Light projection device, light projection receiving device, and distance measuring system

Abstract

The invention relates to a light projection device, a light projection receiving device, and a distance measuring system, and aims to suppress the enlargement of the light area projected on an object when an optical system is at a wide angle. The light projection device according to the present invention comprises: a light source that emits at least one light beam; and an optical system that projects pattern light obtained from the light emitted from the light source onto an object, the optical system including: a first lens group into which the light emitted from the light source is incident; an optical element that obtains the pattern light from the light incident through the first lens group; and a second lens group in which the pattern light emitted from the optical element is incident, the first lens group having a positive refractive power, the second lens group having a positive refractive power, and including a third lens group having a positive refractive power and a fourth lens group having a negative refractive power arranged in this order from one side of the optical element.

Description

Technical Field

[0001] The invention relates to a light projection device, a light projection receiving device and a distance measuring system. Background Art

[0002] Conventional light projection devices project patterned light (eg, dot pattern) onto an object (eg, see Patent Document 1). In such light projection devices, for example, by configuring the optical system to have a wide angle, the patterned light can be projected over a wide range.

[0003] Patent Document 1: Japanese Patent Application No. 2020-527230

[0004] When the optical system is set to a wide angle, a large aberration is generated in the region with a large angle relative to the optical axis, so the area of ​​the light spot projected on the object (for example, the area of ​​the spot light) is enlarged. Therefore, from the perspective of suppressing the expansion of the area of ​​the light projected on the object, the structure disclosed in Patent Document 1 still has room for improvement. Summary of the invention

[0005] The present invention is a solution proposed in view of the above-mentioned problems, and its purpose is to provide a light projection device, a light projection receiving device and a distance measurement system that can suppress the expansion of the light area projected onto the object when the optical system is wide-angle.

[0006] One embodiment of the present invention provides a light projection device, comprising: a light source that emits at least one beam of light; an optical system that projects pattern light obtained from the light emitted by the light source onto an object, the optical system comprising: a first lens group that is incident on the light emitted from the light source; an optical element that obtains the pattern light from the light incident through the first lens group; and a second lens group that is incident on the pattern light emitted from the optical element, the first lens group having positive optical power, the second lens group having positive optical power, and comprising a third lens group having positive optical power and a fourth lens group having negative optical power that are arranged in sequence from the optical element.

[0007] The present invention has the effect of providing a light projection device, a light projection receiving device, and a distance measuring system that can suppress the expansion of the area of ​​pattern light projected onto an object when the optical system is wide-angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a block diagram of the structure of the distance measurement system involved in the first embodiment of the present invention.

[0009] Figure 2 This is a block diagram showing the configuration of a light projection receiving unit according to the first embodiment of the present invention.

[0010] Figure 3This is a schematic diagram of ToF (Time of Flight) photography of an example of the light projection and reception device according to the first embodiment of the present invention.

[0011] Figure 4 This is a schematic diagram of an installation example of a light projection and receiving device.

[0012] Figure 5 It is a schematic diagram of an installation example of a light projection device.

[0013] Figure 6 It is a schematic diagram showing the expansion of the viewing angle of the afocal system converter involved in the comparative example.

[0014] Figure 7 This is a schematic diagram of the optical structure of the light projection unit.

[0015] Figure 8 It is the collimated and divergent optical path diagram.

[0016] Fig. 9 It is the power distribution diagram of collimated type and divergent type.

[0017] Fig. 10A The following are diagrams showing lateral aberrations of various design examples.

[0018] Fig. 10B The following are diagrams showing lateral aberrations of various design examples.

[0019] Fig.11 Schematic diagrams of dot pattern lights of multiple design examples.

[0020] Fig.12 It is a schematic diagram of the optical structure of the light projection unit according to a modified example of the present invention.

[0021] Fig.13 It is a schematic diagram of other examples of the arrangement of the optical elements of the light projection receiving device.

[0022] Fig.14 This is a block diagram of the configuration of a three-dimensional shape generation system according to a second embodiment of the present invention.

[0023] Fig.15 This is a schematic diagram of an example in which the distance measuring system according to the first embodiment of the present invention is used in a portable information terminal.

[0024] Fig.16 This is a schematic diagram of an example in which the distance measurement system according to the first embodiment of the present invention is used in an autonomous driving system for a mobile object.

[0025] Explanation of symbols

[0026] 1: Distance measurement system

[0027] 2: Light projection receiving device

[0028] 3: Computing device

[0029] 10: Light projection receiving part

[0030] 10a: Light projection device

[0031] 20: RGB light receiving unit

[0032] 100: Light projection unit

[0033] 102: Light Source

[0034] 104: First lens group

[0035] 106: Diffractive optical elements

[0036] 108: Second lens group

[0037] 108a: The third lens group

[0038] 108b: The fourth lens group

[0039] 120: ToF light receiving unit

[0040] 122: Optical system

[0041] 124: ToF sensor

[0042] 140: Control Department DETAILED DESCRIPTION

[0043] The first embodiment of the present invention will be described below with reference to the drawings. In the following description, common or corresponding elements are denoted by the same or similar reference numerals, and repeated descriptions are appropriately simplified or omitted.

[0044] Figure 1 It is a block diagram showing the structure of a distance measuring system 1 according to the first embodiment of the present invention.

[0045] like Figure 1 As shown, the distance measuring system 1 includes a light projection receiving device 2 and a computing device 3.

[0046] The distance measuring system 1 of this embodiment measures the distance from the light projection receiving device 2 to the object (referred to as "object OB") using the ToF method. The ToF method irradiates the object OB with distance measuring light (e.g., laser) having a wavelength different from that of visible light. The distance to each part of the object OB (each irradiation position) is calculated based on the time difference between the emission time of the laser and the reception time at each irradiation position.

[0047] In this embodiment, the light projection optical system for emitting laser light uses a diffractive optical element. By projecting patterned light such as dots onto the object OB using a diffractive optical element, high-brightness and high-density point group data can be obtained. The diffractive optical element is hereinafter referred to as a "DOE (Diffractive Optical Element)".

[0048] The light projection receiving device 2 includes a light projection receiving section 10 and an RGB light receiving section 20. The "light projection receiving device" may also be referred to as a "light projection device", "camera device" or "distance measuring device".

[0049] The light projection receiving device 2 is equipped with, for example, a rechargeable battery. In other words, the light projection receiving device 2 is driven by the battery. The light projection receiving device 2 may also be driven by a commercial power source.

[0050] The light projection receiving unit 10 includes a light projection unit 100 , a ToF light receiving unit 120 , and a control unit 140 .

[0051] Figure 2 This is a block diagram of the light projection receiving unit 10 alone.

[0052] The light projection unit 100 projects the pattern light onto the object OB. Figure 2 As shown, the light projection unit 100 includes a light source 102 , a first lens group 104 , a DOE 106 , and a second lens group 108 .

[0053] The control unit 140 controls the light projecting unit 100 and the ToF light receiving unit 120. Specifically, the control unit 140 includes a CPU (Central Processing Unit), a source driving circuit, an imaging signal processing circuit, an input / output circuit, a memory, and the like as a circuit configuration.

