JP7011290B2 - 3D measurement projector and 3D measurement device - Google Patents

Description

An embodiment of the present invention relates to a projector for three-dimensional measurement and a three-dimensional measuring device.

In recent years, the applications of three-dimensional measurement are expanding. Laser radars (LIDAR) mounted on automobiles, drones, robots, etc., 3D sensors mounted on personal computers and smartphones for face recognition, safety monitoring systems, automatic inspection devices at manufacturing sites, etc. are representative of 3D measurement. be.

There is a structured light method as one of the three-dimensional measurement methods. In the structured light method, an object is irradiated with a structured light patterned in a dot shape, and depth information is acquired from the distortion of the pattern (Patent Documents 1 to 3).

Patent Documents 2 and 3 disclose a projector of a structured light type three-dimensional measuring device. The projector of Patent Document 2 patterns the emitted light of the light source into dot-shaped light arranged in a matrix by a condenser lens and a patterning device of a two-dimensional array, and projects the light by the projection lens.

The projector of Patent Document 3 includes a plurality of light emitting elements arranged in an array. The emitted light of the plurality of light emitting elements is patterned by a projection lens and a fan-out diffractive optical element (FO-DOE) so as to include dot light arranged in a matrix, and is projected by the projection lens.

U.S. Pat. No. 8,320,621B2 U.S. Patent Application Publication No. 2014/0211215A1 U.S. Patent Application Publication No. 2016/0025993A1

T. Matsuda, F. Abe, and H. Takahashi, "Laser printer scanning system with a parabolic mirror" Appl. Opt., Vol. 17, no. 6, pp. 878-884, Mar. 1978. P. F. V. Dessel, L. J. Hornbeck, R. E. Meier, and M. R. Douglass, "A MEMS-based projection display," Proc. IEEE, vol. 86, no. 8, pp. 1687-1704, Aug. 1988. K. Nakamura, J. Miyazu, M. Sasaura, and K. Fujiura, "Wide-angle, low-voltage electro-optic beam deflection based onspace-charge-controlled mode of electrical conduction in KTa1xNbxO3," Appl. Phys. Lett. , vol. 89, no. 3, pp. 131115-1-131115-3, Sep. 2006. Y. Kurosaka, S. Iwahashi, Y. Liang, K. Sakai, E. Miyai, W. Kunishi, D. Ohnishi, and S. Noda, "On-chip beam-steering photonic-crystal lasers," Nat. Photon. , vol. 4, no. 7, pp. 447-450, May 2010. J. K. Doylend, et.al., "Two-dimensional free-space beam steering with an optical phased array on silicon-on-insulator," Optics Express, vol. 19, no.22, pp.21595-21604, 2011. X. Gu, T. Shimada, and F. Koyama, "Giant and high-resolution beam steering using slow-light waveguide amplifier," Opt. Exp., vol. 19, no. 23, pp. 22 675-22 683, Nov. 2011. M. Nakahama, X. Gu, T. Shimada, and F. Koyama, "On-Chip high-resolution beam scanner based on Bragg reflector slow-light waveguide amplifier and tunable micro-electro-mechanical system vertical cavity surface emitting laser," Jpn. J. Appl. Phys., Vol. 51, no. 4, pp. 040208-1-040208-3, Mar. 2012.

The projectors described in Patent Documents 2 and 3 emit a plurality of dot lights at the same time. Eyesafe safety standards impose limits on power per unit radiation angle. This means that in the conventional method, the intensity per optical dot is limited, and there is a drawback that the use in a bright outdoor environment is limited.

Further, in the past, there has been a problem that an optical component for generating a dot or line pattern is required separately from the light source.

The present invention has been made in such circumstances, and one of the exemplary purposes of that aspect is to provide a projector that can be used in a structured 3D measuring device.

One aspect of the present invention relates to a structured light type three-dimensional measurement projector. The projector for 3D measurement includes a beam deflection device that includes a light emission structure that emits line light whose far-field image is a line shape from the device surface, and has a variable deflection angle at which the line light is emitted, and a reference surface. It comprises a light sweep controller that synchronously controls the time profile and deflection angle of the line light emitted by the light emitting structure so that the desired structured light is generated on top.

According to certain aspects of the invention, at least one of the problems of conventional projectors can be solved.

It is a block diagram of the 3D measuring apparatus which concerns on embodiment. It is a figure explaining the operation of the 3D measuring apparatus of FIG. It is a figure explaining the operation of the 3D measuring apparatus which concerns on one Embodiment. It is sectional drawing of the light radiation structure which concerns on one Example. It is a conceptual diagram of the structured light emitted from the light emission structure of FIG. It is a figure explaining the line length of a line light. It is sectional drawing of the beam deflection device which concerns on one Example. It is a perspective view of the beam deflection device which concerns on one Example. It is sectional drawing of the beam deflection device which concerns on one Example. 10 (a) to 10 (c) are diagrams showing an example of setting of the structured light setting unit. 11 (a) to 11 (c) are cross-sectional views of the profile adjustment structure. 12 (a) to 12 (c) are cross-sectional views of the window structure. 13 (a) and 13 (b) are diagrams illustrating the expansion of the line length using a plurality of beam deflection devices. 14 (a) to 14 (c) are diagrams showing an arrangement example of two beam deflection devices. 15 (a) and 15 (b) are diagrams showing the arrangement of two beam deflection devices. It is sectional drawing of the beam deflection device which concerns on one Example. 17 (a) and 17 (b) are diagrams showing an arrangement example of four beam deflection devices. 18 (a) to 18 (f) are diagrams showing various structured light patterns. It is a figure explaining 3D measurement by line strain detection which concerns on embodiment. It is a flowchart of 3D measurement which concerns on embodiment.

