple positions to mitigate coherent noise within the optical system 200. The positioning of the diffusing element 235 and the amount by which the diffusing element 235 moves to generate a new coherent noise view are determined by the diffuser design, e.g., an 8-degree angle. In some examples, the diffuser noise can depend at least in part on the repeatability of the positioning of the diffusing element 235. In some examples, the diffuser noise can be the position-to-position variation in the total optical power throughput of the system as the diffusing element 235 moves. The diffuser noise can be sub-wavelength independent and sample independent, to the extent that detailed scattering characteristics can be affected, and can be primarily determined by the structure / design of the diffusing element 235 and secondarily influenced by the rest of the system.

[0049] In some examples, each wavelength or wavelength range of light emitted by a corresponding light source can pass through the diffusing element 235 at the same set of diffuser states or positions. That is, the diffusing element 235 may be moved to a first position for a first wavelength or wavelength range of light emitted by a first photonics die, then the diffusing element 235 may be moved to a second position for the first wavelength of light, then to a third position, and so on. Next, the diffusing element 235 may be moved to the same first position for a second wavelength or wavelength range of light emitted by a second photonics die, then to the same second position, then to a third position, and so on. As a result, the photonics assembly can interrogate each wavelength or wavelength range emitted by each photonics die at each diffuser position. When multiple wavelengths of light experience different diffusing element positions, diffuser noise can become intertwined with wavelength variations. In that case, it can be difficult to verify which portions of the signal can be attributed to diffuser noise as opposed to actual signal changes due to wavelength changes, and therefore which portions of the signal are relevant to the measurement of the sample.

[0050] In Figure 2A, there are eight output couplers 250 with phase shifters, and because each output coupler provides light, this allows the diffusing element 235 to move eight times slower or eight times less, and therefore there is less reliance on the diffusing element 235. Although eight photonics dies and eight output couplers are described with reference to Figure 2A, this is for convenience and ease of explanation, and any suitable number of photonics dies and any suitable number of output couplers may be used in the photonics assembly.

[0051] The diffusing element 235 receives light at a predetermined angle and diffuses the light to provide an angular output spread. In the example of FIG. 2A , the diffusing element 235 receives eight input light beams and then provides eight angular output spreads to generate the illumination profile 245. In some examples, the diffusing element 235 can generate approximately an 8-degree circle for each light beam received from the deflecting prism array 294. By overlapping the light beams, the diffusing element 235 can generate the illumination profile 245 that appears as a "stripes" of light. Generally, there are four main dimensions that can be altered for path length control: the x dimension, the y dimension, the x-angular dimension, and the y-angular dimension. Dimensions and path length control are described in more detail below with reference to FIGS. 2C and 2D .

[0052] As shown in FIG. 2A , the light beams from the output couplers 250 may overlap with each other to generate the illumination profile 245. Because there are eight output couplers, eight overlapping circles are shown in FIG. 2A . Eight output couplers 250 are used for illustrative and descriptive purposes only; any suitable number of output couplers 250 may be used in the optical system 200. The overlap of the light beams in the illumination profile 245 and the circular shape of the light beam from the diffusing element 235 depend, at least in part, on the diffusing element design. Because coherent noise mitigation is more effective when covering a large portion of the illumination profile's angular space, the angular overlap is a result of the light beam's conical shape in angular space. In some examples, different shaped light beams in angular space may exit the diffusing element 235 depending on the diffusing element design. In some examples, the diffusing element 235 can diffuse a rectangular light beam in angular space, resulting in the diffused light covering a specified angular space with little or no overlap. In some examples, the diffusing element may be any suitable shape, such as rectangular, square, linear, circular, elliptical, etc. In some examples, a circular diffusing element may produce a circular far-field angle profile.

