Receiver and distance measuring device of dTOF module
By designing the aperture and light absorbing components in the receiver of the TOF module, the signal crosstalk problem is solved, the ranging performance is improved and the system structure is simplified.
Patent Information
- Application Number
- CN202323463743.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-18
- Publication Date
- 2025-03-04
- Estimated Expiration
- 2033-12-18
AI Technical Summary
The signal crosstalk phenomenon of the TOF module seriously interferes with the solution of the target depth information, resulting in low ranging performance.
A receiver of a dTOF module is designed, including a receiver housing provided with an opening, a filter, a light absorbing member and a detector. The size of the opening is determined according to the principle of small hole imaging. The light-absorbing member is located between the receiver housing and the detector, and is used to absorb reflected light and reduce crosstalk.
It effectively avoids the influence of signal crosstalk, improves the accuracy of ranging, and reduces the system size and complexity.
Smart Images
Figure CN222561779U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of distance measurement, in particular to a receiver and a distance measurement device of a dTOF module. Background Art
[0002] A Time of Flight (ToF) camera is an active optical system that uses a laser pulse at the transmitting end to hit the target object, and a detector at the receiving end to identify the target signal, and then calculates the depth information of the target through the flight time. The distance information of the object can be obtained by the length of the flight time.
[0003] The receiving end of the TOF module includes an optical system with a certain aperture, a narrowband filter, a photodetector and other components. Among them, the function of the narrowband filter is to allow light in the working band to pass through and block light in the non-working band. The passband range of the narrowband filter generally blueshifts as the incident angle increases. Since the surface of the photodetector will reflect the incident signal at various angles, this part of the reflected light will produce a secondary reflection back to the photodetector when it is reflected back to the narrowband filter at a large angle, causing the crosstalk phenomenon of the TOF module. The crosstalk phenomenon of the TOF module will seriously interfere with the calculation of the target depth information, and ultimately have a bad impact on the module's detection distance, detection accuracy and other ranging performance.
[0004] It can be seen that how to solve the signal crosstalk problem of the TOF module to improve the ranging performance of the module is a technical problem that people in this field urgently need to solve. Utility Model Content
[0005] The utility model aims to provide a receiver and a distance measuring device of a dTOF module, so as to solve the technical problem that the distance measuring performance of the module is low due to the signal crosstalk of the TOF module.
[0006] In order to solve the above technical problems, the utility model provides a receiver of a dTOF module, comprising: a receiver housing provided with an opening, a filter, a light absorbing component, and a detector; wherein the size of the opening is determined according to the requirements of the pinhole imaging principle;
[0007] The receiver housing is located above the detector;
[0008] The optical filter is disposed between the receiver housing and the detector, and is located at the opening;
[0009] The light absorbing component is arranged between the receiver housing and the detector, and in the area outside the opening, for absorbing reflected light; the reflected light is the signal light that passes through the opening and the filter to the detector and is reflected by the detector.
[0010] Preferably, the light absorbing component is a light absorbing film plated on the inner surface of the receiver housing; wherein the inner surface of the receiver housing faces the detector.
[0011] Preferably, the light-absorbing film is a thin film formed by mixing an absorbing coating material and a material having a preset absorption spectrum in a solvent, and applying the solvent on the inner surface of the receiver housing.
[0012] Preferably, the filter is surrounded by the light absorption film, and the thickness of the light absorption film is greater than or equal to the thickness of the filter.
[0013] Preferably, the size of the opening is determined by the distance between the detector and the opening, the area of the detector, and the requirements of the pinhole imaging principle.
[0014] Preferably, the diameter of the opening is less than or equal to 300 μm.
[0015] Preferably, the optical filter is an interference filter, comprising multiple layers of thin films of different materials and different thicknesses.
[0016] Preferably, the detector comprises a SPAD array, and the SPAD array includes a plurality of partitions for receiving the signal light.
[0017] Preferably, the ratio of the area of the filter to the area of the absorption component is smaller than a preset value.
