Optical device, vehicle-mounted system and mobile device equipped with the same

Abstract

To provide an optical device that has satisfactory optical performance despite its simple configuration.SOLUTION: An optical device comprises: a deflection unit that deflects illumination light from a light source to scan an object and deflects reflected light from the object; a light guide unit that guides the illumination light from the light source to the deflection unit and guides the reflected light from the deflection unit to a light receiving element; and an optical system 40 that guides the illumination light from the deflection unit to the object and guides the reflected light from the object to the deflection unit. The optical system forms an intermediate image 43 of the object, and has a front group 41 consisting of lenses arranged on the object side with respect to the intermediate image 43 and a rear group 42 consisting of lenses arranged on the deflection unit side with respect to the intermediate image. The rear group consists of three or more and five or less positive lenses.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an optical device that detects an object by receiving light reflected from an illuminated object. [Background technology]

[0002] A known distance measuring device measures the distance to an object by scanning the object by deflecting illumination light from a light source using a deflection unit, and calculating the distance to the object based on the time it takes to receive the reflected light from the object and the phase of the reflected light.

[0003] Patent Document 1 describes a distance measuring device that can change the diameter of illumination light and reflected light by an optical system that is arranged closer to the object than the deflection unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-113408 A Summary of the Invention [Problem to be solved by the invention]

[0005] The distance measuring device described in Patent Document 1 aims to improve distance measuring accuracy by adopting a lens array in the optical system. However, when a lens array is used as in Patent Document 1, the configuration of the optical system becomes complicated, and positioning errors of each component are likely to occur, which increases the difficulty of manufacturing the distance measuring device.

[0006] An object of the present invention is to provide an optical device that has a simple configuration but has good optical performance. [Means for solving the problem]

[0007] In order to achieve the above object, an optical device according to one aspect of the present invention includes a deflection unit that deflects illumination light from a light source to scan an object and deflects reflected light from the object, a light guiding unit that guides the illumination light from the light source to the deflection unit and guides the reflected light from the deflection unit to a light receiving element, and an optical system that guides the illumination light from the deflection unit to the object and guides the reflected light from the object to the deflection unit, wherein the optical system forms an intermediate image of the object and has a front group made of lenses arranged on the object side of the intermediate image, and a rear group made of lenses arranged on the deflection unit side of the intermediate image, The front group consists of two or more positive lenses and two or more negative lenses, The rear group is made up of three or more and five or less positive lenses. and when the focal length of the front group is ff and the focal length of the rear group is fr, it satisfies the conditional expression of 1.8 < ff / fr < 8.0 It is characterized by: Effect of the Invention

[0008] According to the present invention, it is possible to provide an optical device that has a simple configuration but has good optical performance. [Brief description of the drawings]

[0009]

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[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the drawings may be drawn at a scale different from the actual scale for convenience. In addition, in each drawing, the same reference numerals are used for the same components, and duplicated explanations will be omitted.

[0011] Fig. 1 is a schematic diagram (schematic diagram) of a main part of an optical device 1 according to an embodiment of the present invention in a cross section (YZ cross section) including an optical axis. The optical device 1 includes a light source unit 10, a light guiding unit (branching unit) 20, a deflection unit 30, an optical system 40, a light receiving unit 50, and a control unit 60. In Fig. 1, the optical path (illumination optical path) of illumination light from the light source unit 10 toward an object (object) 100 is shown by a solid line, and the optical path (received light path) of reflected light from the object 100 toward the light receiving unit 50 is shown by a dashed line.

[0012] The optical device 1 can be used as a detection device (imaging device) that detects (images) the object 100 by receiving reflected light from the object 100, or as a distance measuring device that obtains the distance (distance information) to the object 100. The optical device 1 according to this embodiment uses a technology called LiDAR (Light Detection And Ranging) that calculates the distance to the object 100 based on the time it takes to receive reflected light from the object 100 and the phase of the reflected light.

[0013] The light source unit 10 has a light source 11, an optical element 12, and an aperture 13. A semiconductor laser, which is a laser with high energy concentration and good directionality, can be used as the light source 11. When the optical device 1 is applied to an in-vehicle system as described later, there is a possibility that a human being is included in the target object 100. Therefore, it is preferable to adopt a light source 11 that emits infrared light that has little effect on the human eye. The wavelength of the illumination light emitted by the light source 11 in this embodiment is 905 nm, which is included in the near-infrared range.

[0014] The optical element 12 has a function of changing the convergence of the illumination light emitted from the light source 11. The optical element 12 according to this embodiment is a collimator lens (light-collimating element) that converts (collimates) the divergent light beam emitted from the light source 11 into a parallel light beam. Note that the parallel light beam here includes not only a strictly parallel light beam but also an approximately parallel light beam such as a weakly divergent light beam or a weakly convergent light beam.

[0015] The diaphragm 13 is a light blocking member having an opening, and determines the light beam diameter (light beam width) by restricting the illumination light from the optical element 12. The shape of the opening of the diaphragm 13 according to this embodiment is elliptical to match the shape of the illumination light, but may be a shape other than elliptical as necessary. The diameter of the opening of the diaphragm 13 according to this embodiment is 1.60 mm in the X direction (long axis direction) and 1.30 mm in the Z direction (short axis direction).

[0016] The light guiding section 20 is a member that branches an illumination light path and a light receiving light path, and guides the illumination light from the light source section 10 to the deflection section 30, and guides the reflected light from the deflection section 30 to the light receiving section 50. The light guiding section 20 according to this embodiment includes a light-transmitting member 21, a perforated (hole-drilled) mirror 22, and a light-source light receiving element 23. The light-transmitting member 21 is a member that reflects a portion of the illumination light that has passed through the opening of the diaphragm 13 and guides it to the light-source light receiving element 23, and a glass substrate, for example, can be used.

[0017] The perforated mirror 22 is a reflective member provided with an opening (hole) that passes the illumination light from the light source unit 10, and reflects the reflected light from the deflection unit 30 toward the light receiving unit 50 by a reflective area (reflecting unit) other than the opening. The opening of the perforated mirror 22 according to this embodiment is an air hole as shown in Fig. 1, but a light-transmitting member may be provided in the opening. In addition, the light-guiding member (branching member) for branching the illumination light and the reflected light is not limited to a perforated mirror, and a beam splitter, a prism, a half mirror, etc. may also be used.

[0018] The light source light receiving element 23 is an element for photoelectrically converting the illumination light from the light source unit 10 and outputting a signal, and for example, a sensor similar to the light receiving element 53 in the light receiving unit 50 described later can be used. The signal output from the light source light receiving element 23 is used when the light source unit 10 is controlled by the control unit 60 described later. Note that, if necessary, an optical element (such as a filter or a lens) for guiding the light from the light transmitting member 21 to the light receiving surface of the light source light receiving element 23 may be disposed between the light transmitting member 21 and the light source light receiving element 23.

[0019] The deflection unit 30 is a member for deflecting the illumination light from the light guiding unit 20 to scan the object 100, and for deflecting the reflected light from the object 100 to guide it to the light guiding unit 20. The deflection unit 30 according to this embodiment is composed of a folding mirror 31 (first deflection element) and a drive mirror 32 (movable mirror, second deflection element).