[0053] FIG. 2B shows an optical system. FIG. 2B is the same view of the photonics assembly shown in FIG. 1, which can be referred to as a side view, with FIG. 2B showing the illumination profile in a narrow dimension and FIG. 2A showing the illumination profile in a broad dimension. Because FIG. 2B is viewed from the side, only one photonics die 215 and one output coupler 250 are shown, but there are multiple photonics dies 215 and multiple output couplers 250 that cannot be seen from the side. The optical system 200 of FIG. 2B can include components numbered similarly to FIG. 2A and can represent elements having similar features and functions.

[0054] Similar to FIG. 2A, FIG. 2B includes a photonics die 215 that emits light through an output coupler 250 toward a collimation lens array 292. The collimation lens array 292 can collimate the light, and a deflecting prism array 294 can receive the collimated light and deflect it toward a diffusing element 235. The diffusing element 235 can then provide the light to a measurement sample volume. In some examples, the light entering the measurement sample volume can have an illumination profile described with reference to FIG. 2A. Similar to FIG. 2A, the diffusing element 235 can generate an 8-degree circle from each light beam received from the output coupler 250.

[0055] In general, the optical system 200 of FIG. 2B provides out-of-phase light through the photonics die 215. The light can be combined on the diffusing element 235 to generate a predetermined illumination profile, which can include a spatial profile of the light as well as a predetermined angular spread of the light. The narrow dimension illumination profile generated in FIG. 2B can provide path length control of the emitted light through the measurement sample volume. If the illumination profile in the narrow dimension varies from a predetermined value, the optical system may be less effective at controlling the path length. Narrow and wide dimension optical systems 200 are described in further detail with reference to FIGS. 2C and 2D.

[0056] Figure 2C is a representation of an illumination profile 245 in angular space generated by a diffusing element of a photonics assembly. Figure 2C is an illumination profile of a light beam angular spread generated by a diffusing element of the optical system described with reference to Figures 2A and 2B. The optical system can generate a predetermined angular space or light beam spread of the angle of the illumination profile 245 incident on the sample. Generating an illumination profile of light (e.g., in both spatial profile and angular space) for a predetermined angular space allows for effective mitigation of coherent noise before the light reaches the sample.

[0057] Generally, coherent noise mitigation is more effective when it covers a large portion of the angular space of the illumination profile. As previously mentioned, the diffusing element may be an 8-degree circular diffuser so that the light beam can be extracted at approximately 8 degrees. In some examples, the diffusing element may provide an angular space ranging from 40-60 degrees by 4-15 degrees. An 8-degree circular diffuser is described herein for illustrative purposes only, as any suitable diffuser having any suitable angular range may be used in each of the described embodiments.

[0058] In some examples, the predetermined beam angle exiting the diffusing element and incident on the sample may be approximately 50 degrees in the first dimension and approximately 8 degrees in the second dimension. Additionally, while 50 degrees by 8 degrees is used for illustrative purposes, any angular space may be used. For example, the angular space may range from 40-60 degrees by 4-15 degrees. The shape of the light beam in angular space is due, at least in part, to the overlapping angles of the light beams, as described with reference to FIG. 2A. Additionally, the light beam angle may be larger in one dimension than in another due to profile sensitivity. In one dimension of angular space, variations may be less sensitive when controlling the optical path length due to geometric considerations of the optical system, while in the second dimension of angular space, variations may be more sensitive and have a smaller angular spread.

[0059] FIG. 2D is a representation of an illumination profile 255 of the shape and size of a light beam. The beam size incident on the sample may be approximately 3 mm in a first direction and approximately 0.2 mm in a second direction. In general, the larger the illumination profile of the light incident on the measurement sample volume, the more signal can be detected from the measurement sample volume; therefore, it may be desirable to increase the illumination profile of the light incident on the measurement sample volume. Similar to the beam angle spread in angle space, the beam size may be less sensitive to variations in a first direction than in other second directions due to optical path length control.