[0054] The control unit 140 is, for example, a single processor or a multi-processor, and includes at least one processor. In a structure including multiple processors, the control unit 140 can be packaged as a single device, or can be composed of multiple devices physically separated in the light projection receiving unit 10.

[0055] The light source 102 is, for example, a light source that emits at least one beam of light. The light source 102 is, for example, an LD (Laser Diode) that emits laser light. The light source 102 emits laser light at a timing controlled by the control unit 140 .

[0056] The first lens group 104 , the DOE 106 , and the second lens group 108 are an example of an optical system that projects pattern light obtained from laser light emitted from the light source 102 onto an object.

[0057] The first lens group 104 is an example, and the laser light emitted from the light source 102 enters the first lens group 104 .

[0058] The DOE 106 is an example of an optical element that obtains patterned light (forms patterned light) from the laser light incident via the first lens group 104. The DOE 106 emits patterned light in which a plurality of dots are arranged in a grid shape (hereinafter referred to as “dot patterned light”), for example.

[0059] The second lens group 108 is an example, and the dot pattern light emitted from the DOE 106 enters the second lens group 108. The second lens group 108 projects the dot pattern light onto the object OB.

[0060] Figure 3 Schematic diagram of an example of ToF photography performed by the light projection receiving device 2. For convenience, Figure 3 The symbol of the RGB light receiving unit 20 is omitted.

[0061] like Figure 3 As shown, the light projection receiving device 2 projects dot pattern light onto the object OB. In order to project such pattern light, it is possible to consider using, for example, a VCSEL (Vertical Cavity Surface Emitting Laser) having a plurality of light-emitting parts arranged in a pattern to form the light source 102, or to form the pattern into a dot shape through the diffraction phenomenon of the microstructure of DOE 106, or to use both methods at the same time. In this way, a high-brightness and high-density dot pattern light can be projected onto the object OB, thereby improving the ranging accuracy.

[0062] The following is a supplementary explanation of the diffraction pattern of the DOE 106 being formed in a dot pattern shape. In this case, the light source 102 is constituted by a point light source such as LD. The laser light emitted from the light source 102 enters the DOE 106 through the first lens group 104 .

[0063] After the laser is incident on DOE106, a number of conjugate points corresponding to the diffraction orders (0th order, ±1st order, ±2nd order, ...) of DOE106 are generated, and the dot pattern light corresponding to the diffraction order is irradiated to infinity.

[0064] When the VCSEL and the DOE 106 are used simultaneously, dot pattern light can be irradiated over a wider range.

[0065] The dot pattern light irradiating the object OB is reflected or scattered by the object OB. The ToF light receiving unit 120 receives light directly reflected by the object OB (hereinafter referred to as “direct reflected light”).

[0066] The ToF light receiving unit 120 is an example of a light receiving unit that receives reflected light from the object OB onto which the dot pattern light is projected. Figure 2 As shown, the ToF light receiving unit 120 includes an optical system 122 and a ToF sensor 124 .

[0067] The optical system 122 includes, for example, an aperture, an imaging optical system, and a filter. Light reflected from the object OB directly irradiated with the dot pattern light passes through the optical system 122 and is received by the ToF sensor 124 .

[0068] The ToF sensor 124 is an imaging element such as a CMOS image sensor, and photoelectrically converts the total exposure amount of a plurality of exposure periods with a predetermined phase difference with respect to the irradiated light, and outputs the converted data to the control unit 140. The light reception data of the ToF sensor 124 is input to the computing device 3 via the control unit 140.

[0069] The operation unit 31 of the operation device 3 is implemented according to the command from the CPU of the operation device 3, and obtains the distance to each part (each irradiation position) of the object OB according to the sum of the exposure amounts during each exposure period input from the ToF sensor 124. SPAD or the like may be used as the ToF sensor 124, and the operation unit 31 obtains the distance according to the time difference between the emission time of the laser light (the light emission time of the light source 102) and the light reception time (the input time from the ToF sensor 124) at each irradiation position.

[0070] In other words, the calculation unit 31 of the calculation device 3 is an example of a distance calculation unit for obtaining the distance to the object OB based on the light reception output of the ToF light receiving unit 120 .

[0071] The RGB light receiving unit 20 includes, for example, an aperture, an imaging optical system, a filter, and an image sensor. The image sensor is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor having an RGB color filter.

[0072] The image sensor may be replaced by other types of imaging elements such as a CCD (Charge Coupled Device) image sensor, etc. The image sensor may also have a complementary color grid filter.

[0073] The image sensor is driven under the control of the control unit 140 to receive visible light (natural light) on the light receiving surface. The image sensor accumulates the optical image formed on each pixel on the light receiving surface as an electric charge corresponding to the amount of light, and outputs it in synchronization with the ToF photography, for example. The control unit 140 outputs RGB image data based on each pixel data to the computing device 3.

[0074] Figure 4 1 is a schematic diagram of an installation of a light-emitting receiving device 2. Symbol 160 represents a battery for driving the light-emitting receiving device 2. For convenience, Figure 4In the figure, the first lens group 104, the DOE 106, and the second lens group 108 are represented by one lens block, and the RGB light receiving unit 20 is omitted.

[0075] exist Figure 4 In the illustrated installation example, the light projection receiving device 2 is configured to be able to capture a panoramic image of the entire celestial sphere. A panoramic image of the entire celestial sphere is a panoramic image obtained by capturing an image within a solid angle of 4π radians.

[0076] Figure 4 The light projection and reception device 2 shown in the figure includes a pair of wide-angle light projection units 100 and a pair of ToF light reception units 120 for forming a hemispherical image, respectively. A pair of RGB light reception units 20 is also provided.

[0077] The pair of RGB light receiving units 20 respectively capture objects (such as object OB) around the light projection receiving device 2. Thus, a pair of hemispherical images are obtained. The control unit 140 synthesizes the pair of hemispherical images, for example, to generate a full celestial sphere panoramic image represented by Mercator projection mapping method.

[0078] The object OB is irradiated with the dot pattern light emitted by a pair of light projection units 100, and the light directly reflected by the object OB is received by the corresponding ToF light receiving unit 120. The computing device 3 calculates the distance to each part of the object OB (each irradiation position) based on the time difference between the emission time of the laser at each irradiation position and the light reception time. By combining the distance information corresponding to each pair of ToF light receiving units 120, the distance information of the entire celestial sphere corresponding to the entire celestial sphere panoramic image can be obtained. In other words, a collection of coordinate points in three-dimensional space, namely a three-dimensional point cloud, can be obtained. The coordinate points of each point cloud can also be attached with color information (such as the RGB value of each coordinate point).

[0079] exist Figure 1 In the example of FIG. 1 , the light projection receiving unit 10 is included in the light projection receiving device 2. However, the light projection receiving unit 10 may also be Figure 2 As shown, it is constructed as a single device independent of the light projection receiving device 2.