(Outline of embodiment)
One embodiment disclosed herein relates to a projector used in a structured light type 3D measuring device. The projector includes a beam deflection device that includes a light emission structure that emits line light whose far-field image is in the shape of a line from the device surface, and has a variable deflection angle at which the line light is emitted, and a desired beam deflection device on the reference surface. It is provided with a light sweep controller that synchronously controls the time profile and deflection angle of the line light emitted by the light emitting structure so that the structured light is generated.

In this embodiment, the structured light is formed in a line shape or a spot shape as a set of a plurality of light spots, but the light spots are not irradiated to the measurement target at the same time. Therefore, as compared with the conventional projector, the intensity of the light spot can be increased even under the eye safety safety standard. This makes it possible to increase the S / N ratio in a bright environment.

Further, since an optical system for patterning the spot light in a matrix shape is not required, the projector can be made thinner (lowered).

The light emission structure may have a VCSEL (Vertical Cavity Surface Emitting Laser) structure in which slow light light propagates.

The beam deflection device may further include a seed light source that photocouples the seed light of the first wavelength to the input end of the light emission structure. The light radiation structure is configured to oscillate as a single substance at the second wavelength, and at least one of the first wavelength and the second wavelength can be controlled. The deflection angle can be controlled by changing the relative relationship between the first wavelength and the second wavelength.

The beam deflection device may be configured with a variable resonator length at least one of the seed source and the light emission structure. This makes it possible to change the wavelength.

The beam deflection device may include a heater that controls the temperature of at least one of the seed source and the light emission structure. By controlling the temperature, the refractive index can be changed, and the effective resonator length and thus the wavelength can be controlled.

The light sweep controller may control the amount of drive current in at least one of the seed light source and the light radiation structure. The refractive index can be changed by controlling the self-heating of the seed light source or the light radiation structure according to the amount of the drive current, and the effective resonator length and thus the oscillation wavelength can be controlled.

At least one of the seed light source and the light emission structure may include an air gap layer and a MEMS (Micro Electro Mechanical Systems) structure that controls the thickness of the air gap layer. By mechanically controlling the resonator length, it is possible to control the wavelength in a wider range, and by extension, a large change in the deflection angle can be obtained.

The beam deflection device may further include a profile adjustment structure formed on the surface of the light emission structure to modulate the longitudinal intensity profile of the line light.

The profile adjustment structure may be defined so that the longitudinal intensity profile of the light spot formed by the line light on the reference plane is uniform.

The profile adjustment structure may divide the longitudinal intensity profile of the line light into a plurality of discrete spots.

The profile adjustment structure may include at least one of a window structure and a lateral confinement structure that determines the cross-sectional profile of the line light.

The projector may include a plurality of beam deflection devices. A plurality of line lights emitted by a plurality of beam deflection devices may be connected in the longitudinal direction to form a structured light.

The projector may include two beam deflection devices. The two beam deflection devices may be arranged so that the slow light propagation directions are opposite to each other.

The projector may include two beam deflection devices. The two beam deflection devices may be arranged so that the slow light propagation directions are at right angles.

Multiple beam deflection devices may be placed at an angle to the reference plane.

The 3D measuring device consists of a 3D measuring projector that irradiates the object to be measured with structured light, an image sensor that captures the structured light projected on the object to be measured, and line distortion of the structured light captured by the image sensor. It may have a shape identification unit for identifying a three-dimensional position of an object to be measured based on the above.

Hereinafter, embodiments will be described in detail with reference to some drawings. In the following description, components having substantially the same function and configuration are designated by the same reference numerals, and duplicate explanations are given only when necessary.

FIG. 1 is a block diagram of a structured light type three-dimensional measuring device according to an embodiment. The three-dimensional measuring device 1 mainly includes a three-dimensional measuring projector (hereinafter, simply referred to as a projector) 100, an image sensor 4, and a shape identification unit 5.

The projector 100 irradiates the object to be measured with the structured light 200. The image sensor 4 captures an image of the structured light projected on the object to be measured. Here, a plane is shown as a virtual measurement object. The shape identification unit 5 identifies the three-dimensional position or shape of the object to be measured based on the line distortion of the structured light captured by the image sensor 4.

In this embodiment, the projector 100 includes a beam deflection device 2 and a light sweep controller 3. The beam deflection device 2 includes a light emission structure 20 that emits line light 202 having a line shape in a far-field image from the device surface, and a deflection angle θ to which the line light 202 is emitted is variably configured. Here, θ = 0 in the direction perpendicular to the device surface. The structured light 200 shown in FIG. 1 includes a plurality of line patterns (light spots) 204_1 to 204_N separated in the first direction (x direction in the drawing), and each line pattern 204 is in the second direction (y direction). Is the length. It should be noted that a plurality of line patterns 204_1 to 204_N are not simultaneously irradiated to the measurement target, and only one line pattern 204 is irradiated to the measurement target at a certain time.

The light sweep controller 3 synchronously controls the time profile of the line light 202 emitted by the light emission structure 20 and the deflection angle θ so that the desired structured light 200 is generated on the reference surface RS.

The above is the basic configuration of the projector 100. Next, the operation will be described. FIG. 2 is a time chart illustrating an example of the operation of the projector 100 of FIG. The light sweep controller 3 sweeps the deflection angle θ over time. Further, in synchronization with this, the intensity of the line light 202 is changed with time. In this example, the line light 202 is repeatedly turned on and off in time.

