JP6424364B2 - Laser range finder, three-dimensional scanner and laser beam deflection apparatus - Google Patents

Description

  The present invention relates to a laser range finder, a three-dimensional scanner and a laser beam deflection apparatus, and more particularly to a laser range finder, a three-dimensional scanner and a laser beam deflection apparatus using, for example, a laser beam.

  An example of the background art is disclosed in Patent Document 1. In the scanning type distance measuring device in this patent document, the measurement light output from the light emitting unit inside is reflected by the deflecting mirror that rotates integrally with the rotating body. For example, when the scanning type distance measuring device is attached to the automatic conveyance vehicle, it is scanned along a locus perpendicular to the traveling direction forward in the traveling direction.

Patent documents 1: Unexamined-Japanese-Patent No. 2010-256179 [G01S 17/93, G01C 3/06, G05D 1/02, B65G 1/00, G01S 17/42]

  However, in the scanning type distance measuring apparatus of Patent Document 1, when the scanning range is wide and the scanning period is short, vibration and noise become large, and a large amount of power is consumed. In particular, in consideration of noise and power consumption when, for example, three-dimensional scanning is performed, there is a problem that it takes time to acquire distance data of the entire area.

  Also, in order to realize three-dimensional scanning at high speed, a sensor equipped with a large number of laser distance measuring units has been developed, but this sensor is expensive. Therefore, for example, in the field of an autonomous mobile robot using a scanning distance measuring apparatus, a sensor that can acquire a wide range of data in a short time and is low in cost is required.

  Therefore, the main object of the present invention is to provide a novel laser range finder, a three-dimensional scanner and a laser beam deflection apparatus.

  Another object of the present invention is to provide a laser range finder, a three-dimensional scanner, and a laser beam deflection apparatus capable of scanning a laser beam without using a mechanical operation unit.

  The present invention adopts the following configuration in order to solve the above-mentioned problems. The reference numerals in the parentheses, the supplementary explanation, and the like indicate correspondences with the embodiments described to help the understanding of the present invention, and the present invention is not limited at all.

  According to a first aspect of the present invention, each of the first and second surfaces is made of an anisotropic optical crystal, has a vertical first surface and a tilted second surface, and from the second surface according to the polarization direction of the laser light incident from the first surface. At least one prism, which emits a second laser beam different from the optical path of the first laser beam or the first laser beam, is disposed sandwiching the prism, and rotates the polarization direction of the incident laser beam by 90 degrees, At least one pair of polarization-rotating elements that can be controlled not to rotate, a pair of polarization filters provided respectively on the outside of the outermost polarization-rotating element and passing laser light of a predetermined polarization direction component, and a prism The laser range finder includes a light emitting and receiving unit that emits a laser beam to the polarizing filter on the first surface side and receives the reflected laser light that has passed through the polarizing filter on the second surface side of the prism.

  In the first invention, at least one of the prisms (18) in the laser range finder (10: a reference symbol exemplifying the corresponding part in the embodiment, hereinafter the same) is, for example, an anisotropic optical crystal such as calcite. And has a vertical first surface and an inclined second surface. In addition, since such a prism is birefringent, depending on the polarization direction of the laser beam incident from the first surface, for example, the first laser beam also called an ordinary ray or the second laser beam also called an extraordinary ray is Emit from. At least one pair of polarization rotation elements (20) is installed such that, for example, when there are two prisms, the two prisms are sandwiched between the three polarization rotation elements. Further, each polarization rotation element can control whether the polarization direction of the incident laser light is rotated 90 degrees or not. A pair of polarizing filters (22) are respectively provided on the outside of the outermost polarization rotation element. For example, one polarizing filter (22a) provided on the light emitting and receiving unit side transmits laser light of a predetermined polarization component, that is, laser light polarized in a certain direction. The other polarizing filter (22b) passes the reflected laser light polarized in the same direction as the laser light emitted to the outside. The light emitting and receiving unit (14) projects the laser light to the polarizing filter on the first surface side of the prism, for example, substantially coaxially, and receives the reflected laser light having passed through the polarizing filter on the second surface side of the prism.

  According to the first invention, it is possible to scan laser light at a plurality of angles without using a mechanical operation unit.