[0080] The light projection unit 100 (also referred to as a light projection device) may be configured as a single device independent of the light projection receiving unit 10 . Figure 5 1 is a block diagram showing the structure of a light projection device 10a configured as a single device.

[0081] like Figure 5 As shown, the light projection device 10a includes a light projection unit 100 and a control unit 140. That is, in this configuration example, the light projection device 10a is composed of Figure 2 The ToF light receiving unit 120 is omitted in the light projection receiving unit 10 shown in the figure.

[0082] The light projection device 10a may not include the control unit 140. That is, the light projection device 10a may be an optical device provided with optical components such as the light source 102, the first lens group 104, the diffractive optical element (DOE) 106, and the second lens group 108. In this case, for example, a signal transmission device such as a cable is connected to a terminal provided in the light projection device 10a. In this way, the light source 102 and the control unit 140 connected to the other end of the cable are connected via the signal transmission device.

[0083] exist Figure 1 In the example of FIG. 1 , the light projection receiving device 2 includes the RGB light receiving unit 20 . However, the light projection receiving device 2 may not include the RGB light receiving unit 20 .

[0084] The computing device 3 is, for example, a terminal device such as a PC (Personal Computer) or a server placed in the cloud. The light projection receiving device 2 and the computing device 3 can communicate with each other by wired communication or wireless communication through the transceiver units they each have. Data can be sent (output) from the light projection receiving device 2 to the computing device 3 via the network, or the transceiver unit can be formed by an interface circuit with a removable storage medium such as an SD card or a personal computer. In other embodiments, the computing unit 31 can be included in the light projection receiving device 2. In this case, the computing unit 31 can also be configured as a processor of the control unit 140, for example. The computing unit 31 can also be configured as a processor independent of the control unit 140.

[0085] In this way, the configuration of each part of the distance measuring system 1 has a degree of freedom, and various design changes can be made.

[0086] Here, there is a prior art solution that expands the light projection viewing angle of dot pattern light to more than 90 degrees of half viewing angle by combining an afocal system converter (hereinafter referred to as "afocal system converter") in a light projection optical system. However, when using an afocal system converter, large aberrations are generated in a region with a large angle away from the optical axis, so the dot pattern light cannot be concentrated at a high density, but irradiates the object in a diffuse state.

[0087] That is, the area of ​​the dot pattern light is too large, and the brightness of the dot pattern light is reduced. As a result of the expansion of the area of ​​the dot pattern light, it is difficult to fully ensure the distance between the dot pattern lights. As a result, it is difficult to obtain sufficient distance measurement accuracy.

[0088] In this regard, the light projection unit 100 of this embodiment includes at least a first lens group 104 having positive power and a second lens group 108 having positive power. The second lens group 108 includes at least a third lens group 108a having positive power and a fourth lens group 108b having negative power, which are arranged in sequence from the DOE 106 side.

[0089] Here, "at least including" means that there may be a configuration example in which other optical elements are added within the technical concept of the present invention. For example, it is conceivable to add a configuration example of a parallel plate that does not contribute substantially to the optical performance to the light projection unit 100 involved in this embodiment, or to add a configuration example of other optical elements while maintaining the configuration and effect of the light projection unit 100 of this embodiment.

[0090] This structure can well compensate for aberrations and suppress the expansion of the dot pattern light in areas with large angles away from the optical axis. Since the expansion of the dot pattern light is suppressed (in other words, since the concentration of the dot pattern light is improved), the brightness of the dot pattern light can be ensured and the contrast can be improved, thereby improving the distance measurement accuracy.

[0091] Since the area expansion of the dot pattern light is suppressed, the distance between the dot pattern lights can be sufficiently ensured. For this purpose, for example, the gap between the dot pattern lights can be used for calibration, thereby improving the distance measurement accuracy.

[0092] Figure 6 It is a schematic diagram showing the expansion of the viewing angle caused by the afocal system converter involved in the comparative example.

[0093] like Figure 6 As shown, the light projection unit 1100 of the comparative example includes a first lens group 1104, a DOE 1106, and a second lens group 1108. In order to expand the viewing angle, the second lens group 1108 of the comparative example is composed of a second lens group 1108a having positive optical power and a second lens group 1108b having negative optical power, thereby becoming an afocal system converter having substantially no optical power.

[0094] Assuming that the viewing angle of the light after diffraction by DOE1106 is θ0 (unit: degree), the viewing angle of the light (parallel light) emitted from the second lens group 1108 is θ (unit: degree), the height of the on-axis light incident on the second lens group 1108a is h1 (unit: mm), and the height of the on-axis light emitted from the second lens group 1108b is h2 (unit: mm), the magnification m of the second lens group 1108 is expressed by the following formula.

[0095] m=θ / θ0=h1 / h2

[0096] The magnification m is the ratio of the viewing angles of the final optical surface of the light projection unit 100 (exemplified as the final optical surface of the second lens group 1108 b ) and the exit surface of the DOE 106 .

[0097] When the focal length of the first lens group 1104 is f1 (unit: mm), the focal length of the second lens group 1108 is f2 (unit: mm), and the focal length of the third lens group 1108a is f 21(unit: mm), the focal length of the fourth lens group 1108b is set to f 22 (unit: mm), when the focal length of the entire light projection unit 1100 is f (unit: mm), the second lens group 1108 has no optical power as an afocal system converter, and therefore, the following equation can be obtained from the similarity ratio.

[0098] f 21 :-f 22 =h1:h 2m =f 21 / -f 22

[0099] The second lens group 1108 is an enlargement optical system for enlarging the angle of view, and since the enlargement magnification m exceeds 1, the following equation holds.

[0100] |f 21 |>|f 22 |

[0101] Thus, in the case of an afocal system converter (in other words, the synthetic power of the enlargement optical system is zero), the negative power of the fourth lens group 1108b becomes greater than the positive power of the third lens group 1108a.

[0102] The enlarging optical system that enlarges the half viewing angle to more than 90 degrees is a fisheye lens. The high-order diffraction light divided by DOE 1106 passes through the fisheye lens (second lens group 1108) at a position higher than the optical axis. Therefore, it is greatly affected by astigmatism.

[0103] The first lens group 1104 located in front of the DOE 1106 has no ability to compensate for the aberration of the higher-order diffraction light split by the DOE 1106. Only the third lens group 1108a, which is a positive lens group located behind the DOE 1106, can compensate for astigmatism.

[0104] However, as described above, the third lens group 1108a has a smaller focal power than the fourth lens group 1108b and has a low aberration compensation capability. In the second lens group 1108 as an afocal system converter, it is difficult to compensate the astigmatism generated by the strong negative fourth lens group 1108b with the weak positive third lens group 1108a.

[0105] In view of this, the refractive power of the first lens group 104 in the light projection unit 100 of the present embodiment is set so that the divergent light enters the DOE 106. In other words, the refractive power of the first lens group 104 is weaker in the light projection unit 100 than in the case of an afocal system converter. Furthermore, in order to offset the astigmatism generated by the fourth lens group 108b in the light projection unit 100, the third lens group 108a is set so that the ratio of its refractive power to the refractive power of the fourth lens group 108b is larger than in the case of an afocal system converter. It is preferable that the refractive power ratio of the third lens group 108a to the fourth lens group 108b is maintained at a level that does not generate significant spherical aberration.