[0060] FIG. 3A illustrates an exemplary optical subsystem within an optical system. The optical system 300 of FIG. 3A includes an optical system 303, a first lens 305, a second lens 307, and a diffusing element 310. The optical system 300 illustrates the wide angular range of light provided by the diffusing element compared to the angle at which the light exits the optical system 303. The optical system 303 may include one or more photonics dies and one or more output couplers. The optical system 303 can provide light to the first lens 305, which can propagate the light along an optical path 306 to the second lens 307. In some examples, the first lens 305 and the second lens 307 can be cylindrical lenses for generally collimating the light into overlapping beams. It can be understood that the optical paths 306, 308, and 311 illustrate only the outer optical beams that define the outer boundaries of the region through which all the optical beams can propagate. For example, light path 306 may show only two outer light beams, but there may be multiple overlapping light beams between the two outer light beams. The outer light beams of light paths 306, 308, and 311 show the general shape and direction of the light paths. A second lens 307 may provide light to a diffusing element 310 along light path 308. Once the light passes through the diffuser, the diffusing element angular range is significantly greater than the smaller separation of angles provided by light system 303.

[0061] 3B-3C show an example optical system without a diffusing element and the corresponding far-field angular separation of light. In FIG. 3B, optical system 301 includes optical system 303, which provides light along optical paths 312 and 313 to lens 317. The light can pass through lens 317 to reach sample volume 320. In some examples, lens 317 can be a slow-axis collimator. In FIG. 3B, the light sources in optical system 303 can be separated by Δx. Light from the light sources can propagate along optical paths 312 and 313, each having a beam spread. The light can proceed to lens 317, which can collimate the light, and then the light can proceed to sample volume 320. In FIG. 3B, optical system 303 can be separated from lens 317 by a distance 319.

[0062] 3C, diagram 302 includes points 321 and 322 that indicate the angular separation of light beams along θx from light sources separated by Δx. In some examples, the angular separation between light sources, which is Δθ, can be the arctangent of the quantity Δx divided by distance 319.

[0063] 3D-3E show an exemplary optical system with a diffuser and corresponding non-overlapping centroid locus far-field angular separation. Optical system 303 is similar to optical system 302 of FIG. 3B, but with the addition of diffusing element 310. That is, optical system 303 may include optical system 303 providing light along optical paths 312 and 313 to lens 317. Lens 317 passes the light to diffusing element 310, after which the light passes through sample 320. In FIG. 3D, the light sources of optical system 303 may be separated by Δx, and optical system 303 may be a distance 319 from lens 317. The light shown in FIG. 3D appears similar to the light in FIG. 3B, but diagram 304 in FIG. 3E shows the non-overlapping far-field angles after diffusing element 310.

[0064] In Figure 3E, diagram 304 includes beam spread centroids 323 and 324 showing the angular separation of light beams along θx from light sources separated by Δx. In some examples, the angular separation between the light sources, Δθ, may be the arctangent of the quantity Δx divided by the distance 319. In Figure 3E, Δθ diffuser is greater than Δθ, and the beam spread also covers a larger area than would result from not using a diffusing element. In Figure 3E, the light beams may be uncorrelated as long as their far-field centroids do not overlap each other.

[0065] 3F-3G show an exemplary optical system having a diffuser and corresponding overlapping centroid loci with far-field angular separation. Optical system 305 is similar to optical system 303 of FIG. 3D and also includes diffusing element 310. That is, optical system 305 may include optical system 303 providing light along optical paths 312 and 313 to lens 317. Lens 317 passes the light to diffusing element 310, after which the light passes through sample 320. In FIG. 3F, the light sources of optical system 303 may be separated by Δx, and optical system 303 may be a distance 319 from lens 317. The light shown in FIG. 3F appears similar to the light in FIG. 3D, but diagram 306 in FIG. 3G shows overlapping far-field angles after diffusing element 310, as opposed to non-overlapping far-field angles after diffusing element 310.

[0066] In Figure 3G, diagram 306 includes beam spread centroid loci 326 and 327 showing the angular separation of light beams along θx from light sources separated by Δx. In some examples, the angular separation between the light sources, Δθ, can be the arctangent of the quantity Δx divided by distance 319. In Figure 3G, Δθ diffuser along θx is greater than Δθ, and the beam spread also covers a larger area than would result from not using a diffusing element. In Figure 3G, the overlapping far-field patterns can be dominated by light passing through diffusing element 310.