[0018] In order to solve the above technical problems, the utility model also provides a distance measuring device, including the receiver and laser transmitter of the above dTOF module.
[0019] The utility model provides a receiver of a dTOF module, comprising: a receiver housing provided with an opening, a filter, a light absorbing component, and a detector; wherein the size of the opening is determined according to the requirements of the pinhole imaging principle; the receiver housing is located above the detector; the filter is arranged between the receiver housing and the detector, at the opening; the light absorbing component is arranged between the receiver housing and the detector, and in an area outside the opening, for absorbing reflected light; the reflected light is the signal light that is emitted to the detector through the opening and the filter, and is reflected by the detector. In the receiver, the light-absorbing component is arranged between the receiver housing and the detector, and is used to absorb the reflected light in the area outside the opening, so that the reflected light will not be reflected by the filter or reflected by the receiver housing and return to the detector again, thereby avoiding the influence of crosstalk as much as possible and improving the accuracy of ranging; secondly, since the light reflected by the target object enters the detector through the pinhole, the area of the filter that will cause secondary reflection is correspondingly reduced, thereby relatively reducing the crosstalk effect caused by the filter and improving the accuracy of ranging; thirdly, since the receiver housing with an opening is provided in the utility model, and the size of the opening is determined according to the requirements of the pinhole imaging principle, the signal light can be clearly imaged into the detector pixel through the pinhole imaging. Compared with the previous method of using a lens to clearly image the signal light into the detector pixel, the receiver provided by the utility model does not need a lens element for imaging, thereby reducing the system volume and complexity.
[0020] In addition, the utility model also provides a distance measuring device, which has the same or corresponding technical features as the receiver of the dTOF module mentioned above, and has the same effect as above. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the embodiments of the present utility model, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0022] Figure 1 This is a schematic diagram of a traditional TOF module receiver;
[0023] Figure 2 A schematic diagram of a receiver of a dTOF module provided by an embodiment of the utility model;
[0024] Figure 3 A schematic diagram of an interference filter provided by an embodiment of the utility model;
[0025] Figure 4 for Figure 1 Schematic diagram of simulation results of crosstalk phenomenon of a traditional TOF module receiver shown;
[0026] Figure 5 for Figure 2 Schematic diagram of simulation results of imaging of the receiver of the dTOF module shown.
[0027] The reference numerals are as follows: 1 is a receiver housing, 2 is a lens, 3 is a filter, 4 is a detector, and 5 is a light absorbing component. DETAILED DESCRIPTION
[0028] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the utility model.
[0029] The core of the utility model is to provide a receiver and a distance measuring device of a dTOF module to solve the technical problem of low distance measuring performance of the module due to signal crosstalk of the TOF module.
[0030] The TOF camera is an active optical system that touches the target object through the laser pulse at the transmitting end, identifies the target signal through the detector at the receiving end, and then obtains the depth information of the target through the flight time calculation. The distance information of the object can be obtained by the size of the flight time. The receiving end of the TOF module includes components such as an optical system with a certain caliber, a narrowband filter, and a photodetector. Among them, the function of the narrowband filter is to allow the light in the working band to pass through and block the light in the non-working band. The passband range of the narrowband filter generally blueshifts with the increase of the incident angle. Since the surface of the photodetector will reflect the incident signal at various angles, this part of the reflected light will produce a secondary reflection back to the photodetector when it is reflected back to the narrowband filter at a large angle, causing the crosstalk phenomenon of the TOF module. The crosstalk phenomenon of the TOF module will seriously interfere with the calculation of the target depth information, and will eventually have a bad impact on the module's detection distance, detection accuracy and other ranging performance.
