Optical module and distance measuring device

Abstract

The objective of the present invention is to emit a distortion-free light beam toward light receiving units arranged two-dimensionally, in an optical module that emits a light beam at a target object and detects the reflected light.　According to the present invention, a light emitting unit is provided with a plurality of light emitting elements. A condensing unit converts light beams emitted from each of the plurality of light emitting elements of the light emitting unit into substantially parallel light beams or light beams having a prescribed angular width, and condenses the same at a prescribed focal center point. An optical conversion unit generates replica light relative to the actual light of the light beam that has passed through the condensing unit, and converts the actual light and the replica light into a prescribed projected light beam. A light detecting unit detects reflected light from the target corresponding to the projected light beam. The projected light beam obtained by conversion by the optical conversion unit has substantially the same distortion aberration as that of the light detecting unit.

Description

Optical module and distance measuring device

[0001] The present technology relates to an optical module, and more particularly to an optical module that irradiates an object with a light beam, and a distance measuring device that uses the optical module.

[0002] Optical modules that irradiate an object with a light beam are used for applications such as distance measurement by measuring the time of flight (ToF) of light and object shape recognition. Known optical modules scan a light beam and detect reflected light from an object corresponding to each scanning position. For example, a device has been proposed that measures distance by irradiating a linear light beam using light-emitting elements arranged one-dimensionally or two-dimensionally (see, for example, Patent Document 1).

[0003] International Publication No. 2020 / 105239

[0004] In the above-mentioned conventional technology, an optical module that irradiates an object with a light beam and detects its reflected light irradiates a linear light beam without distortion regardless of the incident angle of the scanned light beam. However, if the optical lens that receives the reflected light has large distortion aberration, the linear light beam can be distorted from a straight line to a curved line. When the light beam is distorted from a straight line, it may be difficult to detect the reflected light from an object corresponding to a certain scanning position using a single row of light-receiving elements arranged two-dimensionally. Specifically, at the ends of a row of light-receiving elements, the position of the reflected light is shifted, reducing the amount of detectable light and resulting in a decrease in distance accuracy. In contrast, when multiple rows are used for detection, the system is susceptible to noise caused by external light. Furthermore, widening the width of the linear light beam requires increasing the optical output of the light-emitting element, which increases power consumption. Furthermore, considering safety for the human eye, blindly increasing the optical output is not advisable.

[0005] This technology was developed in light of these circumstances, and aims to irradiate a distortion-free light beam onto a two-dimensionally arranged light receiving unit in an optical module that irradiates a light beam onto an object and detects the reflected light.

[0006] The present technology has been made to solve the above-mentioned problems, and a first aspect thereof is an optical module and distance measuring device including: a light-emitting unit having a plurality of light-emitting elements; a focusing unit that converts light beams emitted from each of the plurality of light-emitting elements into substantially parallel light beams or light beams with a predetermined angular width and focuses them at a predetermined center point of an aperture; an optical conversion unit that generates replica light of actual light of the light beam passing through the focusing unit and converts the actual light and the replica light into a predetermined projected light beam; and an optical detection unit that detects reflected light of the projected light beam from an object, wherein the optical conversion unit converts the projected light beam into the projected light beam having a distortion aberration substantially equal to that of the optical detection unit, thereby providing the effect of projecting a projected light beam having a distortion aberration substantially equal to that of the optical detection unit.

[0007] In addition, in this first aspect, the light detection unit may have optical characteristics in which distortion is an equidistant projection, thereby suppressing the effects of variations in optical components, misalignment, and the like.

[0008] In addition, in this first aspect, the plurality of light-emitting elements of the light-emitting unit may be arranged in a predetermined direction, and the optical conversion unit may include a grating having a rectangular cross section, and the optical beam passing through the light-collecting unit may be converted by the grating into an optical beam in a linear direction substantially perpendicular to the arrangement direction of the light-emitting units to generate the replica light. This brings about the effect of generating the replica light by utilizing the rectangular grating.

[0009] In addition, in this first aspect, the light conversion unit may include a meniscus lens having a concave entrance surface and a convex exit surface, the entrance surface of the meniscus lens may include the grating and different distance radii in the horizontal and vertical directions, and the exit surface of the meniscus lens may include different distance radii in the horizontal and vertical directions, and may convert the light into the projection light beam having substantially the same distortion aberration as that of the light detection unit, depending on the shape of the exit surface.

[0010] Furthermore, in this first aspect, the entrance surface of the optical conversion unit may have a radius of curvature in the arrangement direction that is approximately equal to the distance from the center point of the virtual aperture in the arrangement direction to the center point of the entrance surface regardless of the position in the linear direction, and the exit surface may be an optical surface having a high-order surface.

[0011] Furthermore, in this first aspect, the meniscus lens of the optical conversion unit may be an optical lens in which the rectangular grating made of resin is formed on a glass or resin lens, or may be an optical lens in which the rectangular grating is integrally formed on a resin lens.

[0012] In addition, in this first aspect, the light conversion unit may include, in order from the light emission unit, first and second meniscus lenses, each having a concave entrance surface and a convex exit surface, the first meniscus lens having the grating at the entrance surface and having different distance radii in the horizontal and vertical directions, and the second meniscus lens having different distance radii in the horizontal and vertical directions at the exit surface, so as to convert the light into the projection light beam having approximately the same distortion aberration as that of the light detection unit. This provides the effect of generating replica light by the grating at the entrance surface of the first meniscus lens and correcting it by the second meniscus lens, thereby projecting a projection light beam having approximately the same distortion aberration as that of the light detection unit using a plurality of optical elements.

[0013] In addition, in this first aspect, the light conversion unit may include, in order from the light emission unit, first and second meniscus lenses, each having a concave entrance surface and a convex exit surface, the grating being provided on the exit surface of the first meniscus lens and having different distance radii in the horizontal and vertical directions, and the second meniscus lens having different distance radii in the horizontal and vertical directions on the exit surface of the second meniscus lens, so as to convert the light into the projection light beam having substantially the same distortion aberration as that in the light detection unit. This provides the effect of generating replica light by the grating on the exit surface of the first meniscus lens and correcting it by the second meniscus lens, thereby projecting a projection light beam having substantially the same distortion aberration as that in the light detection unit using a plurality of optical elements.

