Optical Isolation Array

Abstract

The present disclosure relates to a light isolation array (which may also be referred to as a "light pipe" or "light pipe array") that allows for high transmission efficiency and separation of light from one location, e.g., a lens, to another location, e.g., an array of photodetector diodes (each "PD"). The light isolation array provides optical separation of input light and can eliminate crosstalk, thereby enhancing resolution by increasing the contrast of the incoming signal. The light isolation array can also protect PDs from contamination when used in outdoor devices.

Description

[Technical field]

[0001] Background of the Disclosure 1. Field of the Disclosure The present disclosure relates to a light isolation array (which may also be referred to as a "light pipe" or "light pipe array") that allows high transmission efficiency and separation of light from one location, e.g., a lens, to another location, e.g., an array of photodetector diodes (each "PD"). The light isolation array provides optical separation of input light and can eliminate crosstalk, enhancing resolution by increasing the contrast of the incoming signal. The light isolation array can also protect PDs from contamination when used in outdoor devices. [Background technology]

[0002] 2. Background of this Disclosure Currently available optical separation arrays use low numerical aperture fiber optic faceplates, which can suffer from oversampling as a result of having too many fibers for each photodiode detector. Other techniques, such as open mechanical apertures, do not allow for optical coating and can suffer from debris contamination at the aperture. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THE DISCLOSURE The disclosed optical isolation array can alleviate many of the problems of current optical isolation arrays. The disclosed optical isolation array can collect and isolate light from one location to another while providing optical isolation of the input light and eliminating or significantly minimizing crosstalk, thus enhancing resolution through increased contrast of the incoming signal. [Means for solving the problem]

[0004] In some embodiments, the light separation array comprises a transparent material having a thickness, a light entrance surface, a light exit surface, a side surface, a plurality of light guides, and a plurality of optical separation channels. The plurality of light guides may have a horizontal light entrance surface that is substantially parallel to the light entrance surface, a horizontal light exit surface that is substantially parallel to the light exit surface, and a vertical sidewall that is substantially parallel to the side surface. The plurality of optical separation channels may be openings in the material between the light guides and may extend from the light entrance surface or the light exit surface to about 5% to 100% or less of the total thickness of the material. Each optical separation channel may have a channel bottom and channel sidewalls (one of the channel sidewalls may be the same surface as the vertical sidewall of the light guide). The optical separation material may be applied to the channel bottom or the channel sidewalls. The optical separation array may transmit light from the horizontal light entrance surface to the horizontal light exit surface (or vice versa) through each light guide, while the optical separation material substantially prevents light from traveling between the individual light guides. The light guide can be a single solid material, such as solid glass or a solid polymer, that allows light to be transmitted through the material with high efficiency. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view of an optical isolation array according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of an optical isolation array according to an embodiment of the present invention. [Figure 3A] FIG. 3A illustrates an individual light guide according to an embodiment of the present invention. [Figure 3B] FIG. 3B illustrates multiple light guides according to an embodiment of the present invention. [Figure 3C] FIG. 3C illustrates multiple light guides according to an embodiment of the present invention. [Figure 4] FIG. 4 illustrates an individual light guide according to an embodiment of the present invention. [Diagram 5] FIG. 5 shows an optical isolation array according to an embodiment of the present invention. [Figure 6] FIG. 6 shows an optical isolation array according to an embodiment of the present invention. [Figure 7] FIG. 7 shows an optical isolation array according to an embodiment of the present invention. [Figure 8] FIG. 8 is a side view of an optical separation channel according to an embodiment of the present invention. [Figure 9] FIG. 9 illustrates an embodiment of the invention in which the optical separation channel is in the shape of a discontinuous ring. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Detailed Description of the Disclosure The light separation array may include a transparent material having a thickness, a light entrance surface, a light exit surface, a side surface, a plurality of light guides, and a plurality of optical separation channels. The light separation array including the light guides can be made of any material having high transmittance (e.g., greater than 90%) at wavelengths of interest for the light emitter and PD / sensor performance, for example, they can be made of a plate-like material composed of a single glass material or a single polymer material. A typical transmission wavelength range of interest for PD is about 350-2500 nm, ideally suitable for transmitting typical laser emission wavelengths of 905 nm, 1310 nm, and 1550 nm. Optical glass having a transmittance of about 97-99% in the visible and near infrared spectrum is a suitable example.