[0031] Figure 1 This is a schematic diagram of a traditional TOF module receiver, such as Figure 1 As shown, the receiver includes a receiver housing 1 with an opening, a lens 2, a filter 3, and a detector 4. The opening of a certain size ensures that the receiving end receives enough signal light, and the filter 3 blocks the interference of ambient light in the non-working band. The solid arrows indicate that the signal light reflected by the target object passes through the opening, the lens 2, and the filter 3 in sequence to reach the detector 4. Since the upper surface of the detector 4 reflects the signal light to a certain extent, reflected light at different angles is emitted to the filter 3. For light reflected at a small angle, such as Figure 1The light represented by the dashed arrow without a circle in the figure can pass through the filter 3, lens 2, and opening to return to the outside of the module without causing crosstalk. Figure 1 For the light indicated by the dotted arrow with a circle in the image, due to the large angle of incidence, the passband range of the filter 3 will be blue-shifted. Therefore, the wavelength of the signal light is not within the passband range of the filter 3 and will be reflected twice by the filter 3 and hit another part of the detector 4, causing signal crosstalk.
[0032] In order to solve the problem of secondary reflection of the detector reflected light hitting the filter, the embodiment of the utility model reduces the size of the opening and coats or deposits a layer of absorption material on the inner surface of the receiving end module to absorb the signal light reflected by the detector, thereby preventing the occurrence of crosstalk.
[0033] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 2 A schematic diagram of a receiver of a dTOF module provided by an embodiment of the utility model, such as Figure 2 As shown, the receiver of the dTOF module includes: a receiver housing 1 provided with an opening, a filter 3, a light absorbing component 5, and a detector 4; wherein the size of the opening is determined according to the requirements of the pinhole imaging principle;
[0034] The receiver housing 1 is located above the detector 4;
[0035] The filter 3 is arranged between the receiver housing 1 and the detector 4, at the opening;
[0036] The light absorbing component 5 is arranged between the receiver housing 1 and the detector 4 and in the area outside the opening, for absorbing reflected light; the reflected light is the signal light that passes through the opening and the filter 3 to the detector 4 and is reflected by the detector 4.
[0037] It should be noted that the receiver housing 1 in the embodiment of the utility model refers to the side of the receiver facing the signal light reflected by the target object. A small hole is opened on the receiver housing 1 so that the detector 4 located inside the receiver housing 1 can receive photons. The size of the opening set on the receiver housing 1 is not limited and is determined according to actual conditions. If the imaging is performed on the detector 4 based on the previous principle of lens imaging, it is necessary to ensure that enough light can enter the detector 4, and then it is necessary to ensure that the opening set on the receiver housing 1 is large enough to ensure the amount of light entering, and it is necessary to set a lens 2 matching the size of the opening between the receiver housing 1 and the detector 4, and the entire optical structure is relatively complex; in addition, the size of the filter 3 set between the lens 2 and the detector 4 matches the lens 2, that is, the size of the filter 3 is also large; in addition, for the light reflected by the detector 4 at a large angle incident on the filter 3, the passband range of the filter 3 will be blue-shifted, and it cannot pass through the filter 3 to the outside of the receiver housing 1, but will be reflected by the filter 3 for the second time and hit another part of the detector 4, causing signal crosstalk.
[0038] Therefore, in the embodiment of the utility model, the principle of pinhole imaging is adopted to image the signal light reflected by the target object on the detector 4. There is no limitation on the size of the opening on the receiver housing 1, as long as it can meet the requirements of pinhole imaging. Specifically, the size of the opening is determined by the distance between the detector 4 and the opening, the area of the detector 4, and the requirements of the pinhole imaging principle. Preferably, the diameter of the opening is less than or equal to 300 μm. The size of the opening required to be set on the receiver housing 1 according to the pinhole imaging principle is much smaller than the size of the opening required to be set on the receiver housing 1 according to the lens imaging principle. Since the embodiment of the utility model is based on the pinhole imaging principle to image on the detector 4, the lens 2 element is not required in the receiver, thereby simplifying the optical structure. Based on the principle of pinhole imaging, it is only necessary to filter the light passing through the opening through the filter 3. Therefore, compared with the previous receiver architecture, the size of the filter 3 provided in the receiver architecture provided by the embodiment of the utility model is greatly reduced. The filter 3 is arranged between the receiver housing 1 and the detector 4, located at the opening. It can be seen that by imaging the signal light reflected by the target object on the detector 4 based on the principle of pinhole imaging, the aperture size can be greatly reduced to less than 300um. When the aperture size is less than 300um, the system requirements of the pinhole imaging model can be met, so that the signal light can be clearly imaged into the pixels of the detector 4 without the imaging lens 2. In this way, on the one hand, the lens 2 element used for imaging at the receiving end can be removed, reducing the volume and complexity of the system, and on the other hand, the area of the filter 3 that will cause secondary reflection can be reduced, reducing the crosstalk effect caused by the filter 3.