Although FIG. 2 shows an example in which the deflection angle θ is swept at a constant inclination, the sweep may be stopped during the light emission period of the line light 202.

As a result, the structured light 200 as shown in FIG. 1 can be generated.

The present invention extends to various devices and circuits grasped as the block diagram of FIG. 1 or derived from the above description, and is not limited to a specific configuration. Hereinafter, more specific examples and modifications will be described not to narrow the scope of the present invention but to help understanding the essence and operation of the invention and to clarify them.

FIG. 3 is a block diagram of the three-dimensional measuring device 1 according to the embodiment. The three-dimensional measuring device 1 emits a beam emitted from a beam deflection device 2, a light sweep controller 3 for controlling a beam emitted from the beam deflection device 2, and a beam deflection device 2, and projects a beam projected on a measurement object on a two-dimensional pixel. It has an image sensor 4 for detection, a shape identification unit 5 for identifying a three-dimensional shape of a measurement object from a detection signal of the image sensor, and a memory 6 for storing various control data.

The beam deflection device 2 has a different deflection angle from the light emission structure 20 in which the far-field image on the reference surface RS (RS1 and RS2 are shown in the figure) directly emits line-shaped line light from the device surface. It has a light sweep structure 21 that sweeps in a direction (θ ₁ to θ ₇ in the figure). Further, the light sweep controller 3 sequentially sweeps the line light directly emitted from the surface of the device at a predetermined deflection angle in time, and creates a structured light pattern consisting of a predetermined number of lines on the reference surface RS at a predetermined line interval. Generate.

The light sweep controller 3 includes a structured light setting unit 31 that sets a pattern of a structured light that is projected onto the reference surface RS, a wavelength setting unit 32 that sets a control wavelength according to the pattern of the structured light, and a beam deflection device 2. Has a drive unit 33 for driving the light.

The image sensor 4 is a global shutter type image sensor, and captures an image of a structured light projected on an object to be measured.

The shape identification unit 5 identifies the three-dimensional position of the object to be measured based on the line distortion of the line light captured by the image sensor 4, the transmission time of the line light, and the deflection angle. The shape identification unit 5 includes a line distortion detection unit 51 that detects line distortion of line light, and a TOF detection unit 52 that calculates the deflection angle of line light by a TOF (Time of Flight) method, if necessary.

Then, AI (Artificial Intelligence) (not shown) that acquires a three-dimensional shape by obtaining the three-dimensional position of the object to be measured for all the line lights forming the structured light and analyzes the feature points of the three-dimensional shape data. Output to the processing unit or monitor.

The memory 6 stores various data such as control data for controlling the beam emitted from the beam deflection device 2, calibration data for three-dimensional shape identification, and three-dimensional shape data of the object to be measured.

FIG. 4 is a cross-sectional view of the light radiation structure 20 according to the embodiment. The light radiation structure 20 is a semiconductor device having a VCSEL (Vertical Cavity Surface Emitting Laser) structure 22 integrated on the semiconductor substrate 23, and the VCSEL structure 22 is a lower DBR (lower DBR) formed on the semiconductor substrate 23. A Distributed Bragg Reflector) 24, an active layer 25, and an upper DBR26 are provided to propagate slow light light. The VCSEL structure 22 has a unique oscillation wavelength λ ₂ determined by the resonance length in the vertical direction (Z direction).

Since the light radiation structure 20 propagates the slow light light while amplifying it, the waveguide length is lengthened to about 2 mm to 10 mm. The drive unit 33 injects a current larger than the oscillation threshold current into the light radiation structure 20 and oscillates at the wavelength λ ₂ determined by the VCSEL structure 22. In this state, when coherent incident light Li is input from the incident port 27 provided on one end side of the light radiation structure 20, the incident light Li propagates while being amplified as slow light light that is multiple-reflected in a substantially vertical direction. The emitted light Lo having a radiation angle θ _r is emitted from the exit port 28 formed on the upper surface of the surface of the light radiation structure 20, and the far-field image of the emitted light Lo has a line shape.

Here, the light sweep structure 21 can use a seed light source 21s that generates coherent incident light Li, and has a tunable laser diode (TLD) structure. The seed light source 21s may be an end face emission type TLD, but a structure in which the seed light source 21s is integrated with the light emission structure 20 is more effective for miniaturization.

The light radiation structure 20 emits emitted light Lo at a radiation angle θ _r corresponding to the wavelength λ ₁ of the seed light Li. Equation (1) holds when the multiple reflection angle of the slow light light in the light radiation structure 20 is θ _i and the emission angle of the emitted light Lo is θ _r .

sinθ _r = nsinθ _i = n√ (1- (λ ₁ / λc) ² )… (1)
n is the refractive index of the waveguide of the light radiation structure 20, λc is the cutoff wavelength of the waveguide, and is equal to λ ₂ .

Since the light emission structure 20 is injected with a current larger than the threshold current, the oscillation state at the single oscillation wavelength λ ₂ is maintained when the incident light Li is not incident, but the incident light having the wavelength λ ₁ is maintained. When Li is input, the incident light Li propagates while being amplified as slow light light that is multiple-reflected, so that the component of the single oscillation wavelength λ ₂ becomes very small.