[0007] 1 and 2 show a light separation array 1 made from a transparent plate-like material having a thickness 2, a light entrance face 3, a light exit face 4, side faces 5, a number of light guides 6, and a number of optical separation channels 7. The plate-like material is a material having a length and width substantially greater than its depth, such as a flat glass sheet. Suitable transparent materials include most glass and polymeric materials that transmit more than 90% of light at the desired wavelength. Although FIGS. 1 and 2 show the light guides and optical separation channels 7 only on the exit face 4 side, the light guides and optical separation channels 7 may additionally or alternatively be located on the light entrance face 3 side. Furthermore, the optical separation channels 7 may extend throughout the entire thickness of the material.

[0008] A plurality of optical separation channels 7 can be formed in the light separation array 1 to create the light guide 6. A suitable process for forming the optical separation channels 7 includes laser filamentation followed by etching. In such a process, a laser is applied to a precursor material, e.g., a flat glass sheet, that does not have any optical separation channels. Laser treatment and a subsequent etching process precisely remove selective portions of the glass precursor material to create the plurality of optical separation channels. The plurality of optical separation channels are essentially empty spaces created by removing portions of the precursor material, which define the lateral boundaries of the light guide 6. In other words, the light guide 6 is the area of ​​the precursor material that remains after a specific area of ​​the precursor material is removed to create the plurality of optical separation channels 7.

[0009] 2, 3A, 3B and 4 each show a plurality of light guides 6 having a horizontal light entrance surface 8 substantially parallel to the light entrance face 3 of a transparent plate-like material, a horizontal light exit surface 9 substantially parallel to the light exit face 4, and vertical side walls 10 substantially parallel to said side faces 5. The plate-like material containing the light guides can be formed from a single solid material and can transmit concentrated light rays through the plate-like material and through the light guides with high efficiency.

[0010] The individual light guides can have optical isolation material applied to their surfaces or optical isolation channels to separate each individual light guide from its neighbors, thereby resulting in high contrast and high resolution. The optical isolation material can be, for example, an opaque material, an absorbing material and / or a reflective material. The material can be applied in one or more layers and / or as a filler for the optical isolation channels. The light transmitted through the light guides can be directed towards the sensor / detector without significant distortion of the optical wavefront caused by the lens or lens array. The degree of optical isolation can be measured by the amount of light attenuation.

[0011] The laser filamentation process allows for control over the dimensions of the filaments formed in the precursor material: multiple, sequentially arranged individual filaments can be formed and subsequently etched to connect the filaments to form optical separation channels.

[0012] The thickness of the light separation array and the transparent material after the laser treatment and etching can be comparable to the thickness of the precursor material before the laser treatment and etching. This is because the light guides are the areas of the precursor material remaining in the light separation array after the areas of the precursor material are removed to form the optical separation channels. In many cases, the horizontal light exit surface of each light guide is flush with the light exit surface of the precursor material before the laser treatment and etching, and in those cases, the thickness of the light separation array is measured from the horizontal light exit surface of the light guides (flush with the light exit surface of the precursor material) to the light entrance surface of the light separation array. In embodiments in which the optical separation channels do not extend through the entire thickness of the light separation array, some of the precursor material remains below the bottom of the optical separation channel. The area of ​​the thickness of the light separation array may be from the light entrance surface of the light separation array to the bottom of the optical separation channel, and when viewed from the side of the light separation array, this area may look like a support for the light guides (see, for example, FIG. 2). The thickness of this area is the thickness of the light separation array minus the depth of the optical separation channel.

