JPS60149985A - Optical distance measuring apparatus - Google Patents

Abstract

PURPOSE:To remove influence due to phase irregularity to an emitting angle, by a method wherein a reflective member is made accessible with respect to a light transmission path and light having an emitting angle range almost same to that of light used as measuring light or light at an optical axis part is used as correction light. CONSTITUTION:Modulation light from a light emitting element 2 is transmitted through a condensing lens 3 and an optical fiber 4 and a shutter 5 changes over light incident to a light receiving part 14 to either one of measuring light and correction light. The shutter 5 is rotated by a motor 9 and, when measuring light is selected, light transmitted through the condensing lens 3 passes the shutter 5 to be incident to the optical fiber 4. On the other hand, when correction light is selected, the light condensed by the condensing lens 3 is reflected by the shutter 5 and incident to an optical fiber 10 for transmitting correction light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical structure of a light wave distance measuring device that measures distance using light waves. As is well known, a light wave ranging device uses a light transmitting optical system to direct light from a light emitting element such as a light emitting diode that is modulated at a certain specified frequency to a reflector such as a corner cube placed at a measuring point. The light emitted and returned from the reflector is imaged on a light receiving element using a light receiving optical system, converted into an electrical signal, and aligned with the reference modulated light.
This is a device that measures distance by detecting the phase delay of 1 modulated light. In the case of such a light wave distance measuring device, a distance measurement error is an important performance problem, and there are various optical and electrical causes of the error.

The present invention relates to an optical structure that eliminates the influence of phase unevenness of a light emitting section among the optical causes and reduces measurement errors.

Normally, in a light wave distance measuring device, in order to correct measurement errors based on the optical path length within the device and the phase shift of the electronic circuit section,
A correction light is provided separately from the measurement light, but unlike the measurement light, which uses radiation near the optical axis of the light emitting part, this correction light is captured by using light in a radiation angle range far away from the optical axis. The method used is mechanically common. However, in this case, if there is phase unevenness due to a difference in the radiation angle, the phase difference between the measurement light and the correction light changes due to changes in the mechanically set position of the optical path or the temperature characteristics of the light emitting element, resulting in distance measurement. There is a problem when the error becomes large. This phase unevenness is small and within an acceptable range in the vicinity of the optical axis in highly directional light emitting elements, which are very effective because they allow a large amount of light to be emitted from the optical range finder. When the radiation angle is far from the optical axis, the phase unevenness with respect to the angle tends to be very large.

Conventional devices for reducing the influence of phase unevenness on the radiation angle include a structure in which a light emitting element and an optical fiber are coupled, and this optical fiber is bent and placed in the optical path; A half mirror is fixed in the backlight optical path from the light emitting element and used as correction light.
There are configurations that utilize light near the optical axis A1, and configurations that utilize light near the optical axis using a shutter and optical system provided between the light transmitting section and the light transmitting optical system.

However, it is difficult to achieve the purpose of the configuration in which the optical fiber is bent unless the optical fiber is bent extremely, and the bending can lead to the optical fiber breaking, impairing the reliability of the optical distance measuring device over time, and also causing radiation For a configuration using a light emitting element with little phase unevenness with respect to angles, it is necessary to select a light emitting element whose light radiation characteristics are close to omnidirectional, and because such a light emitting element has negligible tropism, it is difficult to actually use it. The light output is small in a narrow radiation angle range, and when used in optical coupling with optical fibers, the coupling efficiency with them is very poor, so more power must be transferred to the light emitting element to compensate for the coupling loss. The disadvantage is that the emitted light 14 must be increased by supplying it. Furthermore, the configuration in which the correction light is taken out using a no. The configuration in which corrected light is taken out using a shutter provided between the light optical system and the optical system requires the shutter and shutter drive device to be placed in a crowded place with the light transmitting and receiving optical system, resulting in a disadvantageous structure. It may happen.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light wave ranging device which solves the above-mentioned conventional drawbacks and eliminates the disadvantages caused by phase unevenness, and its features are as follows.