[0106] Figure 7 Schematic diagram of the optical structure of the light projection unit 100 according to the present embodiment. Figure 7 As shown, the light projection unit 100 is configured to make the divergent light incident on the DOE 106 by weakening the optical power of the first lens group 104. In this way, the positive optical power of the second lens group 108 can be enhanced, and as a result, the focal length f2 of the second lens group 108 is positive. For this reason, the fourth lens group 108b is used as a negative lens group, and the aberration generated therein is more offset by the third lens group 108a. As a result, the focusing degree of the dot pattern light is improved.

[0107] Thus, according to this embodiment, aberrations can be well compensated, and the area expansion of the dot pattern light can be suppressed even in a region with a large angle from the optical axis. Since the area expansion of the dot pattern light is suppressed, the brightness of the dot pattern light can be ensured, the contrast can be improved, and the ranging accuracy can be improved.

[0108] For convenience, sometimes the light emitted from DOE106 is substantially parallel light, and the second lens group 1108 is a comparative example of an afocal system converter (for example, see Figure 6 ) is called "collimation type", the light emitted from DOE106 is divergent light, and the focal length of the second lens group 108 is positive in this embodiment (for example, refer to Figure 7 ) is called "divergent type".

[0109] Figure 8 It is a collimated and divergent optical path diagram.

[0110] exist Figure 8 In the example of , the light incident from the first lens group is split from the 0th diffraction order light into ±5th diffraction order light by DOE, and then emitted after the second lens group expands the picture angle. The 5th diffraction order light is emitted from the second lens group at an angle of more than 90 degrees of half viewing angle. In each design, the conditions such as the light projection viewing angle and distortion characteristics of the optical system are unified.

[0111] In addition, the light projection unit 100 is designed so that the full angle of view on the final optical surface (for example, the final optical surface of the fourth lens group 1108 b ) is greater than or equal to 90 degrees and less than or equal to 220 degrees.

[0112] In this embodiment, the first lens group 104 is composed of at least one positive lens. The third lens group 108a is composed of at least two positive lenses. The fourth lens group 108b is composed of at least two negative meniscus lenses. At least one of the optical surfaces of the at least two negative meniscus lenses is an aspherical surface.

[0113] Figure 8 The divergent light projection unit 100 shown is an example of such an optical structure.

[0114] exist Figure 8 In the example of , the first lens group 104 is composed of lenses L1 and L2. The first lens group 104 has positive optical power as a whole, and at least one of the lens L1 and the lens L2 is a positive lens. The second lens group 108 has positive optical power as a whole, and includes lenses L3, L4, L5 and L6. In more detail, the third lens group 108a is composed of positive lens L3 and positive lens L4. The fourth lens group 108b is composed of negative meniscus lenses L5 and L6. At least one of the optical surfaces of the two negative meniscus lenses L5 and L6 is an aspherical surface.

[0115] Fig. 9 It is a schematic diagram of the optical power distribution of the collimating and diverging types.

[0116] The lens with a focal length f2 of 100 mm in the second lens group 108 is a collimating type, and the lens with a focal length f2 less than 20 mm is a diverging type.

[0117] Fig. 9 The numerical values ​​of various design examples of different focal lengths f2 are shown. Fig. 9 The spot diameter (vertical diameter, horizontal diameter) and area of ​​the dot pattern light near the maximum viewing angle when the object OB is irradiated with the dot pattern light using the light projection section of each design example are shown.

[0118] like Fig. 9 As shown, it can be seen that the smaller the focal length f2 is (in other words, the greater the positive power of the focal length f2 is), the larger the focal length f1 is (in other words, the smaller the positive power of the focal length f1 is), and the greater the divergence of the light incident on the DOE is. 22 Regardless of the value of the focal length f2, it remains roughly constant. On the contrary, the focal length f 21 But it changes with the value of focal length f2.

[0119] In this way, Fig. 9In the example, the fourth lens group serves as a negative lens group, and its focal length remains substantially unchanged. At the same time, in each design example, the spot diameter of the point pattern light is changed by weakening the positive optical power of the first lens group and increasing the positive optical power of the third lens group.

[0120] like Fig. 9 As shown in FIG. 1 , when the focal length f2 of the second lens group 108 is 3.14, the area of ​​the dot pattern light becomes the smallest and the contrast is the highest. This minimum area is used as a reference (ratio = 1.00). When the area ratio relative to the minimum area is less than +10%, high contrast can be ensured and the ranging accuracy can be improved.

[0121] exist Fig. 9 In the table, the judgment results of design examples whose area ratio to the minimum area is +10% or less are marked with ○, and the judgment results of design examples whose area ratio to the minimum area exceeds +10% are marked with ×.

[0122] The range that satisfies the condition of "the area ratio relative to the minimum area is +10% or less" is as shown in the following formula. 22 It is substantially constant, and therefore, the following formula can be said to represent the optimal range of the positive refractive power of the third lens group for achieving high contrast.

[0123] 1.5≤f2 / f≤18

[0124] When the value of f2 / f is less than 1.5, the positive refractive power of the third lens group 108a is too strong relative to the negative refractive power of the fourth lens group 108b, so spherical aberration will be generated, causing the spot pattern light to become very blurred.

[0125] When the value of f2 / f exceeds 18, the positive refractive power of the third lens group 108a is too weak relative to the negative refractive power of the fourth lens group 108b. Therefore, the astigmatism generated in the fourth lens group 108b cannot be fully offset by the third lens group 108a.

[0126] In order to achieve high contrast, the following formula may also be satisfied.

[0127] 1.5f≤f2

[0128] like Fig. 9 As shown in the figure, if the positive power of the third lens group 108a is increased in the divergent type, the focal length f 21 and focal length f 22 The ratio of changes greatly. As a result, the following equation holds.

[0129] f 21 / f 22 >-m

[0130] Fig. 10A and Fig. 10B The following are diagrams showing lateral aberrations in various design examples with different focal lengths f2.

[0131] Fig. 10A and Fig. 10B The lateral aberration diagrams are shown for the axial light with diffraction order 0 (field angle 0 degrees) and the axial light with diffraction order 5 (field angle of about 90 degrees) for various design examples with different focal lengths f2.

[0132] Fig. 10A and Fig. 10B In the figure, the transverse aberration diagram of the meridional ray (the left side) and the transverse aberration diagram of the sagittal ray (the right side) are shown in pairs. The transverse aberration of the sagittal ray is symmetrical with respect to the meridional section. Fig. 10A and Fig. 10B In the figure, the lateral aberration of sagittal rays is only shown on the positive side of the pupil coordinates.

[0133] like Fig. 10A and Fig. 10B As shown, the 0th order on-axis light (viewing angle 0 degrees) is well converged in each design example. However, the convergence degree of the 5th order on-axis light (viewing angle about 90 degrees) varies greatly among different design examples.