[0013] The optical separation array and precursor material may have any thickness suitable for the intended application. In some embodiments, the thickness may be about 0.1 to about 50 mm, about 0.1 to about 30 mm, about 0.1 to about 10 mm, about 0.1 to about 5 mm, or about 0.1 to about 1 mm.

[0014] Although it is not necessary for the optical separation channel to extend completely through the thickness of the light separation array, in some embodiments it may be desirable for the optical separation channel to extend completely through said thickness. To make the optical separation channel extend completely through said thickness, the optical separation channel can be filled with an optical separation material to hold the light guides together, and then the material of the light guides can be thinned by reducing its thickness (including the height of the light guides) to make the optical separation channel extend completely through the thickness of the substrate. In some embodiments, the optical separation channel extends from the light entrance or exit face to about 5% to about 100% or less of the thickness of the light separation array, about 50% to 100% or less of the thickness of the light separation array, or about 80% to 100% or less of the thickness of the light separation array. For example, the optical separation channel 7 in FIG. 4 extends about 80% of the thickness from the exit face 4. The optical separation channel 7 in FIG. 3A and FIG. 5 extends completely through the thickness from the exit face 4.

[0015] It is not necessary for the optical separation channel to extend completely from the vertical sidewall of one light guide to the vertical sidewall of the other light guide. In such a case, the optical separation channel can be considered as an "annulus" surrounding the individual light guides, for example as shown in Figures 3A, 3B and 4. Two or more concentric annulus 7 and 7B can be provided as shown in Figure 3C, and in some embodiments, the radial distance between each concentric annulus is 25 μm to 100 μm. In those embodiments, the optical separation channel should have a width large enough to achieve the desired light attenuation for the intended application, depending on the optical separation material used in the optical separation channel. On the other hand, if the width of the optical separation channel is too large, the structural integrity of the optical separation array may be compromised because less material will remain between each light guide.

[0016] As shown in Figures 3A and 3B, the laser treatment and etching process did not remove the portions of the optical isolation array between each optical isolation channel. In contrast, the laser treatment and etching process that produced the optical isolation array of Figure 4 removed most of the precursor material that was present between each optical isolation channel, leaving only the optical isolation channel 7 in the shape of a ring surrounding the optical isolation channel 6, the transparent precursor material portion 20 (also shown as a ring in Figure 4) surrounding the optical isolation channel 7, and the empty space between the portion 20 and the adjacent optical isolation channel (not shown in Figure 4).

[0017] The optical separation channels need not be continuous, for example in the shape of a ring. FIG. 9 shows an embodiment in which the optical separation channels 7 are in the shape of discontinuous rings. The rings have discontinuous areas 22, which may alternate between continuous areas 2 when measured along the perimeter created by the channels 7. FIG. 9 also shows that each discontinuous, concentric optical separation channel 7 may be surrounded by one or more discontinuous, concentric optical separation channels 7. The continuous and discontinuous areas minimize the amount of glass removed from the original starting material, which minimizes the amount of glass strength lost.

[0018] To minimize the amount of light that escapes through the discontinuous areas, the areas of two adjacent optical separation channels 7 can be offset from each other as shown in FIG. 9 so that the escaping light is attenuated by either the first or second optical separation channel.

[0019] In some embodiments, the optical separation channels may have a diameter of about 0.01 to about 10 mm, or about 0.05 to about 5 mm (channel diameter is measured from one side of the optical separation array to the opposite side), a width of about 0.001 to about 5 mm, about 0.001 to about 2 mm, or about 0.015 to about 1 mm (channel width is measured as the distance between the channel sidewalls), and a depth of about 0.01 to about 30 mm, or about 0.01 to about 10 mm, or about 0.05 to about 30 mm, or about 0.05 to about 10 mm, or about 0.05 to about 5 mm (channel depth is measured as the length of the vertical sidewall 10 of the light guiding conduit). Each individual optical separation channel may have different dimensions compared to other individual optical separation channels. Additionally, in embodiments where the width of an optical separation channel spans from one light guiding conduit to another, the width of that optical separation channel is the distance between the vertical sidewalls of those light guiding arrays.

