TWI616646B - Laser based distance measurement device - Google Patents

Abstract

A laser ranging device includes a distance measuring body, an elastic body, an arc reflecting body and a reference sphere, wherein the distance measuring system has a convex tube at the bottom of the distance measuring body, and the elastic system is correspondingly disposed in the convex tube The arc reflecting system is disposed under the elastic body, and the reference ball system is abutted against the arc reflecting body. The arc reflection system is used to reflect the laser beam, and the reference sphere is used as a guide for the movement direction of the arc reflector, so that the distance measurement body maintains the displacement of the parallel optical axis direction and the vertical optical axis direction, so that the measurement result remains correct. .

Description

Laser distance measuring device

The present invention relates to a laser ranging device, and more particularly to a laser ranging device matched with a curved reflector and a reference sphere.

High-precision laser range finder is widely used in various industries, such as precision machinery, machine tool industry, aerospace industry, shipbuilding industry, automobile industry and construction industry. For the three-dimensional measurement of precision machinery industry, the best measurement accuracy is automatic tracking laser range finder, such as LaserTRACER in Germany.

The important components of LaserTRACER include the reference sphere, which is generally a mirrored steel ball. Specifically, the beam quality of the laser beam of the laser ranging device after the process of splitting and reflection, and the mirror quality of the reference sphere. It is closely related. However, during operation, it is easy to cause the spherical surface of the reference sphere to produce flaws, which will affect the beam quality and thus reduce the accuracy of the ranging. Since the reference sphere is made of steel, in the case where the temperature changes greatly, the reference thermal expansion of the sphere due to the temperature changes, which also reduces the accuracy of the distance measurement.

Furthermore, the distance between the reference sphere and the matching convex lens may change due to the running error of the rotating bearing, and the change of the distance may cause the focus of the laser beam to not accurately fall on the center of the reference sphere. Affects the reflection effect and reduces the measurement accuracy.

In the prior art, there is a technique of connecting the angular coupling mirror through the jig and the reference sphere. However, since the contact with the reference sphere is in planar contact, the parallel displacement and angle of the angular coupling mirror during operation are Rotation can cause measurement errors.

Therefore, how to solve the flaws in the aforementioned design has become an issue that the industry is eager to solve.

In order to overcome the various flaws of the prior art, the present invention provides a laser ranging device.

The laser ranging device includes a distance measuring body, a curved reflector body, a reference sphere body and an elastic body, wherein the distance measuring system has a convex tube at the bottom of the distance measuring body; the elastic system is correspondingly disposed in the convex tube; the arc The reflective system is disposed under the elastic body; the reference ball system is abutted against the curved reflector, and the reflective surface inside the curved reflector is used to reflect the laser beam, and the reference ball system is used as the moving direction of the curved reflector. The guiding result is such that the measuring body produces a displacement in the direction of the parallel optical axis and the direction of the vertical optical axis, so that the measurement result remains correct.

Compared with the prior art, since the arc-shaped reflector of the present case does not need to directly reflect the laser beam by the reference sphere, that is, the reference sphere does not affect the measurement quality, and the reference sphere of the present case The material can be made from a low thermal expansion material to improve measurement error.

11‧‧‧Arc reflector

110‧‧‧reflecting surface

12‧‧‧Reference sphere

13‧‧‧ Elastomers

14‧‧‧ verning body

15‧‧‧Target mirror

16‧‧‧Concave tube

17‧‧‧ Linear Displacement Constraints

L1, L2, L3, L4‧‧‧ distance

△L, δ _L , δ _b ‧‧‧ displacement

Radius of R _b , R _c ‧‧‧

The first picture is a schematic diagram of one of the laser ranging devices of the present case; the second picture is the displacement of the parallel measuring optical axis in the measuring body of the present case. Schematic diagram of the operation; Figure 3 is a schematic diagram of the displacement of the measuring body in the vertical direction of the measuring body in the direction of the measuring body; Figure 4 is the model calculation drawing of Figure 3; Figure 5 is the measuring body of the case The XY scatter diagram of the lateral displacement and the optical path difference; and the sixth figure is a schematic structural view of the linear displacement restraining element of the present invention disposed on the curved reflector.

The embodiments of the present disclosure are described in the following specific embodiments, and those skilled in the art can easily understand other advantages and functions of the disclosure by the contents disclosed in the present specification, and can also use other different embodiments. Implement or apply.