[0014] In addition, in this first aspect, the light conversion section may further include a diffusion section that diffuses the projected light beam in the arrangement direction, thereby providing an effect of widening the range of options for the light source of the light emitting section.

[0015] In this first aspect, the rectangular grating may be replaced by a grating having a sinusoidal cross section, which provides the effect of easing the processing conditions for the grating.

[0016] In addition, in this first aspect, the optical conversion unit may convert the actual light and the replica light into the projection light beam in which the light intensity ratio between the actual light and the replica light is not equal, thereby providing the effect of projecting a projection light beam suited to the application.

[0017] In addition, in this first aspect, the optical conversion unit may convert at least a part of the actual light or the replica light into the projected light beam by superimposing the actual light or the replica light, thereby improving robustness and distance measurement performance.

[0018] FIG. 1 is a diagram illustrating an example of a configuration of a distance measurement device 100 according to a first embodiment of the present technology. FIG. 2 is a diagram illustrating an example of a configuration of a semiconductor laser 110 according to the first embodiment of the present technology. FIG. 3 is a diagram illustrating an example of output light from an optical lens 161 according to the first embodiment of the present technology. FIG. 4 is a diagram illustrating an example of a configuration of the optical lens 161 according to the first embodiment of the present technology. FIG. 5 is a diagram illustrating an example of a structure of a grating provided on the optical lens 161 according to the first embodiment of the present technology. FIG. 6 is a diagram illustrating an example of a relationship between a groove depth of a grating provided on the optical lens 161 according to the first embodiment of the present technology and diffraction efficiency. FIG. 7 is a diagram illustrating an example of an amount of deviation of an angle of view of the optical lens 161 according to the first embodiment of the present technology. FIG. 8 is a diagram illustrating an example of a shape of an output light beam 11 formed by the optical lens 161 according to the first embodiment of the present technology. FIG. 9 is a diagram illustrating an example of a configuration of a condenser lens 170 according to the first embodiment of the present technology. FIG. 10 is a diagram illustrating an example of a configuration of a photodetector 180 according to the first embodiment of the present technology. FIG. 11 is a diagram illustrating a first example of output light from the optical lens 161 according to the second embodiment of the present technology. 10 is a diagram showing a third example of emitted light from optical lens 161 according to the second embodiment of the present technology. FIG. 11 is a diagram showing an example of the relationship between the groove depth and diffraction efficiency of the grating provided on optical lens 161 in the third example of the second embodiment of the present technology. FIG. 12 is a diagram showing an example of the configuration of distance measurement device 100 according to the third embodiment of the present technology. FIG. 13 is a diagram showing an example of the configuration of semiconductor laser 110 according to the third embodiment of the present technology. FIG. 14 is a diagram showing an example of emitted light from optical lens 162 according to the third embodiment of the present technology. FIG. 15 is a diagram showing an example of the configuration of distance measurement device 100 according to the fourth embodiment of the present technology. FIG. 16 is a diagram showing an example of emitted light from optical lens 163 according to the fourth embodiment of the present technology. FIG. 17 is a diagram showing a first example of distance measurement device 100 according to the fifth embodiment of the present technology. FIG. 18 is a diagram showing a second example of distance measurement device 100 according to the fifth embodiment of the present technology. FIG. 19 is a diagram showing a first example of distance measurement device 100 according to the sixth embodiment of the present technology. FIG. 20 is a diagram showing a second example of distance measurement device 100 according to the sixth embodiment of the present technology.

[0019] Hereinafter, modes for implementing the present technology (hereinafter referred to as embodiments) will be described. The descriptions will be made in the following order: 1. First embodiment (an example in which real light and replica light diffracted by a grating on the entrance surface of an optical lens are corrected on the exit surface of the optical lens) 2. Second embodiment (an example in which real light or replica light is superimposed) 3. Third embodiment (an example in which a diffusion function for optically diffusing light in the Y direction is added to an optical lens and light sources are arranged one-dimensionally) 4. Fourth embodiment (an example in which a diffusion function for optically diffusing light in the X direction is added to an optical lens and light sources are arranged one-dimensionally) 5. Fifth embodiment (an example in which diffraction and correction are performed by different optical elements)

[0020] 1. First Embodiment [Distance Measuring Device] FIG. 1 is a diagram showing an example of the configuration of a distance measuring device 100 according to a first embodiment of the present technology.

[0021] Distance measurement device 100 is an example of an optical module that irradiates an object with a light beam and detects the reflected light, and is a device that measures the distance to the object by measuring the time of flight of the light. Distance measurement device 100 includes semiconductor laser 110, collimator lens 120, optical lens 161, condenser lens 170, photodetector 180, and control unit 190.

[0022] In the following embodiments, an example of a distance measurement device that measures the distance to an object by measuring the time of flight of light is shown, but the present technology is not limited to this. For example, the present technology can also be used in a distance measurement device that measures distance using a structured light method.

[0023] The semiconductor laser 110 is a laser light source that emits a light beam. In this first embodiment, it is assumed that the semiconductor laser 110 is a surface-emitting semiconductor laser (VCSEL: Vertical Cavity Surface Emitting Laser Diodes). It is also desirable that the semiconductor laser 110 is capable of individually switching the light-emitting units, and that light scanning is possible by switching the light emission of the arranged light-emitting units. Furthermore, instead of switching the light emission in order to perform scanning, the light emission may be switched randomly. The semiconductor laser 110 is an example of a light-emitting unit as defined in the claims.

[0024] The collimator lens 120 is a lens that converts the light beam emitted from the semiconductor laser 110 into a substantially parallel light beam or a light beam with a predetermined angular width. The light beam that passes through this collimator lens 120 spreads with a predetermined angular width depending on the distance, but it is desirable that the light beam is irradiated over the entire linear range of the target object, which corresponds to the range detected by a single linear light-receiving unit, regardless of the distance. In other words, the collimator lens 120 focuses the light beam emitted from the semiconductor laser 110 at a predetermined aperture center point. The collimator lens 120 is an example of a focusing unit as defined in the claims.