In general, apart from the phase unevenness with respect to the radiation angle, there is a problem that the phase unevenness depending on the location of the light emitting surface of the light emitting element increases the error in determining the distance d1.
It is already known that the phase unevenness caused by the location of the light emitting surface can be mixed uniformly by mixing light using a light emitting element, and this problem can be solved. , a light-transmitting member such as an optical fiber or an optical rod, and an optical system that optically couples the light-emitting element and the light-transmitting member. In the present invention, in the light transmitting section, a reflecting member is provided in the light transmitting optical path 1- between the light emitting element and the light transmitting member so that the light incident on the light receiving section is switched by '=7J between the measurement light and the correction light. The light emitted from the light-emitting element is inserted and taken out, and the light in the radiation angle range that is almost the same as the light used as the measurement light, including the optical axis of the light emitting element, or the light in the optical axis portion is used as the correction light. Unlike the case where light at a large angle to the axis is used as correction light, it is not affected by phase unevenness in the radiation angle that leads to measurement errors, and measurement errors are kept small, allowing for accurate distance measurement. . At the same time, it is also possible to use the highly directional light emitting element described above. Therefore, as mentioned above, large amounts of power must be supplied by bending the optical fiber or by using omnidirectional light emitting elements, which have small phase irregularities with respect to the radiation angle but are inefficient as light wave distance measuring devices. The inconvenience of not being able to do so will no longer occur. In addition, since the half mirror is not used in a fixed manner, and the reflective member is not positioned on the light transmission path when the measurement light is selected, the emitted light from the light wave distance measuring device is There is no need to sacrifice flying distance due to decreased impact. Furthermore, the reflecting member and its driving device for switching between the measurement light and the correction light can be placed near the light emitting element A1 of the light transmitting section, eliminating the need for placing it in a crowded place with the light transmitting and receiving optical system, etc. This is Qin Heli.

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a layout diagram of an optical system showing a light transmitting section of a light wave ranging JA system which is an embodiment of the present invention.

The one indicated by the symbol l is a layout diagram showing the optical system of the light transmitting section, in which a condenser lens 3 is disposed in the light beam of the light emitting element 2 that emits distance measuring light, and this condenser lens 3 An optical fiber 4 is installed at the imaging point.

A disc-shaped shutter 5 is provided between the condensing lens 3 and the first optical fiber 4 on the distance measuring light optical path, and a part of the shutter 5 is provided with a reflective member 6 at an angle of approximately 45°, and the other part is transparent. A hole 7 is formed, and when the shutter 5 rotates, the reflecting member 6
The through hole 7 can be switched into and out of the distance measuring light optical path.

This switching is performed by a motor 9 via a drive shaft 8.

When the reflecting member 6 is switched on the distance measuring light optical path, the light beam from the light emitting element 2, passing through the condensing lens 3 and being reflected by the reflecting member 6 is imaged as correction light, but there is another light beam at the imaging point. A second optical fiber 10 for transmitting correction light is provided.

The above is the light transmitting section 1 of the light wave range finder, and FIG. 2 is a diagram showing the entire configuration in a simplified manner, mainly focusing on the optical system.

In FIG. 2, a conventionally known beam splitter 11 is shown.
, Objective Shins 12. Corner cube 13 and light receiving section 1
4 shows the optical structure of the distance measuring light optical path, which is composed of a focusing lens 15.4, and a condenser lens 15.4 on the output end surface side of the second optical fiber on the correction light optical path. ND filter 16. This shows the arrangement of the drive shaft 17.

Next, these effects will be explained using FIGS. 1 and 2.

In Fig. 1, if we ignore the shutter 5,
The modulated light from the light emitting element 2 has a small phase unevenness with respect to the radiation angle and is within a permissible range, is focused by the condensing lens 3, and is imaged on the incident end surface 4a of the first optical fiber 4, This modulated light is transmitted by the first optical fiber 4 and emitted from the output end face 4b.

This Il becomes the emitted light from the light transmitting section 1, that is, the measurement light. The state shown in FIG. 1 is the light transmitting section plus peripheral mechanisms such as the shutter 5, and the shutter 5 is a switching shutter that switches the light incident on the light receiving section 14 into either measurement light or correction light. A through hole 7 for a light transmission optical path is provided at the shutter position for measuring light so that the measuring light passes through, and a reflecting member 6 is attached to the shutter position for correcting light. This shutter 5 is fixed to a drive shaft 8 of a motor 9, and is rotated by the motor 9 according to the measurement light and correction light. When the measurement light is selected, the light passing through the condensing lens 3 is sent to the shutter of the motor 9. Since there is no reflecting member 6 in the position, the light passes through the shutter 5 as it is and enters the incident end face 4a of the first optical fiber 4. However, when the correction light is selected, it is reflected by the reflecting member 6 and used for transmitting the correction light. This is so that the light is incident on the second optical fiber 10.

When the measurement light is selected here, since the reflection member 6 is not set in the light transmission optical path, no light enters the second optical fiber 10, and there is no correction light, so the correction light is selected. At this time, the reflecting member is set in the light transmission optical path and the measurement light optical path is blocked, so that no light enters the first optical fiber 4 and no measurement light exists. In other words,
The selected optical path is blocked from the other optical path.

