Optical measurement device

Abstract

[Problem] To provide an optical measurement device that is capable of mitigating a decrease in measurement accuracy. [Solution] An optical measurement device according to one embodiment of the present disclosure comprises: a light source that emits laser light; an antenna array that transmits split light of the laser light and outputs received light; a light-blocking member that blocks the split light and the received light; and a signal processing circuit that processes a light reception signal which is generated on the basis of the received light and a reference signal which is generated on the basis of blocking of the split light and the received light by the light-blocking member.

Description

Optical Measurement Device

[0001] The present disclosure relates to optical metrology devices.

[0002] In recent years, light detection and ranging (LiDAR) has been developed as an optical measurement device that uses a photonic integration circuit (PIC) in which optical components such as silicon (Si) waveguides are stacked on a silicon-on-insulator (SOI) substrate.

[0003] JP 2022-36224 A JP 2021-39066 A

[0004] When the optical measurement device described above is used in a distance measuring device, the noise level may increase due to the influence of internal reflection, which may result in a decrease in measurement accuracy.

[0005] The present disclosure provides an optical measurement device that can improve the reduction in measurement accuracy.

[0006] A distance measuring device according to one embodiment of the present disclosure comprises: a light source that emits laser light; an antenna array that transmits split light of the laser light and outputs received light; a shading member that blocks the split light and the received light; and a signal processing circuit that processes a received light signal generated based on the received light and a reference signal generated based on the shading of the split light and the received light by the shading member.

[0007] The signal processing circuit may include a subtraction circuit that subtracts the reference signal from the received light signal.

[0008] The light-blocking member may be a shutter placed between the antenna array and the object of distance measurement, and the shutter may be switched between an open state that allows the split light and the received light to pass through and a closed state that blocks the split light and the received light.

[0009] The light-shielding member may be a reference antenna array provided independently from the antenna array, and the reference antenna array may have a light-shielding structure that constantly blocks the split light and the received light.

[0010] The optical measurement device may further include optical systems provided separately for the antenna array and the reference antenna array.

[0011] The light source may be provided in common to the antenna array and the reference antenna array.

[0012] The reference antenna array may include: a waveguide that transmits the split light; and a light-shielding metal wiring that is arranged on a path that transmits the split light from the waveguide.

[0013] The reference antenna array may further include a semiconductor layer disposed around the waveguide, and the semiconductor layer may have an impurity concentration higher than the impurity concentration of the waveguide.

[0014] The reference antenna array may further include: a substrate; a BOX layer provided on the substrate and supporting the waveguide; and a light-shielding contact via extending from the metal wiring through the BOX layer to the substrate.

[0015] The reference antenna array may include: a waveguide that transmits the split light; and an organic light-shielding film that is disposed on a light transmission path of the split light from the waveguide.

[0016] The reference antenna array may further include an insulating film covering the waveguide, the insulating film having a cavity facing the waveguide, and the organic light-shielding film may be filled in the cavity.

[0017] The reference antenna array may further include a substrate, a BOX layer provided on the substrate and supporting the waveguide, an insulating film covering the waveguide, and a cavity penetrating the insulating film and the BOX layer and terminating in the substrate, and the organic light-shielding film may be filled in the cavity.

[0018] The reference antenna array may further include a metal wiring having a light-shielding property, which is arranged in a light transmission path of the split light from the waveguide.

[0019] The reference antenna array may include: a waveguide that transmits the split light; and a multilayer inorganic reflective film that is disposed on a transmission path of the split light from the waveguide.

[0020] The reference antenna array may further include an insulating film covering the waveguide, the insulating film having a cavity facing the waveguide, and the multilayer inorganic reflective film may be provided on the inner surface of the cavity.

[0021] The reference antenna array may include a waveguide that transmits the split light, and a light-shielding metal film that is arranged on a path for transmitting the split light from the waveguide, and the split light may be transmitted along an extension direction of the waveguide.

[0022] The reference antenna array may include a waveguide that transmits the split light, and an organic light-shielding film arranged on a path for transmitting the split light from the waveguide, and the split light may be transmitted along an extension direction of the waveguide.

[0023] The reference antenna array may include a waveguide that transmits the split light, and a multilayer inorganic reflective film arranged on a transmission path of the split light from the waveguide, and the split light may be transmitted along an extension direction of the waveguide.

[0024] The reference signal may be acquired at a timing different from that of the received light signal.

[0025] The reference signal may be acquired simultaneously with the received light signal.

[0026] 1 is a block diagram showing the configuration of an optical measurement device according to a first embodiment. FIG. 2 is a diagram showing an example of a drive sequence of the optical measurement device 1 according to the first embodiment. FIG. 3 is a diagram showing another example of the drive sequence of the optical measurement device 1 according to the first embodiment. FIG. 4 is a diagram showing yet another example of the drive sequence of the optical measurement device 1 according to the first embodiment. FIG. 5 is a diagram showing an example of a digital received light signal subjected to FFT processing. FIG. 6 is a diagram showing an example of a digital reference signal subjected to FFT processing. FIG. 7 is a diagram showing an example of a digital received light signal subjected to subtraction processing and FFT processing. FIG. 8 is a block diagram showing the configuration of an optical measurement device according to a second embodiment. FIG. 9 is a cross-sectional view showing a light-shielding structure of a reference antenna according to the second embodiment. FIG. 10 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a first modified example. FIG. 11 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a first modified example. FIG. 12 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a second modified example. FIG. 13 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a third modified example. FIG. 14 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a fourth modified example. FIG. 15 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a fifth modified example. FIG. 16 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a sixth modified example. FIG. 17 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a seventh modified example. FIG. 18 is a cross-sectional view showing a light-shielding structure of a reference antenna according to an eighth modified example. FIG. 19 is a cross-sectional view showing a light-shielding Fig. 16 is a cross-sectional view showing a light-shielding structure of a reference antenna according to a tenth modified example. Fig. 17 is a cross-sectional view showing a light-shielding structure of a reference antenna according to an eleventh modified example. Fig. 18 is a diagram showing an example of a drive sequence of an optical measurement device according to a second embodiment. Fig. 19 is a block diagram showing an example of a schematic configuration of a vehicle control system. Fig. 20 is an explanatory diagram showing an example of installation positions of an outside-vehicle information detection unit and an imaging unit.