[0025] Note that, here, it is assumed that a surface-emitting semiconductor laser 110 is used, and that a collimator lens 120 is used as a lens that converts the light beam emitted from the semiconductor laser 110 into a substantially parallel light beam. However, if a light source that emits a parallel light beam (for example, a PC-SEL) is used, this collimator lens 120 does not need to be provided.

[0026] The optical lens 161 is a lens that emits the light beam scanned by switching the light emission of the semiconductor laser 110 as the emitted light beam 11. This optical lens 161 is a meniscus lens with a concave entrance surface (S0) and a convex exit surface (S1). The emitted light beam 11 from the optical lens 161 is irradiated onto an object of distance measurement, where it is reflected and scattered. The light reflected from the object in response to the emitted light beam 11 is incident on the distance measurement device 100 as the reflected light beam 12. The optical lens 161 is an example of an optical conversion unit as defined in the claims.

[0027] The incident surface of the optical lens 161 is a biconic surface with different radii of curvature in the horizontal and vertical directions. The incident surface of the optical lens 161 is provided with a grating with a rectangular cross section that is approximately parallel to the vertical axis. The diffraction function of this grating generates replica light in the horizontal direction, which corresponds to the actual light of the light beam from the collimator lens 120. As described below, this allows a horizontal line spread (HFOV: Horizontal Field of View) to be obtained, thereby reducing the number of light-emitting elements arranged in the semiconductor laser 110 and reducing the horizontal area. For this reason, it is desirable that the horizontal radius of curvature rx0 be set approximately equal to the length from the virtual scanning center point (= virtual aperture center point) Ox to the incident surface (S0), regardless of the horizontal position. The virtual scanning center point is the point where the emitted light beams scanned by the light emission switching of the arranged light-emitting elements, as viewed from the illuminated object side, converge when extended in the depth direction of the distance measurement device 100, and is also referred to as a virtual rotation center point. Optically, it is a virtual light-emitting point.

[0028] As will be described later, the diffracted light angles of the actual light and replica light at the incident surface of the optical lens 161 can be adjusted by the shape of the grating, and the actual light and replica light can be arbitrarily arranged as the output light beam 11.

[0029] The exit surface of the optical lens 161 is a biconic surface with different radii of curvature in the horizontal and vertical directions. The exit surface of this optical lens 161 has a free-form shape, and as will be described later, the actual light and replica light generated at the entrance surface are irradiated onto the light-receiving surface of the photodetector 180 as a distortion-free light beam. To achieve this, it is necessary to set the surface shape of the exit surface (S1) so that it is the same as the distortion aberration (deviation) of the condenser lens 170 that receives the reflected light. As an example of such an optical surface shape, an optical surface that satisfies the following Chebyshev polynomials can be assumed. Here, c ｉｊ is the coefficient of the Chebyshev polynomial sum, x and y are the normalized surface coordinates, and N and M are the maximum polynomial degrees in the x and y dimensions, respectively. Also, c is the curvature of the reference sphere, which is expressed by adding a polynomial to this reference sphere. Note that odd terms have been omitted because symmetry about the X and Y axes is assumed.

[0030] In the above example, a Chebyshev polynomial surface is used as an example of an optical surface having a free-form curved shape, but the technology of this embodiment can be applied to optical surfaces in general that have high-order surfaces such as extended polynomial surfaces.

[0031] The condenser lens 170 is a lens that condenses the reflected light beam 12 from the object. The reflected light beam 12 condensed by the condenser lens 170 is guided to a photodetector 180.

[0032] The photodetector 180 detects the light beam 12 reflected from the object. As will be described later, the photodetector 180 has a plurality of linear light receiving sections on the surface facing the condenser lens 170, and detects light by sequentially activating these sections. The photodetector 180 is an example of a light detecting section as defined in the claims.

[0033] The control unit 190 controls the distance measurement operation of the distance measurement device 100. That is, the control unit 190 measures the emission timing of the semiconductor laser 110, the scanning position by switching the emission of the semiconductor laser 110, synchronous control of the selection of the light receiving unit in the photodetector 180, and the light detection timing. This measures the time of flight required for the emitted light to be reflected by the target object and detected as reflected light, thereby measuring the distance to the target object. Various methods can be used for this, including a direct method of observing a reflected wave (direct Time of Flight) and an indirect method using a change in the phase shift of a rectangular wave (indirect Time of Flight). The control unit 190 is an example of a measurement unit described in the claims.

[0034] [Semiconductor Laser] FIG. 2 is a diagram showing an example of the configuration of the semiconductor laser 110 according to the first embodiment of the present technology.

[0035] In the semiconductor laser 110 of the first embodiment, the light-emitting elements 111 are arranged two-dimensionally. Each of the multiple light-emitting elements 111 can be, for example, a single-emitter semiconductor laser. The light-emitting elements 111 can be controlled to emit light sequentially, for example, from left to right in the top row, and then from left to right in the second row. Light from the semiconductor laser 110 enters the incident surface (S0) of the optical lens 161 via the collimator lens 120 and is diffracted by the grating on the incident surface (S0).

[0036] Although the first embodiment exemplifies the semiconductor laser 110 in which the light emitting elements 111 are arranged two-dimensionally, the light emitting elements 111 may be arranged one-dimensionally as in other embodiments described later. Also, the HFOV may be ultimately widened by combining a light beam generated by mechanical scanning with an optical lens.

[0037] [Diffraction] FIG. 3 is a diagram showing an example of light emitted from the optical lens 161 according to the first embodiment of the present technology.

[0038] For simplicity, this example shows four rows and two columns of real light, with replica light (+1st order light and -1st order light) arranged to the left and right of it. When light 21 at the lower left is emitted from optical lens 161 as real light, light 22 at the lower left, which is a +1st order light, and light 23 at the lower left, which is a -1st order light, are emitted simultaneously.

[0039] In this example, a linear light beam spreading in the horizontal direction is scanned in the vertical direction by switching the light emission of the arranged light-emitting elements. However, a linear light beam spreading in the vertical direction may also be scanned in the horizontal direction by switching the light emission of the arranged light-emitting elements. Furthermore, the present invention can also be applied to a so-called zone driving method in which a two-dimensional divided area is scanned by switching the light emission in two dimensions.

