Laser system, laser assembly and method for detecting a change in an optical device

Abstract

Laser system (200), comprising: a case (260); a laser light source in the housing (260); an optical device (220) which is attached to the housing (260) and is designed to allow laser light emitted from the laser light source to pass through the optical device (220); at least one conductive element (230) formed on at least one part of the optical device (220); a first sensor element (240) and a second sensor element (245) in the housing (260); and a measuring circuit (250) which is electrically coupled to the first sensor element (240) and the second sensor element (245) and is designed to measure a characteristic parameter which is indicative of a field between the at least one conductive element (230) and the first sensor element (240) and the second sensor element (245).

Description

Background of the invention

[0001] Laser light sources emit coherent light, which, at different power levels and wavelengths, can be harmful to human eyes and / or skin to varying degrees. Lasers are often housed in sealed enclosures that incorporate an optical diffuser through which the laser light passes before being emitted. For example, time-of-flight (ToF) camera systems often include a laser system / module that contains a laser light source and a diffuser designed to spread the emitted light over a larger area to increase the imaging area. By increasing the area over which the emitted light is spread, the radiation exposure (energy density, measured in J / cm²) decreases. -2 ) and the irradiance (power density, measured in W cm⁻¹) -2To maintain effective operation of the ToF camera system, the laser may have an optical energy / power that would exceed safe limits without the diffuser, but remains within safe limits with the diffuser. In other words, the laser module is harmless to human eyes and / or skin with the diffuser in place, but if the diffuser is removed or knocked out of the laser module, it can become dangerous to human eyes and / or skin.

[0002] Consequently, laser modules of this type are typically packaged in robust, sealed enclosures to minimize the risk of the diffuser being lost during the product's operational lifetime. However, it is still possible that service technicians and / or the owner's technicians may gain access to the laser module and attempt to remove the optical diffuser, or that the optical diffuser may become accidentally dislodged. Additionally or alternatively, it is possible that the optical diffuser may fall out due to a mechanical impact, or that an undetected fault exists in the laser module's assembly, or that some other fault condition results in at least some of the light being emitted unspotted from the laser system.

[0003] US 2019 / 0296522A1 concerns a packaging approach that ensures high-performance optical modules containing VCSELs and VCSEL arrays remain eye-safe. A VCSEL device or VCSEL package can be configured to certify an optical device as eye-safe, enabling the device to withstand a single failure mode. Summary

[0004] The present disclosure relates to a laser system / housing designed to enable the detection of a potentially hazardous displacement, removal, or damage to an optical device intended to modify the light emitted by the laser. The system is designed to measure an electric or magnetic field influenced by the optical device. Consequently, changes to the optical device, such as its position relative to the laser or damage to the optical device, should be detected by a corresponding change in the electric or magnetic field.

[0005] According to a first aspect of the present disclosure, a laser system is provided which comprises the features of claim 1.

[0006] The field between the at least one conductive element and the first sensor element can include an electric field, wherein the measured parameter includes a capacitance that depends on the electric field.

[0007] The laser system further includes a second sensor element, which is mounted in the housing and coupled to the measuring circuit. The measured parameter can include the mutual capacitance between the first and second sensor elements.

[0008] The measured parameter can also be indicative of an electric field between the at least one conductive element and the second sensor element.

[0009] The first sensor element can be a conductive element designed to be capacitively coupled to the at least one conductive element.

[0010] The field between the at least one conductive element and the first sensor element can include a magnetic field, wherein the first sensor element comprises a first coil and wherein the measuring circuit is designed to apply a current to the first coil in order to induce a first magnetic field. The characteristic parameter can include an inductance of the first coil.

[0011] The measuring circuit can include a capacitor coupled to the first coil to form an LC resonant circuit, the measuring circuit being designed to measure the inductance of the first coil by determining a resonant frequency of the LC resonant circuit.

[0012] The laser system can further include a second coil coupled to the measuring circuit, wherein the characteristic parameter includes a current induced in the second coil by the first magnetic field.

[0013] The laser system can further include a magnetic sensor coupled to the measuring circuit, wherein the characteristic parameter includes the first magnetic field measured with the magnetic sensor.

[0014] The measuring circuit can also be designed to compare the measured parameter with a reference value to determine whether the optical device should function properly or not.

[0015] The operation of the laser light source can be based, at least in part, on comparing the measured parameter with a threshold value.

[0016] The at least one conductive element can be designed as a film layer on at least part of a surface of the optical device.

[0017] The first conductive sensor element is optically transparent.

[0018] The optical device can be a non-contact optical device, meaning it has no electrical connections.

[0019] According to a second aspect of the revelation, a time-of-flight camera system is provided, which includes the laser system according to the first aspect.

[0020] According to a third aspect of the disclosure, a method for detecting a change in an optical device within a laser system with the features of claim 16 is provided.

[0021] The measured parameter can include a capacitance that depends on the field between the at least one conductive element and the second sensor element.

[0022] According to a fourth aspect of the present disclosure, a laser assembly with the features of claim 17 is provided.

[0023] The laser assembly can further comprise a first sensor element coupled to the sensor circuit and designed to generate the field influenced by the optical device; wherein the optical device comprises at least one conductive element and wherein the sensor circuit is not electrically connected to the at least one conductive element.