[0027] Hereinafter, specific embodiments to which the present technology is applied will be described in detail with reference to the drawings. The drawings are schematic or conceptual, and the proportions of each part are not necessarily the same as those in reality. In the specification and drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0028] (First embodiment) Fig. 1 is a block diagram showing the configuration of an optical measurement device according to the first embodiment. The optical measurement device 1 shown in Fig. 1 is an example of a distance measuring device, and includes a light source 11, a splitter 12, a circulator 13, a switch array 14, an antenna array 15, a coupler 16, a photodetector 17, a signal processing circuit 18, a collimator 19, a shutter 20, and a control circuit 21.

[0029] The light source 11 emits laser light L0. For example, the light source 11 may be a distributed feedback (DFB) laser, a distributed Bragg reflector (DBR) laser, a ring resonator laser, a vertical cavity surface emitting laser (VCSEL), or a photonic crystal laser.

[0030] The splitter 12 splits the laser light L0 into a first light L1 and a second light L2. The split ratio between the first light L1 and the second light L2 may be 1:1 or any other ratio. The first light L1, which is one of the split lights of the laser light L0, enters the circulator 13. The second light L2, which is the other of the split lights of the laser light L0, enters the coupler 16. The splitter 12 may be, for example, a 1x2 multimode interference (MMI) coupler, a 2x2 MMI coupler, a directional coupler, or a bending directional coupler.

[0031] The circulator 13 transfers the first light L1 split by the splitter 12 to the switch array 14. The circulator 13 also transfers the third light L3 or the fourth light L4 input from the antenna array 15 via the switch array 14 to the coupler 16. The circulator 13 can be a polarization-independent optical circulator element including, for example, a 2×2 coupler, a directional coupler, a bending directional coupler, a Faraday rotator, a half-wave plate, and a polarization beam splitter, a reflecting mirror, or a prism.

[0032] The switch array 14 performs a switching operation to selectively pass the first light L1 to each optical antenna 150 of the antenna array 15. The switch array 14 also performs a switching operation to selectively pass the third light L3 or the fourth light L4 from the antenna array 15 to the circulator 13. The multiple switch elements that make up the switch array 14 can be, for example, a Mach-Zehnder interferometer including a heater for the waveguide, a ring modulation switch including a heater for the waveguide, a Mach-Zehnder interferometer including a junction (PN interface), a ring modulation switch including a junction (PN interface), a MEMS (Micro Electro Mechanical Systems) optical switch, a Mach-Zehnder interferometer having a ferroelectric film, and a ring modulation switch including a ferroelectric film.

[0033] The antenna array 15 has a plurality of optical antennas 150 arranged in a two-dimensional array. The optical antenna 150 selected by the switch array 14 emits a first light L1 toward the object 10. The optical antenna 150 selected by the switch array 14 also outputs, as received light, to the circulator 13 a third light L3 reflected by the object 10 when the shutter 20 is open, or a fourth light L4 input from the antenna array 15 when the shutter 20 is closed. Each optical antenna 150 can be, for example, a fan-shaped grating coupler, a wide waveguide grating coupler, a waveguide with a diffraction grating, a photonic crystal waveguide with a diffraction grating, or a spot size converter.

[0034] The coupler 16 outputs to the photodetector 17 a composite wave obtained by combining the second light L2 input from the splitter 12 and the third light L3 or fourth light L4 input from the circulator 13 .

[0035] The photodetector 17 is a photodiode that photoelectrically converts the combined wave combined by the coupler 16 into an analog optical signal. For the coupler 16 and the photodetector 17, for example, a heterodyne detector, a homodyne detector, or a BPD (Balanced Photo Diode) can be used.

[0036] The signal processing circuit 18 includes an amplifier circuit 181, an analog-to-digital conversion circuit 182, a subtraction circuit 183, and an FFT (Fast Fourier Transform) circuit 184. The amplifier circuit 181 amplifies the analog optical signal photoelectrically converted by the photodetector 17. The amplifier circuit 181 may be, for example, a TIA (Trans Impedance Amplifier) ​​circuit having closed-loop feedback.

[0037] The analog-to-digital conversion circuit 182 converts the analog optical signal amplified by the amplifier circuit 181 into a digital optical signal. The analog-to-digital conversion circuit 182 can be, for example, a time-to-digital converter (TDC) having a frequency-to-time converter using an SAR method, a pipeline method, a σΔ method, or a hybrid method that combines these methods.

[0038] The subtraction circuit 183 performs subtraction processing on the digital optical signal that has been digitally converted by the analog-to-digital conversion circuit 182. In this embodiment, the subtraction circuit 183 performs processing to subtract a reference signal that includes an internal reflection component when the shutter 20 is closed and the antenna array 15 is shielded from light from a light reception signal based on the third light L3 that includes an internal reflection component of the antenna array 15 and a reflected light component of the object 10 when the shutter 20 is normally open.

