CN117083535A - Structured protective window for light isolation - Google Patents

Abstract

The present invention relates to a structured protective window having high transmission efficiency and being capable of optical isolation between different parts of the window. The structured protective window is less prone to glass breakage than conventional protective windows that are typically used to protect and isolate light transmitting and light receiving components in external lidar automotive applications.

Description

Structured protective window for light isolation

Technical Field

The present invention relates to a structured protective window having high transmission efficiency and being capable of optical isolation between different parts of the window. The structured protective window is less prone to glass breakage than conventional protective windows that are typically used to protect and isolate light transmitting and light receiving components in external LiDAR (LiDAR) automotive applications.

Background

The protective window currently available for lidar transmitters and sensors consists of two sheets of glass whose sides are welded together using a polymeric material. The polymeric material optically separates the emitter and the sensor and prevents emitted light from contaminating the sensor in the vicinity. A disadvantage of these conventional protective windows is that breakage can occur at the molten polymer junction.

Disclosure of Invention

The structured protective window of the present invention can transmit light through its substantial glass portion and physically protect the light transmitting portion and the light receiving portion while eliminating or minimizing light pollution of the light source to the light detecting sensor.

In some embodiments, a structured protective window includes a substrate having a thickness, a light transmitting portion, a light receiving portion, and a plurality of optically isolated channels. The plurality of optical isolation channels may be openings in the thickness of the substrate, and each optical isolation channel may have vertical sidewalls substantially parallel to the thickness of the substrate. Adjacent optically isolated channels may have a certain horizontal overlap as well as a certain vertical overlap. The structured protective window may be optically transmissive and the optically isolated channels may attenuate scattered light transmitted within the substrate from the light transmitting portion to the interior of the light receiving portion. An optically isolating material may be coated on at least one vertical sidewall of the plurality of optically isolating channels to enhance light attenuation.

Drawings

Fig. 1 shows an optical system with a structured protective window according to an embodiment of the invention.

FIG. 2 illustrates a plurality of arcuate optical isolation channels in accordance with an embodiment of the present invention.

FIG. 3 illustrates a plurality of arcuate optical isolation channels according to an embodiment of the present invention.

FIG. 3B illustrates two rows of arcuate optical isolation channels according to an embodiment of the present invention.

Fig. 4 illustrates vertical overlap according to an embodiment of the present invention.

Fig. 5 shows a horizontal overlap according to an embodiment of the invention.

Fig. 6 illustrates an arcuate optical isolation channel having a plurality of optical isolation materials coated thereon.

Fig. 7 shows a series of straight optically isolated channels.

Detailed Description

Fig. 1 shows an embodiment in which a structured protective window 1 comprises a plate-like substrate having a thickness 2, a light transmitting portion 3, a light receiving portion 4 generally opposite the light transmitting portion 3, and a plurality of arcuate optical isolation channels 5 between the light transmitting portion 3 and the light receiving portion 4. Fig. 1 also shows the light source 6 located behind the light transmitting section 3 and the light detection sensor 7 located behind the light receiving section 4, as well as the outgoing and incoming directions of the transmitted and reflected light beams 6A.

The plurality of optical isolation channels 5 may attenuate scattered light transmitted from the light transmitting portion into the light receiving portion within the substrate. The scattered light may be misdirected light as the incident light beam passes through the structured protection window. Such a structured protective window may be helpful in applications where it is desirable to isolate the light detection sensor from and prevent contamination by light emitted by the adjacent light source, for example.

The light transmitting portion transmits the outgoing light beam to the target, and the light receiving portion transmits the incident reflected light beam to the light detecting sensor. The plurality of optically isolated channels attenuate scattered light transmitted within the substrate from the light transmitting portion into the light receiving portion as the light beam enters and then exits the light transmitting portion. This attenuation protects the sensitive light detecting sensor from light contamination. In some embodiments, the amount of attenuation of the scattered light (when the structured protective window does not include an optical isolation material) is about 1dB to about 20dB or about 3dB to about 10dB. In some embodiments (when the structured protective window includes the optical isolation material described herein), the amount of attenuation of the scattered light may be about 10dB to about 150dB, about 10dB to about 90dB, or about 30dB to about 65dB. Protective windows such as these may be used in external lidar automotive applications, as well as other applications where it is desirable to prevent a light source from contaminating adjacent light detection sensors.