[0020] It is desirable that the driven mirror 32 is capable of swinging at least around two axes (two-axis driven mirror) to enable two-dimensional scanning of the target object 100. For example, a galvanometer mirror or a MEMS (Micro Electro Mechanical System) mirror can be adopted as the driven mirror 32. The driven mirror 32 according to this embodiment is a MEMS mirror with a swing angle (deflection angle) of ±7.5° around the X axis, a swing angle of ±15.0° around the Y axis, and a swing frequency of about 1 kHz. The swing angle of the driven mirror 32 around the X axis corresponds to the viewing angle (scanning angle) in the YZ cross section, and the swing angle of the driven mirror 32 around the Y axis corresponds to the viewing angle in the ZX cross section.

[0021] The optical system 40 is a member for guiding the illumination light from the deflection unit 30 to the object 100 and guiding the reflected light from the object 100 to the deflection unit 30. The optical system 40 according to this embodiment is an optical system (afocal system) that is composed of a plurality of lenses having refractive power and does not have refractive power as a whole. Specifically, the optical system 40 is a telescope that expands the diameter of the illumination light from the deflection unit 30 by β times and reduces the diameter of the reflected light from the object 100 by 1 / β times.

[0022] The optical system 40 according to this embodiment has a front group 41 having a plurality of lenses and a rear group 42 having a plurality of lenses, which are arranged in order from the side of the object 100 (object side) to the side of the deflection unit 30 (deflection unit side). The front group 41 is configured to collect reflected light from the object 100 to form an intermediate image 43 of the object 100. The rear group 42 is configured to convert the reflected light from the front group 41 into a parallel light beam and cause it to enter the drive mirror 32. With this configuration, the optical system 40 can convert the diameter of the illumination light from the deflection unit 30 and the reflected light from the object 100. In addition to the front group 41 and the rear group 42, the optical system 40 may have other members such as an aperture, a filter, and a cover glass.

[0023] The deflection surface of the drive mirror 32 according to this embodiment is disposed at a position conjugate with the entrance pupil of the optical system 40 when the side of the object 100 is the entrance side. In other words, the deflection surface of the drive mirror 32 is disposed at the position of the entrance pupil of the optical system 40 when the side of the deflection unit 30 is the entrance side. Also, the absolute value of the optical magnification (lateral magnification) β of the optical system 40 according to this embodiment is greater than 1 (|β|>1). As a result, the deflection angle of the chief ray of the illumination light emitted from the optical system 40 is smaller than the deflection angle of the chief ray of the illumination light deflected by the drive mirror 32 and entering the optical system 40, thereby improving the resolution when detecting the object.

[0024] The illumination light from the light source unit 10 is deflected by the deflection unit 30 via the light guide unit 20, and is magnified by the optical system 40 according to the optical magnification β to illuminate the object 100. The reflected light from the object 100 is reduced by the optical system 40 according to the optical magnification 1 / β, deflected by the deflection unit 30, and reaches the light receiving unit 50. This allows the diameter of the illumination light to be further enlarged and the spread angle to be further reduced, so that sufficient illuminance and resolution can be ensured even when the object is located far away. In addition, by enlarging the pupil diameter using the optical system 40, it is possible to capture more reflected light from the object, thereby improving the distance measurement and the accuracy of distance measurement.

[0025] The light receiving section (distance measuring light receiving section) 50 has an optical filter 51, a light collecting section 52, and a light receiving element (distance measuring light receiving element) 53. The optical filter 51 is a member for passing only desired light and blocking (absorbing) other unnecessary light. The optical filter 51 according to this embodiment is a band pass filter that passes only light in a wavelength band corresponding to the illumination light emitted from the light source 11. The light collecting section 52 is a member for collecting the light that has passed through the optical filter 51 on the light receiving surface of the light receiving element 53, and is configured by a single optical element (light collecting lens) in this embodiment. Note that the configuration of the optical filter 51 and the light collecting section 52 is not limited to this embodiment, and the order of arrangement of each member may be changed or each member may be arranged in a plurality of parts as necessary. For example, the light collecting section 52 may be configured by a plurality of light collecting lenses.

[0026] The light receiving element (distance measuring light receiving element) 53 is an element (sensor) for receiving light from the light collecting unit 52, photoelectrically converting the light, and outputting a signal. The light receiving element 53 may be composed of a PD (Photo Diode), an APD (Avalanche Photo Diode), a SPAD (Single Photon Avalanche Diode), or the like. Reflected light from the object 100 illuminated by the illumination light is deflected by the deflection unit 30, reflected by the perforated mirror 22, and enters the light receiving element 53 via the optical filter 51 and the light collecting unit 52.

[0027] The control unit 60 controls the light source 11, the light-source light-receiving element 23, the drive mirror 32, the light-receiving element 53, and the like. The control unit 60 is, for example, a processing device (processor) such as a CPU (Central Processing Unit), or an arithmetic device (computer) equipped with the same. The control unit 60 drives each of the light source 11 and the drive mirror 32 at a predetermined drive voltage and a predetermined drive frequency, and controls the output (amount of illumination light) of the light source 11 in response to a signal from the light-source light-receiving element 23. The control unit 60 can also, for example, control the light source 11 to make the illumination light pulsed light, or perform intensity modulation of the illumination light to generate signal light.

[0028] Furthermore, the control unit 60 can acquire distance information of the object 100 based on the time from the time when the illumination light is emitted from the light source 11 (light emission time) to the time when the light receiving element 53 receives the reflected light from the object 100 (light reception time). At this time, the control unit 60 may acquire the signal from the light receiving element 53 at a specific frequency. Note that the distance information may be acquired based on the phase of the reflected light from the object 100, instead of the time until the reflected light from the object 100 is received. Specifically, the distance information of the object 100 may be acquired by calculating the difference (phase difference) between the phase of the signal from the light source 11 and the phase of the signal output from the light receiving element 53, and multiplying the phase difference by the speed of light.

[0029] The optical device 1 as a distance measuring device using such LiDAR is suitable for an in-vehicle system that identifies an object 100 such as a vehicle, a pedestrian, or an obstacle, and controls the vehicle according to distance information of the object 100. When using LiDAR, it is possible to adopt a coaxial system in which the optical axes of the light source unit 10 and the light receiving unit 50 partially coincide with each other, or a non-coaxial system in which the optical axes do not coincide with each other. The optical device 1 according to this embodiment is provided with a light guide unit 20, thereby realizing a coaxial system while miniaturizing the entire device.

[0030] In an in-vehicle system or the like, it is required to detect objects at a distance from the optical device 1 ranging from close (about 1 m) to long (about 300 m) as the target 100. However, the intensity of the reflected light (signal light) from the target 100 is very weak. For example, when the power of the illumination light emitted from the light source 11 is 1, the reflected light is 10 -7 ~10 -8 The intensity of the reflected light from the object 100 decreases as the distance from the optical device 1 to the object 100 increases. For example, if the distance from the optical device 1 to the object 100 increases tenfold, the intensity of the reflected light received by the optical device 1 decreases to about 1 / 100.

[0031] Here, if reflected light (scattered light) unintentionally generated in each member inside the optical device 1 reaches the light receiving element 53 as unwanted light (stray light), it will have a significant effect on the distance measurement accuracy. For example, if the ratio of unwanted light to the signal light received by the light receiving element 53 increases, the S / N ratio decreases, making it difficult to distinguish between the signal light and the unwanted light, and the distance measurement accuracy will decrease significantly. Note that a method of increasing the amount of illumination light (output of the light source 11) according to an increase in the distance to the object 100 is also conceivable, but this is not preferable because it would have a significant effect on the human eye as the object 100.

