WO2020203129A1 - Dispositif optique de balayage - Google Patents

Dispositif optique de balayage Download PDF

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Publication number
WO2020203129A1
WO2020203129A1 PCT/JP2020/010617 JP2020010617W WO2020203129A1 WO 2020203129 A1 WO2020203129 A1 WO 2020203129A1 JP 2020010617 W JP2020010617 W JP 2020010617W WO 2020203129 A1 WO2020203129 A1 WO 2020203129A1
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WO
WIPO (PCT)
Prior art keywords
lens
light
mirror
focal length
optical device
Prior art date
Application number
PCT/JP2020/010617
Other languages
English (en)
Japanese (ja)
Inventor
武彦 酒井
鈴木　隆史
Original Assignee
日本電産コパル電子株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日本電産コパル電子株式会社 filed Critical 日本電産コパル電子株式会社
Publication of WO2020203129A1 publication Critical patent/WO2020203129A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/12—Scanning systems using multifaceted mirrors

Definitions

  • An embodiment of the present invention relates to a scanning optical device applied to, for example, a three-dimensional ranging image sensor.
  • 3D-LiDER Light Detection and Ringing
  • This sensor measures the distance to an object by, for example, scanning a pulsed laser beam with a polygon mirror and detecting the reflected light from the object.
  • the polygon mirror has a pyramidal trapezoidal shape and has a plurality of reflecting surfaces. The inclination angle of each reflecting surface in the direction along the rotation axis is changed. Therefore, the laser beam applied to the reflecting surface of the rotating polygon mirror is reflected in the horizontal direction and the vertical direction and is applied to the detection region (see, for example, Patent Document 1 and Patent Document 2).
  • JP-A-11-84006 Japanese Unexamined Patent Publication No. 2016-70974 Japanese Patent Application Laid-Open No. 1-100491
  • the first stage is scanned in the Y-axis direction and the second stage is scanned in the X-axis direction. It is necessary to increase the reflective surface of the scanner that scans the direction. Specifically, when scanning the X-axis with a polygon scanner, it is necessary to increase the thickness of the polygon mirror in the Y-axis direction according to the scanning angle. Therefore, the polygon mirror becomes large and the manufacturing cost increases.
  • An embodiment of the present invention provides a scanning optical device capable of obtaining a necessary and sufficient scanning angle by using a small mirror.
  • the scanning optical device of the present embodiment has a first mirror that scans the light from the light source in the first direction within a range of a certain angle, and the first focal point, and the light from the first mirror is the first.
  • a first lens that leads to a focal point a condensing means that has a second focal point and whose second focal point coincides with the first focal point, and a second condensing means that intersects the first direction with light from the condensing means. It includes a second mirror that scans in the direction.
  • FIG. 1 shows the scanning optical device 10 according to the first embodiment.
  • the scanning optical device 10 includes, for example, a laser diode 11 as a light source, a collimating lens 12, a galvano scanner (first mirror) 13 as a scanning means in the Y-axis direction, a first lens 14, a second lens 15, for example, an X-axis direction.
  • a polygon scanner (second mirror) 16 as scanning means, a beam splitter 17, and a photodiode 18 as a light receiving unit are provided.
  • the laser diode 11 generates, for example, a pulsed laser beam (hereinafter, also simply referred to as light).
  • a pulsed laser beam hereinafter, also simply referred to as light.
  • the collimating lens 12 uses the light generated from the laser diode 11 as parallel light.
  • the galvano scanner 13 includes a mirror and a drive unit (not shown) that reciprocates the mirror within a range of a predetermined rotation angle ⁇ 1.
  • the galvano scanner 13 scans parallel light from the collimating lens 12 in the Y-axis direction within a rotation angle ⁇ 1.
  • the angle of incidence of light from the collimating lens 12 to the galvano scanner 13 is not shown.
  • the angle of incidence of light from the collimating lens 12 onto the galvano scanner 13 is determined by the position of the focal point of the second lens 15 and the position of the focal point of the light that passes through the first lens 14 and is scanned in the Y-axis direction.
  • the scanning means in the Y-axis direction is not limited to the galvano scanner 13, and for example, a resonant scanner or a MEMS scanner can be applied.
  • the first lens 14 is, for example, a condensing lens composed of an achromatic lens or an aspherical lens, and has a focal length (first focal length) f1.
  • the focal length f1 of the first lens 14 is adjusted based on the magnification of the scanning angle ⁇ 2 in the Y-axis direction with respect to the rotation angle ⁇ 1 of the galvano scanner 13.
  • the relationship between the angle of ⁇ 2 and ⁇ 1 is such that when the height A of the focal position of the first lens 14 (distance from the center of the lens) A and the height A of the focal position of the second lens 15 match.
  • the angular magnification is determined depending on the focal length of each lens.
  • the galvano scanner 13 is arranged, for example, at the position of the focal length f1 of the first lens 14, and the parallel light scanned in the Y-axis direction by the galvano scanner 13 is focused on the other focal length of the first lens 14.
  • the position of the galvano scanner 13 with respect to the first lens 14 is not limited to the position of the focal length f1 of the first lens 14, and it is sufficient that parallel light can be incident on the first lens 14. Therefore, the position of the galvano scanner 13 may be the focal length f1 or more.
  • the second lens 15 as the condensing means is, for example, a condensing lens composed of an achromatic lens or an aspherical lens, and has a focal length (second focal length) f2.
  • One focal plane of the second lens 15 (a plane passing through the focal point and perpendicular to the optical axis) coincides with the focal plane of the first lens 14, and a polygon scanner 16 is placed on, for example, the other focal plane of the second lens 15.
  • the polygon mirror 16a to be formed is arranged. Therefore, the light from the focal point of the first lens 14 is focused on the central portion of the polygon mirror 16a as parallel light by the second lens 15.
  • the positional relationship between the mirror surface of the polygon mirror 16a constituting the polygon scanner 16 and the second lens 15 is adjusted by the focal length f2 of the second lens 15, and the light from the second lens 15 is the mirror surface of the polygon mirror 16a. Any position may be used as long as it is focused in the center of. Therefore, the position of the polygon mirror 16a may be equal to or greater than the focal length f2 of the second lens 15.
  • the focal length f2 of the second lens 15 may be different from or the same as the focal length f1 of the first lens 14.
  • the focal planes of the first lens 14 and the second lens 15 are aligned with each other, but it is sufficient that the focal points of the first lens 14 and the focal points of the second lens 15 are aligned.