[0067] FIG. 4 illustrates an exemplary optical subsystem of an optical system. In FIG. 4, optical system 400 is a view of a photonics assembly showing broad dimensions. FIGS. 4-8 illustrate similar views of the photonics assembly showing broad dimensions, including components similarly positioned relative to one another within the optical system. Optical system 400 can generate a wide launch beam in the broad dimension or "stripe" width of the beam shape. Similar to FIGS. 2A and 2B, optical system 400 of FIG. 4 includes a photonics die 415, an output coupler 450, an optical subsystem 490, and a diffusing element 435.

[0068] In some examples, optical subsystem 490 is a collimating lens array 492 and a diverging array 494. Collimating lens array 492 can collimate light to provide control of light beam direction for diverging array 494. Diverging array 494 can also be a deflecting array 494, and light can be deflected at an appropriate angle for diffusing element 435, and thus may be referred to herein as a deflecting and diverging array. Although specific examples of components within the optical subsystem are described, any suitable optical components may be used within the photonics assembly to achieve a predetermined illumination profile for diffusing element 435 and incident on the measurement sample volume.

[0069] FIG. 5 illustrates an exemplary optical subsystem of an optical system. In FIG. 5, optical system 500 is a diagram of a partial photonics assembly showing broad dimensions. Similar to FIGS. 2A and 2B, optical system 500 of FIG. 5 includes photonics die 515, output coupler 550, optical subsystem 590, and diffusing element 535. Optical subsystem 590 is a decentered lens array. Decentred lens array 590 may be a single optical element that combines the functionality of the optical components of the optical subsystem of FIG. 2A. Decentred lens array 590 can substantially combine the functions of a collimation lens array and a deflecting prism array. Decentred lens array 590 includes a group of lenses that are decentered from a respective common axis of each lens in the array and can steer light toward diffusing element 535.

[0070]

[0031] Figure 6 illustrates another example of an optical subsystem of an optical system. Similar to optical system 500 of Figure 5, optical system 600 of Figure 6 is a diagram of a partial photonics assembly showing broad dimensions. Optical system 600 of Figure 6 includes a photonics die 615, an output coupler 650, an optical subsystem 690, and a diffusing element 635.

[0071] In the example of Figure 6, optical subsystem 690 is a decentered toroidal lens array. Decentred toroidal lens array 690 may be a single optical element that combines the functionality of the optical components of the optical subsystem of Figure 5. Decentred toroidal lens array 690 can approximately combine the functions of a collimation lens array and a polarizing divergence array. Decentred toroidal lens array 690 can collimate light in a narrow dimension of the illumination profile, at least partially collimate light in a wide dimension using two different focal lengths, and steer a light beam in a wide dimension toward diffusing element 635.

[0072] FIG. 7 illustrates another example of an optical subsystem of an optical system. In the example of FIG. 7, the optical subsystem 790 includes a photonics die 715, an output coupler 750, a cylinder lens array 792, and a crossed cylinder lens array 794. The cylinder lens array 792 and the crossed cylinder lens array 794 can combine the functions of a collimating array and a deflecting array. The cylinder lens array 792 can collimate light in a first direction and not collimate light in a second direction. For example, the cylinder lens array 792 may receive light from the photonics die 715, and the light may have a fast axis and a slow axis. The fast axis may have light that diverges faster than the slow axis. In some examples, when the cylinder lens array 792 is used to collimate light, the cylinder lens array 792 may have a short focal length in the fast axis direction. Additionally, the crossed cylinder lens array 794 may collimate the light in a second direction rather than the first direction, and the crossed cylinder lens array 794 may have a longer focal length in the slow axis direction. The crossed cylinder lens array 794 can provide light to the sample 735.