[0039] The signal light reflected by the target object passes through the opening and the filter 3 in sequence and reaches the detector 4. Since the upper surface of the detector 4 reflects the signal light to a certain extent, reflected light at different angles is directed to the filter 3. For light reflected at a small angle, it can pass through the filter 3 and the opening and return to the outside of the module without causing crosstalk. As for the reflected light at a large angle, in order to avoid the blue shift of the filter 3, which causes secondary reflection by the filter 3 and hits another part of the detector 4, causing signal crosstalk, in the module provided by the embodiment of the utility model, a light absorbing component 5 is set between the receiver housing 1 and the detector 4. There is no limitation on the position of the light absorbing component 5, as long as it is located between the receiver housing 1 and the detector 4. In implementation, if the light absorbing component 5 is located between the receiver housing 1 and the detector 4 (not located on the inner surface of the receiver housing 1), a light absorbing component 5 in contact with the surface of the receiver needs to be set separately to fix the light absorbing component 5 in the receiver. In order to facilitate the placement of the light absorbing component 5, a preferred embodiment is that the light absorbing component 5 is a light absorbing film plated on the inner surface of the receiver housing 1; wherein the inner surface of the receiver housing 1 faces the detector 4. It can be seen that the light absorbing component 5 is a light absorbing film, and it is only necessary to rely on the original receiver housing 1 and plate the light absorbing film on the inner surface of the receiver housing 1, and no additional fixing components are required to fix the light absorbing material, thereby simplifying the structure of the receiver.
[0040] In order to ensure that the reflected light at a large angle can be absorbed by the light-absorbing film as much as possible, in practice, the light-absorbing film is a thin film formed by mixing an absorbing coating material and a material with a preset absorption spectrum in a solvent, and applying the solvent to the inner surface of the receiver housing 1. There is no limitation on the preset absorption spectrum, which is determined according to actual conditions. For example, the TOF camera emits infrared light, so the material of the preset absorption spectrum is an infrared light-absorbing material. The selection of absorbing coating materials in the receiver includes organic dyes, metal nanoparticles, carbon-based materials, etc. The material with characteristic absorption spectrum is mixed in a solvent and applied to the inner surface of the housing of the receiving end of the TOF module. The solvent evaporates naturally to obtain a layer of absorbing film.
[0041] There is no limitation on the size and thickness of the light-absorbing film. In order to enable the light-absorbing film to absorb the light reflected at a large angle after passing through the detector 4, a preferred embodiment is that the filter 3 is surrounded by the light-absorbing film, and the thickness of the light-absorbing film is greater than or equal to the thickness of the filter 3. The ratio of the area of the filter 3 to the area of the absorbing material is less than a preset value. There is no limitation on the preset value, as long as the area of the filter 3 is much smaller than the area of the light-absorbing component 5.
[0042] Figure 2In the embodiment, a light-absorbing material is arranged on the inner surface of the receiver housing 1, and the thickness of the light-absorbing material is equal to the thickness of the filter 3. A layer of light-absorbing material is coated or deposited on the inner surface of the receiver housing 1 to absorb the reflected light of the detector 4. The solid arrow indicates that the signal light passes through the small hole and the filter 3 in sequence to reach the detector 4. Since the upper surface of the detector 4 reflects the signal light to a certain extent, reflected light at different angles is emitted to the filter 3. For light reflected at a small angle, it can pass through the filter 3 and the opening back to the outside of the module without causing crosstalk. For light reflected at a large angle, such as Figure 2 As shown by the dotted arrow in FIG. 1 , since the area of the filter 3 is very small, the reflected light cannot be reflected on the filter 3, but directly hits the light absorbing material on the inner surface of the receiver housing 1 and is completely absorbed. It can be seen that this receiver can solve the crosstalk problem.