[0040] [Optical Lens] FIG. 4 is a diagram showing an example of the configuration of the optical lens 161 according to the first embodiment of the present technology.

[0041] As shown in Fig. 1A, a grating that is approximately parallel to the vertical axis (Y) is provided along the incident surface of the optical lens 161. Fig. 1B is a bird's-eye view of the optical lens 161 from the vertical axis (Y) direction, and it can be seen that gratings extending in the vertical direction are provided at regular intervals on the incident surface that shows a radius of curvature rx0 in the horizontal direction (X).

[0042] FIG. 5 is a diagram showing an example of the structure of a grating provided on the optical lens 161 according to the first embodiment of the present technology.

[0043] Here, if the wavelength of light is λ and the grating pitch is P, the diffracted light angle Θ is expressed by the following equation: where m indicates the order (0, ±1, ±2, ...): sin Θ = m × λ / P

[0044] When the FOV (full) in the direction in which the replica light beam widens the FOV is Θhfov, the diffraction angle of the ±1st order light is "Θhfov / 3", so the pitch P is expressed by the following equation: P=λ / sin(Θhfov / 3)

[0045] In the first embodiment, a grating having a rectangular cross section is assumed, but this rectangular shape does not have to be strictly rectangular, and may have smooth corners. For example, a grating having a sine wave (sin) shape may be used. This makes it easier to process the grating and reduces mass production costs.

[0046] FIG. 6 is a diagram showing an example of the relationship between the groove depth of the grating provided in the optical lens 161 and the diffraction efficiency according to the first embodiment of the present technology.

[0047] The relationship between the zeroth-order and ±1st-order diffraction efficiencies and the normalized groove depth (H / λ) is shown in the graph in the figure, assuming that the groove depth of the grating is H and the refractive index of the material constituting the grating is 1.50. In this first embodiment, it is assumed that the efficiencies of the zeroth-order light and the ±1st-order light are set to be the same, so "0.64" is selected as an example of the value of H / λ. Meanwhile, the light intensity ratio between the zeroth-order light and the ±1st-order light can be changed by setting this normalized groove depth (H / λ). For example, if "1.00" is selected as an example of the value of H / λ, it is possible to emit only replica light.

[0048] The optical lens 161 with such a grating can be formed by nanoimprinting a grating-shaped resin onto a lens made of glass or resin. Also, when the optical lens 161 is made of plastic or resin, it is possible to mold the grating integrally with the optical lens 161.

[0049] As an example of this grating, a stepped grating may be used. In manufacturing the sawtooth shape, the sawtooth shape may be formed by cutting, or the stepped shape may be formed by a semiconductor lithography process.

[0050] FIG. 7 is a diagram showing an example of the amount of deviation of the angle of view of the optical lens 161 according to the first embodiment of the present technology.

[0051] As described above, the surface shape of the exit surface (S1) of the optical lens 161 is set so that the distortion aberration is the same as that of the condenser lens 170 that receives the reflected light. Specifically, it is desirable to keep the amount of deviation between the projected image and the received image within the size of two pixels of the light receiving element over the entire field of view. This allows a linear light beam without distortion to be emitted to the light receiving unit.

[0052] Here, we assume that the condenser lens 170 is an equidistant projection lens. Equidistant projection (y = fΘ) is a characteristic of projecting a spherical space onto the plane of the sensor at equal intervals, and an equidistant projection lens has the optical characteristic of equidistant projection of distortion. This can reduce the adverse effects of variations in optical components and misalignment during mass production. In this case, when the surface shape of the exit surface (S1) of the optical lens 161 is set to be the same as the distortion of the condenser lens 170, it is desirable to keep the deviation from the full angle of view fθ to less than one pixel size of the light receiving element, as shown in the right graph of the same figure. If such measures are not taken, distortion may become more pronounced at the edges of the angle of view, as shown in the comparative example in the left graph of the same figure.

[0053] FIG. 8 is a diagram showing an example of the shape of the emitted light beam 11 formed by the optical lens 161 according to the first embodiment of the present technology.

[0054] As described above, in the optical lens 161 of the first embodiment, the surface shape of the exit surface (S1) is set so as to have the same distortion as that of the condenser lens 170. Therefore, as shown by a in the figure, the replica light beams (+1st order light and −1st order light) arranged on the left and right of the 0th order light do not exhibit noticeable distortion even when they are at the ends of the angle of view.

[0055] On the other hand, if no such measures are taken, distortion becomes more pronounced at the edges of the angle of view, as shown in the comparative example b in the same figure.

[0056] As explained above, the optical surface shape of the optical lens 161, which has a grating on the entrance surface (S0), and the horizontal (X) curvature radius rx0, which is approximately equal to the length from the optical surface to the virtual scanning center point Ox, ensure that the light beam is always incident on the optical surface at an angle perpendicular to the vertical direction. As a result, as shown by a in the figure, the light beam is diffracted and split into zero-order light (actual light) and ±1st-order light (replica light) at equal angular intervals. Furthermore, the light beam is corrected to have the same distortion aberration as the condenser lens 170 by the lens surface shape of the exit surface (S1), and is then emitted from the optical lens 161. This provides the effect of preventing distortion aberration from becoming apparent across the entire field of view.

[0057] [Condenser Lens] FIG. 9 is a diagram showing an example of the configuration of the condenser lens 170 according to the first embodiment of the present technology.

[0058] As shown in Fig. 1A, by assuming an equidistant projection lens as the condenser lens 170, distortion can be prevented even if the optical axis is misaligned, thereby reducing the adverse effects of variations in optical components and misalignment during mass production.

[0059] On the other hand, as shown in the comparative example b in the same figure, if such measures are not taken, the shape will be different at each position, and there is a risk that the characteristics will be vulnerable to deviation of the optical axis.

[0060] [Photodetector] FIG. 10 is a diagram showing an example of the configuration of the photodetector 180 according to the first embodiment of the present technology.