[0032] Such unwanted light is particularly likely to be generated by lens surfaces arranged after the light guiding section 20. In this embodiment, the optical system 40, which is arranged on the object 100 side of the light guiding section 20, has a plurality of lenses, and therefore the illumination light may be reflected (scattered) at each lens surface and become unwanted light. Therefore, in order to suppress the generation of unwanted light at each lens surface of the optical system 40, it is desirable to design the optical device 1 so that light rays contained in the illumination light (illumination light rays) do not perpendicularly enter each lens surface. This will be described with reference to FIG. 2.

[0033] FIG. 2 is a schematic diagram showing illumination light incident on the lens surface 4 arranged on the object 100 side of the deflection unit 30. Illumination light deflected by the swing of the drive mirror 32 is incident on the lens surface 4. That is, illumination light is incident on the lens surface 4 at various angles of incidence. A part of illumination light, indicated by a solid line, illumination light ray A passes through the center of curvature C of the lens surface 4 and is therefore incident perpendicularly on the lens surface 4. In this case, light ray A is reflected by the lens surface 4 and travels along a reflected light path that is in the opposite direction to the illumination light path, so that it may be incident on the light receiving element 53 as unwanted light together with the reflected light from the object 100. Even if an anti-reflection film with a reflectance of about 0.1% is provided on the lens surface 4, some of the light rays may become such unwanted light.

[0034] On the other hand, illumination light ray B, indicated by a dotted line, does not pass through center of curvature C and is therefore incident on lens surface 4 at a certain angle of incidence. In other words, normal line D at the point of incidence of illumination light ray B on lens surface 4 and illumination light ray B are non-parallel to each other (they do not overlap with each other). Therefore, even if illumination light ray B is reflected by lens surface 4, it travels an optical path different from the reflected optical path, so that no unnecessary light is generated. Therefore, in order to suppress the generation of unnecessary light in optical system 40, deflection unit 30 and optical system 40 should be arranged so that each illumination light ray incident on each lens surface does not pass through the center of curvature of each lens surface (does not perpendicularly enter each lens surface).

[0035] Specifically, it is desirable to design each lens in the optical system 40 so that the normal line of the illumination light at the incident point on each lens surface of the optical system 40 and the illumination light are not parallel to each other, in other words, so that each illumination light does not perpendicularly enter each lens surface. For example, by using a well-known optical simulation software or the like to design each lens while checking the incident angle of each illumination light to each lens surface in the optical system 40, it is possible to prevent the illumination light from perpendicularly entering each lens surface. Design parameters of each lens include, but are not limited to, the curvature (radius of curvature), thickness (thickness in the optical axis direction), surface shape, position in the direction perpendicular to the optical axis (eccentricity), etc. Note that the shape of each lens surface may be aspheric, but is desirably spherical in consideration of ease of molding, etc.

[0036] In order to reduce the illumination light perpendicularly incident on each lens surface, the deflection unit 30 and the optical system 40 may be arranged to be shifted from each other in the Y direction. To realize this configuration, the deflection unit 30 may be arranged so that the optical path of the principal ray of the illumination light at the central angle of view in the scanning range of the drive mirror 32 does not coincide with the optical axis of the optical system 40 in a cross section (YZ cross section) including the illumination light path and the reflected light path. In addition, the same effect can be obtained by setting (tilting) the scanning range of the deflection unit 30 asymmetrically with respect to the optical axis of the optical system 40, instead of shifting the deflection unit 30 and the optical system 40 from each other. The shift and tilt may be combined. Furthermore, at least one of the shift and tilt may be combined in addition to the design of each lens described above.

[0037] Here, when the configuration for suppressing the generation of unnecessary light as described above is adopted, the degree of freedom in designing the optical system 40 is reduced compared to when this configuration is not adopted. In particular, in the rear group 42, where the illumination light from the deflection unit 30 is first incident, the degree of freedom in designing the shape and arrangement of each lens is significantly reduced. Therefore, in order to achieve both a compact optical system 40 and good optical performance, it is necessary to appropriately design the number of lenses constituting the rear group 42 and the sign of the refractive power of each lens.

[0038] Therefore, the inventors have found through trial and error that by configuring the rear group 42 with three or more and five or less positive lenses, it is possible to achieve both a compact overall system of the optical system 40 and good optical performance. According to the optical system 40 according to this embodiment, by configuring the rear group 42 with only positive lenses, it is possible to make the optical system 40 compact while correcting aberrations well. If a negative lens is added to the rear group 42, in order to correct aberrations well, the rear group 42 will be larger than when it is configured with only positive lenses.

[0039] Furthermore, by setting the number of positive lenses constituting the rear group 42 to 3 or more and 5 or less, it is possible to suppress the generation of unnecessary light while miniaturizing the optical system 40. If the number of positive lenses is set to 2 or less, the overall focal length of the rear group 42 becomes too long, making it difficult to miniaturize the optical system 40. Also, it becomes difficult to make each light beam incident on each lens surface in the rear group 42 non-parallel to the normal at the point of incidence on each lens surface, making it difficult to sufficiently reduce unnecessary light.

[0040] On the other hand, if the number of positive lenses is six or more, the overall focal length of the rear group 42 becomes short, and the intermediate image 43 becomes too close to the lens surface of the rear group 42. In this case, light rays are concentrated near the intermediate image 43, so the lens surface is significantly affected by scratches and dirt, making it difficult to obtain good optical performance. Also, as the number of positive lenses increases, it becomes more difficult to design the rear group 42 so that the intermediate image 43 does not interfere with the lens surface.

[0041] The number of positive lenses constituting the rear group 42 may be selected depending on whether a smaller size of the optical system 40 or a reduction in unnecessary light is to be prioritized. For example, in order to further reduce the size of the optical system 40, it is preferable that the number of positive lenses constituting the rear group 42 is four or five. Also, in order to optimize the balance between a smaller size of the optical system 40 and a reduction in unnecessary light, it is preferable that the number of positive lenses constituting the rear group 42 is four.

[0042] When the focal length of the front group 41 is ff and the focal length of the rear group 42 is fr, it is desirable that the optical system 40 satisfy the following conditional expression (1). 1.8 <ff / fr<8.0 (1)

[0043] By satisfying conditional expression (1), it becomes possible to detect the object 100 with high accuracy even when the object 100 is located at a distance. If the upper limit of conditional expression (1) is exceeded, the optical magnification of the optical system 40 becomes too large, which is undesirable because it leads to an increase in the size of the entire system and makes it easier for unnecessary light to be generated. If the lower limit of conditional expression (1) is exceeded, the optical magnification of the optical system 40 becomes too small, which is undesirable because it becomes difficult to receive reflected light from the object 100 at a distance.