  Further, the laser range finder according to the first aspect of the present invention has low noise / low vibration, low power consumption and high durability / weatherability etc. with respect to a laser beam deflection apparatus having a mechanical rotating part and a vibrating part. Play an effect.

  A second invention is according to the first invention, further comprising a control unit for controlling on / off of the polarization rotation element, and the polarization rotation element is a polarization of the laser light incident when it is turned on by the control unit. The direction is rotated 90 degrees, and when it is turned off by the control unit, the polarization direction of the incident laser light is not rotated 90 degrees.

  In the second invention, the control unit (12, 24) includes, for example, a processor (12) for controlling the entire system, and a control unit corresponding to each polarization rotation element, and controls on / off of the polarization rotation element. The polarization rotation element rotates the polarization direction of the incident laser light by 90 degrees when it is turned on by the control unit. On the other hand, the polarization rotation element does not rotate the polarization direction of the incident laser light by 90 degrees when it is turned off by the control unit.

  A third invention is a three-dimensional scanner including the laser range finder of the first invention, a mirror to which laser light is projected from the laser range finder, and a motor for rotating the mirror.

In the third invention, the laser range finder (10) can project laser light at 2 ⁿ angles when, for example, n prisms are used. The mirror (62) is irradiated with laser light at, for example, 2 ⁿ angles. A motor (64) controls, for example, the rotation of the mirror. For example, when the mirror that reflected the projected laser light makes one rotation, it is possible to scan one plane (scan plane). For example, if a laser range finder capable of projecting laser light to 2 ⁿ positions is used, 2 ⁿ scan planes can be obtained. The three-dimensional scanner then obtains scan results in three-dimensional space based on the 2 ⁿ scan planes.

  According to the third aspect of the present invention, it is possible to reduce the data of the entire area over a wide range in a short time at a low cost for a three-dimensional scanner using a laser range finder having a mechanical rotating portion and a vibrating portion. It becomes possible to acquire.

  A fourth aspect of the invention is an optical crystal according to an embodiment of the present invention, each of which is made of an anisotropic optical crystal, having a perpendicular first surface and a tilted second surface, and from the second surface according to the polarization direction of laser light incident from the first surface. At least one prism, which emits a second laser beam different from the optical path of the first laser beam or the first laser beam, is disposed sandwiching the prism, and rotates the polarization direction of the incident laser beam by 90 degrees, At least one pair of polarization-rotating elements that can be controlled not to rotate, and a pair of polarization filters provided respectively on the outside of the outermost polarization-rotating elements, each transmitting laser light of a predetermined polarization direction component , Laser beam deflection apparatus.

  In the fourth invention, the laser beam deflection apparatus (10) includes the laser beam deflection apparatus (16) including the prism (18), the polarization rotation element (20), and the polarization filter (22) of the first invention.

  According to the fourth invention, it is possible to deflect the laser light without using a mechanical rotation unit and a vibration unit.

  According to the present invention, laser light can be scanned at a plurality of angles without using a mechanical operation unit.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

FIG. 1 is an illustrative view showing one example of a configuration of a laser range finder according to an embodiment of the present invention. FIG. 2 is an illustrative view showing one example of a path of light emission and reception of laser light and reflected laser light in the laser range finder shown in FIG. 1, and FIG. 2 (A) shows one example of a light projection path of laser light. (B) shows an example of the light reception path of reflected laser light. FIG. 3 is an illustrative view showing one example of a polarization rotation element controlled by a processor and a control unit shown in FIG. FIG. 4 is an illustrative view showing one example of an experiment environment of an operation experiment using the laser range finder shown in FIG. FIG. 5 is an illustrative view showing one example of a projection position of laser light projected from the laser range finder shown in FIG. FIG. 6 is an illustrative view showing one example of an experimental result of an operation test using the laser range finder shown in FIG. FIG. 7 is an illustrative view showing one example of a configuration of a laser range finder according to another embodiment. FIG. 8 is an illustrative view showing one example of a projection position of laser light projected from a laser range finder of another embodiment. FIG. 9 is an illustrative view showing one example of a configuration of a three-dimensional scanner using the laser range finder shown in FIG. FIG. 10 is an illustrative view showing one example of a scan plane scanned by the three-dimensional scanner shown in FIG.