[0061] The photodetector 180 includes a plurality of light receiving sections 181 divided vertically and horizontally. A light beam scanned at a certain position is reflected and scattered by the object and guided to the horizontally arranged linear light receiving sections 181. Because the linear light beam obtained here is straight and without distortion, it is easy to selectively turn on only the light receiving sections 182 in the line required for detecting the reflected light and turn off the light receiving sections 181 in the other lines. This makes it possible to reduce noise caused by the influence of unnecessary light from external light such as sunlight.

[0062] The reflected light beam 12 detected by the photodetector 180 is in the up-down position opposite to the outgoing light beam 11. Therefore, when scanning by switching the light emission of the arranged light-emitting elements is performed from top to bottom, the photodetector 180 must be controlled so that the light-receiving elements 181 are enabled from bottom to top.

[0063] As described above, in the first embodiment of the present technology, replica light is generated by utilizing the optical surface shape of the optical lens 161 having a grating on the entrance surface (S0), and the surface shape of the exit surface (S1) is used to correct the distortion aberration so that it becomes the same as the distortion aberration of the condenser lens 170. This makes it possible to obtain horizontal line spread (HFOV) without making distortion aberration apparent over the entire angle of view.

[0064] 2. Second Embodiment In the first embodiment described above, the replica light (+1st order light and −1st order light) was arranged so as not to overlap on the left and right of the actual light as the light emitted from the optical lens 161. In contrast, in this second embodiment, the actual light or the replica light is arranged so as to overlap. As a result, even if one of the light-emitting units of the light source fails and no light is emitted, a light beam emitted from another light-emitting unit can irradiate the required area, making it possible to provide a robust module. Note that in this second embodiment, only the grating conditions of the optical lens 161 are different, and the rest is the same as in the first embodiment described above, so a detailed description of the overall configuration of the distance measurement device will be omitted.

[0065] [Superimposition of Real Light and Replica Light] FIG. 11 is a diagram showing a first example of light emitted from the optical lens 161 according to the second embodiment of the present technology.

[0066] In this first example, the right half of the real light is superimposed on the left half of the +1st order light, and the left half of the real light is superimposed on the right half of the -1st order light, and this example is particularly effective in the center of the field of view. When the FOV (full) in the direction in which the replica light beam widens the FOV is Θhfov, and half of the 0th order light is superimposed with ±1st order light, the diffraction angle of the ±1st order light is "Θhfov / 4", so the pitch P is expressed by the following equation: P=λ / sin(Θhfov / 4)

[0067] The relationship between the 0th-order and ±1st-order diffraction efficiencies and the normalized groove depth (H / λ) is the same as that shown in FIG. 6 in the first embodiment.

[0068] [Superimposition of Replica Lights] FIG. 12 is a diagram showing a second example of the light emitted from the optical lens 161 according to the second embodiment of the present technology.

[0069] In this second example, no real light is emitted, and only ±1st order light is superimposed to improve robustness over the entire field of view.

[0070] When the drive unit of the light beam is ΘΔh, the diffraction angle of the ±1st order light is "ΘΔh / 2", so the pitch P is expressed by the following equation: P=λ / sin(ΘΔh / 2)

[0071] To realize the arrangement of this second example, in FIG. 6 shown in the first embodiment described above, the normalized groove depth H / λ can be selected to be "1.0" so that the zeroth order is not emitted and the ±1st orders are maximized.

[0072] [Superimposition of Higher-Order Replica Light] FIG. 13 is a diagram showing a third example of light emitted from the optical lens 161 according to the second embodiment of the present technology.

[0073] In the examples up to this point, ±1st-order light has been assumed as the replica light. However, in this technology, it is possible to use even higher-order replica light. In this third example, ±3rd-order light is arranged further outside the ±1st-order light. This makes it possible to widen the FOV while improving the ranging performance and robustness at the center of the field of view. In this example, light 31 to 35 at corresponding positions are emitted simultaneously.

[0074] When the FOV (full) in the direction in which the replica light beam widens the FOV is Θhfov, and half of the zero-order light is superimposed with the ±1st-order light, the diffraction angle of the ±1st-order light is "Θhfov / 8", so the pitch P is expressed by the following equation: P=λ / sin(Θhfov / 8)

[0075] FIG. 14 is a diagram illustrating an example of the relationship between the groove depth of the grating provided in the optical lens 161 and the diffraction efficiency in the third example of the second embodiment of the present technology.

[0076] In the graph in the same figure, by selecting and setting "0.33" as an example of the normalized groove depth H / λ, the efficiencies (light intensity ratios) of the zeroth order light, ±1st order light, and ±3rd order light become 75%, 10%, and 1%, respectively, improving the distance measurement performance in the center of the field of view while shortening the distance measurement distance in the periphery, making it possible to measure distances over a wide field of view.

[0077] As described above, according to the second embodiment, by superimposing the actual light or the replica light, it is possible to improve robustness and distance measurement performance.

[0078] Furthermore, as shown in the second embodiment, by utilizing the superposition of actual light and replica light with a different light intensity ratio resulting from diffraction division, it is possible to counter flare. Specifically, when strong light strikes an object that has retroreflection, the strong light is reflected and enters the photodetector 180, generating flare stray light, which may cause errors in distance measurement. Therefore, as in the second embodiment, by irradiating the object with replica light of a low light intensity, the intensity of the flare stray light can be weakened and its effects can be suppressed.

[0079] 3. Third Embodiment [Distance Measuring Device] FIG. 15 is a diagram showing an example of the configuration of a distance measuring device 100 according to a third embodiment of the present technology.

[0080] In the first embodiment described above, the semiconductor laser 110 generates a two-dimensionally arranged light beam, but in this second embodiment, it is assumed that a one-dimensionally arranged light beam is used.

[0081] The distance measurement device 100 in the third embodiment includes a semiconductor laser 114, a collimator lens 120, an optical lens 162, a condenser lens 170, a photodetector 180, and a control unit 190. That is, the configuration other than the semiconductor laser 114 and the optical lens 162 is the same as that of the first embodiment described above, and therefore detailed description thereof will be omitted.