[0043] In the receiver of the dTOF module, in order to ensure high transmittance within the transmission bandwidth as much as possible and block light outside the transmission bandwidth, the filter 3 used is an interference filter 3, including multi-layer films of different materials and different thicknesses.
[0044] Figure 3 A schematic diagram of an interference filter provided by an embodiment of the utility model, such as Figure 3 As shown, the filter 3 is an interference filter, which includes 1 to N layers of thin films, each layer of which is made of different materials and has different thicknesses. For example, the first layer is made of material 1 and has a thickness of 1; the second layer is made of material 2 and has a thickness of 2; the third layer is made of material 3 and has a thickness of 3; the fourth layer is made of material 4 and has a thickness of 4, and the Nth layer is made of material N and has a thickness of N. The filter 3 in the receiver can be Figure 3 The interference filter structure shown is realized by alternately depositing multiple layers of thin films of different materials and thicknesses and utilizing the interference effect of light to achieve the function of a narrow-band filter, with a transmittance of nearly 100% in the working band and less than 0.1% in the non-working band.
[0045] For the detector 4 in the receiver of the dTOF module, the detector 4 used in the embodiment of the utility model includes a SPAD array, and the SPAD array includes a plurality of partitions for receiving signal light. By partition exposure, the peak power of the laser is reduced. There is no limit on the number of partitions, which is determined according to actual needs.
[0046] Figure 4 for Figure 1 Schematic diagram of simulation results of crosstalk phenomenon of a traditional TOF module receiver shown; Figure 5 for Figure 2The simulation result diagram of the imaging of the receiver of the dTOF module is shown. In the simulation, a beam of signal light is imaged at a specific pixel of the detector 4 through the module receiving end. Due to the existence of crosstalk, other pixels besides the imaging pixel will also receive a light signal with a lower intensity. Figure 4 and Figure 5 It can be seen that after imaging by a traditional receiver, in addition to the imaging pixels, other pixels can also receive light signals of a certain intensity. However, through the receiver of the dTOF module provided by the utility model, only the imaging pixels receive significant light signal intensity, and other pixels receive almost no light signals. Therefore, the crosstalk effect is greatly reduced.
[0047] The receiver of the dTOF module provided by the embodiment of the utility model includes: a receiver housing with an opening, a filter, a light absorbing component, and a detector; wherein the size of the opening is determined according to the requirements of the pinhole imaging principle; the receiver housing is located above the detector; the filter is arranged between the receiver housing and the detector, at the opening; the light absorbing component is arranged between the receiver housing and the detector, and in the area outside the opening, for absorbing reflected light; the reflected light is the signal light that passes through the opening and the filter to the detector and is reflected by the detector. In the receiver, the light-absorbing component is arranged between the receiver housing and the detector, and is used to absorb the reflected light in the area outside the opening, so that the reflected light will not be reflected by the filter or reflected by the receiver housing and return to the detector again, thereby avoiding the influence of crosstalk as much as possible and improving the accuracy of ranging; secondly, since the light reflected by the target object enters the detector through the pinhole, the area of the filter that will cause secondary reflection is correspondingly reduced, thereby relatively reducing the crosstalk effect caused by the filter and improving the accuracy of ranging; thirdly, since the receiver housing with an opening is provided in the utility model, and the size of the opening is determined according to the requirements of the pinhole imaging principle, the signal light can be clearly imaged into the detector pixel through the pinhole imaging. Compared with the previous method of using a lens to clearly image the signal light into the detector pixel, the receiver provided by the utility model does not need a lens element for imaging, thereby reducing the system volume and complexity.