The structured protective window may have any shape as desired for the intended application. Fig. 1 shows a structured protective window 1 in the form of a square sheet material, for example a flat glass sheet, but may also take any other shape. The optical isolation channel may extend into the substrate from the substrate surface on the opposite side from the light source and sensor, or the optical isolation channel may additionally or alternatively extend into the substrate from the substrate surface on the same side as the light source and sensor, or may extend through the entire thickness of the substrate. In some embodiments, two structured protective windows may be glued together to form a combined structured protective window unit. In such embodiments, the location of the optically isolated channels of each individual structured protective window may face toward or away from the light source and sensor. In some embodiments, the optical isolation channels of the innermost structured protective window extend into the substrate from the surface opposite the light source and the sensor, while the optical isolation channels of the outermost structured protective window extend into the substrate from the surface closest to the light source and the sensor, and thus the interior of the combined structured protective window unit has a series of optical isolation channels, while the outermost surface of the combined structured protective window is substantially smooth without any surface structuring. In other embodiments, three or more structured protective windows are adhered together, with the optically isolated channels extending in any of the directions described herein.

The substrate may be made of any material having a high transmittance (e.g., greater than 90%) in a wavelength range required for the performance of the light detection sensor, for example, a plate-like material that may be composed of a single glass material or a single polymer material. Typical transmission wavelengths required for light detection sensors are in the range of about 350nm to 2500nm, with typical laser emission wavelengths of 905nm, 1310nm and 1550nm being well suited. Suitable examples are optical glasses having bulk transmittance of about 97% to about 99% in the visible and near infrared spectra. The substrate may have any thickness suitable for the intended application. In some embodiments, the thickness may be about 100 μm to about 10mm, or about 1mm to about 3mm.

The optically isolated channels may be open segments within the thickness of the substrate that remain after removal of portions of the starting material of the substrate by methods such as laser and etching. For example, as shown in fig. 2, each optically isolated channel 5 may have a vertical sidewall 8 that is substantially parallel to a side 9 of the structured protective window 1. The shape of the optically isolated channel may be a shape ranging from arc-shaped to straight.

For example, as shown in FIG. 3, the plurality of optically isolated channels 5 may be a series of individual and adjacent arcuate optically isolated channels 5 that are continuous, nonlinear, and/or non-uniform. Each individual arcuate optical isolation channel need not have the same curvature, depth, or other dimension as an adjacent individual arcuate optical isolation channel. By creating a shunt path through which a crack fault line must pass to reach the other side of the arcuate optical isolation channel, the random size distribution of the individual arcuate optical isolation channels can increase the mechanical stability and breakage resistance of the structured protective window compared to a series of identically sized optical isolation channels. However, at least for ease of manufacture, it may be effective to create a row of optically isolated channels each having the same dimensions by a laser and etching process, the row of optically isolated channels facing another row of optically isolated channels each having the same dimensions, e.g., as shown in fig. 3, wherein the radius of the upper row of channels is smaller than the radius of the lower row of channels, and vice versa. This facilitates a forming process in which the substrate is processed substantially along one line over the material using the same laser and etching parameters to produce a first row of optically isolated channels, and then the material is processed substantially along a second line to produce a second row of optically isolated channels.

As shown in fig. 3B, one or more individual arcuate optical isolation channels 5 may be at least partially surrounded by additional arcuate optical isolation channels 5B. All of these additional optically isolated channels may be formed in the same manner and may have the same dimensions as the other optically isolated channels described herein, and in combination with the enclosed optically isolated channels, the combined structure of the first and second rows may appear visually similar to an onion sheet. Such a combined concentric structure may provide a greater surface area for the application of the functional coating and may also enhance the optical and mechanical properties described herein. The first and second rows of optically isolated channels shown in fig. 3B may also be at least partially surrounded by additional rows of optically isolated channels. In some embodiments, the distance between each row is 25 μm to 1000 μm.

In addition to providing optical attenuation with or without the use of an optical isolation material (in part because of the refractive index difference between the solid substrate and the open interior of the optical isolation channel), each optical isolation channel may also improve the mechanical stability of the protection window by helping to slow crack propagation. For example, the shape and proximity of each optically isolated channel helps to prevent propagation of cracks originating from a particular location to an adjacent location. The curvature of the channel as it bends may also create compressive and tensile stresses that affect crack propagation. In contrast, if the arcuate optical isolation channels are a series of straight channels without any curvature, the light rays may pass through and they will form a fault line along which the protective window may more easily break.