At this time, the emitted light Lo has a beam spreading angle Δθ _div which is extremely narrow in the radiation angle _θr direction because it becomes coherent light with a uniform wavefront. This beam spread angle Δθ _div is given by the equation (2) using the opening width WL in the longitudinal direction of the exit port 28 of the light radiation structure 20.

Δθ _div ≒ λ ₁ / (WL · cosθ _r )… (2)
That is, the longer the opening width WL of the exit port 28, the narrower the beam spread angle Δθ _div , and at the same time, high output is achieved.

FIG. 5 is a conceptual diagram of a structured light emitted from the light emitting structure 20 of FIG. The structured light generated in the present embodiment will be described with reference to FIG. When seed light of wavelength λ ₁ is input from the left side of the light radiation structure 20, slow light light that is multiple-reflected in the light radiation structure 20 propagates, and the beam spread angle is very large in the deflection angle _θr direction according to Eq. (1). A narrow light beam is emitted from the exit 28. Now, consider a reference plane RS1 whose distance from the light radiation structure 20 is WD1 and which is parallel to the plane on which the light radiation structure 20 is arranged. Consider forming a structured light pattern consisting of line light of. The light beam emitted from the emission port 28 has a line shape on the reference surface RS1 (hereinafter referred to as line light), and by sweeping the wavelength λ ₁ of the seed light in time, the deflection angle θ _r changes. A multi-line structured light pattern (L1 to Ln) is formed on the reference surface RS1. As shown in the equation (2), the width of the line light emitted from the light radiation structure 20 can be narrowed by increasing the length of the light radiation structure 20, and the light output can also be increased. The light intensity can be increased. This makes it possible to increase the S / N ratio in a bright environment.

Here, consider an XX'straight line passing through the center of each line light L1 to Ln on the reference surface RS1, and let the intersection position with each line light L1 to Ln be S1 to Sn. Further, the maximum deflection angle θs_max is determined by the sweep range of the wavelength λ ₁ of the seed light.

Specifically, when the wavelength λ ₁ of the seed light is swept from 990 nm to 950 nm near the cutoff wavelength by about 40 nm, the deflection angle becomes about 10 ° to 75 °, and the maximum deflection angle θs_max exceeds 60 °. Has been obtained. The number of resolution points at this time is a high resolution exceeding 1000.

Next, the line length of each line on the reference plane RS1 will be described. FIG. 6 is a diagram illustrating the line length of the line light 202. For example, the line length with respect to the line light L1 radiating in the substantially vertical direction (that is, θ = 0) in FIG. 5 is largely determined by the lateral opening width WT of the exit port 28. Assuming that the electric field of the emitted light is uniform with the aperture width, the far-field image at a distance becomes furanforfa diffraction and becomes the intensity distribution of the square of the SINC function. If the line length at which the electric field strength 40 becomes 0 is defined at the line end, the line length LT is determined by the diffraction angle θ _d , and the equations (3a) and (3b) hold.
LT = 2WD · tan (θ _d / 2)… (3a)
θ _d ≒ λ / WT… (3b)
The line lengths LT1 and LT2 can be obtained corresponding to the distance WD (WD1 and WD2 in the figure) from the light radiation structure 20. That is, it is necessary to set an appropriate opening width WT according to the size of the object to be measured and the distance WD to the object to be measured, and obtain a desired line length LT. The present embodiment further includes a profile adjusting structure 46 for adjusting the profile of the line light.

FIG. 7 is a cross-sectional view of the beam deflection device according to the embodiment. In this beam deflection device 2, the seed light source 21s and the light radiation structure 20 are monolithically integrated. Here, the light sweep structure 21 includes a seed light source 21s, a light radiation structure 20, heaters 41 and 42 for heating them, and a heat drive unit 43 for controlling the temperature.

In this integrated beam deflection device, a seed light source 21s having a VCSEL structure 22s and a light emitting structure 20 having a VCSEL structure 22 are formed on the same semiconductor substrate.

The VCSEL structure 22s has the same configuration as the VCSEL structure 22 of the light radiation structure 20, and includes a lower DBR 24s, an active layer 25, and an upper DBR 26s formed on the semiconductor substrate 23, and the seed light source 21s and the light radiation structure 20 include. It is in a photobonded state in which the active layer 25 is common via the bonding surface 54. Further, it is preferable that the seed light source 21s and the light radiation structure 20 have slightly different oscillation wavelengths, and the resonator length is changed so that λ ₁ <λ ₂ is satisfied. Further, in consideration of the reflectance, the number of DBR layers of the upper DBR 26s is designed to have high reflection unlike that of the light radiation structure 20.

The seed light source 21s is oscillated in the vertical direction at the wavelength λ ₁ by injecting a current equal to or larger than the threshold current from the drive unit 33 from the drive electrode 45. A part of the light intensity distribution 56 in this oscillation mode exudes as seed light 56s of the light emission structure 20.

On the other hand, a current larger than the threshold current is also injected from the drive unit 33 into the light radiation structure 20 to oscillate at the wavelength λ ₂ . At this time, a part of the light intensity distribution 56 of the seed light source 21s becomes the seed light input Li of the light radiation structure 20 and is photocoupled, and the slow light light having a wavelength λ ₁ is amplified and propagated in the longitudinal direction of the light radiation structure. do. Then, the emitted light Lo is emitted from the exit port 28 formed on the surface of the light emitting structure 20.