Please refer to FIG. 1 , which is a schematic structural view of one of the laser ranging devices of the present invention.

As shown in the figure, the laser ranging device of the present invention comprises a curved reflector 11, a reference sphere 12, an elastic body 13, and a distance measuring body 14, wherein the distance measuring body 14 can be provided with a laser light source, a polarizing plate and a pole. Optical components such as a beam splitter, a 1/4 λ slide, a beam splitter, a displacement sensor, a beam expander, and a laser interferometer sensor.

In the present embodiment, the distance measuring body 14 has a convex tube 16 at the bottom of the distance measuring body 14, and the elastic body 13 is correspondingly disposed in the convex tube 16, and the curved reflector 11 is disposed on the elastic body 13. Below, the reference sphere 12 is placed against the arc reflector 11 , wherein the reflection inside the arc reflector 11 The surface 110 is used to reflect the laser beam, and the reference sphere 12 serves as a guide for the direction of movement of the arc reflector 11 so that the distance measuring body 14 generates a displacement between the parallel optical axis direction and the vertical optical axis direction, and the measurement is performed. The result remains correct.

In one embodiment, the reference sphere 12 can be made of a metal or a non-metal material. For example, the metal material can be a mirror-reflective laser light material such as stainless steel, aluminum, iron or indium steel. The non-metallic material may be ceramic, glass, ruby, carbon fiber or glass ceramic.

In an embodiment, the curved reflector 11 can have a reflective surface 110 built therein, for example, an inner spherical mirror. Depending on the application scenario, the curved reflector 11 may also have other types of reflective units, such as a planar mirror, a cat's eye mirror, a corner-coupled mirror, or an integrated module of a focusing lens and a concave mirror, and With the built-in reflection unit, the structure of the upper half of the arc reflector 11 can also be different from the semicircle of the figure.

In an embodiment, the elastic body 13 can be a compression spring, a plate spring, a disc spring, a spring spring, a dish spring, a rubber spring or an O-ring, and is correspondingly disposed on the convex tube. 16 and the convex tube 16 is located at the bottom of the distance measuring body 14. Specifically, the elastic body 13 applies a force to the direction of the force of the arc reflector 11 to be parallel to the optical axis direction of the laser beam.

In actual implementation, the distance measuring body 14 can be an integral laser interferometer, a Doppler range finder, or an absolute ranging type laser range finder. One end of the elastic body 13 abuts against the distance measuring body 14 , and the other end applies a force to the curved reflector 11 , and the direction of the force is parallel to the direction of the laser optical axis, so that the bottom surface of the curved reflector 11 is curved. The spherical surface of the reference sphere 12 can be continuously contacted.

Please refer to Figure 2, which is the parallel amount of the measuring body in this case. Schematic diagram of the displacement of the metering axis direction.

As shown, L1 is the distance from the intersection of the arc reflector 11 and the reference sphere 12 to the bottom of the distance measuring body 14, L2 is the distance from the target mirror 15 to the bottom of the distance measuring body 14, and L is the target. The total distance (i.e., L1 + L2) of the mirror 15 to the intersection of the arc-shaped reflector 11 and the reference sphere 12. When the distance measuring body 14 generates the displacement ΔL in the direction of the parallel measuring optical axis, L1'=L1+ΔL, L2'=L2-ΔL, the target mirror 15 reaches the intersection of the curved reflecting body 11 and the reference spherical body 12. The original total distance is L1'+L2', which is still equal to L, so there is no optical path difference.

Please refer to Fig. 3 to Fig. 5 together. Fig. 3 is a schematic diagram of the displacement of the measuring body in the direction of the vertical measuring optical axis in the case, and Fig. 4 is the model calculation drawing of Fig. 3, the fifth The figure is an XY scatter diagram of the lateral displacement and optical path difference of the ranging body of the present case, wherein the X axis is the lateral displacement of the distance measuring body 14, and the Y axis is the optical path difference, and the unit is micrometer.

As shown in FIG. 3, where L3 is the distance from the arc-shaped reflector 11 and the reference sphere 12 to the bottom of the distance measuring body 14, L4 is the displacement of the distance measuring body 14 in the direction of the vertical measuring optical axis. The distance between the curved reflector 11 and the reference sphere 12 to the bottom of the distance measuring body 14 is δ _L = L4 - L3.