First Embodiment
Referring to FIG. 1, the laser range finder 10 of the embodiment includes a processor 12, a light emitting / receiving unit 14 also referred to as a laser light source, a laser light deflection device 16, and the like. Then, the laser range finder 10 calculates the distance from the laser range finder 10 to the object by obtaining the time difference between the emission time of the measurement light and the light reception time of the reflected light.

  In the following description, it should be noted that the term "polarization" is used to refer to the vibration of the light wave, and the term "deflection" is used to change the angle of the traveling direction of the laser light.

  The light emitting and receiving unit 14 emits a laser beam, and the emitted laser beam strikes an object and receives the reflected laser beam. The laser light may be referred to as "measurement light", and the reflected laser light may be referred to as "reflected light" or "reflected laser light".

  The laser beam deflector 16 is sometimes referred to as a laser scanner, and includes two polarizing prisms 18 having a vertical first surface and an inclined second surface, and three polarization rotations installed so as to sandwich each polarizing prism 18. It includes a pair of polarization filters 22 provided outside the element 20 and the outermost polarization rotation element 20, respectively. Further, a control unit 24 is connected to each polarization rotation element 20, and the control unit 24 controls on / off of the polarization rotation element 20 according to an instruction of the processor 12. Therefore, the processor 12 and the control unit 24 may be collectively referred to as a "control unit".

  The three polarization rotation elements 20 rotate, for example, the polarization direction of the laser light passing through the inside of the polarization rotation element 20 in a state in which the three polarization rotation elements 20 are turned on by the control unit 24. In each of the polarization rotation elements 20, a liquid crystal variable retarder capable of electrically controlling the retardance is employed.

  A Pockels cell variable retarder, which has better responsiveness than a liquid crystal variable retarder, a TN liquid crystal capable of electrically controlling the rotation of the polarization direction, or the like may be adopted as the polarization rotation element 20 of another embodiment.

The two polarizing prisms 18 consist of anisotropic optical crystals such as calcite. An anisotropic optical crystal differs in refractive index between a light beam (normal light) of polarized light parallel to the optical axis of the crystal and a light beam (abnormal light) of polarized light perpendicular to the optical axis. That is, the refractive index changes in the polarization direction and the incident direction with respect to the direction of the anisotropic optical crystal. For example, the polarizing prism 18 made of calcite, the refractive index n ₀ of ordinary light is larger than the refractive index n _e of the extraordinary ray, usually the light rays refracted larger than the extraordinary ray.

  Then, the light emitting and receiving unit 14 projects the laser light to the first polarizing filter 22a on the first surface side of the polarizing prism 18, and the reflected laser light that has passed through the second polarizing filter 22b on the second surface side of the polarizing prism 18 Receive light.

  As described above, the laser range finder 10 employs the non-mechanical laser scanning method, and does not have a mechanical rotating unit and a vibrating unit. Therefore, the laser range finder 10 exerts effects such as low noise / low vibration, low power consumption and high durability / weatherability to the laser range finder having the mechanical rotating portion and the vibrating portion.

  Here, for example, the light emitting and receiving unit 14 includes a laser diode also referred to as a light source or a light emitting unit, and a photodiode referred to as a light receiving unit. The laser diode is provided with a light guide member for outputting laser light to the outside of the light emitting and receiving unit 14. Further, a collimator lens is provided in the light guide member. Therefore, the laser light output from the laser diode is guided to the collimator lens by the light guide member, and is adjusted in parallel by the collimator lens. Then, the laser beam adjusted to the parallel state is emitted to the outside of the light emitting and receiving unit 14. In addition, the laser beam (beam light) adjusted to the parallel state may be called collimated light.

  At the exit side of the light guide member, a condenser lens is provided so as to surround the periphery of the light guide member. That is, one end of the light guide member penetrates the approximate center of the condensing lens. For example, the reflected laser light is received by the condenser lens. At the focal point of the condenser lens, a photodiode is provided which is disposed to substantially coincide with the optical axis of the laser diode. Therefore, the reflected laser light collected by the collecting lens is input to the photodiode disposed at the focal point of the collecting lens.

  As described above, the light emitting and receiving unit 14 of the present embodiment can receive the reflected laser light on substantially the same optical axis as the projected laser light.