[0044] Furthermore, it is preferable to satisfy the following conditional formula (1a), it is more preferable to satisfy the following conditional formula (1b), and it is even more preferable to satisfy the following conditional formula (1c). 2.0 <ff / fr<7.0 (1a) 2.5 <ff / fr<6.0 (1b) 3.0 <ff / fr<5.0 (1c)

[0045] Furthermore, for the lens in the rear group 42 closest to the deflection unit, when the radius of curvature of the lens surface on the object side is R1B1 and the radius of curvature of the lens surface on the deflection unit side is R2B1, it is desirable that the optical system 40 satisfy the following conditional formula (2). -12.0<(R1B1+R2B1) / (R1B1-R2B1)<-2.0 (2)

[0046] Conditional formula (2) is an equation related to the shape factor of the lens closest to the deflection unit among the positive lenses constituting the rear group 42. By satisfying conditional formula (2), the lens can be made into an appropriate meniscus shape, and the generation of unnecessary light can be suppressed while facilitating the manufacture of the lens. If the upper limit of conditional formula (2) is exceeded, the lens approaches a plano-convex or biconvex shape. In this case, in order to prevent the direction of the normal to the lens surface on the deflection unit side from coinciding with the direction of the light ray, it is necessary to refract the light ray at a very large angle on the lens surface, which is undesirable because it makes it difficult to correct aberrations. If the lower limit of conditional formula (2) is exceeded, the curvature of each lens surface becomes too large, which is undesirable because it makes it difficult to manufacture the lens.

[0047] Furthermore, it is preferable to satisfy the following conditional formula (2a), and it is more preferable to satisfy the following conditional formula (2b). -10.0<(R1B1+R2B1) / (R1B1-R2B1)<-4.0 (2a) -8.0<(R1B1+R2B1) / (R1B1-R2B1)<-6.0 (2b)

[0048] Furthermore, for the lens in the rear group 42 adjacent to the lens closest to the deflection unit, when the radius of curvature of the lens surface on the object side is R1B2 and the radius of curvature of the lens surface on the deflection unit side is R2B2, it is desirable that the optical system 40 satisfy the following conditional formula (3): -6.0<(R1B2+R2B2) / (R1B2-R2B2)<-0.5 (3)

[0049] Conditional formula (3) is an equation related to the shape factor of the second lens, counting from the deflection unit side, among the positive lenses constituting the rear group 42. By satisfying conditional formula (3), the lens can be made into an appropriate meniscus shape, and the generation of unnecessary light can be suppressed while facilitating the manufacture of the lens. If the upper limit of conditional formula (3) is exceeded, the lens approaches a biconvex shape, which is undesirable because it becomes difficult to correct the spherical aberration generated by each lens surface. If the lower limit of conditional formula (3) is exceeded, it is undesirable because it becomes difficult to design the lens so that the direction of the normal to each lens surface does not coincide with the direction of the light ray.

[0050] Furthermore, it is preferable to satisfy the following conditional formula (3a), and it is more preferable to satisfy the following conditional formula (3b). -5.0<(R1B2+R2B2) / (R1B2-R2B2)<-1.0 (3a) -4.0<(R1B2+R2B2) / (R1B2-R2B2)<-2.0 (3b)

[0051] Also, the distance on the optical axis from the lens surface closest to the object in the rear group 42 to the lens surface closest to the deflection unit is defined as Lr, and the distance on the optical axis from the lens surface closest to the deflection unit in the front group 41 to the lens surface closest to the object in the rear group 42 is defined as Li. In this case, it is desirable for the optical system 40 to satisfy the following conditional expression (4). 0.1 <Lr / Li<4.0 (4)

[0052] By satisfying conditional expression (4), the overall length of the optical system 40 can be shortened while maintaining an appropriate distance between the front group 41 and the rear group 42. If the upper limit of conditional expression (4) is exceeded, the distance between the front group 41 and the rear group 42 becomes too short, and the intermediate image 43 becomes too close to each lens surface, which is undesirable because the lens surfaces are significantly affected by scratches and dust, making it difficult to obtain good optical performance. If the lower limit of conditional expression (4) is exceeded, the front group 41 and the rear group 42 become too far apart, and the overall length of the optical system 40 becomes long, reducing the degree of freedom in arranging each lens, and also increasing the manufacturing cost due to the large size of the lens barrel that holds each lens, which is undesirable.

[0053] Furthermore, it is preferable to satisfy the following conditional formula (4a), and it is more preferable to satisfy the following conditional formula (4b). 0.15 <Lr / Li<3.00 (4a) 0.2 <Lr / Li<2.0 (4b)

[0054] In addition, when the average value of the refractive index for the d-line of the positive lenses in the optical system 40 is NPave and the average value of the refractive index for the d-line of the negative lenses in the optical system 40 is NNave, it is desirable that the optical system 40 satisfy the following conditional expression (5). 1.2 <NPave / NNave<1.5 (5)

[0055] In this embodiment, the wavelength of the illumination light is not particularly limited, but when the optical device 1 is used as a distance measuring device, it is required that the illumination light be infrared light that has less effect on the human body and that the wavelength band of the illumination light be narrowed to increase the directivity. Therefore, it is preferable to select the material of each lens constituting the optical system 40 by prioritizing the correction of Petzval sum over the correction of chromatic aberration. Specifically, it is preferable to adopt a material with a high refractive index for the positive lens and a material with a low refractive index for the negative lens.

[0056] By satisfying conditional expression (5), the Petzval sum of the optical system 40 can be well corrected and the occurrence of curvature of field and astigmatic difference can be suppressed. If the upper limit of conditional expression (5) is exceeded, the degree of freedom in selecting the material of each lens decreases, which may increase the difficulty of manufacturing each lens and reduce the internal transmittance, which is not preferable. If the lower limit of conditional expression (5) is exceeded, the Petzval sum of the optical system 40 increases, which is not preferable because it becomes difficult to correct curvature of field and astigmatic difference.

[0057] Furthermore, it is preferable to satisfy the following conditional formula (5a), and it is more preferable to satisfy the following conditional formula (5b): 1.25 <NPave / NNave<1.45 (5a) 1.3 <NPave / NNave<1.4 (5b)

[0058] In addition, the front group 41 according to this embodiment is preferably composed of one or more positive lenses and one or more negative lenses. With this configuration, it is easy to effectively correct the Petzval sum and spherical aberration in the front group 41. Furthermore, it is preferable that the front group 41 is composed of two or more positive lenses and two or more negative lenses. With this configuration, the positive refractive power and the negative refractive power can be shared by multiple lenses, so that the curvature of each lens surface can be reduced and the manufacture of each lens can be facilitated. In addition, by making the incident position of the light beam different for each lens, multiple aberrations can be easily corrected by sharing them among the lenses.

[0059] When the front group 41 has a plurality of positive lenses and a plurality of negative lenses, it is preferable to arrange at least one positive lens and at least one negative lens alternately. For example, it is preferable to arrange the front group 41 to be composed of at least one positive lens, at least one negative lens, at least one positive lens, and at least one negative lens arranged in this order from the object side. In this case, the front group 41 is arranged in such a way that a negative lens is arranged on the deflection part side of a lens group (triplet group) having the same function as a triplet, so that spherical aberration and astigmatic difference can be corrected more satisfactorily.

[0060] Although the number of positive lenses and negative lenses in the front group 41 is not particularly limited, in order to simplify the front group 41 while achieving good aberration correction, it is preferable that the front group 41 is composed of two positive lenses and two negative lenses. Furthermore, it is more preferable that the front group 41 is composed of a positive lens, a negative lens, a positive lens, and a negative lens arranged in this order from the object side to the deflection unit side.