[0024] The optical device can comprise at least one conductive element coupled to the sensor circuit and designed to generate the field influenced by the optical device. The laser assembly can further comprise a first sensor element coupled to the sensor circuit and designed to be used by the sensor circuit to measure the characteristic parameter indicative of the field influenced by the optical device. The field influenced by the optical device can be a magnetic field generated by the at least one conductive element, and the sensor circuit is designed to measure the magnetic field using the first sensor element.Alternatively, the field influenced by the optical device can be an electric field caused by a capacitance between the at least one conductive element and the sensor element, and wherein the sensor circuit is designed to measure the capacitance. Aspects of Revelation

[0025] Exemplary aspects of the present disclosure are set forth in the form of non-restrictive examples in the following numbered sections. 1. Laser system, including: a laser light source for emitting laser light; an optical diffuser designed to scatter the laser light; a first conductive sensor element formed on at least part of the optical diffuser; and a second conductive sensor element, wherein the first conductive sensor element is arranged relative to the second conductive sensor element such that the first conductive sensor element and the second conductive sensor element form a first capacitive sensor. 2. Laser system according to aspect 1, wherein the first conductive sensor element is located in a fixed position relative to the laser light source. 3. Laser system according to one of the above aspects, further comprising: a third conductive sensor element arranged relative to the first conductive sensor element such that the first conductive sensor element and the third conductive sensor element form a second capacitive sensor. 4. Laser system according to aspect 3, wherein the third conductive sensor element is in a fixed position relative to the laser light source and the first conductive sensor element. 5. Laser system according to aspect 3 or aspect 4, wherein a mutual capacitance between the first conductive sensor element and the third conductive sensor element is indicative of a position of the optical diffuser relative to the first conductive sensor element and / or third conductive sensor element. 6. Laser system according to aspect 5, further comprising: a measuring circuit designed to measure the mutual capacitance between the first conductive sensor element and the third conductive sensor element. 7. Laser system according to aspect 6, wherein the measuring circuit is further designed to compare the measured value of the mutual capacitance with a reference capacitance. 8. Laser system according to aspect 7, wherein the reference capacitance is indicative of a mutual capacitance between the first conductive sensor element and the third conductive sensor element when the optical diffuser is in the correct position relative to the first conductive sensor element and / or third conductive sensor element. 9. Laser system according to aspect 7, wherein the reference capacitance is indicative of a safe operating capacitance for the mutual capacitance between the first conductive sensor element and the third conductive sensor element. 10. Laser system according to one of aspects 7 to 9, wherein the operation of the laser light source is based at least partially on the comparison of the measured value of the mutual capacitance with the reference capacitance. 11. Laser system according to one of the above aspects, wherein the first conductive sensor element is designed as a film layer on at least a part of a surface of the optical diffuser. 12. Laser system according to aspect 11, wherein the first conductive sensor element is optically transparent. 13. Laser system according to aspect 12, wherein the first conductive sensor element comprises indium tin oxide, ITO. 14. Laser system according to one of the above aspects, further comprising a fourth conductive sensor element formed on at least a part of the optical diffuser. 15. Laser system according to aspect 14, wherein the fourth conductive sensor element is arranged relative to the second conductive sensor element such that the fourth conductive sensor element and the second conductive sensor element form a third capacitive sensor. 16. Laser system according to aspect 14, wherein the fourth conductive sensor element is arranged relative to the third conductive sensor element such that the fourth conductive sensor element and the third conductive sensor element form a third capacitive sensor. 17. Laser system according to one of the above aspects1, further comprising: a housing wherein the laser and the first conductive sensor element are arranged in a fixed position relative to the housing. 18. Laser system according to aspect 1, further comprising: a measuring circuit that is electrically coupled to the first conductive sensor element and the second conductive sensor element, wherein the measuring circuit is designed to measure a capacitance between the first conductive sensor element and the second conductive sensor element. 19. Time-of-flight camera system comprising the laser system according to any of the above aspects. 20. Method for determining the position of an optical diffuser within a laser system, wherein the optical diffuser comprises a first conductive sensor element formed on at least a part of the optical diffuser, the method comprising: Measuring a capacitance indicative of the position of the optical diffuser within the laser system using a second conductive sensor element of the laser system, wherein the first conductive sensor element is arranged relative to the second conductive sensor element such that the first conductive sensor element and the second conductive sensor element form a first capacitive sensor. 21. Method according to aspect 20, wherein the laser system further comprises a third conductive sensor element and the measured capacitance comprises a mutual capacitance between the first conductive sensor element and the third conductive sensor element. 22. Procedure according to aspect 20 or aspect 21, furthermore comprehensively: Comparing the measured capacitance with a reference capacitance to determine whether the optical diffuser is properly positioned in the laser system or not. 23. Laser system, comprehensive: a laser light source for emitting laser light; an optical diffuser designed to scatter the laser light; a first guiding element that is formed on at least part of the optical diffuser; a second guiding element; and a measuring circuit coupled to the second conductive element and designed to measure a characteristic parameter indicative of a field between the first conductive element and the second conductive element. 24. Laser system according to aspect 23, wherein the field between the first conducting element and the second conducting element comprises an electric field and wherein the measured characteristic includes a capacitance that depends on the electric field. 25. Laser system according to aspect 23, wherein the field between the first conducting element and the second conducting element comprises a magnetic field and wherein the second conducting element comprises a first coil designed to induce the magnetic field. 26. Laser system according to aspect 25, wherein the measuring circuit is designed to measure an inductance of the first coil. 27. Laser system according to aspect 26, wherein the measuring circuit includes a capacitor coupled to the first coil to form an LC resonant circuit, and wherein the measuring circuit is designed to measure the inductance of the first coil by determining a resonant frequency of the LC resonant circuit. 28. Laser system according to aspect 25, further comprising a second coil coupled to the measuring circuit, and wherein the measuring circuit is designed to measure a current induced in the second coil by the magnetic field. 29. Laser system according to aspect 25, further comprising a magnetic sensor coupled to the measuring circuit, and wherein the measuring circuit is designed to use the magnetic sensor to measure the magnetic field. Drawings