[0073] FIG. 8 shows another example of the optical subsystem of optical system 800. In the example of FIG. 8, optical subsystem 890 includes a fast-axis collimator array 892 (which may be, for example, a cylinder array) and a slow-axis focusing and steering array 894. The fast-axis collimator array 892 and the slow-axis focusing and steering array 894 can combine the functionality of the cylinder lens array and crossed cylinder lens array of FIG. 7 along with singlet lenses. The fast-axis collimator array 892 may receive light from a photonics die 815 having a fast axis and a slow axis. The fast-axis collimator array 892 can collimate the light along the fast axis but not the slow axis. The slow-axis focusing and steering array 894 can focus the light along the slow axis and steer the light toward the diffusing element 835. While specific optical elements are described herein, there may be various ways to achieve the appropriate illumination profile incident on the diffuser and incident on the measurement sample volume. In some examples, additional optical elements may be used between the photonics die and the measurement sample volume. In some examples, the photonics assembly may not include a diffusing element. In some examples, the light beam may be folded within the photonics assembly. In some examples, the light beam may be split, then the beam may be allowed to expand in angle and spatial profile, and then the beams may be combined together. Other components of the photonics assembly may be varied, including, but not limited to, the optical components of the photonics assembly, the positioning of the optical components relative to each other, the number of light sources, the type of diffusing element, any combination thereof, etc., so long as an illumination profile having a predetermined beam angle and spatial profile is incident on the diffuser and incident on the measurement sample volume.

[0074] FIG. 9 shows an exemplary block diagram of an optical device 900, which may in some cases take the form of any of the optical devices described with reference to FIGS. 1-8 . The optical device may include a processor 902, input / output (I / O) mechanisms 904 (e.g., input / output devices such as a touchscreen, a crown or buttons, an I / O port, or a haptic interface), one or more optical units 906 (e.g., photonics dies that may include laser diodes), memory 908, sensors 910 (e.g., an optical sensing system), and a power source 912 (e.g., a rechargeable battery). The processor 902 may control some or all of the operation of the optical device 900. The processor 902 may communicate, either directly or indirectly, with some or all of the components of the optical device 900. For example, a system bus or other communication mechanism 914 may provide communication between the processor 902, the I / O mechanisms 904, the optical unit 906, the memory 908, the sensors 910, and the power source 912.

[0075] Processor 902 may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, processor 902 may be a microprocessor, a central processing unit (CPU), an application specific integrated circuit (ASIC), a digital signal processor (DSP), or a combination of such devices. As used herein, the term "processor" is intended to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitable computing element(s).

[0076] It should be noted that components of optical device 900 may be controlled by multiple processors. For example, select components of optical device 900 (e.g., sensor 910) may be controlled by a first processor, and other components of optical device 900 (e.g., optical unit 906) may be controlled by a second processor, and the first and second processors may or may not be in communication with each other.

[0077] The I / O mechanism 904 may send and / or receive data from a user or another electronic device. An I / O device may include a display, a touch-sensitive input surface, one or more buttons (e.g., a graphical user interface "home" button), one or more cameras, one or more microphones or speakers, one or more ports such as a microphone port, and / or a keyboard. Additionally or alternatively, an I / O device or port may transmit electronic signals over a communications network, such as a wireless and / or wired network connection. Examples of wireless and wired network connections include, but are not limited to, a cellular connection, a Wi-Fi® connection, a Bluetooth® connection, an IR connection, and an Ethernet connection.

[0078] The memory 908 can store electronic data that can be used by the optical device 900. For example, the memory 908 may store electronic data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, and data structures or databases. The memory 908 can be configured as any type of memory. By way of example only, the memory 908 may be implemented as random access memory, read-only memory, flash memory, removable memory, other types of storage elements, or a combination of such devices.

[0079] The optical device 900 may also include one or more sensors 910 located substantially anywhere on the optical device 900. The sensor(s) 910 may be configured to sense one or more types of parameters, such as, but not limited to, pressure, light, touch, heat, movement, relative motion, biometric data (e.g., biological parameters), etc. For example, the sensor(s) 910 may include thermal sensors, position sensors, light or optical sensors, accelerometers, pressure transducers, gyroscopes, magnetometers, health monitoring sensors, etc. Additionally, the one or more sensors 910 may utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasonic, piezoelectric, and thermal sensing technologies.