  • the condensing means is not limited to the second lens 15 as a condensing lens, and for example, an elliptical mirror or a parabolic mirror can be applied. In this case, if the focal point of the elliptical mirror or parabolic mirror is aligned with the focal plane of the first lens 14, the reflected light from the elliptical mirror or parabolic mirror is focused on the center of the mirror surface of the polygon mirror 16a. Good.
  • the polygon scanner 16 includes, for example, a polygon mirror 16a having five mirrors and a drive unit (not shown) that rotates the polygon mirror 16a in a certain direction.
  • the polygon mirror 16a is not limited to a pentagonal prism, and may be a tetragonal prism or a hexagonal prism.
  • the light guided to the polygon mirror 16a by the second lens 15 is scanned in the X-axis direction as the polygon mirror 16a rotates. Therefore, the scanning space is raster-scanned by the laser beam in the X-axis direction and the Y-axis direction.
  • the light reflected from the object in the scanning space is guided to the polygon mirror 16a, and the light reflected by the polygon mirror 16a is guided in the order of the second lens 15, the first lens 14, and the galvano scanner 13.
  • the light reflected by the galvano scanner 13 is guided to the photodiode 18 by the beam splitter 17 and the third lens 19 as a condenser lens, and is converted into an electric signal by the photodiode 18.
  • the beam splitter 17 is arranged between the galvano scanner 13 and the collimating lens 12, but the present invention is not limited to this, and the beam splitter 17 may be arranged between the collimating lens 12 and the laser diode 11.
  • the separation means for separating the light from the laser diode 11 and the light from the galvano scanner 13 is not limited to the beam splitter 17, and has, for example, an opening through which the light from the laser diode 11 passes, and the galvano scanner 13 has an opening. It may be a mirror that reflects the light from the photodiode 18 in the direction of the photodiode 18.
  • the light receiving unit is not limited to the photodiode 18, but may be a line sensor or an image sensor.
  • the third lens 19 for condensing can be omitted.
  • the size of the light receiving unit becomes small, so that a third lens 19 for condensing light is required.
  • the light from the second lens 15 is focused on the central portion of the polygon mirror 16a constituting the polygon scanner 16. Therefore, the thickness T1 of the polygon mirror 16 can be reduced, and the necessary and sufficient scanning angle in the Y-axis direction can be obtained by the thin polygon mirror 16a.
  • the light from the galvano scanner 13 spreads in the Y-axis direction according to a set scanning angle, for example, ⁇ 2. Therefore, in order to satisfy the scanning angle ⁇ 2 and reduce the thickness T2 of the polygon mirror 16a, it is necessary to shorten the distance L between the polygon mirror 16a and the galvano scanner 13. However, since it is necessary to prevent the polygon mirror 16a from interfering with the galvano scanner 13, there is a limit to shortening the distance L. Therefore, in the case of the configuration of the comparative example, it is difficult to secure the scanning angle ⁇ 2 in the Y-axis direction and reduce the thickness of the polygon mirror 16a as in the first embodiment.
  • the area of one mirror is small because the thickness T1 of the polygon mirror 16a is thinner than the thickness T2 of the comparative example. Therefore, since the mirror can be easily processed, the polygon mirror 16a can be easily manufactured.
  • the thin polygon mirror 16a is lightweight, it is possible to reduce the size of the motor (not shown) that drives the polygon mirror 16a. Therefore, the polygon scanner 16 can be miniaturized, and the manufacturing cost can be reduced.
  • the size of the galvano mirror can be reduced. Therefore, even when a mirror other than the polygon scanner 16 is used, the same effect as described above can be obtained.
  • FIG. 2 shows the scanning optical device 10 according to the second embodiment.
  • the same components as those in the first embodiment operate in the same manner as in the first embodiment and can be deformed in the same manner as in the first embodiment.
  • one focal point of the second lens 15 is aligned with the focal point of the first lens 14.
  • the first lens 14 is omitted, and the collimating lens 12a has a condensing function.
  • the light from the laser diode 11 is incident on the collimating lens 12a.
  • the collimating lens 12a has a focusing function and has a focal length (third focal length) f3.
  • the light from the collimating lens 12a is scanned by the galvano scanner 13 in an angle range of ⁇ 1 in the Y-axis direction, for example. Therefore, the focal point of the light from the collimating lens 12a is scanned by the galvano scanner 13 in the angle range of ⁇ 1 in the Y-axis direction.
  • One focal plane of the second lens 15 coincides with the focal plane of the collimating lens 12a. Therefore, the light from the laser diode 11 is guided to one focal plane of the second lens 15 via the collimating lens 12a and the galvano scanner 13.
  • the angle of incidence of light from the collimating lens 12a to the galvano scanner 13 is not shown.
  • the incident angle ⁇ 2 from the collimating lens 12a to the mirror surface of the polygon mirror 16a is determined by the focal position on the incident side of the second lens 15 and the scanning angle ⁇ 1 of the galvano scanner 13 scanned in the Y-axis direction.
  • a polygon mirror 16a constituting the polygon scanner 16 is arranged on the other focal plane of the second lens 15. Therefore, the light guided by the galvano scanner 13 to the focal plane of the collimating lens 12a and one of the focal planes of the second lens 15 is focused by the second lens 15 as parallel light on the central portion of the polygon mirror 16a.
  • the position of the mirror surface of the polygon mirror 16a is optimally located slightly farther than the focal length f2 of the second lens 15 depending on the maximum angle of ⁇ 1.
  • the light guided by the polygon mirror 16a is scanned by the polygon mirror 16a in the X-axis direction. Therefore, the scanning space is raster-scanned by the laser beam in the X-axis direction and the Y-axis direction.
  • the light reflected from the object in the scanning space is guided to the polygon mirror 16a, and the light reflected by the polygon mirror 16a is guided to the second lens 15 and the galvano scanner 13 in this order.
  • the light reflected by the galvano scanner 13 is guided to the photodiode 18 by the beam splitter 17 and the third lens 19, and is converted into an electric signal by the photodiode 18.
  • the light from the galvano scanner 13 can be focused on the central portion of the polygon mirror 16a by the second lens 15. Therefore, the thickness of the polygon mirror 16a can be reduced as in the first embodiment.
  • the first lens 14 of the first embodiment can be omitted. Therefore, the optical path length can be shortened, and the scanning optical device 10 can be miniaturized.
  • the first lens 14 can be omitted, the number of parts can be reduced and the manufacturing cost can be reduced.
  • first and second embodiments have described the scanning optical device applied to the LiDER, the first and second embodiments are not limited to the LiDER and are applied to other fields of optical scanning. It is possible to do.
  • the present invention is not limited to each of the above embodiments as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof.
  • various inventions can be formed by appropriately combining the plurality of components disclosed in each of the above embodiments. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate.