[0026] Aspects of the present revelation are described only by way of example with reference to the following drawings, in which the following applies: Fig. 1A, Fig. 1B and Fig. Figure 1C shows three typical examples of laser systems / assemblies that illustrate the scattering effect of optical diffusers on laser light; Fig. 2A shows an exemplary schematic representation of a side view of a laser system / laser assembly according to one aspect of the present disclosure; Fig. Figure 2B shows an exemplary schematic representation of a top view of the laser system / laser assembly of Fig. 2A; Fig. Figure 3 shows four different, non-restrictive examples of configurations of the at least one conducting element of Fig. 2A; Fig. 4A and Fig. Figure 4B shows exemplary schematic, side views of the capacitive coupling between the capacitive sensor elements and the at least one conductive element of the system. Fig. 2A; Fig. Figure 4C shows an exemplary schematic, side view of the capacitive coupling when the optical device of the system is... Fig. 2A away; Fig. 5A and Fig. Figure 5B shows exemplary diagrams of the electric fields between the capacitive sensor elements of the system of Fig. 2A; Fig. Figure 6A shows an exemplary schematic representation of a side view of a laser system / laser assembly according to another aspect of the present disclosure; Fig. Figure 6B shows an exemplary schematic representation of a top view of the laser system / laser assembly of Fig. 6A; Fig. Figure 6C shows an exemplary schematic, side view of the magnetic fields of the laser system / laser assembly of Fig. 6A; Fig. Figure 7A shows an exemplary schematic representation of a laser system / laser assembly according to another aspect of the present disclosure; Fig. Figure 7B shows an exemplary schematic, side view of the magnetic fields of the laser system / laser assembly of Fig. 7A; Fig. Figure 8A shows an exemplary schematic representation of a laser system / laser assembly according to a further aspect of the present disclosure; and Fig. Figure 8B shows an exemplary schematic, side view of the magnetic fields of the laser system / laser assembly of Fig. 8A.

[0027] The drawings are purely schematic and representative. They are not to scale. Detailed description

[0028] The present disclosure discloses a novel laser system that enables the detection of an optical device of the system, for example, an optical diffuser or a lens, throughout the entire lifetime of the laser system. The optical device comprises at least one conductive element, for example, formed from ITO. One or more sensor elements can be mounted in a fixed position relative to the laser light source. These one or more sensor elements can measure a capacitance or inductance that changes with any alteration of the capacitive or inductive coupling between the conductive elements of the optical device and the one or more sensor elements.Therefore, if the optical device is removed, partially or completely displaced, or damaged, the capacitance / inductance measurement should change, indicating that the laser system may no longer be safe to operate. Optionally, the laser can be deactivated if the capacitance / inductance measurement indicates potentially unsafe operation.

[0029] Fig. 1A, Fig. 1B and Fig. Figure 1C shows three typical examples of laser systems / assemblies that illustrate the scattering effect of optical diffusers on laser light. Fig. Figure 1A shows a laser system / laser assembly 100 comprising a laser 110, a refractive lens 130, and a diffractive optical diffuser 120. The light emitted by the laser 110 passes through a refractive lens 130 and subsequently a diffractive optical diffuser 120. Fig. Figure 1B shows a laser system / laser assembly 100 comprising a laser 110 and a combination of a refractive lens and a diffractive diffuser 140. The light emitted by the laser 110 passes through the combination of refractive lens and diffractive diffuser 140. Fig. Figure 1C shows a laser system / laser assembly 100 with a laser 110 and a combination of a diffractive lens and a diffractive diffuser 150. The light emitted by the laser 110 passes through the combination of a diffractive lens and a diffractive diffuser 150.

[0030] Optical diffusers are used to homogenize light and spread a narrower source light into a wider angular range. In each example in Fig. Figures 1A-1C show the light rays, represented by solid lines, along the path of light when the optical diffusers are present. It can be seen that the light emitted by the optical diffusers spreads over a relatively wide angular range, resulting in a relatively lower optical power per unit area. The dashed lines represent the path of light that would result if the optical diffusers were not present. It can be seen that in this case, the light would spread over a relatively narrow angular range, resulting in a relatively higher optical power per unit area.If the optical power of laser 110 is set such that the light emitted by the laser system / laser assembly 100 is normally within safe limits (for example, the power per unit area is below the maximum permissible limits), it can be seen that anything that impairs the operation of the optical diffuser (for example, damage, removal, displacement, incorrect assembly, or any other fault) can cause the light emitted by the system / laser assembly to be at least partially undiffed. The higher power per unit area of ​​this light can exceed the maximum permissible limits and therefore be dangerous.

[0031] Fig. Figure 2A shows an exemplary schematic representation of a side view of a laser system / laser assembly 200 according to one aspect of the present disclosure. The laser system 200 comprises a laser 210 mounted in a housing 260, which may be a laser of any type (for example, a VCSEL); an optical device 220 attached to the housing 260, which may be an optical device of any type designed to modify or influence the laser light, such as an optical diffuser or an optical lens / difference element designed to project the laser light as a dot pattern; and at least one conductive element 230 formed on the optical device 220. The at least one conductive element 230 may be formed with an optically transparent film, for example, indium tin oxide (ITO).The term “optically transparent” is to be understood as meaning that the light absorption of the film is so low that the system 200 can emit a functional amount of light (i.e., an amount of light sufficient for the operating purposes of the laser system 220).

