Patent ID: 12222443

It is known from prior art, in order to avoid unexpected wave guiding effect inside the optical cover, to use separate optical apertures.FIG.1shows the example which uses two separate optical covers51and52for a LiDAR device as optical device, with the first one optical cover51covering the light source1and the second optical cover52covering the detection element2. LiDAR is provided inside a housing4. The working principle is that light source1emits infra-red (IR) light7through optical cover51to the target3, and the reflected back light8travels through the optical cover52to the detection element2. The two optical covers are separated physically from each other in order to block unexpected light6.

However compared with one full piece of optical cover according to the present invention, separate optical covers have the disadvantages above as:increase the cost of the optical cover itself.increases the complexity and cost for the housing of the optical device. The housing has to be designed to hold each optical cover separately with sufficient mechanical resistance. It might reduce mechanical resistance, humidity resistance and/or chemical resistance for the whole packaging . . . .

According to the present invention and described inFIG.2, a solution based on the use of one single piece of optical cover with virtually separate optical apertures rather than applying separate optical covers. Also taken LiDAR as an example, the optical cover5can be a stand-alone LiDAR cover housed by the LiDAR housing4.

According to an embodiment of the present invention, the optical cover5may extended outside the LiDAR housing4as shown inFIG.3.

According to the present invention, the optical cover5may be flat or bent. The optical decoupling zone9also called is a part of the optical cover5where guided light6can either be redirected or absorbed by using diffusing, absorbing and/or multilayer elements.

According to the present invention, the optical decoupling zone9is placed in the interface between the first51and the second52optical apertures.

It is understood that the number and the location of the optical decoupling zone9also called optical decoupling zone, may varied depending on the design of the housing or the detection device and/or the optical device.

Compared with separate optical covers, the use of one single optical cover with virtually separate optical apertures according to the present invention, presents advantages as described above.

Particularly in automotive field, the detection device according to the present invention as LiDAR for example, may be implemented/attached directly on automotive glazing or trim element or applique. As the optical cover may be extended outside the protective housing, the detection device may be attached to the glazing easily through its extended optical cover, the glazing may be a windshields, backlites, sidelites and sunroofs, where it is required to have one piece of glazing or plastic.

Thus, it is proposed to use the optical decoupling zone9as part of the optical cover to realize virtually separate optical apertures51,52. Depending on the design and requirement of the detection device100, the optical decoupling zone9can be located at any place of the optical cover, and multiple optical decoupling zones9can also be used either to create multiple separate optical apertures51,52, or to improve the efficiency of reducing unexpected electromagnetic waves. Most of the times, the optical decoupling zone9is located at the interface between two separate optical apertures51,52.

It should be noted that for light rays in the following figures, it is only to demonstrate their final endings6(either extracted or absorbed), but not their complete optical paths (like multiple reflections, scattering and directions).

InFIG.4, diffusing elements are used as optical decoupling in the optical decoupling zone9between the at least the first and the second aperture51,52, outside the field of view (FOV) of the light source and the sensitive element in a way to avoid the stray light travelling from the light source1to the sensitive element2within the optical cover5. Diffusing elements diffuse or scatter unexpected electromagnetic waves6to other directions, so that they can finally be extracted from the optical cover5. One or more diffusing element may be used alone or in combination with another diffusing element or absorbing element or multilayer, wavelength-changing elements.

According to the present invention, the optical cover5may be made of glass or plastic. More preferably, the optical cover is made of glass. InFIG.4a, the diffusing elements911may be formed or attached additionally at one or both surfaces of the optical cover5. These surface diffusing elements may include random surface microstructures, microstructure arrays, diffractive gratings, and so on.

Moreover, diffusing elements912as shown inFIG.4bcan be created inside the cover material5, close to the surface or not. The diffusing elements may include air bubbles, chemical particles or any suitable material.