[0134] Here, for convenience, the design example when the focal length f2 is n is recorded as design example [n].

[0135] In design example [3.14], the light emitted from the light projection unit 100 forms an image well in the meridional cross section, and astigmatism occurs in the sagittal direction. However, in the sagittal direction, the main ray, the upper ray, and the lower ray form an image at the same position. That is, astigmatism can be well compensated.

[0136] In the design example with a small focal length f2 (e.g., design example [1.2]), spherical aberration is generated with respect to the upper and lower rays in the meridional section. In the sagittal direction, large astigmatism is generated. Therefore, not only is the blur caused by spherical aberration large, but also large astigmatism is generated, and the contrast is reduced.

[0137] In the design example with a large focal length f2 (e.g., design example

[100] ), spherical aberration is well compensated in the meridional section. On the other hand, large astigmatism is generated in the sagittal direction. Due to the generation of astigmatism, for example, the point pattern light is projected in a larger size in the sagittal direction, and the contrast is reduced.

[0138] Fig.11 It is a schematic diagram of the dot pattern light in the design examples of various focal lengths f2. Fig.11 Design examples are shown when the focal length f2 is 1.2 mm, 3.14 mm, and 100 mm, respectively.

[0139] Fig.11In the figure, a dot pattern light with a half angle of 90 degrees is used to compare how the dot pattern light changes when the focal length f2 changes (from another point of view, the lateral aberration changes).

[0140] If the focal length f2 is too short (in other words, if the positive power of the second lens group 108 is too strong), a large spherical aberration is generated in the meridional cross section and astigmatism is generated in the sagittal direction. Therefore, as shown in design example [1.2], the dot pattern light is blurred as a whole.

[0141] On the other hand, if the focal length f2 is too long (in other words, the positive optical power of the second lens group 108 becomes weak, becoming a design close to a collimating type), a large astigmatism is generated in the sagittal direction, and the point pattern light expands in the sagittal direction, as shown in, for example, design example

[100] .

[0142] like Fig.11 As shown, the design example [3.14] has the best aberration balance.

[0143] This embodiment does not have the restriction that the second lens group 108 must be designed using an afocal system converter, and therefore has a higher degree of design freedom than the prior art.

[0144] Three numerical examples of the light projection unit 100 according to the present embodiment are shown below. The light projection unit 100 according to each numerical example has the following structure: Figure 8 The structure shown. That is, the first lens group 104 is composed of lenses L1 and L2. The first lens group 104 has positive power as a whole, and at least one of the lens L1 and the lens L2 is a positive lens. The second lens group 108 has positive power as a whole, and includes lenses L3, L4, L5 and L6. More specifically, the third lens group 108a is composed of positive lens L3 and positive lens L4. The fourth lens group 108b is composed of negative meniscus lenses L5 and L6. At least one of the optical surfaces of the two negative meniscus lenses L5 and L6 is an aspherical surface.

[0145] The symbols used in the numerical examples are described below.

[0146] f: focal length of the entire light projection unit 100 (unit: mm),

[0147] f 11 : focal length of the first lens group 104 (unit: mm),

[0148] f2: focal length of the second lens group 108 (unit: mm),

[0149] f 21 : focal length of the third lens group 108a (unit: mm),

[0150] f 22 : focal length of the fourth lens group 108b (unit: mm),

[0151] Y': light source height (unit: mm),

[0152] θ: the angle of view of the light emitted from the second lens group 108 (unit: degree),

[0153] m: magnification (=θ / θ0), where θ0 is the viewing angle on the exit surface of DOE 106 (unit: degree),

[0154] R: The curvature radius or paraxial radius of each surface of the optical element (unit: mm),

[0155] D: The thickness of the optical element on the optical axis or the interval between optical elements (unit: mm),

[0156] Nd: refractive index of d-line (wavelength 587.562nm),

[0157] νd: Abbe number of the d-line,

[0158] d: diffraction lattice constant (unit: mm)

[0159] Below is the formula for aspherical shapes.

[0160] Z=Ch 2 / {1+√(1-(1+K)C 2 h 2 )}+A4·h 4 +A6·h 6 +A8·h 8 +A 10 ·h 10

[0161] The radius of curvature R of the aspherical element represents the radius of curvature on the optical axis (paraxial curvature radius). In the above formula, the symbol Z represents the amount of droop. The symbol C represents the paraxial curvature (1 / R). The symbol h represents the height from the optical axis (unit: mm). The symbol K represents the cone coefficient. The symbols A4, A6, ... represent aspherical coefficients of even powers above the fourth power. The "e" contained in the value of the aspherical coefficient to be described later represents a base of 10, and the number to the right of e is the power of the exponent.

[0162] 《Numerical Example 1》

[0163] The specific numerical configuration of the light projection unit 100 involved in Numerical Example 1 is shown in Table 1. The focal length f of the light projection unit 100 as a whole is 1.00 mm. The focal length f2 of the second lens group 108 is 3.14 mm. The aperture value is 0.17. The light source height Y' is 0.3 mm. The viewing angle θ (full viewing angle) is 200 degrees.

[0164] [Table 1]

[0165]

[0166] The sixth surface is the emission surface of DOE106. The diffraction lattice constant d of DOE106 is 0.0092 mm.

[0167] The 11th surface is an aspherical surface. The conic coefficient K and various aspherical coefficients of the 11th surface are shown below.

[0168] K=-1.3587

[0169] A4=-0.0011568

[0170] A6=-4.5931e-05

[0171] A8=-2.4547e-07

[0172] The 12th surface is an aspherical surface. The conic coefficient K and various aspherical coefficients of the 12th surface are shown below.

[0173] K=10.00

[0174] A4=-0.00021622

[0175] A6=2.0901e-06

[0176] A8=-4.3773e-09

[0177] The numerical values ​​of the conditional expressions in Numerical Example 1 are as follows.

[0178] f2 / f=3.14

[0179] f 21 / f 22 (=-1.63)>-m(=-2.97)

[0180] 《Numerical Example 2》

[0181] The specific numerical configuration of the light projection unit 100 involved in Numerical Example 2 is shown in Table 2. The focal length f of the light projection unit 100 as a whole is 1.00 mm. The focal length f2 of the second lens group 108 is 1.5 mm. The aperture value is 0.17. The light source height Y' is 0.3 mm. The viewing angle θ (full viewing angle) is 200 degrees.

[0182] [Table 2]

[0183]

[0184] The sixth surface is the emission surface of DOE 106. The diffraction lattice constant d of DOE 106 is 0.0110 mm.

[0185] The 11th surface is an aspherical surface. The conic coefficient K and various aspherical coefficients of the 11th surface are shown below.

[0186] K=-1.3587

[0187] A4=-0.0011568

[0188] A6=-4.5931e-05

[0189] A8=-2.4547e-07

[0190] The 12th surface is an aspherical surface. The conic coefficient K and various aspherical coefficients of the 12th surface are shown below.