[0061] Here, when the front group 41 has one or more positive lenses and one or more negative lenses, the average focal length of the positive lenses in the front group 41 is denoted by ffPave, and the average focal length of the negative lenses in the front group 41 is denoted by ffNave. In this case, it is desirable for the optical system 40 to satisfy the following conditional expression (6). -1.0 <ffPave / ffNave<-0.2 (6)

[0062] By satisfying conditional expression (6), the relationship between the refractive power of the positive lens and the refractive power of the negative lens constituting the front group 41 can be made appropriate, and the aberrations occurring in the positive lens can be effectively corrected by the negative lens. If the upper limit of conditional expression (6) is exceeded, the negative refractive power of the front group 41 becomes too large, which is undesirable because the focal length of the front group 41 becomes long and it becomes difficult to reduce the size of the optical system 40. If the lower limit of conditional expression (6) is exceeded, the positive refractive power of the front group 41 becomes too large, which is undesirable because it becomes difficult to correct the spherical aberration occurring in the front group 41 and the various aberrations occurring in the rear group 42.

[0063] Furthermore, it is preferable to satisfy the following conditional formula (6a), and it is more preferable to satisfy the following conditional formula (6b). -0.8 <ffPave / ffNave<-0.3 (6a) -0.75 <ffPave / ffNave<-0.40 (6b)

[0064] Moreover, it is desirable that the optical system 40 satisfy the following conditional expression (7). 0.65 <fr / Lr<2.20 (7)

[0065] By satisfying conditional expression (7), it is possible to shorten the overall length of the optical system 40 while maintaining an appropriate distance between the front group 41 and the rear group 42. If the upper limit of conditional expression (7) is exceeded, the focal length of the rear group 42 becomes too long, which is undesirable as it becomes difficult to reduce the size of the optical system 40. If the lower limit of conditional expression (7) is exceeded, the distance between the front group 41 and the rear group 42 becomes too short, which brings the intermediate image 43 too close to each lens surface, which is undesirable as it becomes difficult to obtain good optical performance due to the large influence of scratches and dust on each lens surface.

[0066] Furthermore, it is preferable to satisfy the following conditional formula (7a), and it is more preferable to satisfy the following conditional formula (7b). 0.70 <fr / Lr<2.00 (7a) 0.85 <fr / Lr<1.50 (7b)

[0067] It is desirable that all the lenses constituting the optical system 40 are spaced apart from each other in the optical axis direction. In other words, it is desirable that the optical system 40 does not have a cemented lens, and all the lenses in the optical system 40 are single lenses. If the optical system 40 has a cemented lens, there is a possibility that each lens constituting the cemented lens may peel off or become decentered due to temperature changes. Therefore, by configuring the optical system 40 with only single lenses, it is possible to maintain good optical performance even when temperature changes occur. This effect is particularly noticeable when the optical system 40 is placed in an environment where the temperature changes drastically, such as when the optical system 40 is installed in an in-vehicle system.

[0068] As described above, the optical device 1 according to this embodiment can achieve both miniaturization of the optical system 40 and reduction of unnecessary light, and can obtain good optical performance with a simple configuration. As a result, when the optical device 1 is applied to a distance measuring device, good distance measuring accuracy can be achieved.

[0069] [Example 1] Hereinafter, an optical system 40 according to Example 1 of the present invention will be described. This example corresponds to Numerical Example 1 described later. In the optical system 40 according to this example, the description of the same configuration as the optical system 40 according to the above-mentioned embodiment will be omitted.

[0070] FIG. 3 is a diagram showing a cross section (YZ cross section) including the optical axis OAL of the optical system 40 according to this embodiment. In FIG. 3, the object side (+Z side) is on the left side, and the deflection unit side (-Z side) is on the right side, and a plurality of reflected light paths corresponding to a plurality of angles of the drive mirror 32 are shown. The optical system 40 according to this embodiment is a telescope composed of a plurality of lenses L111 to L118 having refractive power, and the entire system does not have refractive power. In this embodiment, all of the lens surfaces of the lenses L111 to L118 are spherical, which makes it easy to manufacture each lens. Also, in this embodiment, all of the lenses L111 to L118 are single lenses, which realizes good environmental resistance of the optical system 40.

[0071] As shown in FIG. 3, in this embodiment, the drive mirror 32 is shifted in the Y direction so that the central axis OAM of the drive mirror 32 does not coincide with the optical axis OAL of the optical system 40. The central axis OAM here coincides with the optical path of the chief ray Rc (not shown) at the central angle of view in the scanning range of the illumination light immediately after being deflected by the drive mirror 32. That is, the drive mirror 32 is disposed so that the incident point of the chief ray Rc on the deflection surface (the intersection point between the deflection surface and the optical path of the chief ray Rc) and the optical axis OAL are separated from each other. Furthermore, the scanning range of the drive mirror 32 is set so that the central axis OAM is inclined (non-parallel) with respect to the optical axis OAL. With these configurations, it is possible to reduce unnecessary light by preventing the chief ray Rc from being perpendicularly incident on each lens surface. Furthermore, in this embodiment, each lens is designed so that illumination light other than the chief ray Rc is also not perpendicularly incident on each lens surface, thereby making it possible to further reduce unnecessary light.

[0072] The front group 41 according to this embodiment is composed of a positive lens L111, a negative lens L112, a positive lens L113, and a negative lens L114, which are arranged in this order from the object side to the deflection unit side. This configuration allows the front group 41 to be simplified while excellently correcting spherical aberration and astigmatic difference. Specifically, spherical aberration is mainly corrected by a triplet group composed of the lenses L111 to L113 through which a light beam passes with a relatively large diameter, and astigmatic difference is mainly corrected by the negative lens L114 through which the difference in the passing position of the light beam according to the angle of view (degree of light beam separation) is relatively large.

[0073] The rear group 42 in this embodiment is composed of a positive lens L115, a positive lens L116, a positive lens L117, and a positive lens L118, which are arranged in this order from the object side to the deflection unit side. That is, the rear group 42 is composed of four positive lenses. This configuration realizes both compactness of the entire optical system 40 and good optical performance.

[0074] [Example 2] Hereinafter, an optical system 40 according to a second embodiment of the present invention will be described. This embodiment corresponds to Numerical Example 2 described later. In the optical system 40 according to this embodiment, the description of the same configuration as that of the optical system 40 according to the first embodiment described above will be omitted.

[0075] 4 is a diagram showing a cross section including an optical axis OAL of an optical system 40 according to this embodiment. The optical system 40 according to this embodiment is a telescope that is composed of lenses L121 to L129 and has no refractive power as a whole. The optical system 40 according to this embodiment is designed so that each illumination light beam is not perpendicularly incident on each lens surface, similar to the first embodiment.

[0076] The front group 41 according to this embodiment is composed of a positive lens L121, a negative lens L122, a positive lens L123, and a negative lens L124, which are arranged in this order from the object side to the deflection unit side. The rear group 42 according to this embodiment is composed of a positive lens L125, a positive lens L126, a positive lens L127, a positive lens L128, and a positive lens L129, which are arranged in this order from the object side to the deflection unit side. That is, the rear group 42 is composed of five positive lenses. Compared to the first embodiment, the number of positive lenses in the rear group 42 according to this embodiment is one more, so that the positive refractive power of the rear group 42 can be strengthened, and the positive refractive power of the front group LF41 can be strengthened accordingly, so that the optical system 40 can be made more compact.