[0020] The initial depth and width of the optical isolation channels are created by a laser and subsequently expanded toward their final values ​​by etching. Figures 2, 3A and 7 show light guiding arrays with optical isolation channels 7 having channel depth 15, channel width 16 and channel diameter 17.

[0021] The total number of optical separation channels and corresponding light guides created is not particularly limited. It may be desirable to structure the periodicity and dimensions of the optical separation channels and corresponding light guides to match the periodicity and dimensions of the PD array of the LiDAR sensor, so that the light transmitted through each light guide is received by the corresponding PD. For example, if the PD array is a grid of 100x100 PDs with a specific PD size and spacing, the optical separation array of the present invention can be structured with a 100x100 array of separate light guides, each transmitting light to a separate corresponding PD. This numerical and dimensional correspondence between the optical separation array and the PDs provides optical separation of the input light and can eliminate crosstalk, thereby enhancing resolution by increasing the contrast of the incoming signal.

[0022] In some embodiments, a suitable number of optical separation channels are formed to provide about 0.25 to about 10,000, about 0.25 to about 100, or about 0.25 to about 5 light-conducting conduits per square millimeter of the optical separation array.

[0023] The light guides remaining after forming the optical separation channel by removing a portion of the precursor material are not limited in shape and size. When viewed from their exit surface, the light guides can be, for example, circular, square, or hexagonal, and any shape desired for the corresponding PD can be created. The light guides can be disposed over a substantial majority of the light entrance or exit surface of the material, or over any portion thereof. In some embodiments, each light guide can have a height of about 100 μm to about 50 mm, about 100 μm to about 30 mm, about 100 μm to about 10 mm, or about 100 μm to about 5 mm, and a diameter of about 10 μm to about 10 mm, or about 10 μm to about 5 mm, or other similar dimensions. Each individual light guide can have different dimensions compared to other individual light guides. 2 and 3A show a light guide array having light guides 6 with vertical sidewalls 10 whose length is the height of the light guide, and horizontal exit surfaces 9, with each individual guide having a guide width 21. FIG.

[0024] The aspect ratio (ratio of height to diameter) of each light guide can be, for example, in the range of about 100:1 to about 1:1, or about 100:1 to about 10:1, or about 30:1 to about 10:1, or about 30:1 to about 5:1. A high aspect ratio can be more difficult to create the optical separation channels and subsequent coatings, meaning that laser filamentation and etching can be a more desirable process compared to photolithography, which can produce light guides with undesirable tapers.

[0025] The light separating array of the present invention need not have a light entrance face that is parallel to the light exit face. The light separating array may be curved, which may be particularly useful for accommodating PDs on a three-dimensional surface, for example, each light guide conduit (and corresponding light entrance face and / or light exit face) may be tilted to direct light toward a corresponding PD, for example at an angle within 80-100° relative to the PD.

[0026] The operation of the laser and the specifications of suitable lasers are known to those skilled in the art and are not particularly limited. Suitable wavelengths are 400-1600 nm, preferably 1064 / 532 nm (Nd:YAG), or 1030 / 515 nm (Er:YAG). The pulse duration can be ultrashort pulse (UKP) with 18 bursts at 1 ns>t>50 fs. The repetition rate can be 10 kHz-2 MHz. The power can be 5200 W on average. The energy can be 50 μJ-40 mJ. The raw beam can be Gaussian, flat-top, donut or Airy. The mechanical part can be an XYZ motion drive with dual (or multiple) beam paths (one fixed optics + one scanner), with XY axis speeds of 100-2000 mm / s and scanner speeds of 500-5000 mm / s, with precision / repeatability of <5 μm.