  For a specific configuration of the light emitting and receiving unit 14, refer to Japanese Patent Application Laid-Open No. 2014-109686. Further, in another embodiment, the light emitting and receiving unit 14 may be employed in which the technology described in, for example, Japanese Patent Application Laid-Open No. 2002-246636 and the like is used.

  FIG. 2A shows an example of a light projection path of the laser light emitted from the light emitting and receiving unit 14. Referring to FIG. 2A, the laser light emitted by the light emitting and receiving unit 14 passes through the first polarizing filter 22a. At this time, in the first polarization filter 22a, laser light of a predetermined polarization component, that is, laser light polarized in a predetermined direction passes. The laser beam that has passed through the first polarization filter 22a passes through the first polarization rotation element 20a. In the first polarization rotation element 20a, it is controlled whether the polarization direction of the laser light passing through the inside is rotated 90 degrees or not. For example, if the first polarization rotation element 20a is on, the polarization direction of the laser light is rotated by 90 degrees. On the other hand, if the second polarization rotation element 20b is off, the polarization direction of the laser light is not rotated by 90 degrees.

  The laser beam whose polarization direction is controlled by the first polarization rotation element 20a is incident on the vertical first surface of the first polarization prism 18a. The incident laser beam emits a laser beam of a normal ray or a laser beam of an extraordinary ray from the second surface according to the polarization direction.

  The laser light emitted from the first polarizing prism 18a is again controlled by the second polarization rotating element 20b to determine whether or not the polarization direction is rotated by 90 degrees, and enters the second polarizing prism 18b. The laser beam incident from the first surface of the second polarizing prism 18b emits the laser beam of the ordinary ray or the laser beam of the extraordinary ray from the second plane again according to the polarization direction.

For example, with reference to FIG. 3, one case of eye laser beam L ₀ to the polarization prism 18 is incident, according to the polarization direction of the laser beam L _0, the first laser beam L ₁ and the second laser beam L ₂ Is emitted. The first laser light L ₁ or the second laser light L ₂ passes through the polarization rotation element 20 and is incident on the first surface of the second polarizing prism 18. In this case, the polarization rotation element 20 and the third laser light L ₁₁ that corresponds to the first laser beam L ₁ if off is emitted from the second surface, the first laser light L ₁ when the polarization rotating element 20 is ON the fourth laser light L ₁₂ is emitted from the second surface corresponding to. The fifth laser beam L ₂₁ is emitted from the second surface of the polarization rotating element 20 corresponds to the second laser beam L ₂ If on, the second laser beam L ₂ polarization rotator 20 is off corresponding sixth laser beam L ₂₂ is emitted from the second surface.

As described above, in this embodiment, since the laser light passes through the two polarizing prisms 18, it is possible to deflect the laser light with four (= 2 ² ) resolutions.

When the laser beam passes through one polarizing prism 18, the angle of the laser beam is deflected with two (= 2 ¹ ) resolutions. When the laser light passes through the three polarizing prisms 18, the laser light is deflected at a resolution of 8 (= 2 ³ ). That is, in accordance with the n polarizing prisms used in the laser beam deflecting device 16, the angle of the laser beam is deflected with a resolution of 2 ⁿ .

  In addition, for example, the third to sixth laser beams described above are controlled by the polarization rotation element 20 at the final stage to control whether the polarization direction is rotated 90 degrees, and are projected to the outside through the second polarization filter 22 b.

  Referring to FIGS. 2A and 2B, the polarization rotation element 20 of the final stage, that is, the third polarization rotation element 20c of the third stage in the embodiment, and the second provided in the polarization rotation element 20 of the final stage The polarization filter 22 b does not contribute to the polarization of the resolution of the deflection angle of the laser light. However, the polarization rotation element 20 of the final stage is used so that the number of polarization rotation elements 20 to be turned on among all the polarization rotation elements 20 is an even number. Then, the number of polarization rotation elements 20 that are turned on is an even number, so that the polarization direction of the laser light emitted to the outside from the second polarization filter 22 b and the polarization direction of the reflected laser light of the laser light are equal. It can.

  Further, the laser light emitted to the outside and striking the object is diffused. Therefore, the reflected laser light contains various polarization direction components. A second polarizing filter 22b is provided to pass the reflected laser beam polarized in the same direction as the laser beam projected to the outside.