[0077] [Example 3] Hereinafter, an optical system 40 according to a third embodiment of the present invention will be described. This embodiment corresponds to Numerical Example 3 described later. In the optical system 40 according to this embodiment, the description of the same configuration as that of the optical system 40 according to the first embodiment described above will be omitted.

[0078] 5 is a diagram showing a cross section including an optical axis OAL of an optical system 40 according to this embodiment. The optical system 40 according to this embodiment is a telescope that is composed of lenses L131 to L137 and has no refractive power as a whole. The optical system 40 according to this embodiment is designed so that each illumination light beam is not perpendicularly incident on each lens surface, similar to the first embodiment.

[0079] The front group 41 according to this embodiment is composed of a positive lens L131, a negative lens L132, a positive lens L133, and a negative lens L134, which are arranged in this order from the object side to the deflection unit side. The rear group 42 according to this embodiment is composed of a positive lens L135, a positive lens L136, and a positive lens L137, which are arranged in this order from the object side to the deflection unit side. That is, the rear group 42 is composed of three positive lenses. Compared to the first embodiment, the rear group 42 according to this embodiment has one less positive lens, so that the rear group 42 can be simplified further, and the distance between the front group 41 and the rear group 42 can be increased to more sufficiently secure the distance between the intermediate image 43 and the lens surfaces before and after it.

[0080] [Example 4] Hereinafter, an optical system 40 according to a fourth embodiment of the present invention will be described. This embodiment corresponds to Numerical Example 4 described later. In the optical system 40 according to this embodiment, the description of the same configuration as that of the optical system 40 according to the first embodiment described above will be omitted.

[0081] 6 is a diagram showing a cross section including an optical axis OAL of an optical system 40 according to this embodiment. The optical system 40 according to this embodiment is a telescope that is composed of lenses L141 to L149 and has no refractive power as a whole. The optical system 40 according to this embodiment is designed so that each illumination light beam is not perpendicularly incident on each lens surface, similar to the first embodiment.

[0082] The front group 41 in this embodiment is composed of a positive lens L141, a negative lens L142, a positive lens L143, a positive lens L144, and a negative lens L145, which are arranged in this order from the object side to the deflection unit side. The rear group 42 in this embodiment is composed of a positive lens L146, a positive lens L147, a positive lens L148, and a positive lens L149, which are arranged in this order from the object side to the deflection unit side. That is, the rear group 42 is composed of four positive lenses.

[0083] The optical magnification (β=2.0) of the optical system 40 according to this embodiment is lower than the optical magnification (β≧3.5) of the optical system 40 according to Examples 1 to 3. Therefore, the optical system 40 according to this embodiment is more suitable for detecting an object 100 at a short distance than the optical systems 40 according to Examples 1 to 3. Even in this configuration, by appropriately designing the rear group 42, it is possible to achieve both a compact optical system 40 and good optical performance.

[0084] [Numerical Example] Numerical Examples 1 to 4 of optical system 40 corresponding to the above-mentioned Examples 1 to 4 are shown below. In the surface data, the surface number indicates the order of the lens surface when counted from the object side, r indicates the radius of curvature of the lens surface [mm], and d indicates the distance on the optical axis between adjacent lens surfaces [mm]. nd indicates the refractive index for the d-line (wavelength 587.6 nm) of the medium between adjacent lens surfaces, and νd indicates the Abbe number based on the d-line of the medium between adjacent lens surfaces.

[0085] In the various data, the optical magnification β indicates the magnification of the optical system 40 (when illuminated), the entrance pupil diameter indicates the diameter [mm] of the entrance pupil of the optical system 40 when the target object 100 side is the incident side (when receiving light), the shift amount indicates the distance [mm] between the central axis OAM and the optical axis OAL on the YZ cross section, and the tilt amount indicates the angle [degrees] between the central axis OAM and the optical axis OAL on the YZ cross section.

[0086] The light ray angle data indicates the angles [degrees] between the optical axis OAL and the chief ray (central ray) and marginal rays (upper ray and lower ray) of the light reflected from the object 100 illuminated by the illumination light at the central angle of view in the scanning range of the drive mirror 32. Here, the data indicates the angle of each ray immediately before it enters the lens surface closest to the object in the optical system 40, the angle of each ray immediately after it exits from the lens surface closest to the deflector in the optical system 40, and the difference between them.

[0087] (Numerical Example 1) Surface Data Lens surface number rd nd νd L111 1 41.107 6.30 2.001 29.139 2 119.720 10.91 L112 3 -60.247 2.00 1.516 64.141 4 1918.293 25.88 L113 5 -654.854 3.20 2.001 29.139 6 -55.770 15.63 L114 7 -17.579 1.30 1.516 64.141 8 -46.620 28.47 L115 9 -495.348 3.10 2.001 29.139 10 -68.368 4.50 L116 11 82.093 3.50 2.001 29.139 12 -1551.590 0.30 L117 13 35.125 4.10 2.001 29.139 14 67.954 0.30 L118 15 23.198 3.80 2.001 29.139 16 31.108 Various data Optical magnification β 3.8 Entrance pupil diameter [mm] 14.8 Shift amount [mm] 4.1 Tilt amount [degrees] 9.6 Beam Angle Data Object side Deflector side Difference Upper ray 0.041 0.050 0.009 Chief ray 0.035 0.000 -0.035 Lower ray 0.028 -0.052 -0.080

[0088] (Numerical Example 2) Surface Data Lens surface number rd nd νd L121 1 39.383 7.25 2.001 29.139 2 202.116 9.86 L122 3 -52.981 2.00 1.516 64.141 4 -401.197 24.46 L123 5 -228.481 3.16 2.001 29.139 6 -40.023 10.55 L124 7 -13.435 1.30 1.516 64.141 8 363.802 13.05 L125 9 -28.664 2.80 2.001 29.139 10 -26.765 5.12 L126 11 -343.608 3.38 2.001 29.139 12 -63.244 0.30 L127 13 85.978 3.54 2.001 29.139 14 -523.346 0.30 L128 15 34.916 4.10 2.001 29.139 16 70.744 0.30 L129 17 23.759 3.72 2.001 29.139 18 32.157 Various data Optical magnification β 3.5 Entrance pupil diameter [mm] 14.8 Shift amount [mm] 4.3 Tilt amount [degrees] 9.4 Beam Angle Data Object side Deflector side Difference Upper ray 0.039 0.069 0.030 Chief ray 0.033 0.000 -0.033 Lower ray 0.028 0.103 0.075

[0089] (Numerical Example 3) Surface Data Lens surface number rd nd νd L131 1 55.792 4.65 2.001 29.139 2 199.307 8.49 L132 3 -110.557 2.00 1.516 64.141 4 2336.958 63.19 L133 5 -717.748 2.60 2.001 29.139 6 -57.176 3.76 L134 7 -27.455 1.30 1.516 64.141 8 -46.650 44.86 L135 11 73.363 3.67 2.001 29.139 12 10121.070 0.30 L136 13 34.226 4.19 2.001 29.139 14 64.311 0.30 L137 15 24.042 3.75 2.001 29.139 16 31.557 Various data Optical magnification β 3.5 Entrance pupil diameter [mm] 14.8 Shift amount [mm] 4.1 Tilt amount [degrees] 9.5 Beam Angle Data Object side Deflector side Difference Upper ray 0.038 -0.014 -0.052 Chief ray 0.032 0.000 -0.032 Lower ray 0.026 0.068 0.042