[0191] K=10.00

[0192] A4=-0.00021622

[0193] A6=2.0901e-06

[0194] A8=-4.3773e-09

[0195] The numerical values ​​of the conditional expressions in Numerical Example 2 are as follows.

[0196] f2 / f=1.5

[0197] f 21 / f 22 (=-1.22)>-m(=-3.53)

[0198] 《Numerical Example 3》

[0199] The specific numerical configuration of the light projection unit 100 involved in Numerical Example 3 is shown in Table 3. The focal length f of the light projection unit 100 as a whole is 1.00 mm. The focal length f2 of the second lens group 108 is 18 mm. The aperture value is 0.17. The light source height Y' is 0.3 mm. The viewing angle θ (full viewing angle) is 200 degrees.

[0200] [Table 3]

[0201]

[0202] The sixth surface is the emission surface of DOE 106. The diffraction lattice constant d of DOE 106 is 0.0101 mm.

[0203] The 11th surface is an aspherical surface. The conic coefficient K and various aspherical coefficients of the 11th surface are shown below.

[0204] K=-1.3587

[0205] A4=-0.0011568

[0206] A6=-4.5931e-05

[0207] A8=-2.4547e-07

[0208] The 12th surface is an aspherical surface. The conic coefficient K and various aspherical coefficients of the 12th surface are shown below.

[0209] K=10.00

[0210] A4=-0.00021622

[0211] A6=2.0901e-06

[0212] A8=-4.3773e-09

[0213] The numerical values ​​of the conditional expressions in Numerical Example 3 are as follows.

[0214] f2 / f=18

[0215] f 21 / f 22 (=-2.75) >-m(=-3.28)

[0216] Numerical Examples 1 to 3 all satisfy various conditional expressions. This makes it possible to compensate for aberrations well, and suppress the area diffusion of the dot pattern light even in an area with a large angle from the optical axis. Since the area expansion of the dot pattern light is suppressed, the brightness of the dot pattern light can be ensured, the contrast is improved, and the ranging accuracy is improved.

[0217] The above describes the exemplary embodiments of the present invention. The embodiments of the present invention are not limited to the above description, and various modifications can be made as long as they are within the scope of the present invention. For example, the contents of the appropriate combination of the exemplary embodiments or obvious embodiments in the specification are also included in the embodiments of the present application.

[0218] In the above-described embodiment, the DOE 106 is used as an example of an optical element that obtains patterned light from the laser light incident through the first lens group 104 . However, in other embodiments, the DOE 106 may be replaced with a reflecting mirror.

[0219] Fig.12 The optical structure of the light projection unit 100 according to a modification example is shown.

[0220] like Fig.12 As shown, the light projection unit 100 of the modified example is provided with a reflector M between the first lens group 104 and the second lens group. The control unit 140 controls the driving of the reflector M. The reflector M is used to, for example, surround the vertical Fig.12The axis of the drawing rotates, and the laser light incident through the first lens group 104 is bent in sequence to have the same emission angle as the 0th, 1st, 2nd, etc. diffraction order lights in the above-mentioned embodiment, and is projected onto the object OB as point pattern lights in sequence.

[0221] As an example, by making the arrangement Fig.12 By flashing a plurality of light sources in directions orthogonal to the plane of the drawing and rotating the reflector M around the above-mentioned axis, a grid-shaped dot pattern of light can be irradiated onto the object OB.

[0222] As described above, the reflecting mirror M is an example of a reflecting mirror that guides the laser light incident through the first lens group 104 to the object OB as pattern light.

[0223] In order to obtain the viewing angle of the entire surrounding of the device, the light projection receiving device 2 of the above embodiment is as follows Figure 4 As shown, the device has a light projection unit 100 and a ToF light receiving unit 120 on both sides, but the present invention is not limited thereto.

[0224] Fig.13 This is another example of the arrangement of the optical elements of the light projection and receiving device 2. Fig.13 The light projection receiving device 2 shown in the figure has a light projection unit 100 and a ToF light receiving unit 120 on one surface of the light projection receiving device 2. In addition, an apparatus 200 such as a tripod serving as a support unit and a rotating table, i.e., a rotating device 220, which is arranged above the apparatus 200 and rotated by, for example, an electric motor, may be provided. In this case, the light projection receiving device 2 rotates the device itself by the rotating device 220, and obtains the distance image of all the surroundings while changing the shooting direction.

[0225] The rotation control unit of the light projection receiving device 2 has a predetermined rotation mode when controlling the rotation of the rotation mechanism 220. For example, the rotation control unit of the light projection receiving device 2 has the following mode:

[0226] (1) Rotate only the specified distance

[0227] (2) Stop rotation to project and receive light

[0228] (3) Rotate only the specified distance

[0229] (4) Stop rotation to project and receive light

[0230] Control, project and receive light around the device multiple times.

[0231] Fig.14 It is a block diagram of the structure of the three-dimensional shape generation system 4 according to the second embodiment of the present invention.

[0232] like Fig.14 As shown in FIG. 4 , the three-dimensional shape generation system 4 includes a light projection receiving device 2 and a computing device 3A. Figure 1 The distance measurement system 1 is constituted by adding a generation processing unit 32 to the computing device 3.

[0233] In addition to the computing unit 31, the computing device 3A also includes a generation processing unit 32 for generating three-dimensional shape information based on the obtained three-dimensional point group. The three-dimensional shape information is information representing the three-dimensional shape of an object that can be processed by a computer or the like. The information representing the three-dimensional shape is information that can determine the geometric three-dimensional shape. For example, when a sphere is represented, the coordinates and radius of the center, and when a polyhedron (polygon) is represented, the coordinates of the vertices of the polyhedron correspond to the information representing the three-dimensional shape. In the three-dimensional shape information, in addition to the information representing the three-dimensional shape of the object, information related to the color and material of the object can also be added.

[0234] The storage unit 33 of the computing device 3A includes a setting information management DB 301 , a storage processing management DB 302 , a point cloud management DB 303 , and a three-dimensional shape management DB 304 .

[0235] The setting information management DB 301 is used to store and manage various information. The storage processing management DB 302 is used to store and manage various processing programs for generating three-dimensional shapes. The point cloud management DB 303 is used to store and manage the three-dimensional point cloud information obtained by the distance measurement system. The three-dimensional shape management DB 304 is used to store and manage three-dimensional shape information.

[0236] The setting information management DB 301 is composed of a setting information management table. The setting information management table is a table for managing the three-dimensional point cloud data used to generate the three-dimensional shape, and the execution order and processing mode of the generation process (three-dimensional shape generation process) used to generate the three-dimensional shape. In the setting information management table, the file name of the three-dimensional point cloud data, and the execution order and processing mode of the three-dimensional shape generation process are associated and managed.

[0237] The three-dimensional shape generation process includes, for example, a registration process, a noise removal process, a segmentation process, and a modeling process.

[0238] The registration process converts multiple 3D point clouds into a unified 3D point cloud. The noise removal process is used to remove unnecessary point groups from the 3D point group.