[0032] The laser system / laser assembly 200 also includes a first sensor element 240, which is mounted in the housing 260 such that it is in a fixed position relative to the laser 210, and a measuring circuit 250 (also referred to as sensor circuit 250), which is electrically coupled to the first sensor element 240 and is designed to detect the integrity of the optical element 220 (for example, to detect whether the integrity of the optical element 220 is compromised by damage and / or displacement and / or removal, etc.).(has been lost, so that it can no longer perform its function properly), by measuring a characteristic parameter that is indicative of a field (such as an electric field or a magnetic field) that is affected or changed by changes to the at least one conductive element 230 (such as damage to the at least one conductive element and / or a change in the position of the at least one conductive element 230 relative to the first sensor element 240). In this exemplary aspect of the disclosure, the first sensor element 240 is a conductive element designed to be capacitively coupled to the at least one conductive element 230, such that the first sensor element 240 effectively forms one conductive plate of a capacitor and the at least one conductive element 230 forms the other conductive plate of the capacitor.Therefore, in the following explanations, the first sensor element 240 is often referred to as the first capacitive sensor element 240.

[0033] Fig. Figure 2B shows an exemplary schematic representation of a top view of the laser system / laser assembly 200. The laser system 200 also includes a second sensor element 245, which is electrically conductive and electrically coupled to the measuring circuit 250. In this exemplary aspect of the disclosure, the second sensor element 245 is also a conductive element, designed to be capacitively coupled to the at least one conductive element 230, such that the second sensor element 245 effectively forms one conductive plate of a further capacitor, and the at least one conductive element 230 forms the other conductive plate of the further capacitor. Therefore, in the following explanation, the second sensor element 245 is often referred to as the second capacitive sensor element 245.The first capacitive sensor element 240 and the second capacitive sensor element 245 can each be made of any suitable electrically conductive material (for example, copper) and can have any suitable size and shape. They can be the same or different in size and shape. Likewise, they can be made of the same or different materials.

[0034] The at least one conductive element 230 can, for example, be a single conductive element covering at least part of the surface of the optical device 220. Alternatively, it can be two or more conductive elements, each covering a different part of the surface of the optical device 220.

[0035] Fig. Figure 3 shows four different, non-restrictive examples of top views of configurations of the at least one conductive element 230. Example (a) shows a single conductive element 230 that may partially or completely cover the surface of the optical device 220. Example (b) shows multiple strips of conductive elements 230. Example (c) shows multiple strips of conductive elements 230 in a different orientation. Example (d) shows another arrangement of multiple strips of conductive elements 230. It can be seen that each of the at least one conductive element 230 may have any suitable size or shape and may be arranged on any suitable part of the optical device 220. In addition, some exemplary optical devices may have an optical part through which light can pass and be scattered, and a mounting / housing part in which the optical part is seated, for example, a plastic bezel.The term “optical device” here includes both purely optical devices and optical devices plus mounting / housing part, so that at least one conductive element 230 can be formed on the optical part and / or the mounting / housing part.

[0036] Fig. Figure 4A shows an exemplary schematic, side view of the capacitive coupling between the capacitive sensor elements 240, 245 and the at least one conductive element 230. As can be seen, the first capacitive sensor element 240 is capacitively coupled to the at least one conductive element 230 to form a first capacitive sensor 420 (i.e., the first capacitive sensor element 240 and the at least one conductive element 230 act as a pair of conductive plates separated by a dielectric, which in this example can be a gas such as air). Similarly, the second capacitive sensor element 245 is capacitively coupled to the at least one conductive element 230 to form a second capacitive sensor 430 (i.e.,The second capacitive sensor element 245 and the at least one conductive element 230 act as a pair of conductive plates separated by a dielectric, which in this example can be a gas such as air. In this example, the same at least one conductive element 230 is part of both the first capacitive sensor 420 and the second capacitive sensor 430 (for example, because there is only one conductive element 230, as in the example of ). Fig. 3(a), or because the same strip of conductive elements is arranged over both the first and the second capacitive sensor element 240, 245). As a result, the first capacitive sensor 420 and the second capacitive sensor 430 are electrically coupled in this example. The first capacitive sensor element 240 and the second capacitive sensor element 245 are arranged relative to each other such that they have a mutual capacitance 410. However, each capacitive sensor element 240, 245 can be capacitively coupled to one or more conductive elements on the optical device 220 to a greater or lesser degree, and may or may not be capacitively coupled to the same conductive element(s) on the optical device 220.

[0037] It can be seen that the capacitances 420 and 430 depend on the dielectric constant e between the two conductors, the area A of the conductive plates, and the distance d between the conductive plates (C = eA / d). The measuring circuit 250 is designed to measure the mutual capacitance 410 between the first and second capacitive sensor elements 240 and 245. It can be seen that, due to capacitive coupling, the effective capacitance between the capacitive sensor elements 240 and 245, and thus the measured value of the mutual capacitance 410, depends on the capacitances 420 and 430. Therefore, if the capacitances 420 and 430 change, the measured value of the mutual capacitance 410 also changes.

[0038] Fig. Figure 4B shows another exemplary schematic, side view of the capacitive coupling between the capacitive sensor elements 240, 245 and the at least one conductive element 230. This is based on the example of Fig. 4A is very similar, but the position of the optical device 220, and thus of at least one conductive element 230, is further away from the capacitive sensor elements 240, 245. This greater distance reduces the capacitances 420 and 430, which results in a different measured value for the mutual capacitance 410 compared to, for example, Fig. 4A changes.

[0039] Fig. Figure 4C shows another schematic example in which the optical device 220 has been completely removed. As a result, the capacitive coupling 420 and 430 has been eliminated, so that the measured value of the mutual capacitance 410 changes again compared to the example of Fig. 4C changes.