[0027] One possible method for forming the optical separation channel and related light guide lines of the present invention is to use a laser to form an array of filaments, and then etch the filaments to expand and connect the filaments to form the optical separation channel. The laser treatment and etching process may remove all of the material between the individual light guide lines, but removing too much material may be unnecessary for the function of the optical separation array and may weaken the structural integrity of the optical separation array. Suitable etching processes are known to those skilled in the art and are not particularly limited. For example, etching solutions with or without alkaline liquid, acid and other additives can be used. Dry etching with plasma or steam assistance can also be used.

[0028] An optical isolation material, e.g., a coating or filler, can be applied to one or more surfaces of the optical isolation channel or one or more surfaces of the light guides to optically isolate each light guide, as shown, for example, in FIG. 6. The material can be an opaque material, an absorbing material, and / or a reflective material. An optical material can also be applied. The material can also act as a mechanical stabilizer for the light isolation array by damping twists and bends. Opaque absorbing and reflective materials can help contain the light in each light guide, and the optical material can change or enhance the function of the light isolation array. Other suitable materials include anti-reflective (AR) coatings and bandpass (BP) coatings. The material can be applied via known techniques.

[0029] The optical isolation material can substantially prevent light from traveling between the individual light guides. In some embodiments, it is desirable for the optical isolation material to have high absorbance in the wavelength range sensed by the target PD so that light of the relevant wavelength does not contaminate adjacent light guides and PDs. In this regard, it may be desirable for the attenuation of light leakage from each light guide to be in the range of 10-150 dB, preferably 10-90 dB, and most preferably 30-65 dB. Suitable optical isolation materials include absorbing materials, such as glass frit, preferably black glass frit, graphite, carbon black, metals, and / or other absorbing materials having an extinction coefficient A (k value) greater than 0.01 at the relevant wavelength, which can be, for example, SiC, TiN, and silicon oxycarbide. The material can include absorbing pigments, such as black spinels, such as manganese ferrite spinels, carbon black, and / or graphite. Suitable binders for the absorption pigments include silicones, organic binders (such as epoxy, polyurethane or acrylic resins), and / or inorganic-organic hybrid binders (such as ormocer).

[0030] In addition to or as an alternative to the absorbing material, a reflective material can be applied to the optical separation channels and / or the light guides. Figure 8 shows an embodiment having a reflective coating 11 applied to the light entrance face 3, the light exit face 4, the optical separation channel 7, the vertical sidewall 10 of the light guide 6 (which is the same surface as the channel sidewall 19) and the channel bottom 18, an absorbing coating 12 applied to the reflective coating 11 and filling most of the optical separation channel 7, a bandpass filter coating 13 applied to the horizontal exit surface 9 of the light guide 6, and an anti-reflective coating 14 applied to the bandpass filter coating 13. In other embodiments, one or more of these optical separation materials can be applied to one or more different surfaces. Some of these materials can fill the optical separation channels and "glue" the light guides together, which enhances stability and allows the horizontal exit surface 9 to be easily polished to be completely or nearly completely flat without destruction while retaining the mechanical strength of the entire array. All of the materials described can be applied by known techniques, including liquid coating, vapor deposition, and physical deposition techniques, such as CVD, PE CVD, ALD, and PE ALD.

[0031] Suitable absorbing materials may include high-k materials (e.g., low melting point metals and solder pastes) that absorb light at the relevant wavelengths while supporting the stability of the entire optical isolation array structure; binder systems that support the stability of the optical array with pigments that absorb light at the relevant wavelengths; and binder systems that contain organic groups that fill the optical isolation channels and can be carbonized after filling by rapid laser heating or heat treatment under inert atmosphere. Suitable binder systems include organic polymers (e.g., epoxies, polyurethanes, and acrylics), silicone-based polymers (e.g., silsesquioxanes and low crosslinked silicones), inorganic-organic hybrid materials (e.g., ormocer), and glass frits.