Abstract

Un miroir 13 déplace la lumière provenant d'une source de lumière 11 dans une première direction à l'intérieur d'une plage d'angles fixe. Une première lentille 14 a un premier point focal et guide la lumière du miroir vers le premier point focal. Un moyen de convergence de lumière 15 a un second point focal qui correspond au premier point focal. Un second miroir 16 déplace la lumière provenant du moyen de convergence dans une seconde direction qui croise la première direction.
PCT/JP2020/010617 2019-04-01 2020-03-11 Dispositif optique de balayage WO2020203129A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019-070091 2019-04-01
JP2019070091A JP2020170049A (ja) 2019-04-01 2019-04-01 走査光学装置

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WO2020203129A1 true WO2020203129A1 (fr) 2020-10-08

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5417745U (fr) * 1978-06-21 1979-02-05
JPH01100491A (ja) * 1987-10-14 1989-04-18 Matsushita Electric Ind Co Ltd レーザレーダ画像形成装置
US5760951A (en) * 1992-09-01 1998-06-02 Arthur Edward Dixon Apparatus and method for scanning laser imaging of macroscopic samples
JP2011099816A (ja) * 2009-11-09 2011-05-19 Sony Corp 集光レンズ及び３次元距離測定装置
JP2014219330A (ja) * 2013-05-09 2014-11-20 国立大学法人東京大学 計測システム

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5417745U (fr) * 1978-06-21 1979-02-05
JPH01100491A (ja) * 1987-10-14 1989-04-18 Matsushita Electric Ind Co Ltd レーザレーダ画像形成装置
US5760951A (en) * 1992-09-01 1998-06-02 Arthur Edward Dixon Apparatus and method for scanning laser imaging of macroscopic samples
JP2011099816A (ja) * 2009-11-09 2011-05-19 Sony Corp 集光レンズ及び３次元距離測定装置
JP2014219330A (ja) * 2013-05-09 2014-11-20 国立大学法人東京大学 計測システム

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