[0040] Fig. Figure 5A shows an exemplary schematic representation of an electric field between the capacitive sensor elements 240, 245 with the optical device 220 properly inserted, for example. Fig. 4A. It can be seen that changes in the relative distance between the at least one conductive element 230 and the first sensor element 240 change the electric field between the at least one conductive element 230 and the first sensor element 240, which leads to a change in the capacitance 420. This in turn changes the mutual capacitance 410 between the first sensor element 240 and the second sensor element 245 for the reasons already explained. Fig. Figure 5B shows an exemplary schematic representation of an electric field between the capacitive sensor elements 240, 245 when the optical device 220 has been removed. It can be seen that the E-field is quite different, which leads to a difference in the measured mutual capacitance 410. Likewise, damage to one of the at least one conductive element 230 can also change the E-field, leading to a difference in the measured mutual capacitance 410, which allows the damage to be detected. In addition, the extent of damage to the optical device 220 can be determined from the extent of the change in the E-field based on the measured mutual capacitance. Furthermore, if two or more conductive elements 230 are present (as, for example, in Fig. (as shown in Figures 3b-3d), damage in a specific area of ​​the optical device 220 may affect only one of the conductive elements 230, thus limiting the extent of the change in the electric field. In contrast, extensive damage to the optical device 220 may affect many more of the conductive elements 230, leading to a significant change in the electric field. Consequently, the presence of two or more conductive elements 230 can further aid in determining the extent of damage to the optical device 220.

[0041] If Fig. 4A, where the optical device 220 is shown in its correct position, it is understood that throughout the entire lifetime of the system 220, the measured value of the mutual capacitance 410 can be indicative of the integrity of the optical device 220, in particular indicative of whether the optical device 220 should still function properly or not, for example, that it is still in its correct position and / or that it is not damaged. For example, a change in the mutual capacitance 410 may indicate that the electric field between the first sensor element 240 and the at least one conductive element 230 has changed because the optical device 220 has been moved to a different position, removed entirely, or damaged, which may render the laser system 200 unsafe for further use. Therefore, the measuring circuit 250 may be designed to measure the mutual capacitance intermittently (e.g.,The mutual capacitance 410 is measured periodically or before each activation of the laser 210 to detect the integrity of the optical device 220. The measuring circuit 250 can, for example, be coupled to a laser driver circuit (not shown in the figures) and output a signal indicating the integrity of the optical device, which can be indicative of whether the optical device 220 should still be functioning correctly or not. The laser driver can be designed to control the laser 210 so that it emits light only when the signal indicates that the optical device 220 should be functioning correctly. Alternatively, the measuring circuit 250 can also be part of the laser driver itself, such that the laser driver is coupled to the capacitive sensor elements 240, 245 and is designed to perform the functionality of the measuring circuit 250 described here.

[0042] The measuring circuit 250 can be designed to measure the mutual capacitance 410 and compare it to a reference capacitance. The reference capacitance can be stored, for example, in a memory, such as within the measuring circuit 250 or elsewhere that the measuring circuit 250 can access. It can be a value determined at the time of manufacture / configuration of the device, when the mutual capacitance is indicative of the optical device 220 being in an undamaged condition and in the correct position, or it can be a value determined based on an understanding of what the mutual capacitance should approximately be when the optical device 220 is properly positioned.The reference capacitance can be a value that corresponds to the capacitance when the optical device 220 is functioning properly; in this case, the measuring circuit 250 can allow a tolerance on either side of the reference capacitance (for example, to account for measurement noise, etc.) within which the optical device 220 is considered to be functioning properly. Alternatively, it can include a threshold value(s) for the permissible mutual capacitance, outside of which the optical lens 220 is considered to be malfunctioning.

[0043] The measuring circuit 250 can be configured in any suitable way to measure the mutual capacitance 410. For example, it can be configured to use an impedance measurement based on a discrete Fourier transform, as described here: https: / / www.analog.com / en / products / ad5933.html, or by applying an oscillation signal to the capacitive sensor elements 240, 245, as described here: https: / / en.wikipedia.org / wiki / Capacitive_sensing

[0044] It is evident, therefore, that according to the present disclosures, the laser system 200 can be designed such that a potentially dangerous change in the optical device 220 can be detected quickly. Furthermore, by implementing the two capacitive sensor elements 240, 245 and detecting the change in the optical device 220 based on a change in their mutual capacitance 410, the laser system 220 can be manufactured without requiring any electrical connections (e.g., wiring) to the optical device 220, in particular no electrical connection between the measuring circuit 250 (or any other electrical component of the system) and the conductive element 230 (i.e., the at least one conductive element 230 is an electrically isolated element or a passive element, since it is not electrically driven or physically electrically coupled to anything).In other words, the system 200 is designed to enable indirect or non-contact detection of the optical device 220, since there is no physical electrical connection (in the form of wiring) between the circuit 250 and the optical device 220. This makes the manufacture of the laser system 200 simple and relatively inexpensive.

[0045] Fig. 6A and Fig. Figure 6B shows exemplary schematic representations of side and top views of a laser system / laser assembly 600 according to one aspect of the present disclosure. The laser system / laser assembly 600 is designed to detect the optical device 220 by inductive measurement.

[0046] The system comprises a first sensor element 640 and a measuring circuit 650. In this example, the system 600 is designed to measure a characteristic parameter that is indicative of a magnetic field between the first sensor element 640 and the conductive element 230. The first sensor element 640 comprises a coil 641 (shown in Fig. 6B), which forms an inductor. The coil 641 is designed to generate a magnetic field when an alternating current (AC) is passed through it by the measuring circuit 650. The AC signal applied to the coil 641 can be an alternating signal of any form, for example, signals that reduce frequency disturbances, such as the type described in US2016 / 0363462 A1, which is deemed to be included in its entirety by reference herein, and / or it can be a frequency step, and / or it can be a combination of successive frequencies to eliminate disturbances.