  Thus, by providing the polarization rotation element 20 and the second polarization filter 22b at the final stage, as shown in FIG. 2B, the paths of the laser light and the reflected laser light become the same. That is, the reflected laser light follows the path substantially the same as the light projection path and is received by the light emitting and receiving unit 14.

  Therefore, regardless of the deflection direction of the laser beam emitted from the laser range finder 10, the reflected laser beam returns to the light emitting and receiving unit 14, so that accurate distance measurement is realized regardless of the projection position of the laser beam on the object. It is possible to

  Control of the polarization rotation element 20 will be specifically described with reference to FIG. The polarization rotation element 20 is connected to the control unit 24 that controls the voltage applied to the polarization rotation element 20 as described above. A control signal for instructing on / off of the polarization direction from the processor 12 and a deflection angle up to the previous stage are input to each control unit 24. The control unit 24 controls on / off of the polarization rotation element 20 based on the control signal. In addition, the control unit 24 applies a voltage (hereinafter referred to simply as “applied voltage” so as to rotate the 1⁄2 wavelength retardance according to the optical path length, that is, rotate the polarization direction by 90 degrees based on the deflection angle up to the previous stage. Control).

  For example, the incident angle is θ, the thickness (optical path length) of the polarization rotation element 20 is d, the wavelength of the laser light is λ, the retarder characteristic is k, and the applied voltage is v. Then, when the retardance generated in proportion to the optical path length d and the applied voltage v is 1⁄2 wavelength (90 degrees), the equation shown in Equation 1 holds.

[Equation 1]

  Further, when the equation shown in the equation 1 is solved for the applied voltage v, the equation shown in the equation 2 is obtained. Then, the control unit 24 determines the voltage to be applied to the polarization rotation element 20 by substituting the incident angle θ, that is, the deflection angle up to the previous stage into the equation of Formula 2. That is, the applied voltage v to the polarization rotation element 20 is controlled using the equation shown in Equation 2.

[Equation 2]

  By calculating the applied voltage v in this manner, it is possible to control polarization rotation with high accuracy.

  In the control unit 24 connected to the first polarization rotation element 20 a of the first stage, “0 degree” is input to the control unit 24 as the deflection angle up to the previous stage because there is no former stage.

  Also, in another embodiment, the ambient temperature t may be added to Equations 1 and 2. That is, in another embodiment, the polarization rotation element 20 may be controlled more accurately by the applied voltage v in which the ambient temperature t is taken into consideration.

  Subsequently, experimental results of an operation experiment using the laser range finder 10 of the embodiment will be described. First, referring to FIG. 4, a laser range finder 10 and a grid sheet are prepared as an experiment environment of the operation experiment, and the laser beam emitted from the light emitting and receiving unit 14 of the laser range finder 10 After being transmitted, it is made to be irradiated to the grid paper. Further, the grid paper is disposed at a position 2.0 m forward with reference to the position on the side where the laser light is projected to the laser light deflection device 16.

  Next, referring to FIG. 5, first, the position where the laser beam projected from the light emitting and receiving unit 14 is irradiated without passing through the laser beam deflecting device 16 is recorded on the grid paper. Then, on the three polarization rotation elements 20, try the on / off patterns of the three polarization rotation elements 20 so that the number of the polarization rotation elements 20 to be turned on becomes even, and record the projection position of the laser light in each pattern Do.

  Referring to the experimental result shown in FIG. 6, the first polarization rotating element 20a in the first stage is turned on, and the second polarization rotation element 20b in the second stage is turned off, and then the third polarization rotation in the third stage When the element 20 c was turned on, the position irradiated with the laser beam was the light emitting position A.

  When the first polarization rotation element 20a in the first stage is turned off and the second polarization rotation element 20b in the second stage is turned on, then the third polarization rotation element 20c in the third stage is turned on. The irradiation position was the light projection position B.

  When the first polarization rotation element 20a in the first stage and the second polarization rotation element 20b in the second stage are turned off and the third polarization rotation element 20c in the third stage is turned off, the position where the laser light is irradiated is It became the floodlight position C.

  When the first polarization rotation element 20a in the first stage and the second polarization rotation element 20b in the second stage are turned on and the third polarization rotation element 20c in the third stage is turned off, laser light is emitted. The position became the light emitting position D.