In order to improve mechanical stability and attenuate scattered light signals between two opposite sides of the plurality of optically isolated channels, each arcuate optically isolated channel should overlap to some extent with its adjacent optically isolated channel. Such overlapping may form a series of consecutively interleaved arcuate optical isolation channels, for example, as shown in fig. 3 and 4, wherein the terminus 10 of one arcuate optical isolation channel 5 bisects an imaginary line between the start and terminus of an adjacent arcuate optical isolation channel 5, wherein the terminus 10 points toward the concave side of the adjacent arcuate optical isolation channel 5. When light contacts the arcuate optical isolation channels, it is reflected or absorbed without any space between adjacent channels allowing light to pass from one side of the channel to the other. In this way, the series of optically isolated channels attenuate scattered light of the outgoing light beam transmitted from the light transmitting portion to the light receiving portion and the inside of the light detecting sensor within the substrate.

This relationship between adjacent arcuate optical isolation channels is referred to herein as vertical overlap and horizontal overlap. The vertical overlap is the distance between the end point and the start point of adjacent arcuate optical isolation channels (distance a in fig. 4). In some embodiments, the vertical overlap has a minimum of 10 μm and a maximum of the smaller radius of the arcuate optical isolation channel (if one of them is smaller, otherwise the radius of either) minus the channel width. This can be expressed as 10 μm vertical overlap smaller radius-channel width ("formula A"). In some embodiments, the vertical overlap is about 50 μm to about 500 μm, about 100 μm to about 400 μm, or about 200 μm to about 300 μm. Vertical overlap may be achieved by adjusting the curvature and other dimensions of the arcuate optical isolation channels during the structuring process that forms the arcuate optical isolation channels.

The horizontal overlap is the distance between the outermost peripheries of adjacent arcuate optical isolation channels (distance B in fig. 5). In some embodiments, the minimum of the horizontal overlap is 30 μm plus twice the channel width, and the maximum is the radius of the smaller arcuate optical isolation channel (if one of them is smaller, otherwise the radius of either) minus twice the channel width. This can be expressed as 30 μm+ (2 x channel width). Ltoreq.horizontal overlap. Ltoreq.smaller radius- (2 x channel width) ("formula B"). In some embodiments, the horizontal overlap is about 50 μm to about 500 μm, about 100 μm to about 400 μm, or about 200 μm to about 300 μm. The horizontal overlap may be achieved by adjusting the curvature and other dimensions of the arcuate segments during the structuring process that forms the arcuate optical isolation channels.

The vertical overlap and the horizontal overlap play an important role in the mechanical and optical properties of the structured protective window.

The dimensions of the arcuate optical isolation channel depend on the intended application. In some embodiments, each arcuate optical isolation channel has a radius of about 25 μm to about 10mm, about 50 μm to about 3mm, about 200 μm to about 3mm, or about 500 μm to about 3mm. In some embodiments, the radii of adjacent arcuate optical isolation channels are different, e.g., one radius is greater than the other radius, as shown in fig. 3. The arcuate optical isolation channels may be non-parallel to one another. As mentioned above, this distribution of different sizes and positions helps to improve mechanical stability.

In some embodiments, it may be desirable for the optically isolated channels to be a series of straight channels, rather than an arcuate channel, as shown in FIG. 7. Fig. 7 also shows that adjacent two sets of optically isolated channels may be offset from each other. As with the arcuate optical isolation channels, these optical isolation channels also attenuate scattered light that is transmitted within the substrate from the light transmitting portion to the interior of the light receiving portion.

In addition to being straight rather than arcuate, groups of adjacent straight, parallel and offset optical isolation channels may or may not have the same dimensions and other characteristics as the arcuate optical isolation channels described herein. In some embodiments, the distance between adjacent parallel optically isolated channels may be the same or different and may be about 25 μm to about 1000 μm.

Because of the vertical overlap and the horizontal overlap, the arcuate optical isolation channels are relatively close to each other, so they can be located between the light transmitting portion and the light receiving portion of the device. However, this is not possible for adjacent straight, parallel and offset optically isolated channels, as the distance between each adjacent channel may be greater than the distance between the light transmitting and light receiving portions of the device. In this case, one of the two adjacent optical isolation channels may be located between the first light transmitting portion and its adjacent light receiving portion, and the other of the two optical isolation channels may be located between the adjacent light receiving portion and the second light transmitting portion. In other words, adjacent sequences may be one or more light transmissive portions, one or more straight, parallel and offset optically isolated channels, one or more light receiving portions, and then one or more straight, parallel and offset optically isolated channels.