The control of the thermal drive unit 43 will be described. In FIG. 7, for the sake of explanation, the heater 41 for heating the seed light source 21s and the heater 42 for heating the light radiation structure 20 are shown under the substrate 23, but are arranged on the upper surface of the beam deflection device 2 from the viewpoint of heating efficiency. Further, due to thermal isolation, a structure capable of heat separation such as a void 57 is formed in the vicinity of the bonding surface 54. By adjusting the temperature of each of the heaters 41 and 42, the refractive index changes and the oscillation wavelengths λ ₁ and λ ₂ change, so that the deflection angle θ of the emitted light Lo can be swept.

As can be seen from the equation (1), it is possible to change the deflection angle of the emitted light Lo by changing the cutoff wavelength λc of the light radiation structure 20. In the light radiation structure 20 having the VCSEL structure 22, the cutoff wavelength λc is equal to the single oscillation wavelength λ ₂ of the light radiation structure 20, so the equation (1) is rewritten as the equation (4).

sinθ _r = nsinθ _i = n√ (1- (λ ₁ / λ ₂ ) ² )… (4)
Efficient deflection control can be performed by controlling the heaters 41 and 42 so that the changes of the single oscillation wavelengths λ ₁ and λ ₂ of the seed light source 21s and the light radiation structure 20 are opposite to each other. Of course, the temperature of either the seed light source 21s or the light radiation structure 20 may be changed.

FIG. 8 is a perspective view of the beam deflection device according to the embodiment. A drive electrode 45 is formed on the surface of the beam deflection device 2 on the seed light source 21s side. The drive electrode 45 may serve as a shielding portion. A drive electrode 33a and a heater electrode 42a are formed on the surface of the beam deflection device 2 on the light radiation structure 20 side. Region 48 is injected with protons to enhance electrical isolation between the seed light source 21s and the light emitting structure 20. By further narrowing the distance between the electrodes 33a (42a), the opening width WT can be defined by the distance between them.

FIG. 9 is a cross-sectional view of a beam deflection device with a micromachine structure. The difference from FIG. 7 is that the seed light source 21s and the upper DBRs 26s and 26 of the light radiation structure 20 are provided with air gap layers 58s and 58, respectively, and the thickness of the air gap layers 58s can be changed by the MEMS (Micro Electro Mechanical Systems) structure. It is a point that is composed. By changing the thickness of the air gap layer 58s, the position of the high reflection mirror configured by the upper DBR 26s can be controlled, whereby the cavity length of the seed light source 21s can be changed and the oscillation wavelength λ ₁ can be changed. Further, a MEMS driving unit 60 for controlling this MEMS structure is provided. As a result, the light sweep structure 21 has a seed light source 21s having a MEMS structure and a MEMS driving unit 60. In FIG. 9, the drive unit 33 is omitted.

The MEMS drive unit 60 changes the layer thickness of the air gap layer 58 of the seed light source 21s by changing the voltage applied to the MEMS control electrode 59, and controls to sweep the oscillation wavelength λ ₁ .

A MEMS structure that changes the air gap layer 58 may be formed on the light radiation structure 20 side as well. In that case, it is efficient to control the single oscillation wavelengths λ ₁ and λ ₂ so that the changes are opposite to each other, as in the case of thermal control.

(Generation of structured light)
Using the beam deflection device 2 configured as described above, the light sweep controller 3 sweeps the line light in time and generates a structured light based on the time when the line light is transmitted and the deflection angle of the line light. .. As a result, various structured lights consisting of a predetermined number of lines are generated at predetermined line intervals.

First, using FIGS. 1 and 5, a method of forming a structured light pattern consisting of seven line lights on a reference surface RS1 in which the distance from the beam deflection device 2 to the reference surface (hereinafter referred to as a working distance) is WD1 away. Will be explained. That is, as shown in FIG. 5, when the seven line lights L1 to L7 (n = 7) are swept at the time of t1 to t7, respectively, and the line lights are formed so as to be arranged at equal intervals on the reference surface RS1. Is.

Then, points S1 to S7 at equal intervals are defined on the XX'straight line connecting the centers of the seven line lights L1 to L7. The setting value for projecting such a multi-line pattern may be input from the setting input of FIG. 1, or the pattern data of the structured light stored in the memory 6 in the form of a database table is read out. You may.

FIG. 10A is an example of setting items set by the structured light setting unit 31 for a multi-line pattern formed by seven line lights. This multi-line pattern is a case where the working distance is WD1 and the inclination θA of the reference plane RS1 is 0 with respect to the beam deflection device 2, that is, the reference plane parallel to the beam deflection device 2. Data items include "device number", "sending time", "optical output", "position", "deflection angle", "sending information" and the like.

The "device number" is a number for identifying a beam deflection device to be controlled when a plurality of beam deflection devices 2 are used at the same time. The "sending time" is the time for sending the line light. However, in the case of the thermal drive shown in FIG. 7 and the MEMS drive shown in FIG. 9, it takes time for the wavelength to stabilize. Therefore, the transmission time is defined as the time when the wavelength is stable, or the transmission time is the time when a predetermined modulation indicating that the wavelength is stable is applied to the line light and this modulation is started. This modulation of the transmission time is configured to be demodulated by the line distortion detection unit 51 on the light receiving side.

The "optical output" is the optical output power of each line light, and is usually set to the same value for each transmission time, but a different value can be set for each line light. In addition, the light output is changed and set depending on the surface roughness state of the object to be measured.

The "position" is the position of the center of line light on the reference plane. The “deflection angle” is a deflection angle θ _i ( _i = 1 to 7) with respect to each position Si of the line light, and is an equation (5) from the working distance WD1 and the position Si ( _i = 1 to 7) of the line light. It can be represented by (see FIG. 3).