[0082] Like the optical lens 161 of the first embodiment described above, the optical lens 162 is a meniscus lens with a concave entrance surface (S0) and a convex exit surface (S1), both surfaces of which are biconic surfaces. However, the grating direction of this optical lens 162 is rotated 90 degrees from that of the first embodiment described above, and a grating approximately parallel to the horizontal direction (X) is provided along the entrance surface. The exit surface (S1) of this optical lens 162 is also provided with a diffusion function. Specifically, by providing a microcylindrical lens with curvature only in a linear direction approximately perpendicular to the Y direction, the optical lens 162 emits a light beam that is expanded only in the Y direction without acting in the X directions, thereby achieving an FOV similar to that of a two-dimensionally arranged light beam. Instead of using a microcylindrical lens, a diffraction element that diffuses light only in the Y direction may be used.

[0083] The optical lens 162 is an example of the optical conversion section described in the claims.

[0084] FIG. 16 is a diagram showing a configuration example of a semiconductor laser 110 according to the third embodiment of the present technology.

[0085] The semiconductor laser 114 in this third embodiment is a laser light source that emits a light beam from light-emitting elements 111 that are arranged one-dimensionally. Each of the plurality of light-emitting elements 111 emits light individually, and the light-emitting elements are switched in sequence. This switches the position of the line, and scanning is performed. In other words, the arrangement direction of the plurality of light-emitting elements 111 becomes the scanning direction.

[0086] [Diffraction] FIG. 17 is a diagram showing an example of light emitted from the optical lens 162 according to the third embodiment of the present technology.

[0087] In this example, for simplicity, real light is shown in four rows and one column. Replica light (+1st order light and -1st order light) is arranged on the left and right of the real light. Compared to the first embodiment described above, the light beam is expanded only in the Y direction (diffusion direction) and is emitted. When the bottom light 41 is emitted from the optical lens 162 as real light, the bottom light 42 of +1st order light and the bottom light 43 of -1st order light are emitted simultaneously. [Modification]

[0088] In this third embodiment, the optical lens 161 of the first embodiment may be used by disposing a uniaxial cylindrical lens instead of the collimator lens 120. In this case, the uniaxial cylindrical lens has a diffusing function.

[0089] In this way, according to the third embodiment of the present technology, by providing a diffusion function that optically diffuses light in the Y direction, the semiconductor laser 114 in which the light-emitting elements 111 are arranged one-dimensionally can be used as a light source.

[0090] 4. Fourth Embodiment [Distance Measuring Device] FIG. 18 is a diagram showing an example of the configuration of a distance measuring device 100 according to a fourth embodiment of the present technology.

[0091] In the third embodiment, the diffusion function is in the Y direction, but in this fourth embodiment, it is assumed that the diffusion function is in the X direction.

[0092] The distance measurement device 100 in the fourth embodiment includes a semiconductor laser 114, a collimator lens 120, an optical lens 163, a condenser lens 170, a photodetector 180, and a control unit 190. That is, the configuration other than the optical lens 163 is the same as that of the third embodiment described above, and therefore detailed description thereof will be omitted.

[0093] Like the optical lens 161 of the first embodiment described above, the optical lens 163 is a meniscus lens with a concave entrance surface (S0) and a convex exit surface (S1), both surfaces of which are biconic surfaces. However, unlike the optical lens 163 of the third embodiment described above, the exit surface (S1) of this optical lens has an X-direction diffusion function added. Specifically, a micro-cylindrical lens having a curvature only in the arrangement direction approximately perpendicular to the X direction is provided, and the exiting light beam is expanded only in the X direction without acting on the Y directions, enabling an FOV similar to that of a two-dimensionally arranged light beam. Note that instead of a micro-cylindrical lens, a diffraction element that diffuses light only in the X direction may be used.

[0094] The optical lens 163 is an example of the optical conversion section described in the claims.

[0095] [Diffraction] FIG. 19 is a diagram showing an example of light emitted from the optical lens 163 according to the fourth embodiment of the present technology.

[0096] For simplicity, this example shows one row and four columns of real light. Replica light (+1st order light and -1st order light) is arranged on the left and right of the real light. Compared to the first embodiment described above, the light beam is expanded only in the X direction (diffusion direction) and is emitted. When the leftmost light 51 is emitted from the optical lens 162 as real light, the leftmost light 52 of +1st order light and the leftmost light 53 of -1st order light are emitted simultaneously.

[0097] As described above, according to the fourth embodiment of the present technology, by providing a diffusion function that optically diffuses light in the X direction, the semiconductor laser 114 in which the light-emitting elements 111 are arranged one-dimensionally can be used as a light source.

[0098] 5. Fifth Embodiment In the first embodiment described above, a grating is provided on the entrance surface (S0) of the optical lens 161 to generate replica light, and the exit light beam is corrected by the surface shape of the exit surface (S1). However, these functions may be realized by separate optical elements (optical members). In this fifth embodiment, an example will be described in which the generation of replica light by diffraction and its correction are realized separately by multiple optical lenses.

[0099] First Example FIG. 20 is a diagram showing a first example of the distance measurement device 100 according to the fifth embodiment of the present technology.

[0100] In this first example, two optical lenses 164 and 165 are provided instead of the optical lens 161 in the first embodiment. The optical lens 164 has a grating on its incident surface to generate replica light, but does not require a correction function on its exit surface. The optical lens 165, which is provided after the optical lens 164, corrects the light beam from the optical lens 164 on the incident surface or exit surface to make it the same as the distortion aberration of the condenser lens 170.

[0101] The optical lenses 164 and 165 are an example of the optical conversion section described in the claims.

[0102] Second Example FIG. 21 is a diagram showing a second example of the distance measurement device 100 according to the fifth embodiment of the present technology.

[0103] In this second example, two optical lenses 166 and 167 are provided instead of the optical lens 161 in the first embodiment. The optical lens 166 is a lens that has a grating on its exit surface and generates replica light. The optical lens 167, which is provided after the optical lens 166, corrects the light beam from the optical lens 166 on the entrance surface or exit surface so that the distortion aberration is the same as that of the condenser lens 170.

[0104] The optical lenses 166 and 167 are an example of the optical conversion section described in the claims.