[0239] Segmentation is used to mark specific points in a 3D point cloud to distinguish them from other point clouds, or to distinguish multiple specific point clouds from each other by marking them with different labels. Segmentation can also be performed together with clustering to group the points in the marked point cloud that are close to each other.

[0240] The modeling process is to compare a specific point cloud in the 3D point cloud with a 3D model shape and replace the specific point cloud with the model shape. In addition, the 3D model shape is a model such as a prototype or template used to generate 3D shape information from the 3D point cloud.

[0241] The processing modes include: manual processing that performs part or all of the three-dimensional shape information generation processing based on the user's operation input without performing storage processing; automatic processing that performs part or all of the three-dimensional shape information generation processing based on pre-stored storage processing without operating input; and hybrid processing that mixes manual processing and automatic processing to perform part or all of the three-dimensional shape information generation processing.

[0242] The generation processing unit 32 receives input operations from the user, including, for example, operations for setting point cloud setting information indicating a three-dimensional point cloud to be processed and operations for setting processing setting information indicating the execution order and processing mode of each process in the three-dimensional shape information generation process.

[0243] Next, the generation processing unit 32 performs the three-dimensional shape information generation processing set by the input operation. Specifically, the generation processing unit 32 searches the point cloud management DB 303 by using the point cloud setting information as a search keyword, thereby reading out the three-dimensional point cloud data associated with the point cloud setting information. In addition, the storage processing management DB 302 is searched by using the processing mode of the generation processing in the processing setting information as a search keyword, thereby reading out the processing program associated with the processing setting information. Next, the generation processing unit 32 generates the three-dimensional shape information based on the three-dimensional point cloud data read from the storage unit 33, the processing program, and the generation processing execution order and processing mode in the processing setting information.

[0244] When the processing mode includes manual processing and mixed processing, the generation processing unit 32 generates an operation screen for receiving operation input for generating three-dimensional shape information, displays it on a display unit (display, etc.), and receives a predetermined input operation of the user on the displayed operation screen. The input operation includes an operation input for executing a process in which the manual processing mode is selected in the three-dimensional shape information generation process. The generation processing unit 32 generates three-dimensional shape information based on the operation input information.

[0245] The generation processing unit 32 converts the generated three-dimensional shape information into a CAD format or the like, and stores the converted three-dimensional shape information in the three-dimensional shape management DB 304 or an external recording medium or the like.

[0246] The 3D shape generation system of this embodiment can generate 3D shape information based on the point cloud obtained by the distance measurement system. In this way, it will be easy to model existing buildings in the fields of architecture, construction and civil engineering, and can be used for BIM (Building Information Modeling) / CIM (Construction Information Modeling).

[0247] The generation processing unit 32 is not limited to being provided on the computing device 3A having the computing unit 31A, and may be provided, for example, in another terminal device connected to the computing device 3A via wired communication or wireless communication, or in a server provided in the cloud. Alternatively, a device that performs three-dimensional shape generation processing by multiple devices (e.g., the computing device 3A and a server connected to the computing device 3A) may be provided.

[0248] Reference below Fig.15 , Fig.16 The application of the distance measuring system 1 in various detection systems is described. In addition to the distance measuring system 1, the detection systems in these application examples also have the respective functional modules described below. For the convenience of illustration, Fig.15 , Fig.16 In the figure, functional modules such as the judgment unit of the detection system are shown as being outside the detection system. Fig.15 , Fig.16 The various detection systems shown have a control unit that receives information from the distance measuring system 1 and controls the various detection systems based on the information from the distance measuring system 1 .

[0249] Fig.15 An example of a shape measurement system as a detection system is shown, and a distance measurement system 1 is used in user authentication of an electronic device. A portable information terminal 60X as an electronic device has a user authentication function. The authentication function can be implemented by dedicated hardware, or by controlling a CPU (Central Processing Unit) of the portable information terminal 60X to execute a program in a ROM (Read Only Memory) or the like.

[0250] When performing user authentication, light is projected from the light source device of the distance measuring system 1 mounted on the portable information terminal 60X to the user 61X who uses the portable information terminal 60X. The light receiving element of the distance measuring system 1 receives the light reflected from the user 61X and its surroundings, and the image processing unit 62X generates image data (takes pictures). The judgment unit 63X judges the consistency between the image information of the user 61X photographed by the distance measuring system 1 and the pre-registered user information, and judges whether the user is a registered user. Specifically, the shape (contour or unevenness) of the face, ears, head, etc. of the user 61X can be measured and used as user information.

[0251] exist Fig.15 In the application example, the detection of user 61X by ranging system 1 can achieve the same effect as that of ranging system 1 (improvement of detection accuracy). In particular, since light can be projected at a large angle from the light projection device and information of user 61X can be detected within a wide range, the amount of information used to identify the user increases compared to a case where the detection range is narrow, and improvement of recognition accuracy can be achieved.

[0252] Fig.15 This is an example of mounting the distance measuring system 1 on the portable information terminal 60X, but the user authentication using the distance measuring system 1 can also be used for fixed personal computers, OA equipment such as printers, building security systems, etc. In terms of functions, in addition to the personal authentication function, it can also be used to scan three-dimensional shapes such as faces. In this case, by mounting the distance measuring system 1 that can project light at a large angle, high-precision scanning can also be achieved.

[0253] Fig.16 The application of the distance measuring system 1 in a mobile autonomous driving system as an example of a detection system is shown. Fig.16 In the application example, the distance measuring system 1 is used for sensing an object located outside a moving body 70X. The moving body 70X is an autonomous moving body capable of automatically traveling while recognizing external conditions.

[0254] The moving body 70X is equipped with a distance measuring system 1, which irradiates light in the direction of travel of the moving body 70X and its surrounding area. In the room 71X which is the moving area of ​​the moving body 70X, a table 72X is placed in the direction of travel of the moving body 70X. Among the light projected by the light source device of the distance measuring system 1 mounted on the moving body 70X, the light reflected from the table 72X and its surroundings is received by the light receiving element of the distance measuring system 1, and the electrical signal after photoelectric conversion is sent to the signal processing unit 73X. The signal processing unit 73X obtains information related to the layout of the room 71X, such as the distance to the table 72X, the position of the table 72X, and the surrounding conditions other than the table 72X, based on the electrical signal sent from the light receiving element. Based on the obtained information, the judgment unit 74X judges the moving path and moving speed of the moving body 70X, and the driving control unit 75X controls the travel of the moving body 70X (the operation of the motor as the driving source, etc.) based on the judgment result of the judgment unit 74X.

[0255] exist Fig.16 In the application example, the indoor 71X arrangement detection by the ranging system 1 can obtain the same effect as the ranging system 1 (improvement of detection accuracy). In particular, since the light is projected at a large angle from the light projection device, the information of the indoor 71X can be detected in a wide range, so more information can be obtained compared to the case where the detection range is narrow, and the autonomous driving accuracy of the moving body 70X can be improved.