[0090] (Numerical Example 4) Surface Data Lens surface number rd nd νd L141 1 34.971 5.10 2.001 29.139 2 153.153 9.60 L142 3 -31.435 3.50 1.516 64.141 4 -157.459 12.40 L143 5 -131.553 4.60 1.516 64.141 6 -32.263 1.70 L144 7 179.847 3.30 2.001 29.139 8 -85.115 8.30 L145 9 -19.306 6.50 1.516 64.141 10 -31.578 21.60 L146 11 -290.125 3.40 2.001 29.139 12 -69.894 5.00 L147 13 133.185 3.60 2.001 29.139 14 -361.726 0.30 L148 15 50.144 4.20 2.001 29.139 16 112.513 0.30 L149 17 25.536 5.00 2.001 29.139 18 36.897 Various data Optical magnification β 2.0 Entrance pupil diameter [mm] 14.8 Shift amount [mm] 6.0 Tilt amount [degrees] 15.6 Beam Angle Data Object side Deflector side Difference Upper ray 0.080 0.138 0.058 Chief ray 0.073 0.000 -0.073 Lower ray 0.066 -0.226 -0.292

[0091] Various numerical values ​​in Numerical Examples 1 to 4 are shown in Table 1. As shown in Table 1, the optical systems 40 according to Numerical Examples 1 to 4 all satisfy the above-mentioned conditional expressions (1) to (7).

[0092] [Table 1]

[0093] [In-vehicle system] Fig. 7 is a configuration diagram of an optical device 1 according to this embodiment and an in-vehicle system (driving support device) 1000 including the optical device 1. The in-vehicle system 1000 is held by a movable moving body (moving device) such as an automobile (vehicle), and is a device for supporting driving (piloting) of the vehicle based on distance information of objects such as obstacles and pedestrians around the vehicle acquired by the optical device 1. Fig. 8 is a schematic diagram of a vehicle 500 including the in-vehicle system 1000. Fig. 8 shows a case where the distance measurement range (detection range) of the optical device 1 is set in front of the vehicle 500, but the distance measurement range may be set to the rear or side of the vehicle 500.

[0094] 7, the in-vehicle system 1000 includes an optical device 1, a vehicle information acquisition device 200, a control device (ECU: electronic control unit) 300, and a warning device (warning section) 400. In the in-vehicle system 1000, a control section 60 included in the optical device 1 has functions as a distance acquisition section (acquisition section) and a collision determination section (determination section). However, if necessary, the in-vehicle system 1000 may be provided with a distance acquisition section and a collision determination section separate from the control section 60, or each of them may be provided outside the optical device 1 (for example, inside the vehicle 500). Alternatively, the control device 300 may be used as the control section 60.

[0095] 9 is a flowchart showing an example of the operation of the in-vehicle system 1000 according to this embodiment. The operation of the in-vehicle system 1000 will be described below with reference to this flowchart.

[0096] First, in step S1, the light source unit 10 of the optical device 1 illuminates an object around the vehicle, and the light receiving unit 40 receives the reflected light from the object, and based on the signal output by the light receiving unit 40, the control unit 60 acquires distance information of the object. In step S2, the vehicle information acquisition device 200 acquires vehicle information including the vehicle speed, yaw rate, steering angle, etc. In step S3, the control unit 60 uses the distance information acquired in step S1 and the vehicle information acquired in step S2 to determine whether the distance to the object is within a preset distance range.

[0097] This makes it possible to determine whether or not an object exists within a set distance around the vehicle, and to determine the possibility of a collision between the vehicle and the object. Steps S1 and S2 may be performed in the reverse order to that described above, or may be performed in parallel with each other. If an object exists within the set distance, the control unit 60 determines that there is a "possibility of collision" (step S4), and if there is no object within the set distance, it determines that there is no "possibility of collision" (step S5).

[0098] Next, when the control unit 60 judges that there is a "possibility of collision", it notifies (transmits) the judgment result to the control device 300 and the warning device 400. At this time, the control device 300 controls the vehicle based on the judgment result of the control unit 60 (step S6), and the warning device 400 issues a warning to the user (driver) of the vehicle based on the judgment result of the control unit 60 (step S7). Note that the notification of the judgment result may be sent to at least one of the control device 300 and the warning device 400.

[0099] The control device 300 performs control of the vehicle, such as applying the brakes, releasing the accelerator, turning the steering wheel, generating a control signal to generate a braking force on each wheel and suppressing the output of the engine or motor, etc. The warning device 400 warns the driver, for example, by issuing a warning sound, displaying warning information on the screen of a car navigation system or the like, or applying vibrations to the seat belt or steering wheel.

[0100] As described above, according to the in-vehicle system 1000 of this embodiment, the above-mentioned processing can detect and measure the distance to an object, and it becomes possible to avoid a collision between the vehicle and the object. In particular, by applying the optical device 1 according to each of the above-mentioned embodiments to the in-vehicle system 1000, it is possible to realize high distance measurement accuracy, and therefore it becomes possible to detect an object and judge a collision with a high degree of accuracy.

[0101] In this embodiment, the in-vehicle system 1000 is applied to driving assistance (collision damage reduction), but the application is not limited thereto, and the in-vehicle system 1000 may be applied to cruise control (including full-speed following function) and automatic driving. The in-vehicle system 1000 is not limited to vehicles such as automobiles, but may be applied to moving bodies such as ships, aircraft, and industrial robots. The in-vehicle system 1000 is not limited to moving bodies, but may be applied to various devices that use object recognition, such as intelligent transport systems (ITS) and surveillance systems.

[0102] Furthermore, the in-vehicle system 1000 and the moving device 500 may be provided with a notification device (notification unit) for notifying the manufacturer of the in-vehicle system or the dealer of the moving device, etc., of the collision of the moving device 500 with an obstacle. For example, the notification device may be one that transmits information (collision information) related to the collision between the moving device 500 and an obstacle to a preset external notification destination by e-mail or the like.

[0103] In this way, by adopting a configuration in which the notification device automatically notifies collision information, it is possible to promptly take measures such as inspection and repair after a collision occurs. The destination of the collision information may be an insurance company, a medical institution, the police, or any other party set by the user. The notification device may be configured to notify the destination of not only collision information but also failure information of each part and consumption information of consumables. The detection of the presence or absence of a collision may be performed using distance information acquired based on the output from the above-mentioned light receiving unit 2, or may be performed by another detection unit (sensor).

[0104] [Variations] Although the preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various combinations, modifications, and changes are possible within the scope of the gist of the present invention.

[0105] For example, the optical system 40 according to each embodiment does not have to be a telescope that reduces the diameter of the reflected light from the object 100, but may be an optical system that expands the diameter of the reflected light from the object as necessary. Also, the optical system 40 does not have to be an afocal system, but may be an optical system having refractive power in its entirety as necessary.