[0105] In this way, as shown in the fifth embodiment, instead of the optical lens 161 in the first embodiment described above, the generation of replica light and its correction can be realized separately by using a plurality of optical lenses.

[0106] 6. Sixth Embodiment In the first embodiment described above, replica light (+1st order light and −1st order light) is generated on the left and right of the actual light as the light emitted from the optical lens 161. In contrast, in this sixth embodiment, an optical lens whose diffraction grating is oriented perpendicular to the diffraction grating of the optical lens is disposed after the optical lens that generates replica light (+1st order light and −1st order light) on the left and right of the actual light. This generates actual light from the light emitted from the optical lens and replica light (+1st order light and −1st order light) above and below, making it possible to irradiate an area with a light beam that is expanded both vertically and horizontally. Note that the sixth embodiment differs from the first embodiment in that two optical lenses are disposed. In all other respects, the sixth embodiment is similar to the first embodiment described above. Therefore, a detailed description of the overall configuration of the distance measurement device will be omitted.

[0107] First Example FIG. 22 is a diagram showing a first example of the distance measurement device 100 according to the sixth embodiment of the present technology.

[0108] In this first embodiment, a grating approximately parallel to the vertical axis (Y) is provided along the incident surface of the first optical lens 1681. A grating approximately parallel to the horizontal direction (X) is provided along the incident surface of the second optical lens 1682. That is, the diffraction gratings of the optical lenses 1681 and 1682 are oriented perpendicular to each other. This allows the light beam to irradiate an area that is wide in all directions.

[0109] Second Example FIG. 23 is a diagram showing a second example of the distance measurement device 100 according to the sixth embodiment of the present technology.

[0110] In this first embodiment, a grating that is approximately parallel to the horizontal direction (X) is provided along the incident surface of the first optical lens 1691. Then, a grating that is approximately parallel to the vertical axis (Y) is provided along the incident surface of the second optical lens 1692. That is, the diffraction gratings of the optical lenses 1691 and 1692 are oriented orthogonal to each other. This allows the light beam to irradiate an area that is wide in all directions.

[0111] 24 is a diagram illustrating an example of light emitted from an optical lens according to the sixth embodiment of the present technology. In the drawing, the horizontal FOV (full) in which the FOV is expanded by the replica light beam is represented as Θhfov, and the vertical FOV (full) in which the FOV is expanded by the replica light beam is represented as Θvfov.

[0112] In this sixth embodiment, by arranging two optical lenses 1681 and 1682, or 1691 and 1692, whose diffraction gratings are oriented perpendicular to each other, the light beam can be made to irradiate an area that is wide in all directions.

[0113] Note that the above-described embodiment shows an example for realizing the present technology, and the matters in the embodiment and the matters specifying the invention in the claims correspond to each other. Similarly, the matters specifying the invention in the claims and the matters in the embodiment of the present technology having the same name correspond to each other. However, the present technology is not limited to the embodiment, and can be realized by applying various modifications to the embodiment within the scope of the gist thereof.

[0114] The processing procedures described in the above embodiments may be considered as a method having a series of these procedures, or as a program for causing a computer to execute the series of procedures, or as a recording medium for storing the program. Examples of such a recording medium include a CD (Compact Disc), an MD (MiniDisc), a DVD (Digital Versatile Disc), a memory card, and a Blu-ray (registered trademark) Disc.

[0115] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0116] The present technology may also be configured as follows: (1) An optical module including: a light-emitting unit having a plurality of light-emitting elements; a focusing unit that converts a light beam emitted from each of the plurality of light-emitting elements into a substantially parallel light beam or a light beam with a predetermined angular width and focuses it at a predetermined center point of an aperture; an optical conversion unit that generates replica light for actual light of the light beam that has passed through the focusing unit and converts the actual light and the replica light into a predetermined projected light beam; and an optical detection unit that detects light reflected from an object with respect to the projected light beam, wherein the optical conversion unit converts the actual light into the projected light beam having substantially the same distortion aberration as that of the optical detection unit. (2) The optical module described in (1) above, wherein the optical detection unit has an optical characteristic in which distortion aberration is an equidistant projection. (3) The optical module described in (1) above, wherein the plurality of light-emitting elements of the light-emitting unit are arranged in a predetermined direction; and the optical conversion unit includes a grid having a rectangular cross section, and converts the light beam that has passed through the focusing unit into a linear light beam that is substantially perpendicular to the arrangement direction of the light-emitting units using the grid to generate the replica light. (4) The optical module described in (3), wherein the light conversion unit includes a meniscus lens having a concave entrance surface and a convex exit surface, the entrance surface of the meniscus lens includes the grating and has different distance radii in the horizontal and vertical directions, and the exit surface of the meniscus lens has different distance radii in the horizontal and vertical directions, converting the projection light beam into the projection light beam having a distortion aberration substantially equal to that of the light detection unit. (5) The optical module described in (4), wherein the entrance surface of the light conversion unit has a radius of curvature in the arrangement direction substantially equal to the distance from a virtual aperture center point in the arrangement direction to a center point of the entrance surface regardless of its position in the linear direction, and the exit surface is an optical surface having a high-order surface. (6) The optical module described in (4) or (5), wherein the meniscus lens of the light conversion unit is an optical lens in which the rectangular grating made of resin is formed on a glass or resin lens. (7) The optical module according to (4) or (5), wherein the meniscus lens of the optical conversion unit is a resin lens and is an optical lens integrally formed with the rectangular grating.(8) The optical module described in (3), wherein the light conversion unit comprises, in order from the light emitting unit, first and second meniscus lenses, each having a concave entrance surface and a convex exit surface, wherein the entrance surface of the first meniscus lens is provided with the grating and has different distance radii in the horizontal and vertical directions, and the exit surface of the second meniscus lens is provided with different distance radii in the horizontal and vertical directions, thereby converting the projection light beam into one with approximately the same distortion aberration as that of the light detection unit. (9) The optical module described in (3), wherein the light conversion unit comprises, in order from the light emitting unit, first and second meniscus lenses, each having a concave entrance surface and a convex exit surface, wherein the exit surface of the first meniscus lens is provided with the grating and has different distance radii in the horizontal and vertical directions, and the exit surface of the second meniscus lens is provided with different distance radii in the horizontal and vertical directions, thereby converting the projection light beam into one with approximately the same distortion aberration as that of the light detection unit. (10) The optical module according to any one of (3) to (9), wherein the light conversion unit further includes a diffusion unit that diffuses the projected light beam in the arrangement direction. (11) The optical module according to any one of (3) to (10), wherein the light conversion unit includes a grating having a sinusoidal cross section instead of the rectangular grating. (12) The optical module according to any one of (1) to (11), wherein the light conversion unit converts the actual light and the replica light into the projected light beam having an unequal light intensity ratio. (13) The optical module according to any one of (3) to (12), wherein the light conversion unit converts at least a portion of the actual light or the replica light into the projected light beam by superimposing them.(14) A distance measuring device comprising: a light emitting unit having a plurality of light emitting elements; a focusing unit that converts the light beams emitted from each of the plurality of light emitting elements into approximately parallel light beams or light beams of a predetermined angular width and focuses them at a predetermined center point of an aperture; a light converting unit that generates replica light of the actual light of the light beam that has passed through the focusing unit and converts the actual light and the replica light into a predetermined projected light beam; a light detecting unit that detects reflected light from an object of the projected light beam; and a measuring unit that measures a distance to the object by measuring a time of flight, which is the time from when the projected light beam is irradiated until the light detecting unit detects the reflected light, wherein the light converting unit converts the projected light beam into a light beam that is approximately equal to the distortion aberration in the light detecting unit.