[0048] A receiver of a dTOF module is described above, and this embodiment further provides a distance measuring device, including the receiver of the dTOF module and a laser transmitter. The laser transmitter includes multiple emission partitions, and the receiver of the dTOF module includes multiple receiving partitions. The emission partitions correspond to the receiving partitions one by one, and the peak power of the laser is reduced by partition exposure.
[0049] The receiver of the dTOF module included in the ranging device provided in this embodiment has been described in detail above, and will not be repeated here.
[0050] The distance measuring device provided in the embodiment of the utility model includes a receiver of a dTOF module. The receiver of the dTOF module is provided with a receiver housing with an opening, a filter, a light absorbing component, and a detector; wherein the size of the opening is determined according to the requirements of the pinhole imaging principle; the receiver housing is located above the detector; the filter is arranged between the receiver housing and the detector, at the opening; the light absorbing component is arranged between the receiver housing and the detector, and in the area outside the opening, for absorbing reflected light; the reflected light is the light that the signal light is projected to the detector through the opening and the filter, and is reflected by the detector. In the receiver, the light-absorbing component is arranged between the receiver housing and the detector, and is used to absorb the reflected light in the area outside the opening, so that the reflected light will not be reflected by the filter or reflected by the receiver housing and return to the detector again, thereby avoiding the influence of crosstalk as much as possible and improving the accuracy of ranging; secondly, since the light reflected by the target object enters the detector through the pinhole, the area of the filter that will cause secondary reflection is correspondingly reduced, thereby relatively reducing the crosstalk effect caused by the filter and improving the accuracy of ranging; thirdly, since the receiver housing with an opening is provided in the utility model, and the size of the opening is determined according to the requirements of the pinhole imaging principle, the signal light can be clearly imaged into the detector pixel through the pinhole imaging. Compared with the previous method of using a lens to clearly image the signal light into the detector pixel, the receiver provided by the utility model does not need a lens element for imaging, thereby reducing the system volume and complexity.
[0051] The above is a detailed introduction to the receiver and ranging device of a dTOF module provided by the utility model. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the utility model, the utility model can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.
[0052] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.
Claims
1. A receiver of a dTOF module, characterized in that: include: A receiver housing (1) having an opening, a filter (3), a light absorbing component (5), and a detector (4) are provided; wherein the size of the opening is determined according to the requirements of the pinhole imaging principle; The receiver housing (1) is located above the detector (4); The optical filter (3) is arranged between the receiver housing (1) and the detector (4), and is located at the opening; The light absorbing component (5) is arranged between the receiver housing (1) and the detector (4) and in an area outside the opening, and is used to absorb reflected light; the reflected light is the signal light that passes through the opening and the filter (3) to the detector (4) and is reflected by the detector (4).
2. The receiver of the dTOF module according to claim 1, characterized in that: The light absorbing component (5) is a light absorbing film plated on the inner surface of the receiver housing (1); wherein the inner surface of the receiver housing (1) faces the detector (4).
3. The receiver of the dTOF module according to claim 2, characterized in that: The filter (3) is surrounded by the light absorbing film, and the thickness of the light absorbing film is greater than or equal to the thickness of the filter (3).
4. The receiver of the dTOF module according to claim 1, characterized in that: The size of the opening is determined by the distance between the detector (4) and the opening, the area of the detector (4), and the requirements of the pinhole imaging principle.
5. The receiver of the dTOF module according to claim 1, characterized in that: The diameter of the opening is less than or equal to 300 μm.
6. The receiver of the dTOF module according to claim 1, characterized in that: The optical filter (3) is an interference filter, comprising multiple layers of thin films made of different materials and with different thicknesses.
7. The receiver of the dTOF module according to any one of claims 1 to 6, characterized in that: The detector (4) comprises a SPAD array, which includes a plurality of partitions for receiving the signal light.
8. The receiver of the dTOF module according to claim 1, characterized in that: The ratio of the area of the filter (3) to the area of the light absorbing component (5) is smaller than a preset value.
9. A distance measuring device, characterized in that: A receiver and a laser transmitter comprising the dTOF module according to any one of claims 1 to 8.