[0039] The FFT circuit 184 performs FFT processing on the digital optical signal that has been subjected to subtraction processing in the subtraction circuit 183, and calculates the peak frequency of the difference frequency of the composite wave. The difference frequency of the composite wave depends on the distance from the optical measurement device 1 to the object 10. The distance from the optical measurement device 1 to the object 10 is proportional to the difference frequency between the transmitted light (second light L2) and the received light (third light L3). For example, when the distance from the optical measurement device 1 to the object 10 is relatively short, the difference frequency becomes small. When the distance from the optical measurement device 1 to the object 10 is relatively long, the difference frequency becomes large. The peak frequency of the difference frequency is output from the FFT circuit 184 to the outside of the optical measurement device 1 as depth data indicating the distance from the optical measurement device 1 to the object 10 and speed data indicating the speed.

[0040] The collimator 19 focuses the first light L1 emitted from the antenna array 15 onto the object 10. The collimator 19 also focuses the third light L3 from the object 10 towards the antenna array 15.

[0041] The shutter 20 is an example of a light-blocking member arranged in the light transmission path of the first light L1 emitted from the antenna array 15 and in the light reception path of the antenna array 15. In this embodiment, the shutter 20 is arranged between the collimator 19 and the object 10. The shutter 20 switches between an open state in which the first light L1 and the third light L3 pass and a closed state in which the first light L1 and the third light L3 are blocked, based on the control of the control circuit 21. The shutter 20 may be, for example, a mechanical shutter that opens and closes blades, or an optical shutter with a variable light-blocking function that utilizes liquid crystal including LCOS (Liquid Crystal on Silicon) or MEMS.

[0042] The control circuit 21 controls the signal processing circuit 18 and the shutter 20 .

[0043] Next, an example of a drive sequence of the optical measurement device 1 according to this embodiment will be described with reference to Figures 2 to 4. In each figure, "State" indicates the drive state of the entire optical measurement device 1. "Select Out" indicates the selection of the switch array 141. "CHIRP" indicates the optical frequency of the light source 11. "FBEAT" indicates the output of the photodetector 17. "Raw Data" indicates the output of the analog-to-digital conversion circuit 182. "Pre-Processing" indicates the output of the subtraction circuit 183. "Depth Data" indicates the output of the FFT circuit 184.

[0044] 2 is a diagram showing an example of a drive sequence of the optical measurement device 1 according to the first embodiment. In FIG. 2, first, when the optical measurement device 1 is started up (see Bootup in State), the laser light L0 emitted from the light source 11 is split into a first light L1 and a second light L2 by the splitter 12. At start-up, the shutter 20 is closed, so the antenna array 15 is in a light-blocking state. Therefore, a fourth light L4 including an internal reflection component of the antenna array 15 is detected as an analog reference signal by the photodetector 17. This reference signal is converted into a digital reference signal REF by the analog-to-digital conversion circuit 182.

[0045] In the first frame following startup, when the control circuit 21 changes the shutter 20 from the closed state to the open state, the photodetector 17 measures an analog light reception signal based on the third light L3. This analog light reception signal is converted into a digital light reception signal PT by the analog-to-digital conversion circuit 182.

[0046] Next, the subtraction circuit 183 performs pre-processing by subtracting the digital reference signal REF from the digital received light signal PT, and then the FFT circuit 184 performs FFT processing on the digital received light signal after the subtraction processing.

[0047] For the second frame and thereafter, the optical measurement device 1 is driven in accordance with the same sequence as the first frame described above. That is, in the drive sequence shown in Fig. 2, a digital reference signal REF is acquired at startup, and the acquired digital reference signal REF is used in the subtraction process of each frame.

[0048] Fig. 3 is a diagram showing another example of the drive sequence of the optical measurement device 1 according to the first embodiment. In Fig. 3, the optical measurement device 1 acquires a digital reference signal REF at the beginning of each frame. That is, in the drive sequence shown in Fig. 3, a digital reference signal REF is acquired for each frame, and the acquired digital reference signal REF is used in the subtraction process of the corresponding frame.

[0049] Fig. 4 is a diagram showing yet another example of the drive sequence of the optical measurement device 1 according to the first embodiment. In Fig. 4, the optical measurement device 1 acquires a digital reference signal REF before each measurement of the digital light receiving signal PT within a frame. That is, in the drive sequence shown in Fig. 4, a digital reference signal REF is acquired for each measurement of the digital light receiving signal PT, and the acquired digital reference signal REF is used in a subtraction process with the corresponding digital light receiving signal PT.

[0050] Fig. 5A is a diagram showing an example of a digital received light signal PT that has been subjected to FFT processing. Fig. 5B is a diagram showing an example of a digital reference signal REF that has been subjected to FFT processing. Fig. 5C is a diagram showing an example of a digital received light signal PT that has been subjected to subtraction processing and FFT processing. In each diagram, the horizontal axis represents frequency, and the vertical axis represents power spectral density function (PSD).

[0051] As shown in Fig. 5A, the digital light receiving signal PT before subtraction processing contains a superposition of the reflected light component from the object 10 and the internal reflection component from the antenna array 15. On the other hand, as shown in Fig. 5B, the digital reference signal REF contains only the internal reflection component from the antenna array 15. Therefore, by calculating the difference between the two signals in the subtraction circuit 183, the internal reflection component, which is a noise component, can be removed as shown in Fig. 5C.

[0052] Therefore, according to this embodiment, the SNR (signal-noise ratio) is improved, making it possible to improve the deterioration of distance measurement accuracy.

[0053] (Second embodiment) Fig. 6 is a block diagram showing the configuration of an optical measurement device according to a second embodiment. In Fig. 6, the same components as those in the optical measurement device 1 according to the first embodiment described above are given the same reference numerals, and detailed description thereof will be omitted. Below, the following description will be centered on the points that differ from the first embodiment.