[0047] Fig. Figure 6C shows a representation of a magnetic field (B-field) 642 induced by an alternating current (AC) applied to the coil 641. This, in turn, induces eddy currents 644 in the at least one conductive element 230, generating a magnetic field 646 that opposes the magnetic field 642. This affects the inductance of the coil 641. Changes to the optical device 220 alter the electric field between the first sensor element 640 and the conductive element 230, which again changes the inductance of the coil 641. Therefore, the parameter for which the measuring circuit 650 is designed is, in this example, the inductance of the coil 641. The measuring circuit 650 can be designed to measure the inductance of the coil 641 in any suitable manner (in Fig. (6A-6C not shown). For example, the measuring circuit 650 can include a capacitor of known capacitance coupled to the first coil 641 to form an LC resonant circuit. The measuring circuit 650 can also include any suitable circuit for measuring the resonant frequency of the LC resonant circuit, which changes when the inductance is altered. Optionally, the determined resonant frequency / inductance of the coil 641 can be compared with a reference value, which is indicative of the optical device 220 being correctly positioned (similar to the above description of comparing the determined capacitance with a reference capacitance). Thus, it is evident that damage / removal / displacement / misalignment, etc.,the optical device 220 can be detected based on the inductance of the coil 641 by non-contact (indirect) detection of the optical device 220 without requiring a physical electrical connection with the optical device 220 (in particular, no electrical connection is required between the at least one conductive element 230 and the measuring circuit 650).

[0048] Fig. Figure 7A shows an exemplary schematic representation of a top view of a laser system / laser assembly 700 according to one aspect of the present disclosure. The system 700 is very similar to the system 600, however, the technique for detecting the optical device 220 is different.

[0049] The system 700 comprises a first sensor element 740, which has a first coil 741 coupled to a measuring circuit 750. The laser system 700 also comprises a second sensor element 745, which has a second coil 746 that is electrically coupled to the measuring circuit 750. The measuring circuit 750 is designed to apply an alternating current (AC) to the coil 741 to induce a magnetic field, in the same manner as described above.

[0050] Fig. Figure 7B shows a representation of a magnetic field (B-field) 742 induced by an alternating current (AC) applied to the coil 741. It also shows eddy currents 744 in the at least one conducting element 746 and the induced magnetic field 746, similar to the above with reference to Fig. 6C is described. As described above, the magnetic field 746 influences the magnetic field 742.

[0051] The influence or distortion of the magnetic field between the first sensor element 740 and the conductive element 230 can affect the current induced in the second coil 745. If the optical device 220 changes, for example, if it is damaged, displaced, or removed entirely, the influence of the magnetic field 746 (or the absence of the magnetic field 746) on the magnetic field 742 will change the magnitude of the current induced in the second coil 745. Therefore, in this example, the characteristic parameter for which the measuring circuit 750 is designed is the current induced in the second coil 745 (such as the peak current, the average current, etc.), which is indicative of the electric field between the first sensor element 740 and the conductive element 230.Optionally, the measured current parameter can be compared with a reference value that indicates the correct positioning of the optical device 220 (similar to the above description of comparing the determined capacitance with a reference capacitance). Thus, it is evident that damage, removal, displacement, misalignment, etc., of the optical device 220 can be detected without requiring a physical electrical connection to the optical device 220.

[0052] Fig. Figure 8A shows an exemplary schematic representation of a top view of a laser system / laser assembly 800 according to one aspect of the present disclosure. The system 800 is very similar to the system 700, however, the measured parameter for detecting changes in the magnetic field is different.

[0053] System 800 comprises the first sensor element 740 and the coil 741 as described above. The coil 741 is coupled to a measuring circuit 850. System 800 also includes a sensor 845, which is coupled to the measuring circuit 850. The measuring circuit 850 is designed to apply an alternating current (AC) to the coil 741 to induce a magnetic field, in the same manner as described above.

[0054] Fig. Figure 8B shows a representation of the magnetic field (B-field) 742 induced by an alternating current (AC) applied to the coil 741. It also shows eddy currents 744 in the at least one conducting element 746 and the induced magnetic field 746, as described above with reference to Fig. 7B described. Also as described above, the magnetic field 746 influences the magnetic field 742.

[0055] The sensor 845 is designed to measure the magnetic field between the first sensing element 840 and the conductive element 230 (for example, it may be a suitably designed Hall sensor or a magnetic resistance sensor such as AMR, GMR, or TMR, and it may be capable of measuring the magnetic field strength and / or the magnetic field angle). If the diffuser 220 is damaged or its position changes, particularly if the optical device is completely removed, the change in the magnetic field 746 (or the absence of the magnetic field 746) will change the magnetic field measured by the sensor 845. Therefore, the measuring circuit 850 may be designed in any suitable way to measure the magnetic field with the sensor 845.Optionally, the measured magnetic field can be compared with a reference value that indicates the correct positioning of the optical device 220 (similar to the above description of comparing the determined capacitance with a reference capacitance). Thus, it is evident that damage, removal, displacement, misalignment, etc., of the optical device 220 can be determined without requiring a physical electrical connection to the optical device 220.

[0056] In each of the above references Fig. In the examples described in 6-8, the laser systems are designed to detect the optical device 220 by measuring a parameter indicative of a magnetic field between the first conductive sensor element and the at least one conductive element 230. In one example, the measured parameter is the inductance of the loop 641 (which changes with changes in the magnetic field), in another example, the measured parameter is the current induced in the second coil 745 (which changes with changes in the magnetic field), and in yet another example, the measured parameter is the measured magnetic field.

[0057] Similarly, describe Fig. Examples 2 to 5 all involve the measurement of a capacitance that is influenced by a capacitance between the first sensor element and the at least one conductive element 230 on the optical device 220. However, it is evident that the capacitance between the first sensor element and the at least one conductive element 230 depends on an electric field between the first sensor element and the at least one conductive element 230. Therefore, in these examples, the measured parameter is inherently indicative of the electric field between the first sensor element and the at least one conductive element 230.