By analyzing as shown in Figure 4, you get a program:

Where R _{b is} the radius of the reference sphere 12; R _{c is} the radius of the arc reflector 11; and δ _b is the lateral displacement of the distance measuring body 14.

As shown in Fig. 5, when the lateral displacement δ _{b of} the distance measuring body 14 is at plus or minus 5 μm, the resulting optical path difference is much smaller than 10 nm. The runout error of the rotating shaft can generally be controlled at plus or minus 5 micrometers. Therefore, the optical path difference of the displacement of the vertical measuring optical axis generated by the measuring body 14 has little influence on the measurement result.

Please refer to FIG. 6 , which is a schematic structural view of the linear displacement restraining element 17 of the present invention which is sleeved on the curved reflector 11 . As shown, the linear displacement restraining element 17 is fitted with the convex tube 16 to cover the arc reflector 11 to limit and maintain the range of motion of the arc reflector 11, thereby reducing measurement errors. In one embodiment, the linear displacement restraining element 17 can be a retaining plate, a hollow ring, a linear slide or a linear bearing. The linear displacement restraining element 17 is disposed perpendicular to the optical axis of the laser beam.

In summary, the arc-shaped reflector of the present case does not need to directly reflect the laser beam by the reference sphere, so the spherical surface of the reference sphere does not affect the measurement quality, and the reference sphere can be composed of various materials, such as Made of low expansion coefficient material, it can greatly reduce the measurement error caused by dimensional thermal expansion. Moreover, since the arc-shaped reflector and the reference sphere in this case can always maintain the contact relationship of the arc facing the arc surface, the arc reflector The distance from the center to the center of the reference sphere is not changed by the operation of the device, and the measurement error caused by the optical path difference can be avoided.

The above-mentioned embodiments are merely illustrative of the technical principles, features, and functions of the present disclosure, and are not intended to limit the scope of the disclosure. Any person skilled in the art can do without departing from the spirit and scope of the disclosure. The above embodiments are modified and changed. However, any equivalent modifications and changes made using the teachings of this disclosure should still be the following patent application. Covered by the scope. The scope of protection of the present disclosure should be as set forth in the following patent application.

Claims (11)

A laser ranging device includes: a distance measuring body having a convex tube at a bottom of the distance measuring body; an elastic body correspondingly disposed in the convex tube; and an arc reflecting body disposed on the elastic body And a reference sphere, the top of which is opposite to the arc reflector, wherein the reference sphere is made of a low expansion coefficient material, and the reflective surface of the arc reflector is used to reflect the laser beam, and the reference sphere system is The guiding of the moving direction of the arc reflector enables the measuring body to maintain the displacement of the parallel optical axis direction and the vertical optical axis direction, so that the measurement result remains correct. The laser ranging device according to claim 1, wherein the reference ball system is made of a metal or a non-metal material. The laser ranging device according to claim 2, wherein the metal material is a material of a mirror surface of stainless steel, aluminum, iron or indium steel that can reflect laser light. The laser ranging device according to claim 2, wherein the non-metal material is ceramic, glass, ruby, carbon fiber or glass ceramic. The laser ranging device according to claim 1, wherein the reflecting surface is built in the arc reflecting body, and the reflecting surface can be an inner spherical mirror, a plane mirror, a cat eye mirror, and an angle. Coupling mirror or integrated module of focusing lens and concave mirror. The laser distance measuring device according to claim 1, wherein the elastic system is a compression spring, a plate spring, a disc spring, a spring spring, Pan spring, rubber spring or O-ring. The laser distance measuring device according to claim 1, wherein the elastic body applies a force applying direction of the arc reflector to be parallel to an optical axis direction of the laser beam. The laser ranging device of claim 1, further comprising a linear displacement restraining element sleeved on the arc reflector to limit the range of motion of the arc reflector. The laser distance measuring device according to claim 8, wherein the linear displacement restraining element is a holding piece, a hollow ring, a linear sliding track or a linear bearing. The laser ranging device according to claim 8, wherein the linear displacement restraining element is disposed perpendicular to an optical axis direction of the laser beam. The laser ranging device according to claim 1, wherein the ranging system comprises a laser light source, a polarizing plate, a polarization beam splitter, a 1/4 λ slide, a beam splitter, a displacement sensor, and an expansion. Beam mirror and laser interferometer sensor.