[0054] In the optical measurement device 2 according to this embodiment, a reference antenna array 152 that is always shielded from light is provided independently from a ranging antenna array 151. While a light source 11 and a signal processing circuit 18 are provided in common between the antenna array 151 and the reference antenna array 152, optical systems are provided separately. These optical systems include splitters 120 to 122, circulators 131 and 132, switch arrays 141 and 142, couplers 161 and 162, and photodetectors 171 and 172.

[0055] The splitter 120 splits the light emitted from the light source 11 into two laser beams L0. The splitter 121 splits one laser beam L0 into a first beam L1 and a second beam L2. The splitter 122 splits the other laser beam L0 into the first beam L1 and the second beam L2.

[0056] The circulator 131 transfers the first light L1 split by the splitter 121 to the switch array 141. The circulator 131 also transfers the third light L3 input from the antenna array 151 via the switch array 141 to the coupler 161.

[0057] The circulator 132 transfers the first light L1 split by the splitter 122 to the switch array 142. The circulator 132 also transfers the fourth light L4 input from the reference antenna array 152 via the switch array 142 to the coupler 162.

[0058] The switch array 141 performs a switching operation to selectively pass the first light L1 transferred from the circulator 131 to each optical antenna 150 of the antenna array 151. The switch array 141 also performs a switching operation to selectively pass the third light L3 from the antenna array 151 to the circulator 131.

[0059] The switch array 142 performs a switching operation to selectively pass the first light L1 transferred from the circulator 132 to each optical antenna 150 of the reference antenna array 152. In addition, the switch array 141 performs a switching operation to selectively pass the fourth light L4 from the reference antenna array 152 to the circulator 132.

[0060] A plurality of optical antennas 150a are arranged in a two-dimensional array in the antenna array 151. The optical antenna 150a selected by the switch array 141 emits the first light L1 toward the object 10. In addition, the optical antenna 150a selected by the switch array 141 outputs the third light L3 reflected by the object 10 to the circulator 131.

[0061] A plurality of reference antennas 150b are arranged in the reference antenna array 152. Each reference antenna 150b is an example of a light-shielding member that constantly blocks the first light L1 and the third light L3, and has a light-shielding structure that prevents light from being emitted or incident. The light-shielding structure of the reference antenna 150b will now be described with reference to FIGS. 7 to 18. Here, the extension direction of the waveguide is defined as the X direction, the direction perpendicular to the X direction on the same plane is defined as the Y direction, and the direction perpendicular to the X and Y directions is defined as the Z direction.

[0062] 7 is a cross-sectional view showing the light-shielding structure of the reference antenna 150b according to the second embodiment. FIG. 7 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In the reference antenna 150b shown in FIG. 7, a BOX layer 1502 is formed on a substrate 1501. The BOX layer 1502 is made of, for example, silicon oxide (SiO ２ The substrate 1501 and the BOX layer 1502 constitute an SOI (Silicon On Insulator) substrate.

[0063] The BOX layer 1502 supports a waveguide 1503 extending in the X direction. The waveguide 1503 can be formed using, for example, single crystal silicon or amorphous silicon. A diffraction grating with a concave-convex shape is formed at the end of the waveguide 1503. The waveguide 1503 is also covered with an insulating film 1504 such as a silicon oxide film.

[0064] In the insulating film 1504, a metal wiring 1505, a contact via 1506, and a metal wiring 1507 are arranged to face the waveguide 1503. The metal wiring 1505, the contact via 1506, and the metal wiring 1507 may be made of, for example, aluminum (Al), tungsten (W), copper (Cu), tantalum (Ta), titanium oxide (TiO ２ ), and metals having light-shielding properties such as titanium nitride (TiN) can be used.

[0065] In the reference antenna 150b having the light-shielding structure described above, the first light L1 travels along the X direction through the waveguide 1503 and is emitted. As shown in Fig. 7 , metal wiring 1505 and metal wiring 1507 functioning as light-shielding films are arranged in the light transmission path of the first light L1. Therefore, the first light L1 is reflected by the metal wiring 1505 and metal wiring 1507 and is not irradiated onto the object 10.

[0066] (First Modification) Figures 8A and 8B are cross-sectional views showing the light-shielding structure of a reference antenna 150b according to a first modification. Figure 8A is a cross-sectional view of the reference antenna 150b taken along the XZ plane. Figure 8B is a cross-sectional view of the reference antenna 150b taken along the YZ plane. On the BOX layer 1502 of the reference antenna 150b shown in Figures 8A and 8B, a semiconductor layer 1508 is formed around the waveguide 1503. The impurity concentration of the semiconductor layer 1508 is higher than the impurity concentration of the waveguide 1503. Therefore, the semiconductor layer 1508 functions as a light-absorbing film.

[0067] In the reference antenna 150b having the light-shielding structure described above, the first light L1 travels through the waveguide 1503 in the X direction and is emitted. As shown in FIGS. 8A and 8B , metal wiring 1505 and metal wiring 1507, which function as light-shielding films, are arranged in the light transmission path of the first light L1. Therefore, the first light L1 is reflected by the metal wiring 1505 and metal wiring 1507 and is not irradiated onto the object 10. Furthermore, light incident on the semiconductor layer 1508 is absorbed. This makes it possible to suppress internal reflection.

[0068] (Second Modification) Fig. 9 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a second modification. Fig. 9 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. The reference antenna 150b shown in Fig. 9 has a contact via 1509. The lower end portion of the contact via 1509 extends through the BOX layer 1502 to the substrate 1501. This makes the potential of the metal wiring 1507 the same as the potential of the substrate 1501.