[0106] In addition, although each member is integrated (held integrally) in each embodiment, each member may be configured as a separate body if necessary. For example, the light source unit 10 and the light receiving unit 50 may be detachable from the light guiding unit 20 or the deflection unit 30. In that case, a connection part (joint part) for connecting the members to each other may be provided on a holding member (housing) that holds each member. In this case, in order to improve the accuracy of positioning the light source unit 10 and the light guiding unit 20, the diaphragm 13 may be provided in the light guiding unit 20 and held by a holding member common to the light guiding member. [Explanation of symbols]

[0107] 1 Optical device 11 Light source 20 Light guide section 30 Deflection section 40 Optical system 41 Front group 42 Rear group 43 Intermediate image 53 Photodetector 100 Objects

Claims

1. a deflection unit that deflects illumination light from a light source to scan an object and also deflects reflected light from the object; a light guiding section that guides the illumination light from the light source to the deflection section and guides the reflected light from the deflection section to a light receiving element; an optical system that guides the illumination light from the deflection unit to the object and guides the reflected light from the object to the deflection unit, the optical system includes a front group made of lenses that form an intermediate image of the object and are disposed closer to the object side than the intermediate image, and a rear group made of lenses that are disposed closer to the deflection unit than the intermediate image, the front group is composed of two or more positive lenses and two or more negative lenses, the rear group is composed of three or more and five or less positive lenses, Let ff be the focal length of the front group and fr be the focal length of the rear group. 1.8<ff / fr<8.0 An optical device characterized in that the following condition is satisfied:

2. The first lens in the rear group closest to the deflection unit has a meniscus shape with a concave surface facing the deflection unit side. When the radius of curvature of the lens surface of the first lens on the object side is R1B1 and the radius of curvature of the lens surface on the deflection unit side is R2B1, -12.0<(R1B1+R2B1) / (R1B1-R2B1)<-2.0 2. The optical device according to claim 1, wherein the following condition is satisfied:

3. The second lens in the rear group adjacent to the lens closest to the deflection unit has a meniscus shape with a concave surface facing the deflection unit side, and when the radius of curvature of the lens surface of the second lens on the object side is R1B2 and the radius of curvature of the lens surface on the deflection unit side is R2B2, -6.0<(R1B2+R2B2) / (R1B2-R2B2)<-0.5 3. The optical device according to claim 1, wherein the following condition is satisfied:

4. A deflection unit that deflects illumination light from a light source to scan an object and also deflects reflected light from the object; a light guiding section that guides the illumination light from the light source to the deflection section and guides the reflected light from the deflection section to a light receiving element; an optical system that guides the illumination light from the deflection unit to the object and guides the reflected light from the object to the deflection unit, the optical system includes a front group made of lenses that form an intermediate image of the object and are disposed closer to the object side than the intermediate image, and a rear group made of lenses that are disposed closer to the deflection unit than the intermediate image, the rear group is composed of three or more and five or less positive lenses, a first lens in the rear group closest to the deflection unit and a second lens adjacent to the first lens each have a meniscus shape with a concave surface facing the deflection unit, Regarding the first lens, the radius of curvature of the lens surface on the object side is R1B1, the radius of curvature of the lens surface on the deflection unit side is R2B1, and regarding the second lens, the radius of curvature of the lens surface on the object side is R1B2, and the radius of curvature of the lens surface on the deflection unit side is R2B2, -12.0<(R1B1+R2B1) / (R1B1-R2B1)<-2.0 -6.0<(R1B2+R2B2) / (R1B2-R2B2)<-0.5 An optical device characterized in that the following condition is satisfied:

5. When the focal length of the front group is ff and the focal length of the rear group is fr, 1.8<ff / fr<8.0 5. The optical device according to claim 4, wherein the following condition is satisfied:

6. Let Lr be the distance on the optical axis from the lens surface in the rear group closest to the object side to the lens surface closest to the deflection unit, and Li be the distance on the optical axis from the lens surface in the front group closest to the deflection unit to the lens surface in the rear group closest to the object side, 0.1<Lr / Li<4.0 6. The optical device according to claim 1, wherein the following condition is satisfied:

7. When the average value of the refractive index of the positive lens in the optical system with respect to the d line is NPave, and the average value of the refractive index of the negative lens in the optical system with respect to the d line is NNave, 1.2<NPave / NNave<1.5 7. The optical device according to claim 1, wherein the following condition is satisfied: 1.0<x<x1 / x2 / ...

8. The front group has one or more positive lenses and one or more negative lenses, and the average focal length of the positive lenses in the front group is denoted by ffPave and the average focal length of the negative lenses in the front group is denoted by ffNave. -1.0<ffPave / ffNave<-0.2 8. The optical device according to claim 1, wherein the following condition is satisfied:

9. 9. The optical device according to claim 1, wherein the front group comprises at least one positive lens, at least one negative lens, at least one positive lens, and at least one negative lens, arranged in that order from the object side to the deflection unit side.

10. Let fr be the focal length of the rear group, and Lr be the distance on the optical axis from the lens surface in the rear group closest to the object side to the lens surface closest to the deflection unit, 0.65<fr / Lr<2.20 10. The optical device according to claim 1, wherein the following condition is satisfied:

11. 11. The optical device according to claim 1, wherein all lenses in the optical system are spaced apart from one another in the optical axis direction.

12. An optical device as described in any one of claims 1 to 11, characterized in that, for each of a plurality of lens surfaces possessed by the optical system, the normal to a light ray contained in the illumination light from the deflection section at the point of incidence and the light ray are non-parallel to each other.

13. The optical device according to any one of claims 1 to 12, characterized in that the deflection unit is arranged so that the optical path of the chief ray of the illumination light at a central angle of view in the scanning range of the deflection unit does not coincide with the optical axis of the optical system.

14. 14. The optical device according to claim 1, wherein the optical system increases a diameter of the illumination light from the deflection unit and reduces a diameter of the reflected light from the object.

15. 15. The optical device according to claim 1, wherein the optical system has no refractive power as a whole.

16. 16. An in-vehicle system comprising the optical device according to claim 1, and determining a possibility of a collision between a vehicle and an object based on distance information of the object obtained by the optical device.

17. 17. The in-vehicle system according to claim 16, further comprising a control device that outputs a control signal for generating a braking force on the vehicle when it is determined that there is a possibility of a collision between the vehicle and the object.

18. 18. The in-vehicle system according to claim 16, further comprising a warning device that issues a warning to a driver of the vehicle when it is determined that there is a possibility of a collision between the vehicle and the object.

19. 19. The in-vehicle system according to claim 16, further comprising a notification device that notifies an outside party of information relating to a collision between the vehicle and the object.

20. A moving device comprising the optical device according to claim 1 , the moving device being capable of holding and moving the optical device.

21. 21. The moving device according to claim 20, further comprising a determination unit that determines a possibility of a collision with the object based on distance information of the object obtained by the optical device.

22. 22. The moving device according to claim 21, further comprising a control unit that outputs a control signal for controlling movement when it is determined that there is a possibility of a collision with the object.

23. 23. The moving device according to claim 21, further comprising a warning unit that issues a warning to a driver of the moving device when it is determined that there is a possibility of a collision with the object.

24. 24. The mobile device according to claim 21, further comprising a notification unit that notifies an outside party of information regarding the collision with the object.

Images