[0058] Consequently, in all the above examples, the sensor / measuring circuits of the laser systems are designed to detect the integrity of the optical device 220 by measuring a characteristic parameter (e.g., capacitance, inductance, induced current, magnetic field, etc.) that is indicative of a field (such as an electric field or a magnetic field) that is affected or altered by changes to the at least one conductive element 230 (such as damage to the at least one conductive element and / or a change in the position of the at least one conductive element 230 relative to the first sensor element 240).

[0059] It is evident, therefore, that according to the present disclosures, the laser system can be designed in such a way that a potentially dangerous change to the optical device 220 can be detected quickly. Furthermore, the detection is indirect / non-contact, i.e., there are no electrical connections (e.g., wiring) between the sensor circuit 260 and the optical device 220, which keeps the manufacture of the laser system simple and relatively inexpensive.

[0060] The person skilled in the art will easily recognize that various changes or modifications can be made to the aspects of the disclosure described above without deviating from the scope of protection of the disclosure.

[0061] For example, in the capacitance-based implementation, more than two capacitive sensor elements 240, 245 can be present in the laser system 200, such as three or four. The mutual capacitance between two or more pairs of these elements can be determined by the measuring circuit 250, which can help to improve the accuracy with which changes to the optical device 220 are detected.

[0062] In the capacitance-based examples above, the dielectric between the capacitor plates is typically a gas, such as air. However, it can be a dielectric of any suitable type. For example, a liquid or solid dielectric can be present between the two capacitive sensor elements 240 and 245, and a gaseous dielectric can be present between the capacitive sensor elements 240, 245 and the at least one conductive element 230. In another example, a solid dielectric can be present between the capacitive sensor elements 240, 245 and the at least one conductive element 230, which may or may not be optically transparent depending on its arrangement relative to the laser 210.

[0063] While in the above capacitance-based examples two capacitive sensor elements 240, 245 are present and the mutual capacitance between them is measured, alternatively a single capacitive sensor element can be provided. In this case, the capacitance of the capacitive coupling between the capacitive sensor element and the at least one conductive element 230 can be measured to detect the optical device 220. However, in this case, a single physical electrical connection (or connections) to at least a part of the at least one conductive element 230 may be required to measure the capacitance between the capacitive sensor element 240 and the at least one conductive element 230, or to ground a plate of the capacitive coupling so that the grounded capacitance is measured.In this case, however, there would still be no need for a physical electrical connection between the sensor circuit 250 and the at least one conductive element 230, since the conductive element would only need to be held at a reference potential, such as ground. Therefore, in this example of an optical device 232 with a single electrical connection, the detection performed by the measuring circuit would still be an indirect / non-contact detection of the optical device 220, which simplifies manufacturing compared to direct detection systems that require one or more electrical connections between the optical device 220 and the sensor circuit.It follows that in all aspects of the present disclosure the optical device 220 is either a non-contact device (in that it has no electrical connections and the conductive elements are passive / insulated) or a device with only a single connection (in that it has an electrical connection for connection to a reference potential), but even in the case of a device with only a single connection there is still no physical electrical connection to the sensor circuit.

[0064] While in the above examples for magnetic field measurement at least one coil is always present inside the housing 260, which is controlled by an AC signal, in an alternative this coil can instead be formed on a part of the optical device 220 and electrically coupled to the measuring circuit 650, 750, 850 for control with the AC signal. In this alternative, the at least one conductive element 230 can be the coil on the optical device 220, and it can be optically transparent (e.g., ITO) or not optically transparent. In this example, the first sensor element can be omitted, and the system can then include the second sensor element 745 or the sensor 845 described above to measure a parameter that is indicative of the magnetic field induced by the AC signal. Changes to the optical device 220 change the magnetic field at the second conductive sensor element 745 or the sensor 845 described above.the sensor 845, so that the optical device can be detected based on the measured parameter. In this particular embodiment, the system would be designed to detect the optical device 220 directly / by contact, i.e., there would be an electrical connection between the optical device and the sensor circuit. However, a number of different detection modalities can be employed by changing the type of signals applied to the at least one conductive element 230, in order to enable, for example, measurements of the impedance and resistance of the at least one conductive element and measurements of the magnetic field generated by the at least one conductive element, all of which can be indicative of the integrity of the optical element. As a result, the system can have a certain degree of redundancy, so that the reliability and thus the safety of the detection can be improved.In particular, two different types of measurements would take place, so that even if one of the types is faulty and incorrectly indicates that the optical device is completely intact, the other type of detection should still recognize that there is a problem regarding its integrity. In another, similar example, the measurement of capacitance / electric field can be employed in a direct / contact measurement system. In this specific example, the at least one conductive element 230 can be electrically connected to the sensor circuit, and the sensor circuit can be configured to apply a suitable signal (such as a voltage) to the at least one conductive element and to measure the capacitance between the at least one conductive element 230 and the capacitive sensor element 240 and / or the capacitive sensor element 250.This can be particularly useful for creating redundancy in dual-terminal impedance measurement systems that have two electrical connections on the optical device used for impedance measurement. For example, if there were a fault in the sensor circuit that incorrectly measured the impedance / resistance and indicated that the optical device was completely intact, or if the optical device had been removed and replaced with a resistor, the electric field measurement could still indicate a problem regarding its integrity. Thus, by implementing the field measurement according to the present disclosure, additional safety and redundancy can also be achieved in direct / contact detection systems.

[0065] The measuring circuits in each of the in Fig. The examples shown in Figures 2-8 can be separate from a laser driver designed to control the laser 210, or they can be part of the laser driver. Furthermore, while the sensor elements 240, 245, 640, 740, 745, and 840 in the examples above are all implemented as independent components in the housing 260 (for example, mounted on a circuit board), they can alternatively be located at any suitable location. For example, they can be integrated into the laser driver or into the laser 210. Similarly, the sensor 845 in the example of Fig. 8 may be located at any suitable location, for example, integrated into the laser driver or integrated into the laser 210.