As described above, since the laser beam deflecting device 16 uses two polarizing prisms 18, the angle of the laser beam is deflected by 4 (= 2 ² ) resolutions, that is, the projection position of the laser beam is It was confirmed that there were four.

  Next, it is verified whether the swing angle of the laser light, that is, the position where the laser light is irradiated is appropriate. First, for each of the four projection positions A-D, from the polarizing prism 18 based on the equations shown in Equations 3 and 4 using Snell's law, the horizontal swing angle and the vertical swing angle are Calculate the emission angle of

In the following equation, the outgoing angle is θ _out , the refractive index of the ordinary ray of the polarizing prism 18 is n ₀ , the refractive index of the extraordinary ray is n _e, and the prism angle of the polarizing prism 18 is φ, to the polarizing prism 18 the angle of incidence of the φ _a. In the number 4, crystals causing birefringence, i.e. the angle of incidence with respect to the crystal axes of the anisotropic optical crystal and [psi _a, the refractive index when the incident angle (incident direction) Ψ _a n _{ea (Ψ a} And). The number 3 usually indicates the emission angle theta _out of the light beam, the number 4 indicates the outgoing angle theta _out of the extraordinary ray.

[Equation 3]

[Equation 4]

  As described above, the refractive index to the extraordinary ray of the anisotropic optical crystal changes in the incident direction to the crystal axis of the three-dimensional space. The refractive index with respect to the three-dimensional incident direction has a property of becoming an ellipsoid (refractive index ellipsoid).

The anisotropic optical crystal used in the first embodiment is calcite, and calcite is a uniaxial crystal. Therefore, when a refractive index ellipsoid is used, the change of the refractive index with respect to an extraordinary ray is determined by the incident direction with respect to the center (crystal axis) of the refractive index ellipsoid. And n _ea (Ψ _a ) of _a uniaxial crystal is represented by a distance from the center of a two-dimensional ellipse when the refractive index ellipsoid is captured in two dimensions. Therefore, the relationship between n _ea , n ₀ and n _e can be expressed by the equation shown in equation 5.

[Equation 5]

Further, when the equation of the equation 5 is solved for n _ea (Ψ _a ), the equation shown in the equation 6 is obtained. Then, the resulting value of the number 6 _{n ea} (Ψ _a), by substituting the _{n ea} in number 4 ([psi _a), it is possible to calculate the output angle theta _out in Equation 2.

[Equation 6]

The refractive index n _ea (Ψ _a ), uniaxial crystal, refractive index ellipsoid and the like in the anisotropic optical crystal are widely and generally known, and therefore, the detailed description of each term will be given. I omit it.

Further, since _{a a} is determined by the emission angle θ _out from the polarizing prism 18 in the previous stage, when calculating the accurate emission angle θ _out , it is necessary to calculate the emission angle θ _out in the control unit 24 of each stage. .

In another embodiment, the polarizing prism 18 during implementation, since through the path the ray can not be represented by the law of specific birefringence Snell, for more accurate output angle theta _out calculations, O. N. The vector algorithm described in Stavroudis's article ("Ray-Tracing Foumulas for Uniaxial Crystals", J. of Optical Society of America, vol 52 (2), pp. 187-191, 1962) may be used.

  Referring back to FIG. 6, the swing angle [mrad] of the light emitting and receiving unit 14 with respect to the optical axis is shown in the column of actual measurement and calculation in the experimental result. For example, the calculation result of the swing angle of the light emitting position A is “97” in the horizontal direction and “116” in the vertical direction. On the other hand, the value of the swing angle obtained from the light projection position A shown in FIG. 5 is “96”, and the length is “118”.

  In addition, while the calculation result of the swing angle of the light projection position B is “83” in the horizontal direction and “116” in the vertical direction, the value of the swing angle obtained from the light emission position B shown in FIG. It became "82" and the vertical became "118". Furthermore, while the calculation result of the swing angle of the light emitting position C is “83” in the horizontal direction and “116” in the vertical direction, the value of the swing angle obtained from the light emitting position C shown in FIG. It became "82" and the vertical became "99". Then, while the calculation result of the swing angle of the light projection position D is “97” in the horizontal direction and “100” in the vertical direction, the value of the swing angle obtained from the light emission position D shown in FIG. It became "97" and the vertical became "100".