[0117] REFERENCE SIGNS LIST 11 Emitted light beam 12 Reflected light beam 100 Distance measuring device 110 Semiconductor laser 111 Light emitting element 114 Semiconductor laser 120 Collimator lens 161 to 167, 1681, 1682, 1691, 1692 Optical lens 170 Condenser lens 180 Photodetector 181, 182 Light receiving unit 190 Control unit

Claims

1. An optical module comprising: a light-emitting unit having a plurality of light-emitting elements; a focusing unit which converts the light beam emitted from each of the plurality of light-emitting elements into an approximately parallel light beam or a light beam of a predetermined angular width and focuses it at a predetermined aperture center point; a light conversion unit which generates replica light of the actual light of the light beam that passes through the focusing unit and converts the actual light and the replica light into a predetermined projection light beam; and a light detection unit which detects reflected light from an object with respect to the projection light beam, wherein the light conversion unit converts the projection light beam into a projection light beam with approximately the same distortion aberration as that in the light detection unit.

2. The optical module according to claim 1, wherein the light detection section has optical characteristics in which distortion aberration is an equidistant projection.

3. An optical module as described in claim 1, wherein the plurality of light-emitting elements of the light-emitting section are arranged in a predetermined direction, and the light conversion section has a lattice having a rectangular cross section, and the light beam passing through the light-collecting section is converted by the lattice into a linear light beam in a direction approximately perpendicular to the arrangement direction of the light-emitting section to generate the replica light.

4. An optical module as described in claim 3, wherein the light conversion unit comprises a meniscus lens having a concave entrance surface and a convex exit surface, the entrance surface of the meniscus lens is provided with the grating and has different distance radii in the horizontal and vertical directions, and the exit surface of the meniscus lens is provided with different distance radii in the horizontal and vertical directions and converts the projection light beam into one having a distortion aberration approximately equal to that in the light detection unit.

5. An optical module as described in claim 4, wherein the entrance surface of the optical conversion unit has a radius of curvature in the arrangement direction that is approximately equal to the distance from the center point of the virtual aperture in the arrangement direction to the center point of the entrance surface regardless of the position in the linear direction, and the exit surface is an optical surface having a high-order surface.

6. The optical module according to claim 4, wherein the meniscus lens of the optical conversion section is an optical lens in which the rectangular lattice made of resin is formed on a glass or resin lens.

7. The optical module according to claim 4, wherein the meniscus lens of the optical conversion section is a resin lens and is an optical lens integrally formed with the rectangular lattice.

8. An optical module as described in claim 3, wherein said light conversion section comprises, in order from said light emitting section, first and second meniscus lenses, each having a concave entrance surface and a convex exit surface, said first meniscus lens having said grating at said entrance surface and a different distance radius in the horizontal and vertical directions, and said second meniscus lens having a different distance radius in the horizontal and vertical directions at said exit surface, and converts the projection light beam into one having a distortion aberration approximately equal to that in said light detection section.

9. An optical module as described in claim 3, wherein the light conversion section comprises, in order from the light emitting section, first and second meniscus lenses, each having a concave entrance surface and a convex exit surface, the first meniscus lens having the grating at the exit surface and having different distance radii in the horizontal and vertical directions, and the second meniscus lens having different distance radii at the exit surface in the horizontal and vertical directions, and converts the projection light beam into one having a distortion aberration approximately equal to that in the light detection section.

10. The optical module according to claim 3, wherein the light conversion section further comprises a diffusion section that diffuses the projected light beam in the arrangement direction.

11. The optical module according to claim 3, wherein the optical conversion section is provided with a grating having a sinusoidal cross section instead of the rectangular grating.

12. The optical module according to claim 1, wherein the light conversion section converts the actual light and the replica light into the projection light beam having an unequal light amount ratio.

13. The optical module according to claim 1, wherein the optical conversion section converts at least a portion of the actual light or the replica light into the projection light beam by superimposing the actual light or the replica light.

14. A distance measuring device comprising: a light emitting unit having a plurality of light emitting elements; a focusing unit which converts the light beam emitted from each of the plurality of light emitting elements into a substantially parallel light beam or a light beam of a predetermined angular width and focuses it at a predetermined aperture center point; a light conversion unit which generates replica light of the actual light of the light beam passing through the focusing unit and converts the actual light and the replica light into a predetermined projected light beam; a light detection unit which detects reflected light from an object of the projected light beam; and a measurement unit which measures a distance to the object by measuring a time of flight, which is the time from when the projected light beam is irradiated to when the reflected light is detected by the light detection unit, wherein the light conversion unit converts the projected light beam into a light beam having a distortion aberration substantially equal to that of the light detection unit.

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