According to an embodiment of the present invention, the optical cover5may be a laminated glass sheets. As shown inFIG.4c, the surface diffusing elements913may be formed within the optical cover5, by locating them on either surface of the two glass sheets501and503in contact with the interlayer502. The interlayer is used to laminate the two glass sheets together.

Surface diffusing elements911and913can be generated by different techniques, including acid etching, sand blasting, laser blasting, Ion implementation, optical lithography and so on. In glazing industry, it is also possible to create enamels diffusing patterns by enamel printing with dedicated silk screening. Material diffusing elements912can be created either during the fabrication process or afterwards as well.

InFIGS.5a, bandc, the solution using absorbing elements is shown as optical decoupling element921,922,923in optical decoupling zone9between the apertures51and52. Absorbing elements921,922,923are used to absorb unexpected electromagnetic waves.

The absorbing elements921as shown inFIG.5amay be applied on the external surface of the optical cover5. The surface absorbing elements921can be some separate elements attaching to the surface, like black silicone pad, or black enamels printed on one or both surfaces of the optical cover.

In case of laminated glass sheets or laminated plastic or laminated combination glass/plastic used as optical cover5, as shown inFIG.5borFIG.5c, the interlayer502at the optical decoupling zone9can be modified as an absorbing element922. By using die cut technique at the separator zone9, the original interlayer can be replaced by a second interlayer, which has a higher absorption at the wavelengths of the unexpected electromagnetic waves6, as shown inFIG.5b.

Taken the example of LiDAR placed behind an automotive glazing or a trim element or an applique as cover, PVB interlayer used to laminate the glazing can be replaced by another interlayer (like ITO or black PVB) highly absorptive to IR light of LiDAR in the area wherein the LiDAR is placed. Alternatively, the interlayer can be prepared with a printed pattern, to have the black printed PVB at the optical decoupling zone9.

For optical covers using laminated glazing, the surface absorbing elements923(e.g. black enamels) as shown inFIG.5ccan also be located on either surface of the two glass sheets501and503in contact with the interlayer502.

As shown inFIG.6as an embodiment of the present invention, multilayer elements may be used in the optical decoupling zone9between the two apertures51and52as optical decoupling element. The multilayer element may be an antireflective (AR) coating931is placed at the one surface of the optical cover to transmit light61externally. It is preferred to apply a highly reflective coating932at the opposite surface to reflect light62to the AR coated area to be finally extracted outside the optical cover5. These multilayer coatings can be produced directly on the surface of the optical cover5, or can be as additional elements attached to the optical cover5.

The multilayer element and more particularly the AR coating may be applied by known coating techniques available, including Physical Vapor Deposition (PVD) methods (such as sputtering deposition, thermal vapor deposition), Chemical deposition methods (such as chemical reduction, pyrolytic coating like Chemical Vapor Deposition (CVD), sol-gel deposition), Plasma-Assisted Chemical Vapor Deposition (PACVD) . . . .

According to another embodiment of the present invention, wavelength-changing elements may be used as decoupling element provided between the at least the first and the second aperture51and52in the optical decoupling zone9, outside the field of view (FOV) of the light source1and the light sensitive element2in a way to avoid the stray light travelling from the light source1to the light sensitive element2within the optical cover5.

The same configuration as show inFIG.5may be applied in case a wavelength-changing elements is used as optical decoupling element. Wavelength-changing elements absorb the wavelength of light that should be isolated between two optical apertures, and emit light with another wavelength, based on fluorescence, non-linear optical effect, and other effects. So that light with original wavelength is not influencing two separated apertures.

According to another embodiment of the present invention, the optical decoupling elements to obtain separate optical apertures on one single optical cover according to the present invention, may be used alone or in combination thereof. In the meantime, one element can offer combined functions. For example, black enamel patterns can both be absorbing and diffusing.

According to the present invention, the optical device is provided inside a protective housing4. Its design may depend on the type of the optical device and the optical cover is placed in order to protect the optical device. The optical cover is transparent at the operating wavelength of the said optical device.