θ _i = tan ^-1 (S _i / WD1)… (5)
This deflection angle is also configured so that the line light is subjected to a predetermined modulation indicating the deflection angle in the same manner as the “transmission time” and can be demodulated by the line distortion detection unit 51 on the receiving side.

When the reference surface is tilted at an angle θ _A (reference surface RS2), the intersection (indicated by a white circle) between the straight line of each deflection angle and the straight line AA'indicating the reference surface RS2 is obtained. The deflection angle θ _i at which the distance between the intersections is a predetermined distance may be obtained.

"Sending information" is an item for setting whether or not to apply line optical modulation indicating the transmission time t and the deflection angle θ (t) to each line light, respectively. It will not be set.

FIG. 10B is an example of setting the deflection angle and the wavelength corresponding to the transmission time of the structured light set by the wavelength setting unit 32. The wavelength setting unit 32 obtains a wavelength for controlling the deflection angle of the beam deflection device 2 from the setting items set by the structured light setting unit 31. Using the deflection angle θ _i at each transmission time ti, the oscillation wavelengths λ ₁ and λ ₂ in the seed light source 21s and the light radiation structure 20 are obtained from the equation (4) and stored in the memory 6 in the form of a database table.

FIG. 10C is an example of driving conditions for radiating the structured light set by the driving unit 33. The control voltages Vs (i) and V (i) that oscillate at the wavelengths λ ₁ and λ ₂ are set for the seed light source 21s and the light emission structure 20 at each transmission time ti set by the wavelength setting unit 32, respectively. In the line light modulation in which the signal indicating the wavelength and the deflection angle is superimposed on the line light, it is determined whether or not the modulation is performed according to the presence or absence of the transmission information set by the structured light setting unit 31. Then, the drive unit 33 drives the seed light source 21s and the light radiation structure 20 based on this drive condition.

(Adjusting the profile of line light)
As described in FIG. 6, in the profile of line light, assuming that the electric field of the emitted light is uniform in the aperture width, the far-field image at a distance is Franforfa diffraction. In order to obtain a long line length LT, it is necessary to narrow the opening width WT of the exit port 28 and increase the diffraction angle θ _d .

FIG. 11A is a cross-sectional view of the profile adjusting structure 46 using the oxidative stenosis structure. Since the oxidation narrowing layer 90 is provided on the upper part of the active layer 25 to narrow the current and change the refractive index distribution in the lateral direction, a refractive index waveguide structure can be formed. Therefore, the opening width WT can be narrowed to about 1 μm together with the current narrowing width CW. In this case, the aperture width WT is the same as or wider than the current narrowing width CW, so that the laser beam generated in the active layer can be effectively diffracted.

FIG. 11B is an explanatory diagram of the profile adjusting structure 46 using the ion implantation structure. An ion implantation region 92 can be provided in the upper DBR26 region to narrow the current. This ion implantation structure has a gain waveguide structure. Therefore, the current narrowing width CW can be set as wide as 10 μm to 15 μm, and a large output of the light radiation structure 20 becomes possible. Therefore, the aperture width WT is made smaller than the current narrowing width CW, and the diffraction angle θ _d is set by the aperture width WT. In the gain waveguide structure, since the wavefront is curved and the intensity distribution has bimodality, it can be expected to contribute to the direction of making the intensity distribution of the line light uniform.

FIG. 11C is an explanatory diagram of the profile adjustment structure 46 using the window structure. It is desirable that the intensity distribution of the line light is as uniform as possible. In the present embodiment, a window structure 110 is shown in which a distributed lens having transmittance and phase characteristics distributed in the line direction is formed at the exit port 28. In FIG. 11 (c), the window structure 110 is adopted for the oxidative stenosis structure of FIG. 11 (a), but the present invention is not limited to this, and the ion implantation structure and other current stenosis of FIG. 11 (b) are used. Effective for structures. Hereinafter, an example of the window structure 110 will be shown.

FIG. 12A is a cross-sectional view of a window structure using an ND filter. The ND filter structure 120a in which the transmittance of the central portion of the window structure 110 is lowered is formed, and the intensity of the central portion of the line light is reduced to make the intensity distribution uniform.

FIG. 12B is an example of a SINC function window structure. The structure 120b that adjusts the electric field distribution at the outlet 28 to the shape of the SINC function makes it possible to make the profile of the line light uniform.

FIG. 12C is an example of a multi-window structure. The multi-window structure 120c is formed on the upper portion of the window structure 110 with a material having a high reflectance such as gold (Au). With this multi-window structure 120c, the profile of the line light can be made into a wavy line shape.

(Expansion of line length LT)
Subsequently, the expansion of the line length LT will be described. 13 (a) and 13 (b) are diagrams illustrating the expansion of the line length LT. As shown in FIG. 13A, the three beam deflection devices 2 may be mounted on the trapezoidal substrate 130. As shown in FIG. 13B, the line length LT can be expanded by mounting the beam deflection devices 2 so that the diffraction angles are in contact with each other or overlap with each other.

(Cross pattern generation)
If you want to form a cross-shaped structured light, you can arrange the two beam deflection devices orthogonally. However, in the beam deflection device of the present embodiment, since the propagation direction of the slow light light is unidirectional, the deflection angle cannot be swept in the direction opposite to the propagation direction. Therefore, it is preferable to overlap the projection positions of the structured lights projected from the two beam deflection devices 2. 14 (a) to 14 (c) are examples of cases where two beam deflection devices 2a and 2b are arranged close to each other and orthogonally to each other.