  At any light projection position, it was confirmed that the swing angle (deflection angle) obtained from the light projection position shown in FIG. 4 and the swing angle (deflection angle) obtained by calculation substantially coincide with each other.

  As described above, the laser range finder 10 according to the first embodiment can scan laser light at a plurality of angles without using a mechanical operation unit.

  Further, the laser beam deflection apparatus 16 can deflect the laser beam without using a mechanical rotation unit and a vibration unit.

  The deflection angle of the polarizing prism 18 in the second and subsequent stages changes as the sum of the rotations of the polarization directions of all the polarization rotating elements 20 preceding the polarizing prism 18. Therefore, for example, the deflection angle of the second polarizing prism 18b in the second stage is the exclusive OR (XOR) of on / off of the first polarization rotating element 20a in the first stage and the second polarization rotating element 20b in the second stage. To change.

  In the first embodiment, the position of the irradiated laser light is in the form of a matrix, but the oscillation direction of the laser light can be swung vertically or horizontally. Therefore, in another embodiment, the position of the irradiated laser beam may be linear.

Further, as a minimum configuration of the laser range finder 10 of the first embodiment, the configuration shown in FIG. 7 can be employed. The laser range finder 10 of the minimum configuration has a polarizing prism 18 and a pair of polarization rotating elements 20 installed with the polarizing prism 18 interposed therebetween, and a pair of polarizing filters 22 provided on the outer side of the outermost polarization rotating element 20 respectively. And a light emitting and receiving unit 14 that emits a laser beam to the first polarizing filter 22a and receives the reflected laser light that has passed through the second polarizing filter 22b. That is, in the laser range finder 10 of the minimum configuration, the configuration of the laser light deflection device 16 is the minimum. When the number of polarizing prisms 18 included in the laser beam deflector 16 is one, the angle of the laser beam in the laser beam deflector 16 is deflected with two (= 2 ¹ ) resolutions so that the laser beam is projected. There will be two positions.

Although detailed illustration of the configuration of the laser beam deflection device 16 is omitted, when the number of polarizing prisms is eight, the angle of the laser beam in the laser beam deflection device 16 is deflected with 256 (= 2 ⁸ ) resolutions . Therefore, as shown in FIG. 8, the laser range finder 10 can also project 256 laser light projection positions.

  In other embodiments, the polarizing prism 18 may be replaced with a microprism having the same performance. In this case, since the thickness of the microprism is smaller than that of the polarization prism 18, the laser range finder 10 (laser light deflector 16) can be miniaturized.

  Furthermore, in still other embodiments, the light projection path and the light reception path may be different. For example, in still another embodiment, a half mirror is provided between the polarization rotation element 20 of the final stage and the second polarization filter 22b. In this case, instead of the light emitting and receiving unit 14, a light emitting unit is provided at the same position as the light emitting and receiving unit. In addition, a light receiving unit is provided on the path when the reflected laser light is reflected by the half mirror. In this case, the reflected laser light is received by the light receiving unit without passing through the polarization rotation element 20, the polarization prism 18, and the first polarization filter 22a. That is, the light projection path and the light reception path are in different states.

  Although an example is shown in which the number of polarization rotation elements 20 that are turned on is controlled to be an even number at all, the number of polarization rotation elements 20 that are turned on is: It may be even or odd and always constant. For example, in another embodiment, the polarization rotation element 20 of the final stage may be controlled such that the number of polarization rotation elements 20 that are turned on is always an odd number. When the number of polarization rotating elements 20 that are turned on is controlled to be an odd number, and the polarization direction transmitted by each polarizing filter 22 is controlled such that the number of polarization rotating elements 20 is an even number. Each polarizing filter 22 may be attached so as to rotate by 90 degrees with respect to.

Second Embodiment
Referring to FIG. 9, a three-dimensional scanner 60 includes the laser range finder 10 of the first embodiment, a mirror 62, a motor 64, and the like. The laser beam projected by the laser range finder 10 is emitted to the mirror 62 whose rotation is controlled by the motor 64. The laser beam reflected by the mirror 62 is projected to a three-dimensional space. At this time, since the mirror 62 is rotating, the reflected laser beam can scan a three-dimensional space in a plane.