In some embodiments, the sidewalls 8 of the optically isolated channels may have a depth into the thickness of the substrate in the range of about 50 μm to about 10mm or about 200 μm to about 2 mm. In some embodiments, the width 11 of the optically isolated channel may be in the range of about 10 μm to about 1mm or about 20 μm to about 200 μm.

Suitable processes for forming the optically isolated channels include laser filamentation followed by etching. In this process, a laser is applied to a precursor substrate (e.g., a flat glass plate) that does not have any optically isolated channels. The laser and subsequent chemical etching processes remove selected portions of the glass precursor material in a precise manner to form a plurality of optically isolated channels. The plurality of optically isolated channels are essentially empty spaces created by removing portions of the precursor material.

Each optical isolation channel may be formed by making a series of continuous filaments, etching the filaments together, connecting the filaments, forming individual optical isolation channels.

The optical isolation channels do not have to extend completely through the entire thickness of the structured protective window, although in some embodiments it may be desirable for the optical isolation channels to extend completely through the thickness. In some embodiments, the optical isolation channel extends from the light-in side or light-out side of the substrate through about 5% to about 100%, about 50% to about 100%, about 5% to about 95%, or about 50% to about 95% of the thickness of the structured guard window.

The total number of individual optically isolated channels formed is not particularly limited. Further, the structured protective window may have one or more optically isolated channels, e.g., a first plurality of optically isolated channels in one location of the protective window and a second plurality of optically isolated channels in another location.

The structured protective window need not have parallel faces. The faces may be arcuate, which is particularly useful for mounting light detecting sensors on three-dimensional surfaces.

The operation of the laser and the appropriate laser specifications are well known to those skilled in the art and are not particularly limited. Suitable wavelengths are 400nm to 1600nm, preferably 1064nm/532nm (Nd: YAG) or 1030nm/515nm (Er: YAG). The pulse duration may be a 1ns > t >50fs ultrashort pulse (UKP) with 1-8 bursts. The repetition frequency may be 10kHz to 2kHz. The power average may be 5W to 200W. The energy may be 50 muj to 40mJ. The original beam may be a gaussian beam, a flat top beam, a ring beam, or an airy beam. The machine may be an XYZ motion drive with an accuracy/repeatability of less than 5 μm, with a dual (or multiple) beam path (1 fixed optics +1 scanner), an XY axis speed of 100mm/s to 2000mm/s, and a scanner speed of 500mm/s to 5000mm/s.

Suitable etching processes are well known to those skilled in the art and are not particularly limited. For example, liquid etching may be used with or without lye, acid, and other additives. Plasma and steam assisted dry etching may also be used.

The surface of the optically isolating channel, e.g. at least one side wall and/or at least one channel bottom, may be coated with an optically isolating material to help attenuate scattered light between the light transmitting portion and the light receiving portion. For example, the optical isolation material may be an opaque material, an absorptive material, and/or a reflective material. Optical materials may also be coated. By reducing distortion and bending, these materials can also act as mechanical stabilizers for the structured protective window. Other suitable materials include anti-reflection (AR) and Bandpass (BP) coatings. These materials may be coated by known techniques. The optical isolation material may be coated in one or more layers in combination and/or as a filler for the optical isolation channels.

In some embodiments, it is desirable for the optical isolation material to have a higher absorbance in the wavelength region sensed by the target light detection sensor so that light of the relevant wavelength does not contaminate adjacent light detection sensors. Suitable optical isolation materials may be absorptive materials (e.g., glass frit, preferably black glass frit), graphite, carbon black, metals, and/or other absorptive materials, including materials having an extinction coefficient (k value) greater than 0.01 at the relevant wavelengths, such as SiC, tiN, and silicon oxycarbide. The material contains an absorptive colorant, such as, for example, black spinel (e.g., manganese ferrite spinel), carbon black, and/or graphite. Suitable binders for the absorptive colorant include silicones, organic binders (e.g., epoxy, polyurethane, or acrylic), and/or inorganic-organic hybrid binders (e.g., organically modified ceramics).

In addition to or as an alternative to the absorbing material, the optically isolated channels may be coated with a reflective material. Fig. 6 shows an embodiment in which vertical sidewalls 8 and channel bottom 13 of an optically isolated channel 5 are coated with a reflective coating 12, an absorptive coating 14 is coated over the reflective coating 12 and fills the majority of the optically isolated channel 5, a bandpass filter coating 15 is coated over the substrate surface, and an anti-reflective coating 16 is coated over the bandpass filter coating 15. In other embodiments, one or more optical isolation materials may be applied to one or more different surfaces. Some of these materials can fill the optically isolated channels, thereby improving stability, and making the substrate surface easy to polish, making it perfect or nearly perfect plane without breakage, while maintaining the mechanical strength of the entire structured protective window. All of the described materials can be coated by known techniques including liquid coating, vapor deposition and physical deposition techniques such as CVD, PE CVD, ALD and PE ALD.