[0032] Suitable reflective materials include materials with high reflectivity at the relevant wavelengths (e.g. metallic silver, aluminum, indium doped tin oxide and aluminum doped zinc oxide), materials with a lower refractive index than the material used for the light guide and propagating total internal reflection, and alternating layers of low and high refractive index materials with specific layer thicknesses that construct a Bragg reflector to reflect a specific wavelength (e.g. SiO 2 TiO 2 SiO 2 alternating layers of

[0033] The optical isolation arrays of the present disclosure are useful, for example, as crosstalk prevention devices in collision avoidance of human-operated or autonomous vehicles in automobiles, trucks and aircraft, such as drones, and anywhere collision avoidance is required. They are also useful in (multi-)spectral cameras for selective analysis of multi-wavelength optical signals, such as smartphones, and are useful in high-resolution medical applications and space and automotive applications. The optical isolation arrays are useful in LiDAR systems, and in X-ray imaging faceplates and X-ray collimation arrays and biometric sensors.

[0034] Although the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for the elements thereof without departing from the scope of the present disclosure. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims

1. (a) a transparent material having a thickness, a light entrance surface, a light exit surface, a side surface, a plurality of light guides, and a plurality of optical separation channels, wherein said transparent material is comprised of a single glass material or a single polymer material; (i) the plurality of light guides have horizontal light entrance surfaces substantially parallel to the light entrance face, horizontal light exit surfaces substantially parallel to the light exit face, and vertical sidewalls substantially parallel to the side faces; and (ii) the plurality of optical separation channels are openings in the material between the light guides and extend from the light exit surface through between about 5% and 100% of the thickness; and (b) an optical isolation material applied to vertical sidewalls of the plurality of light guides; 1. An optical isolation array comprising: the light isolation array transmits light through each light guide from the horizontal light entrance surface to the horizontal light exit surface while the optical isolation material substantially prevents light from traveling between the light guides. The optical isolation array.

2. 2. The optical isolation array of claim 1, wherein the light guides transmit at least 90% of light at wavelengths between 350 and 2500 nm.

3. 2. The optical isolation array of claim 1, wherein the attenuation of light leakage from each light guide is in the range of 10 to 150 dB.

4. 10. The light isolating array of claim 1, wherein the light isolating array comprises about 0.25 to about 5 light guiding conduits per square meter of the light isolating array.

5. 10. The light isolation array of claim 1, wherein the light guide conduits have a height of about 100 μm to about 50 mm and a diameter of about 10 μm to about 10 mm.

6. 10. The light isolation array of claim 1, wherein the light guides have an aspect ratio of about 30:1 to about 5:

1.

7. The optical isolation array of claim 1 , wherein the optical isolation channel extends through 100% of the thickness of the material.

8. The optical isolation array of claim 1 , wherein the optical isolation channel extends through approximately 80% to 100% of the thickness of the material.

9. 2. The light isolation array of claim 1, wherein a horizontal light exit surface of each light guide is coplanar with the light exit face.

10. 10. The light isolation array of claim 1, wherein the optical isolation channels do not extend completely from a vertical sidewall of one light guide to a vertical sidewall of another light guide.

11. 10. The optical separation array of claim 1, wherein the optical separation channel has a diameter of about 0.01 to about 10 mm, a width of about 0.001 to about 5 mm, and a depth of about 0.01 to about 30 mm.

12. The light isolation array of claim 1 , wherein the optical isolation material comprises an opaque material, an absorptive material and / or a reflective material.

13. The light isolation array of claim 1 , wherein the optical isolation material comprises a light absorbing material applied onto a light reflecting material.

14. The optical isolation array of claim 1 , wherein the optical isolation material is also applied to a bottom of the optical isolation channel.

15. The optical separation array of claim 1, wherein the optical separation channel is a ring surrounding individual light guide tubes.

16. The optical isolation array of claim 15, wherein the rings are two or more concentric rings, the radial distance between each concentric ring being between 25 μm and 100 μm.

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