[0069] In the reference antenna 150b having the above-described light-shielding structure, the first light L1 travels through the waveguide 1503 along the X direction and is emitted. As shown in FIG. 9 , metal wiring 1505 and metal wiring 1507 functioning as light-shielding films are arranged in the light transmission path of the first light L1. Therefore, the first light L1 is reflected by the metal wiring 1505 and metal wiring 1507 and is not irradiated onto the object 10. Furthermore, in this modification, a contact via 1509 penetrates the BOX layer 1502. Therefore, even if light enters the BOX layer 1502, the contact via 1509 reflects the light toward the waveguide 1503. This makes it possible to block the light traveling through the BOX layer 1502.

[0070] (Third Modification) Fig. 10 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a third modification. Fig. 10 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In the reference antenna 150b shown in Fig. 10, an organic light-shielding film 1510 is provided on an insulating film 1504. The organic light-shielding film 1510 is formed using an organic material having light-absorbing properties and is disposed opposite the waveguide 1503.

[0071] In the reference antenna 150b having the light-shielding structure described above, the first light L1 travels along the X direction through the waveguide 1503 and is emitted. As shown in Fig. 10 , an organic light-shielding film 1510 is disposed in the light transmission path of the first light L1. Therefore, the first light L1 is absorbed by the organic light-shielding film 1510 and is not irradiated onto the object 10.

[0072] (Fourth Modification) Fig. 11 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a fourth modification. Fig. 11 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In the reference antenna 150b shown in Fig. 11, the organic light-shielding film 1510 described in the third modification is formed on the upper surface of the insulating film 1504 and fills a cavity 1511 provided in the insulating film 1504. The cavity 1511 is formed to face the end of the waveguide 1503.

[0073] In the reference antenna 150b having the light-shielding structure described above, the first light L1 travels along the X direction through the waveguide 1503 and is emitted. As shown in Fig. 11 , the light transmission path of the first light L1 includes an organic light-shielding film 1510 filled in a cavity 1511. Therefore, the first light L1 is absorbed by the organic light-shielding film 1510 and is not irradiated onto the object 10.

[0074] (Fifth Modification) Fig. 12 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a fifth modification. Fig. 12 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In the reference antenna 150b shown in Fig. 12, the organic light-shielding film 1510 described in the third modification is formed on the upper surface of the insulating film 1504 and fills the cavity 1512. The cavity 1512 penetrates the insulating film 1504 and the BOX layer 1502 and terminates at the substrate 1501.

[0075] In the reference antenna 150b having the light-shielding structure described above, the first light L1 travels through the waveguide 1503 in the X direction and is emitted. As shown in FIG. 11 , an organic light-shielding film 1510 formed on the insulating film 1504 is present in the light transmission path of the first light L1. Therefore, the first light L1 is absorbed by the organic light-shielding film 1510 and is not irradiated onto the object 10. Furthermore, in this modification, the organic light-shielding film 1510 extends to the BOX layer. This allows light traveling through the BOX layer 1502 to be absorbed.

[0076] (Sixth Modification) Fig. 13 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a sixth modification. Fig. 13 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. The reference antenna 150b shown in Fig. 13 differs from the fifth modification in that the metal wiring 1507 extends in the X direction so as to face the end of the waveguide 1503.

[0077] In the reference antenna 150b having the light-shielding structure described above, the first light L1 travels through the waveguide 1503 in the X direction and is emitted. As shown in FIG. 12 , a metal wiring 1507 exists in the light transmission path of the first light L1. Therefore, the first light L1 is reflected by the metal wiring 1507. Furthermore, an organic light-shielding film 1510 filled in the cavity 1512 exists in the traveling direction of the light reflected by the metal wiring 1507. Therefore, the reflected light is absorbed by the organic light-shielding film 1510 and does not leak outside the reference antenna 150b.

[0078] (Seventh Modification) Fig. 14 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a seventh modification. Fig. 14 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In the reference antenna 150b shown in Fig. 14, a multilayer inorganic reflective film 1513 is provided on an insulating film 1504. In the multilayer inorganic reflective film 1513, first inorganic reflective films 1513a and second inorganic reflective films 1513b are alternately stacked in the Z direction. The refractive index of the first inorganic reflective film 1513a is different from the refractive index of the second inorganic reflective film 1513b.

[0079] In the reference antenna 150b having the above-described light-shielding structure, the first light L1 travels along the X direction through the waveguide 1503 and is emitted. As shown in Fig. 14, a multilayer inorganic reflective film 1513 is disposed in the light transmission path of the first light L1. Therefore, the first light L1 is reflected by the multilayer inorganic reflective film 1513 and is not irradiated onto the object 10.

[0080] (Eighth Modification) Fig. 15 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to an eighth modification. Fig. 15 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In the reference antenna 150b shown in Fig. 15, the multilayer inorganic reflective film 1513 described in the seventh modification is formed on the upper surface of the insulating film 1504 and also on the inner surface of a cavity 1511 provided in the insulating film 1504.

[0081] In the reference antenna 150b having the above-described light-shielding structure, the first light L1 travels along the X direction through the waveguide 1503 and is emitted. As shown in Fig. 15 , the light transmission path of the first light L1 includes a multilayer inorganic reflective film 1513 that is filled on the inner surface of a cavity 1511. Therefore, the first light L1 is reflected by the multilayer inorganic reflective film 1513 and is not irradiated onto the object 10.

[0082] (Ninth Modification) Fig. 16 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a ninth modification. Fig. 16 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In the first to ninth modifications described above, the first light L1 is emitted from the waveguide 1503 toward the upper surface 1515 of the chip on which the reference antenna 150b is mounted.