[0080] The power supply 912 may be implemented by any device capable of providing energy to the optical device 900. For example, the power supply 912 may be one or more batteries or rechargeable batteries. Additionally or alternatively, the power supply 912 may be a power connector or power cord that connects the optical device 900 to another power source, such as a wall outlet.

[0081] In the foregoing description, for purposes of explanation, specific terminology was used to provide a thorough understanding of the described embodiments. However, it will be apparent to those skilled in the art that specific details are not required to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise form disclosed. It will be apparent to those skilled in the art that numerous modifications and variations are possible in light of the above teachings.

[0082] Although the embodiments of the present disclosure have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will be apparent to those skilled in the art, and such changes and modifications are to be understood as being included within the scope of the embodiments of the present disclosure as defined by the appended claims.

Claims

1. a photonics die including a plurality of output couplers; an optical emitter configured to emit light; A movable diffuser; a photonics assembly comprising: the photonics die is configured to split the light and transmit the light to each of the plurality of output couplers; the movable diffuser is positioned to receive overlapping light beams from the plurality of output couplers and transmit diffused light to a sample; The detector is positioned to receive light returned from the sample.

2. 10. The photonics assembly of claim 1, comprising a plurality of phase shifters positioned to transmit light to each output coupler of the plurality of output couplers.

3. A photonics assembly as described in claim 1, comprising an optical subsystem arranged to receive the light from the plurality of output couplers and direct the light toward the movable diffuser.

4. The photonics assembly of claim 3 , wherein the optical subsystem is configured to collimate the light received from the plurality of output couplers in a first direction.

5. The photonics assembly of claim 4 , wherein the optical subsystem is configured to collimate the light received from the plurality of output couplers in a second direction.

6. The photonics assembly of claim 1 , wherein the movable diffuser is a circular diffuser.

7. 10. The photonics assembly of claim 1, wherein the overlapping light beams have an illumination profile after passing through the movable diffuser, the illumination profile having a first dimension and a second dimension.

8. The photonics assembly of claim 7, wherein the illumination profile has a first angle in the first dimension in a range of 40 to 60 degrees.

9. The photonics assembly of claim 7 , wherein the illumination profile has a first angle in the second dimension in a range of 4 to 15 degrees.

10. The photonics assembly of claim 1 , wherein the detector comprises a plurality of pixels.

11. 1. A method of operating a photonics assembly, comprising: emitting light from a light emitter; splitting the light to each of a plurality of output couplers of a photonics die; receiving the light beams from the plurality of output couplers at a movable diffuser, the light beams overlapping at the movable diffuser; diffusing the light beam using a movable diffuser to generate diffused light having an illumination profile; providing the diffused light to a sample; and and measuring the returned light received from the sample using a detector.

12. The method of claim 11 , comprising moving the movable diffuser between a set of predetermined positions.

13. The method of claim 11 , comprising repeatedly moving the movable diffuser between the set of predetermined positions according to a repeating sequence.

14. The method of claim 11 , comprising using a set of phase shifters to create a varying phase relationship between the light beams.

15. The method of claim 11 , wherein the photonics assembly comprises: an optical subsystem positioned to receive the light beams from the plurality of output couplers and direct the light beams toward the movable diffuser.

16. The method of claim 15 , wherein the optical subsystem is configured to collimate the light beams received from the plurality of output couplers in a first direction.

17. 17. The method of claim 16, wherein the optical subsystem is configured to collimate the light beams received from the plurality of output couplers in a second direction.

18. The method of claim 11 , wherein the movable diffuser is a circular diffuser.

19. The method of claim 11, wherein the illumination profile has a first angle in a first dimension in a range of 40 to 60 degrees.

20. 20. The method of claim 19, wherein the illumination profile has a first angle in a second dimension in a range of 4 to 15 degrees.

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