[0256] Fig.16 This is an example of a distance measuring system 1 mounted on an autonomous moving body 70X traveling indoors 71X, but it can also be used for autonomous vehicles traveling outdoors (so-called automatic vehicles). It can also be applied to a driving assistance system for a moving body such as a car that is not autonomous but driven by a driver. In this case, the distance measuring system 1 can be used to detect the surrounding conditions of the moving body, and the driver's driving can be supported based on the detected surrounding conditions.

[0257] In addition to the above, the distance measuring system 1 can also be used in an article inspection system in a factory, etc. Specifically, based on the information obtained by the distance measuring system 1, the state of each article is determined by a determination unit of the article inspection system.

[0258] The distance measuring system 1 can also be applied to the motion control of movable devices. The multi-joint arm of a movable device has multiple arms connected by bendable joints, and is equipped with a hand at the front end. The multi-joint arm is used, for example, in an assembly line in a factory, and the hand is used to hold the object when inspecting, transporting, and assembling the object. The object and its surrounding area are detected by the distance measuring system 1, and the judgment unit of the movable device judges various information related to the object based on the information obtained by the distance measuring system 1, such as the distance to the object, the shape of the object, the position of the object, and the relative positional relationship when there are multiple objects. Then, based on the judgment result of the judgment unit, the drive control unit controls the motion of the multi-joint arm.

[0259] Furthermore, the distance measuring system 1 can be used in a driving assistance system for a mobile object such as a car. The distance measuring system 1 installed in the car detects the driver driving the car and the surrounding area, and the judgment unit of the driving assistance system judges the driver's facial (expression) and posture information based on the information obtained by the distance measuring system 1. Then, based on the judgment result of the judgment unit, the control unit performs appropriate driving assistance corresponding to the driver's situation.

[0260] Shape measurement systems, mobile objects, article inspection systems, movable devices, and driving assistance systems are all examples of detection systems. The distance measurement system 1 of this embodiment can suppress the expansion of the pattern light area projected onto the object and project at a large angle. Therefore, the detection system using the distance measurement system 1 can perform high-precision detection over a wide range.

[0261] The present invention has the following aspects.

[0262] [1] A light projection device, comprising:

[0263] A light source, emitting at least one beam of light;

[0264] The optical system projects the pattern light obtained from the light emitted from the light source onto the object.

[0265] The optical system comprises:

[0266] a first lens group, into which the light emitted from the light source is incident;

[0267] an optical element that obtains the patterned light from the light incident through the first lens group; and

[0268] a second lens group, into which the pattern light emitted from the optical element is incident,

[0269] The first lens group has positive optical power,

[0270] The second lens group has positive refractive power and includes a third lens group having positive refractive power and a fourth lens group having negative refractive power, which are sequentially arranged from the optical element side.

[0271] [2] The light projection device as described in [1], wherein, when the overall focal length of the optical system is f (unit: mm), the focal length of the first lens group is f1 (unit: mm), and the focal length of the second lens group is f2 (unit: mm), the following equation is satisfied:

[0272] f1>0

[0273] 1.5≤f2 / f≤18.

[0274] [3] The light projection device described in [1], wherein the optical element is a diffractive optical element for forming the light incident through the first lens group into the pattern light.

[0275] [4] The light projection device as described in [3], wherein when the focal length of the third lens group is set to f 21 , the focal length of the fourth lens group is f 22 , when the ratio of the viewing angle on the final optical surface of the optical system to the viewing angle on the exit surface of the diffractive optical element is m, the following formula is satisfied:

[0276] f 21 / f 22 >-m.

[0277] [5] A light projection device as described in [1], wherein the first lens group is composed of at least one positive lens, the third lens group is composed of at least two positive lenses, the fourth lens group is composed of at least two negative meniscus lenses, and at least one of the optical surfaces of the at least two negative meniscus lenses is aspherical.

[0278] [6] The light projection device as described in [1], wherein the full viewing angle of the final optical surface of the optical system is greater than or equal to 90 degrees and less than or equal to 220 degrees.

[0279] [7] The light projection device as described in [1], wherein, when the overall focal length of the optical system is f (unit: mm) and the focal length of the second lens group is f2 (unit: mm), the following equation is satisfied:

[0280] 1.5f≤f2.

[0281] [8] The light projection device described in [1], wherein the optical element is a reflector for guiding the light incident through the first lens group as the pattern light to the object.

[0282] [9] A light projection receiving device, comprising:

[0283] The light projection device according to any one of claims 1 to 8;

[0284] a light receiving unit for receiving reflected light from the object onto which the pattern light is projected; and

[0285] The control unit is used to control the light source and the light receiving unit.

[0286]

[10] A distance measurement system, comprising:

[0287] [9] The light projection receiving device described in [9]; and

[0288] The distance calculation unit is used to calculate the distance to the object based on the output of the light receiving unit after receiving the light.

Claims

1. A light projection device, comprising: A light source, emitting at least one beam of light; The optical system projects the pattern light obtained from the light emitted from the light source onto the object. The optical system comprises: a first lens group, into which the light emitted from the light source is incident; an optical element, forming the light incident through the first lens group into the patterned light; and a second lens group, into which the pattern light emitted from the optical element is incident, The first lens group has positive optical power, The second lens group has positive refractive power and includes a third lens group having positive refractive power and a fourth lens group having negative refractive power, which are sequentially arranged from the optical element side.

2. The light projection device according to claim 1, wherein: When the overall focal length of the optical system is f (unit: mm), the focal length of the first lens group is f1 (unit: mm), and the focal length of the second lens group is f2 (unit: mm), the following equation is satisfied: f1＞0 1.5≤f2 / f≤18.

3. The light projection device according to claim 1, wherein: The optical element is a diffractive optical element for forming the light incident through the first lens group into the pattern light.

4. The light projection device according to claim 3, wherein: When the focal length of the third lens group is assumed to be f 21 , the focal length of the fourth lens group is f 22 , when the ratio of the viewing angle on the final optical surface of the optical system to the viewing angle on the exit surface of the diffractive optical element is m, the following formula is satisfied: f 21 / f 22 >-m。 5. The light projection device according to claim 1, wherein The first lens group is composed of at least one positive lens, the third lens group is composed of at least two positive lenses, the fourth lens group is composed of at least two negative meniscus lenses, and at least one of the optical surfaces of the at least two negative meniscus lenses is an aspherical surface.

6. The light projection device according to claim 1, wherein: The total viewing angle of the final optical surface of the optical system is greater than or equal to 90 degrees and less than or equal to 220 degrees.

7. The light projection device according to claim 1, wherein When the overall focal length of the optical system is f (unit: mm), and the focal length of the second lens group is f2 (unit: mm), the following equation is satisfied: 1.5f≤f2.

8. The light projection device according to claim 1, wherein The optical element is a reflector for guiding the light incident through the first lens group to the object as the pattern light.

9. A light projection receiving device, comprising: The light projection device according to any one of claims 1 to 8; a light receiving unit for receiving reflected light from the object onto which the pattern light is projected; and The control unit is used to control the light source and the light receiving unit.

10. A distance measurement system, comprising: The light projection receiving device according to claim 9; and The distance calculation unit is used to calculate the distance to the object based on the output of the light receiving unit after receiving the light.

Images