[0083] On the other hand, in this modification, the first light L1 is emitted from the waveguide 1503 toward a side end surface 1516 of the chip. Therefore, a metal film 1514 that blocks the first light L1 covers the side end surface 1516. The metal film 1514 may be made of, for example, aluminum (Al), tungsten (W), copper (Cu), tantalum (Ta), or titanium oxide (TiO ２ ), and metals having light-shielding properties such as titanium nitride (TiN) can be used.

[0084] In the reference antenna 150b having the above-described light-shielding structure, the first light L1 is transmitted through the waveguide 1503 in the X direction. A metal film 1514 is present in the light transmission path of the waveguide 1503. Therefore, the first light L1 is reflected by the metal film 1514 and is not irradiated onto the object 10. Note that the metal film 1514 may be formed from the side end surface 1516 to a portion of the upper surface 1515 as shown in FIG. 16 .

[0085] (Tenth Modification) Fig. 17 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to a tenth modification. Fig. 17 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In this modification, similar to the above-described ninth modification, the first light L1 is emitted from the waveguide 1503 toward the side end surface 1516. Therefore, in this modification, in order to block this first light L1, the organic light-shielding film 1510 described in the fifth modification covers the side end surface 1516.

[0086] In the reference antenna 150b having the light-shielding structure described above, the first light L1 is transmitted through the waveguide 1503 in the X direction. As shown in FIG. 17 , an organic light-shielding film 1510 is present in the light transmission path of the first light L1. Therefore, the first light L1 is absorbed by the organic light-shielding film 1510 and is not irradiated onto the object 10. Note that in this modification, the organic light-shielding film 1510 may be formed from the side end surface 1516 to a part of the upper surface 1515, as shown in FIG.

[0087] (Eleventh Modification) Fig. 18 is a cross-sectional view showing the light-shielding structure of a reference antenna 150b according to an eleventh modification. Fig. 18 is a cross-sectional view of the reference antenna 150b cut along the XZ plane. In this modification, as in the above-described ninth and tenth modifications, the first light L1 is emitted from the waveguide 1503 toward the side end surface 1516. Therefore, in this modification, in order to block this first light L1, the multilayer inorganic reflective film 1513 described in the seventh modification covers the side end surface 1516.

[0088] In the reference antenna 150b having the above-described light-shielding structure, the first light L1 travels through the waveguide 1503 in the X direction and is emitted. As shown in FIG. 18 , a multilayer inorganic reflective film 1513 is present in the light transmission path of the first light L1. Therefore, the first light L1 is reflected by the multilayer inorganic reflective film 1513 toward the waveguide 1503, and is not irradiated onto the target object 10. Note that in this modification, the multilayer inorganic reflective film 1513 may be formed from the side end surface 1516 to a portion of the upper surface 1515, as shown in FIG.

[0089] In the second embodiment and each of the above-described modified examples, it is desirable that the internal reflection characteristics be the same between the optical antenna 150a and the reference antenna 150b. Therefore, for example, it is desirable to design the optical antenna 150a and the reference antenna 150b so that the antenna physical shape and waveguide wiring length are the same. This allows one reference antenna 150b to correspond to multiple optical antennas 150a, so the number of reference antennas 150b can be less than the number of optical antennas 150a. As a result, it is possible to prevent the optical measurement device 2 from becoming larger. Note that the number of reference antennas 150b may be one or more.

[0090] The coupler 161 outputs a composite wave obtained by combining the second light L2 split by the splitter 121 and the third light L3 transferred from the circulator 13 to the photodetector 171. The coupler 162 outputs a composite wave obtained by combining the second light L2 split by the splitter 122 and the fourth light L4 transferred from the circulator 132 to the photodetector 172.

[0091] The photodetector 171 (first photodetector) photoelectrically converts the combined wave combined by the coupler 161 into an analog optical signal. The photodetector 172 (second photodetector) photoelectrically converts the combined wave combined by the coupler 162 into an analog reference signal.

[0092] The drive sequence of the optical measurement device 2 according to this embodiment will be described below with reference to Fig. 19. Fig. 19 is a diagram showing an example of the drive sequence of the optical measurement device 2 according to the second embodiment.

[0093] 19, when the optical measurement device 2 is activated, the light emitted from the light source 11 is split into two laser beams L0 by the splitter 120. The two laser beams L0 are split into a first beam L1 and a second beam L2 by the splitters 121 and 122, respectively.

[0094] The first light L1 split by the splitter 121 is input to the antenna array 151 via the circulator 131 and the switch array 141 at each measurement of the frame. On the other hand, the first light L1 split by the splitter 122 is input to the reference antenna array 152 via the circulator 131 and the switch array 141.

[0095] The first light L1 input to the antenna array 151 is irradiated toward the object 10, and as a result, the third light L3 reflected by the object 10 is received by the switch array 141. On the other hand, the first light L1 input to the reference antenna array 152 is not irradiated toward the object 10, and the fourth light L4 including an internal reflection component is output from the reference antenna array 152.

[0096] The third light L3 is combined with the second light L2 by the coupler 161, and the combined wave is detected as an analog received light signal by the photodetector 171. On the other hand, the fourth light L4 is combined with the second light L2 by the coupler 162, and the combined wave is detected as an analog reference signal by the photodetector 172.

[0097] The analog light receiving signal and the analog reference signal are simultaneously converted into a digital light receiving signal PT and a digital reference signal REF by an analog-to-digital conversion circuit 182. Next, a subtraction circuit 183 subtracts the digital reference signal REF from the digital light receiving signal PT. Finally, an FFT circuit 184 performs FFT processing on the digital light receiving signal PT after the subtraction processing.