In FIG. 14A, the beam deflection device 2a is arranged so as to be tilted in the deflection angle direction. Further, in FIG. 14B, the beam deflection device 2b is arranged so as to be tilted in the diffraction angle direction. In FIG. 14C, the two beam deflection devices 2a and 2b are both tilted and arranged.

(Expansion of deflection angle)
Since the beam deflection device of the present embodiment cannot sweep the deflection angle in the direction opposite to the slow light propagation direction, the deflection angle can be expanded by arranging the two beam deflection devices 2a and 2b in parallel. However, the beam deflection device of the present embodiment is difficult to emit vertically (θ = 0) and has a deflection angle of at least about 3 ° to 5 °. Therefore, the beam deflection devices 2a and 2b are tilted by at least about 5 °, and the slow light propagation directions are arranged in parallel in the opposite direction. FIG. 15A is an example of arranging the two beam deflection devices 2a and 2b on a straight line, and FIG. 15B is a case where the two beam deflection devices 2a and 2b are arranged side by side.

FIG. 16 is a cross-sectional view of the beam deflection device 2 according to the embodiment. The prism 160 is arranged in the longitudinal direction of the exit port 28 of the light radiation structure 20. The prism 160 enables vertical emission without tilting and mounting the beam deflection devices 2a and 2b.

FIG. 17A is an arrangement example in which four beam deflection devices are arranged. As shown in FIG. 15B, the beam deflection devices 2X and 2X'are arranged side by side to expand the deflection angle in the X direction, and similarly, the beam deflection devices 2Y and 2Y'are used to increase the deflection angle in the Y direction. To expand. According to this configuration, as shown in FIG. 17B, there are four reference planes Rs_X flooded by the beam deflection devices 2X and 2X'and four reference planes Rs_Y flooded by the beam deflection devices 2Y and 2Y'. It can be effectively orthogonal to the vertical of the beam deflection device.

18 (a) to 18 (f) are diagrams showing structured lights that can be generated by the projector 100. FIG. 18A shows a line pattern 204 generated at a certain time. FIG. 18B shows a striped structured light 200 formed by sweeping the line pattern 204 of FIG. 18A. According to the projector 100 according to the embodiment, it is possible to arbitrarily control the interval of the line pattern 204 (for example, unequal interval) as shown in FIG. 18 (b). FIG. 18 (c) is a cross pattern 206 generated at a certain time, which includes two orthogonal line patterns 204x and 204y. The cross pattern 206 can be realized by a combination of two beam deflection devices 2 arranged orthogonally as described with reference to FIGS. 14 (a) to 14 (c). When the cross pattern 206 of FIG. 18 (c) is swept, a grid-like structured light 208 as shown in FIG. 18 (d) is formed.

FIG. 18 (e) is a diagram showing a line pattern 210 obtained by modulating line light so as to include a plurality of spots 212 discrete in the longitudinal direction. Such a line pattern 210 can be realized by the window structure 110 shown in FIG. 11 (c). The structured light 214 of FIG. 18F can be realized by arranging two beam deflection devices 2 capable of forming the line pattern 210 of FIG. 18E at right angles.

(3D measurement)
FIG. 19 is an explanatory diagram of three-dimensional measurement by line strain detection according to the embodiment. Assuming that the line light is emitted from the light emission structure 20 at a deflection angle θ ₃ , the point S3 is reached on the XX'straight line of the reference surface RS1 at a distance WD1 from the light emission structure 20. At this time, the line light is observed at an angle in the S3 direction when viewed from the center R point of the image sensor 4.

Assuming that the object to be measured is at the R3 point, line light is observed at an angle in the R3 direction when viewed from the central R point of the image sensor 4. That is, the line light moves by Δθ in the figure and is observed. This Δθ is imaged as a movement of pixel points on the image sensor 4. Similarly, since the same applies to all the pixels in the Y direction of the image sensor 4, line distortion is observed on the image sensor 4.

There are S2 points and R4 to R7 points in the R3 direction when viewed from the image sensor 4, but the image sensor side is notified of the emission time t of the line light and the θ (t) information indicating the deflection angle. It can be determined that the reflection is from the R3 point. The position of the R3 point can be calculated by trigonometry. The information on the emission time t and the deflection angle θ (t) of the line light transmitted from the beam deflection device 2 is modulated by the line light itself as shown in FIGS. 10 (a) and 10 (c), or is light. It is sent directly from the sweep controller 3 to the shape identification unit 5.

Since the beam deflection device 2 is thermally driven or MEMS-driven, it is considered that the oscillation wavelengths λ ₁ and λ ₂ fluctuate, and the deflection angle of the transmitted line light may not be accurate. In that case, the TOF detection circuit can calculate the position of the R3 point from the arrival time of the light of the path S-R3-R, and obtain the deflection angle θ ₃ at that time. Then, using the calculated θ ₃ , line distortion may be detected for the entire line.

FIG. 20 is a flowchart of three-dimensional measurement according to the embodiment. First, in step ST1, a desired structured light is first set, and in step ST2, the line light forming the structured light is temporally swept from the beam deflection device 2 and projected onto the object to be measured. In step ST3, θ (t) information indicating the reflection angle of the line light on the image sensor 4, the transmission time of the line light, and the deflection angle is acquired.

In step ST4, the line distortion detection unit 51 uses the reflection angle of the line light captured by the image sensor 4 and the θ (t) information indicating the transmission time t and the deflection angle of the line light to measure 3 of the object to be measured. Find the dimensional position.