[0066] While in the examples above relating to capacitance determination the optical device 220 comprises at least one conductive element 230, in an alternative scenario the optical device 220 may not comprise any conductive element 230. In this case, the optical device 220 can effectively act as a dielectric with a different dielectric constant than the other dielectric located near the capacitive sensor elements 240, 245 (usually air). Therefore, if the optical device 220 is removed or damaged, this can affect the capacitance between the capacitive sensor elements 240, 245, since the effective dielectric constant in the electric field between the capacitive sensor elements 240, 245 can change. Thus, the optical device 220 can also be detected without having at least one conductive element 230.

[0067] Although the figures show that the laser 210, the sensor elements, and the measuring circuit are all directly attached to the housing 260, it is clear that any suitable arrangement and mounting of the components can be chosen. For example, various components can be mounted on different levels and positions within the housing 260, such as the capacitive sensor elements 240, 245, or the inductive coil sensor element 640 on one or more higher levels, between the level on which the laser 210 is mounted and below the level of the optical device 220. Furthermore, the housing 260 shown in the figures can have any suitable construction / shape and is not limited by the exemplary representation in the figures.

[0068] Throughout the entire revelation, the term "electrically coupled" or "electrical coupling" encompasses both a direct electrical connection between components and an indirect electrical connection (for example, when the two components are electrically connected via at least one other component). The term "electrical connection" refers to a physical electrical connection between two components, such as a wired connection.

Claims

[1] Laser system (200), comprising: a case (260); a laser light source in the housing (260); an optical device (220) which is attached to the housing (260) and is designed to allow laser light emitted from the laser light source to pass through the optical device (220); at least one conductive element (230) formed on at least one part of the optical device (220); a first sensor element (240) and a second sensor element (245) in the housing (260); and a measuring circuit (250) which is electrically coupled to the first sensor element (240) and the second sensor element (245) and is designed to measure a characteristic parameter which is indicative of a field between the at least one conductive element (230) and the first sensor element (240) and the second sensor element (245). [2] Laser system (200) according to claim 1, wherein the field between the at least one conductive element (230) and the first sensor element (240) comprises an electric field and wherein the measured parameter comprises a capacitance that depends on the electric field. [3] Laser system (200) according to claim 2, wherein the measured parameter comprises a mutual capacitance between the first sensor element (240) and the second sensor element (245). [4] Laser system (200) according to claim 3, wherein the measured parameter is further indicative of an electric field between the at least one conductive element (230) and the second sensor element (245). [5] Laser system (200) according to claim 2, wherein the first sensor element (240) is a conductive element designed to be capacitively coupled to the at least one conductive element (230). [6] Laser system (200) according to claim 1, wherein the field between the at least one conductive element (230) and the first sensor element (240) comprises a magnetic field and wherein the first sensor element (240) comprises a first coil and wherein the measuring circuit is designed to apply a current to the first coil in order to induce a first magnetic field. [7] Laser system (200) according to claim 6, wherein the characteristic parameter comprises an inductance of the first coil. [8] Laser system (200) according to claim 7, wherein the measuring circuit comprises a capacitor coupled to the first coil to form an LC resonant circuit, and wherein the measuring circuit (250) is designed to measure the inductance of the first coil by determining a resonant frequency of the LC resonant circuit. [9] Laser system (200) according to claim 6, wherein the second sensor element (245) comprises a second coil coupled to the measuring circuit (250), and wherein the characteristic parameter comprises a current induced in the second coil by the first magnetic field. [10] Laser system (200) according to claim 6, further comprising a magnetic sensor coupled to the measuring circuit (250), wherein the characteristic parameter comprises the first magnetic field measured with the magnetic sensor. [11] Laser system (200) according to claim 1, wherein the measuring circuit (250) is further designed to compare the measured parameter with a reference value in order to determine whether the optical device (220) should function properly or not. [12] Laser system (200) according to claim 11, wherein the operation of the laser light source is based at least partially on the comparison of the measured parameter with the reference value. [13] Laser system (200) according to claim 1, wherein the at least one conductive element (230) is formed as a film layer on at least a part of a surface of the optical device (220). [14] Laser system (200) according to claim 1, wherein the optical device is a non-contact optical device (220) so that it has no electrical connections. [15] Laser system (200) according to claim 1, which is included in or combined with a time-of-flight camera system. [16] Method for detecting a change in an optical device (220) within a laser system (200), wherein the optical device (220) has at least one conductive element (230) formed on at least a part of the optical device (220), and wherein the laser system (200) comprises: a laser light source (110) arranged such that emitted laser light passes through the optical device (220), a first sensor element (240) mounted in a fixed position relative to the laser light source, and a second sensor element (245) mounted in a fixed position relative to the laser light source, wherein the method comprises: Detecting the change in the optical device (220) by measuring a characteristic parameter that is indicative of a field between the at least one conductive element (230) and the first sensor element (240) and the second sensor element (245). [17] Laser assembly (600), comprising: a laser; an optical device (220) comprising at least one conductive element (230) designed to modify light emitted by the laser (110); a first coil (641); and a measuring circuit (250) which is electrically connected to the first coil (641) and which is designed to measure a characteristic parameter indicative of a field influenced by the optical device (220), wherein the first coil (641) generates the field; and wherein the measuring circuit (250) is not electrically connected to the at least one conductive element (230). [18] Laser assembly (600) according to claim 17, wherein the field influenced by the optical device (220) is a magnetic field generated by means of the at least one conductive element (230), and wherein the measuring circuit (250) is designed to measure the magnetic field by means of a first sensor element (240) and a second sensor element (245).

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