[0098] According to the present embodiment described above, the subtraction circuit 183 calculates the difference between a digital reference signal containing only the internal reflection component of the reference antenna array 152 and a digital received light signal in which the reflected light component of the target object 10 and the internal reflection component of the antenna array 151 are superimposed. Because the internal reflection component of the antenna array 151 is substantially the same as the internal reflection component of the reference antenna array 152, it is possible to remove the internal reflection component, which is a noise component, from the digital received light signal. Therefore, in this embodiment as well, as in the first embodiment, the SNR (signal-noise ratio) decreases, making it possible to improve the degradation of ranging accuracy.

[0099] Furthermore, in this embodiment, the light-shielded reference antenna array 152 is provided independently from the ranging antenna array 151. Therefore, optical transmission and reception can be performed by the ranging antenna array 151 and the reference antenna array 152 at the same time. Therefore, the internal reflection component can be measured more accurately during ranging, and the ranging accuracy can be improved compared to the first embodiment.

[0100] In this embodiment, a first optical system consisting of a splitter 121, a circulator 131, a switch array 141, a coupler 161, and a photodetector 171 is provided between the light source 11 and the antenna array 151, and a second optical system consisting of a splitter 122, a circulator 132, a switch array 142, a coupler 162, and a photodetector 172 is provided between the light source 11 and the reference antenna array 152. In other words, optical systems are provided individually for the antenna array 151 and the reference antenna array 152. However, in this embodiment, an optical system may be provided in common between the reference antenna array 152 and the antenna array 151. In this case, the optical measurement device 2 is driven in the time-division sequence shown in FIGS. 2 to 4.

[0101] <Application to a Mobile Body> The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0102] FIG. 20 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0103] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 20, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0104] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0105] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0106] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0107] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0108] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0109] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0110] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0111] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0112] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 20, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0113] FIG. 21 is a diagram showing an example of the installation position of the imaging unit 12031.

[0114] In FIG. 21 , a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

[0115] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0116] 21 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0117] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0118] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0119] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 determines the collision risk, which indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0120] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0121] An example of a vehicle control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to, for example, the image capturing unit 12031 among the components described above. Applying the technology according to the present disclosure to the image capturing unit 12031 can improve distance measurement accuracy. As a result, the performance of the vehicle 12100 can be improved.

[0122] The present technology can be configured as follows:

[0123] (1) An optical measurement device comprising: a light source that emits laser light; an antenna array that transmits split light of the laser light and outputs received light; a light-shielding member that blocks the split light and the received light; and a signal processing circuit that processes a light-receiving signal generated based on the received light and a reference signal generated based on the blocking of the split light and the received light by the light-shielding member.

[0124] (2) The optical measurement device according to (1), wherein the signal processing circuit includes a subtraction circuit that subtracts the reference signal from the received light signal.

[0125] (3) The optical measurement device according to (1) or (2), wherein the light-blocking member is a shutter disposed between the antenna array and an object to be measured, and the shutter switches between an open state that passes the split light and the received light and a closed state that blocks the split light and the received light.

[0126] (4) The optical measurement device according to (1) or (2), wherein the light-shielding member is a reference antenna array provided independently from the antenna array, and the reference antenna array has a light-shielding structure that constantly blocks the split light and the received light.

[0127] (5) The optical measurement device according to (4), further comprising optical systems provided separately for the antenna array and the reference antenna array.

[0128] (6) The optical measurement device according to (4) or (5), wherein the light source is provided in common to the antenna array and the reference antenna array.

[0129] (7) The optical measurement device according to any one of (4) to (6), wherein the reference antenna array includes: a waveguide that transmits the split light; and a metal wiring having a light-shielding property that is arranged on a light transmission path of the split light from the waveguide.

[0130] (8) The optical measurement device according to (7), wherein the reference antenna array further includes a semiconductor layer disposed around the waveguide, and the semiconductor layer has an impurity concentration higher than an impurity concentration of the waveguide.

[0131] (9) The optical measurement device according to (7), wherein the reference antenna array further includes: a substrate; a BOX layer provided on the substrate and supporting the waveguide; and a light-shielding contact via extending from the metal wiring through the BOX layer to the substrate.

[0132] (10) The optical measurement device according to any one of (4) to (6), wherein the reference antenna array includes: a waveguide that transmits the split light; and an organic light-shielding film that is disposed on a light transmission path of the split light from the waveguide.

[0133] (11) The optical measurement device according to (10), wherein the reference antenna array further includes an insulating film covering the waveguide, the insulating film having a cavity facing the waveguide, and the organic light-shielding film is filled in the cavity.

[0134] (12) The optical measurement device described in (10), wherein the reference antenna array further includes: a substrate; a BOX layer provided on the substrate and supporting the waveguide; an insulating film covering the waveguide; and a cavity penetrating the insulating film and the BOX layer and terminating in the substrate, and the organic light-shielding film is filled in the cavity.

[0135] (13) The optical measurement device according to (12), wherein the reference antenna array further includes a metal wiring having a light-shielding property that is arranged in a light transmission path of the split light from the waveguide.

[0136] (14) The optical measurement device according to any one of (4) to (6), wherein the reference antenna array includes: a waveguide that transmits the split light; and a multilayer inorganic reflective film that is disposed on a light transmission path of the split light from the waveguide.

[0137] (15) The optical measurement device according to (14), wherein the reference antenna array further includes an insulating film covering the waveguide, the insulating film having a cavity facing the waveguide, and the multilayer inorganic reflective film is provided on an inner surface of the cavity.