In step ST5, a three-dimensional position is obtained for all the line lights forming the structured light, and a three-dimensional image of the object to be measured is obtained.

Step ST6 is performed when the accuracy of the deflection angle cannot be obtained, and the TOF detection unit 52 obtains the deflection angle of the line light from the arrival time of the line light and notifies the line distortion detection unit 51. The line distortion detection unit 51 calculates a three-dimensional position using this deflection angle. Of course, it is also possible to obtain a three-dimensional image only by the TOF detection unit 52.

As described above, according to the present embodiment, since the three-dimensional measurement is performed using a beam deflection device having a wide deflection angle of 60 ° or more and a resolution point of 1000 or more, it is possible to obtain high-resolution three-dimensional data. It is possible. Further, it is possible to increase the output by adopting the gain waveguide structure and the lengthening of the light radiation structure of the present embodiment. Therefore, three-dimensional measurement that is strong against external light can be performed.

Further, when a plurality of beam deflection devices are arranged, the diffraction angle and the deflection angle can be expanded without using a lens system, so that the projection area can be expanded without reducing the resolution. Therefore, it is possible to perform three-dimensional measurement by projecting light on a large object to be measured relatively close. Further, by arranging a plurality of beam deflection devices, it is possible to form an optimum structure light pattern according to the object to be measured.

Further, since the deflection angle can be set according to the object to be measured, low power consumption can be achieved as compared with the type in which the structure pattern is flooded all at once.

Further, since the deflection angle of the line light emitted from the beam deflection device can be accurately acquired on the image sensor side, high-resolution three-dimensional measurement can be performed.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The present embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... 3D measuring device 2 ... Beam deflection device 3 ... Light sweep controller 4 ... Image sensor 5 ... Shape identification unit 6 ... Memory 20 ... Light radiation structure 21 ... Light sweep structure 21s ... Seed light source 22 ... VCSEL structure 31 ... Structured light Setting unit 32 ... Wavelength setting unit 33 ... Drive unit 51 ... Line distortion detection unit 52 ... TOF detection unit.

Claims (16)

The far-field image includes a light emitting structure that emits line light having a line shape having a length in the first direction from the device surface so that the line light is swept in a second direction perpendicular to the first direction. A beam deflection device in which the deflection angle at which the line light is emitted is variable, and
A light sweep controller that synchronously controls the time profile of the line light emitted by the light emitting structure and the deflection angle so that a desired structured light is generated on the reference surface.
A projector for 3D measurement of the structured light system, which is characterized by being equipped with. The projector for three-dimensional measurement according to claim 1, wherein the light emission structure has a VCSEL (Vertical Cavity Surface Emitting Laser) structure in which slow light light propagates. The beam deflection device further comprises a seed light source that photocouples the seed light of the first wavelength to the input end of the light emission structure.
The light radiation structure is configured to oscillate as a single substance at the second wavelength.
The projector for three-dimensional measurement according to claim 2, wherein at least one of the first wavelength and the second wavelength is controllably configured. The projector for three-dimensional measurement according to claim 3, wherein the beam deflection device is characterized in that at least one resonator length of the seed light source and the light radiation structure is variably configured. The projector for three-dimensional measurement according to claim 3 or 4, wherein the beam deflection device includes a heater for controlling the temperature of at least one of the seed light source and the light radiation structure. The projector for three-dimensional measurement according to claim 3 or 4, wherein the light sweep controller controls the amount of driving current of at least one of the seed light source and the light radiation structure. The third or four claim, wherein at least one of the seed light source and the light emission structure includes an air gap layer and a MEMS (Micro Electro Mechanical Systems) structure for controlling the thickness of the air gap layer. Projector for 3D measurement. The beam deflection device according to any one of claims 1 to 7, further comprising a profile adjusting structure formed on the surface of the light emitting structure and modulating the longitudinal intensity profile of the line light. Projector for 3D measurement. The projector for three-dimensional measurement according to claim 8, wherein the profile adjusting structure divides the intensity profile in the longitudinal direction of the line light into a plurality of discrete spots. The projector for three-dimensional measurement according to claim 8, wherein the profile adjusting structure has at least one of a window structure and a lateral confinement structure for determining a cross-sectional profile of the line light. It is equipped with a plurality of the beam deflection devices.
The projector for three-dimensional measurement according to any one of claims 1 to 10, wherein a plurality of line lights emitted by a plurality of beam deflection devices are connected in the longitudinal direction to form the structured light. The two beam deflection devices are provided.
The projector for three-dimensional measurement according to claim 2, wherein the two beam deflection devices are arranged so that the slow light propagation directions are opposite to each other. The two beam deflection devices are provided.
The projector for three-dimensional measurement according to claim 2, wherein the two beam deflection devices are arranged so that the slow light propagation directions are at right angles. The projector for three-dimensional measurement according to claim 2, wherein the plurality of beam deflection devices are arranged at an angle with respect to the reference surface. The projector for three-dimensional measurement according to any one of claims 1 to 14, which irradiates the object to be measured with a structured light.
An image sensor that captures the structured light projected onto the object to be measured, and
A shape identification unit that identifies the three-dimensional position of the object to be measured based on the line distortion of the structured light imaged by the image sensor.
A three-dimensional measuring device characterized by having. Claims 2 to 7 are characterized in that the opening width of the VCSEL structure in the first direction is determined so that the length of the line light in the first direction becomes a desired length on the reference surface. The projector for 3D measurement described in any of.

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