  Further, the projection position of the laser beam projected by the laser range finder 10 changes as shown in the first embodiment. Therefore, when the light projection position of the laser light is changed when one surface (hereinafter, scan surface) is scanned by the laser light reflected by the mirror 62, the light projection position of the laser light reflected by the mirror 62 changes. The laser beam is scanned in a different plane from that before the laser beam. That is, each time the projection position of the laser beam is changed, different scan planes are obtained.

  Referring to FIG. 10, for example, the number of laser light projection positions projected by the laser range finder 10 according to the first embodiment is four. Therefore, the three-dimensional scanner 60 having the laser range finder 10 of the first embodiment can scan four scan planes.

For example, in a three-dimensional scanner using a conventional laser range finder, four conventional laser range finders have to be prepared to obtain four scan planes. On the other hand, in the case of the three-dimensional scanner 60 of this embodiment, only one laser range finder 10 for obtaining four scan planes may be used, and the laser range finder 10 (laser light deflection apparatus 16) is used. The number of polarizing prisms 18 to be used may be two (= log ₂ 4).

That is, in the case of obtaining n scan planes in the three-dimensional scanner 60 of this embodiment, one laser range finder 10 may be prepared in which “log ₂ n” polarizing prisms 18 are used. Then, the three-dimensional scanner 60 can obtain the scan result of the three-dimensional space based on the plurality of scan planes.

  As described above, the three-dimensional scanner 60 of the second embodiment is relatively inexpensive and has a wide range compared to a three-dimensional scanner using a laser range finder having a mechanical rotation unit and a vibration unit. It becomes possible to acquire data of the entire area in a short time.

  The specific numerical values mentioned in the present specification are merely examples, and can be appropriately changed in accordance with the change of the specification of the product.

DESCRIPTION OF SYMBOLS 10 ... Laser range finder 12 ... Processor 14 ... Light emission and reception part 16 ... Laser beam deflection apparatus 18 (18a, 18b) ... Polarization prism (1st polarization prism, 2nd polarization prism)
20 (20a, 20b, 20c) ... polarization rotation element (first polarization rotation element, second polarization rotation element, third polarization rotation element)
22 (22a, 22b) ... polarization filter (first polarization filter, second polarization filter)
24 ... control unit 60 ... 3D scanner 62 ... mirror 64 ... motor

Claims (4)

Each of the first and second laser beams is made of an anisotropic optical crystal and has a vertical first surface and a tilted second surface, and the second laser beam or the second laser beam according to the polarization direction of the laser beam incident from the first surface. At least one prism emitting a second laser beam different from an optical path of the first laser beam;
At least one pair of polarization rotating elements installed so as to sandwich the prism and capable of controlling whether or not the polarization direction of the laser light incident on each is rotated 90 degrees or not.
The laser light is emitted to a pair of polarizing filters provided on the outer side of the outermost polarization rotation element, each transmitting laser light of a predetermined polarization direction component, and the polarizing filter on the first surface side of the prism. A laser range finder comprising: a light emitting and receiving unit configured to emit light and receive a reflected laser beam that has passed through a polarizing filter on the second surface side of the prism. It further comprises a control unit that controls on / off of the polarization rotation element,
The polarization rotation element rotates the polarization direction of the incident laser light by 90 degrees when turned on by the control unit, and does not rotate the polarization direction of the incident laser light by 90 degrees when turned off by the control unit. The laser range finder according to claim 1. The laser range finder according to claim 1,
A three-dimensional scanner comprising: a mirror to which laser light is projected from the laser range finder; and a motor that rotates the mirror. Each of the first and second laser beams is made of an anisotropic optical crystal and has a vertical first surface and a tilted second surface, and the second laser beam or the second laser beam according to the polarization direction of the laser beam incident from the first surface. At least one prism emitting a second laser beam different from an optical path of the first laser beam;
At least one pair of polarization rotating elements installed on both sides of the prism and capable of controlling whether or not the polarization direction of the laser beam incident thereon is rotated 90 degrees, and outside each, and outside the outermost polarization rotating elements. A laser light deflecting device comprising a pair of polarizing filters, each provided for transmitting laser light of a predetermined polarization direction component.