[0138] (16) The optical measurement device according to any one of (4) to (6), wherein the reference antenna array includes: a waveguide that transmits the split light; and a metal film having a light-shielding property that is arranged on a light transmission path of the split light from the waveguide; and the split light is transmitted along an extension direction of the waveguide.

[0139] (17) The optical measurement device according to any one of (4) to (6), wherein the reference antenna array includes: a waveguide that transmits the split light; and an organic light-shielding film that is disposed on a light transmission path of the split light from the waveguide; and the split light is transmitted along an extension direction of the waveguide.

[0140] (18) The optical measurement device according to any one of (4) to (6), wherein the reference antenna array includes: a waveguide that transmits the split light; and a multilayer inorganic reflective film that is disposed on a light transmission path of the split light from the waveguide; and the split light is transmitted along an extension direction of the waveguide.

[0141] (19) The optical measurement device according to any one of (1) to (3), wherein the reference signal is acquired at a timing different from that of the light receiving signal.

[0142] (20) The optical measurement device according to any one of (1) to (18), wherein the reference signal is acquired simultaneously with the light receiving signal.

[0143] It should be noted that the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, the effects described in this specification are merely examples and are not intended to be limiting, and other effects may also be obtained.

[0144] 1, 2: Optical measurement device 11: Light source 15, 151: Antenna array 20: Shutter 18: Signal processing circuit 152: Reference antenna array 183: Subtraction circuit 1501: Substrate 1502: BOX layer 1503: Waveguide 1504: Insulating film 1507: Metal wiring 1508: Semiconductor layer 1509: Contact via 1510: Organic light-shielding film 1511, 1512: Cavity 1513: Multilayer inorganic reflective film 1514: Metal film

Claims

1. An optical measurement device comprising: a light source that emits laser light; an antenna array that transmits split light of the laser light and outputs received light; a light-shielding member that blocks the split light and the received light; and a signal processing circuit that processes a received light signal generated based on the received light and a reference signal generated based on the blocking of the split light and the received light by the light-shielding member.

2. The optical measurement device according to claim 1, wherein said signal processing circuit includes a subtraction circuit that subtracts said reference signal from said received light signal.

3. An optical measurement device as described in claim 1, wherein the light blocking member is a shutter disposed between the antenna array and the object to be measured, and the shutter switches between an open state that passes the split light and the received light, and a closed state that blocks the split light and the received light.

4. An optical measurement device according to claim 1, wherein the light-shielding member is a reference antenna array provided independently from the antenna array, and the reference antenna array has a light-shielding structure that constantly blocks the split light and the received light.

5. The optical measurement device according to claim 4, further comprising an optical system provided separately for said antenna array and said reference antenna array.

6. The optical measurement device according to claim 4, wherein said light source is provided in common with said antenna array and said reference antenna array.

7. An optical measurement device according to claim 4, wherein the reference antenna array includes: a waveguide for transmitting the split light; and light-shielding metal wiring arranged in a path for transmitting the split light from the waveguide.

8. The optical measurement device according to claim 7, wherein the reference antenna array further includes a semiconductor layer disposed around the waveguide, and the impurity concentration of the semiconductor layer is higher than the impurity concentration of the waveguide.

9. The optical measurement device of claim 7, wherein the reference antenna array further includes: a substrate; a BOX layer provided on the substrate and supporting the waveguide; and a light-shielding contact via extending from the metal wiring through the BOX layer to the substrate.

10. The optical measurement device according to claim 4, wherein the reference antenna array includes: a waveguide for transmitting the split light; and an organic light-shielding film disposed on a light transmission path for the split light from the waveguide.

11. The optical measurement device according to claim 10, wherein the reference antenna array further includes an insulating film covering the waveguide, the insulating film having a cavity facing the waveguide, and the organic light-shielding film filling the cavity.

12. The optical measurement device described in claim 10, wherein the reference antenna array further includes: a substrate; a BOX layer provided on the substrate and supporting the waveguide; an insulating film covering the waveguide; and a cavity that penetrates the insulating film and the BOX layer and terminates in the substrate, and the organic light-shielding film is filled in the cavity.

13. The optical measurement device according to claim 12, wherein the reference antenna array further includes a metal wiring having a light-shielding property, arranged in a light transmission path of the split light from the waveguide.

14. The optical measurement device according to claim 4, wherein the reference antenna array includes: a waveguide for transmitting the split light; and a multilayer inorganic reflective film disposed on a transmission path of the split light from the waveguide.

15. The optical measurement device according to claim 14, wherein the reference antenna array further includes an insulating film covering the waveguide, the insulating film having a cavity facing the waveguide, and the multilayer inorganic reflective film is provided on the inner surface of the cavity.

16. An optical measurement device as described in claim 4, wherein the reference antenna array includes: a waveguide that transmits the split light; and a light-shielding metal film that is arranged on a path for transmitting the split light from the waveguide; and the split light is transmitted along the extension direction of the waveguide.

17. The optical measurement device according to claim 4, wherein the reference antenna array includes: a waveguide that transmits the split light; and an organic light-shielding film arranged on a light transmission path for the split light from the waveguide; and the split light is transmitted along the extension direction of the waveguide.

18. The optical measurement device according to claim 4, wherein the reference antenna array includes: a waveguide that transmits the split light; and a multilayer inorganic reflective film arranged on a transmission path of the split light from the waveguide; and the split light is transmitted along the extension direction of the waveguide.

19. The optical measurement device according to claim 1, wherein the reference signal is acquired at a timing different from that of the received light signal.

20. The optical measurement device according to claim 1, wherein the reference signal is acquired simultaneously with the received light signal.

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