Suitable absorbing materials also include high-k materials that absorb light of the relevant wavelengths and at the same time support the stability of the entire structured protective window (e.g., low melting point metals and solder pastes; binder systems that support the stability of the structured protective window with colorants that absorb light of the relevant wavelengths; and binder systems that fill the optically isolated channels and contain organic groups that can be carbonized after filling by rapid laser heating or tempering in an inert atmosphere). Suitable binder systems include organic polymers (e.g., epoxy, polyurethane, and acrylic), silicone-based polymers (e.g., silsesquioxanes and silicones with low degree of crosslinking), inorganic-organic hybrid materials (e.g., organically modified ceramics), and glass frits.

Suitable reflective materials include materials having high reflectivity in the relevant wavelengths (e.g., metallic silver, aluminum, indium doped tin oxide, and aluminum doped zinc oxide), and low and high refractive index alternating layers of material having a particular layer thickness that create a bragg reflector (e.g., siO ₂ ，TiO ₂ And SiO ₂ Is a layer of alternating layers).

The structured protective window can be used as a crosstalk suppressor in manual or autopilot vehicle crashes, for example in automobiles, trucks and aircraft (e.g., unmanned aircraft), and wherever collision avoidance is desired. They can also be used in (multi) spectral cameras that selectively analyze multi-wavelength optical signals, such as smart phones, as well as high resolution medical applications, aerospace and automotive applications. The structured protective window may be used in LiDAR systems, X-ray imaging panels, X-ray collimation arrays, and biometric sensors. The structured protective window may be a component of an optical system comprising the structured protective window, the light source and the light sensor.

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

Claims (16)

1. A structured protective window comprising:

a substrate having a thickness, a light transmitting portion, and a light receiving portion; and

a plurality of arcuate optical isolation channels are located in the thickness of the substrate, each optical isolation channel having a vertical sidewall substantially parallel to the thickness, wherein adjacent optical isolation channels have a vertical overlap of formula a and a horizontal overlap of formula B,

wherein the optical isolation channel attenuates scattered light transmitted from the light transmitting portion to the inside of the light receiving portion within the substrate,

formula A: vertical overlap of 10 μm or less or smaller radius-channel width,

formula B:30 μm+ (2X channel width). Ltoreq.horizontal overlap. Ltoreq.smaller radius- (2X channel width).

2. The structured protective window of claim 1, wherein the vertical overlap is from about 50 μιη to about 500 μιη.

3. The structured protective window of claim 1, wherein the horizontal overlap is from about 50 μιη to about 500 μιη.

4. The structured protective window of claim 1, wherein the radii of adjacent arcuate optical isolation channels differ.

5. The structured protective window of claim 1, wherein at least one vertical sidewall and/or at least one channel bottom of the plurality of optically isolated channels is coated with an optically isolated material.

6. A structured protective window according to claim 5 wherein said optical isolation material comprises an opaque material, an absorbing material and/or a reflective material.

7. A structured protective window according to claim 5 wherein said optical isolation material comprises a light absorbing material coated on a light reflecting material.

8. A structured protective window according to claim 5 wherein optically isolating channel bottoms are also coated with said optically isolating material.

9. A structured protective window according to claim 1 wherein the substrate is comprised of a single glass material or a single polymeric material.

10. The structured protective window of claim 1 wherein the delta attenuation is from about 1dB to about 20dB.

11. The structured protective window of claim 1 wherein the delta attenuation is from about 10dB to about 150dB.

12. The structured protective window of claim 1, wherein the optical isolation channel extends through about 5% to about 100% of the substrate thickness.

13. The structured protective window of claim 1, wherein the optically isolated channels have a width of about 10 μιη to about 1mm and a depth of about 50 μιη to about 10mm.

14. The structured protective window of claim 1, wherein the plurality of arcuate optical isolation channels comprises a first row of optical isolation channels each having a same size, the first row of optical isolation channels facing another row of optical isolation channels each having a same size.

15. The structured protective window of claim 14, wherein the first row of optically isolated channels is at least partially surrounded by a second row of optically isolated channels.

16. An optical system comprising the structured protective window of claim 1, a light source, and a light sensor.