To explain in more detail including the above, first consider the case where the measurement light is selected, the emitted light from the light emitting element 2 is focused by the condensing lens 3, and the light transmitting light path through hole 7 of the shutter 5 is condensed. After passing through, an image is formed on the incident end surface 4a of the first optical fiber 4. Here, the optical axis of the light emitting element 2 and the optical axis of the first optical fiber 4 are made to coincide with each other at the entrance part, and the angle of incidence on the entrance end surface 4a is 01 degrees on one side with respect to the optical axis. The measurement light transmitted by the first optical fiber 4 is emitted from the output end face 4b at an angle of 01 degrees on one side, substantially along the optical axis. Next, is this measurement light the first reflection surface of the beams blitter 11? It is reflected by 1a, passes through objective lens 5 and 2, and is emitted to the outside as a parallel beam of light. Furthermore, this emitted light is reflected by a corner cube 13 installed at the distance measurement point, and the reflected light passes through the objective lens 12 again, and the light beam splitter 1
1 second reflecting surface] 1 b, and is reflected by the light receiving part ■4
It becomes the distance N1 measurement information.

Here, the output end surface 4b and the light receiving section 14 are located at the focal point of the objective lens 12, so that light at an angle of 01 degrees on one side with respect to the optical axis of the first optical fiber 4 is emitted from and incident on the objective lens 12. be. Further, when the correction light is selected, the emitted light from the light emitting element 2 is collected by the condensing lens 3, reflected by the reflection member 6 that is covered by the shutter 5, and then reflected by the second optical fiber. 10
The image is formed on the incident end surface 10a of the. Here, the optical axis of the light emitting element 2 and the optical axis of the second optical fiber 10 are made to coincide with each other, and the angle of incidence on the incident end face 10a is the same as the angular range when the measurement light is applied, and the angle of incidence is 01 on one side with respect to the optical axis. It's a degree. In (J), the correction light transmitted by the second optical fiber 10 is from the output end surface tob to the L1 side with respect to the optical axis. The light is emitted at an angle of 1 degree, and the light in that angular range is focused by the condensing lens 15 and enters the light receiving section 14, and the light is corrected for measurement errors based on the optical path length in the device and the phase shift of the electronic circuit section. Become.

Furthermore, an ND filter 16 whose density changes depending on the rotation angle is provided on the front surface of the light receiving section 14, and is rotated by a drive shaft I7 of a motor or the like (not shown) to filter the measurement light from the corner cube 13. The amount of reflected incident light and the amount of corrected light focused by the condenser lens 15 are adjusted.

In this embodiment, the reflecting member 6 is attached to the shutter 5, and this shutter 5 is rotated by the motor 9, but the structure is such that the reflecting member is directly moved in and out of the optical path according to the measurement light and correction light without using a shutter. But what the heck?
can not use. FIG. 3 is an example of this, and one reflecting member 6 is rotated by a drive shaft 8 of a motor 9 according to the measurement light and the correction light, and is moved in and out of the optical path. In this way, any means for driving the reflecting member 6 may be used as long as the measurement light and the correction light can be switched. Furthermore, in this embodiment, the light reflected by the reflection member 6 is transferred to the second optical fiber 10.
However, it is also possible to use optical components such as condensing lenses and mirrors instead of using optical fibers. Further, in this embodiment, light having the same angle range with respect to the optical axis of the light emitting element is used as the measurement light and the correction light.

Since the phase unevenness with respect to the radiation angle can be small within this angular range, the size of the reflecting member 6 may be reduced to reflect only the light on the optical axis and use it as correction light. However, when selecting this correction light, it is necessary to block light other than the optical axis portion so that it does not reach the measurement optical path.

FIG. 4 shows another embodiment of the present invention, in which the light emitting element 2 is located at the focal point of the condensing lens 18, the entrance end surface 4a is located at the focal position of the condensing lens 19, and the entrance end surface Oa is the condensing lens. 20
The emitted light from the light emitting element 2 is turned into a parallel light beam by the condensing lens 18, and when this parallel light beam is used as measurement light, it passes through the transparent hole 7 for the light transmission optical path and is condensed by the focusing lens 19. The incident end face 4 of the first optical fiber 4 receives light.
When the correction light is used, the light is reflected by the reflecting member 6, then condensed by the condenser lens 20, and imaged onto the incident end surface of the second optical fiber 10], Oa. In this example, light is combined in the parallel beam part.

Since it can be switched, the light emitting element 2 and the condensing lens 18,
The first optical fiber 4 and the condensing lens 19, the second
The optical fiber 10, the condensing lens 20, a part of the shutter, etc. can be made into a unit, making adjustment easier.

As explained above, according to the present invention, a reflecting member is moved in and out on the light transmission optical path between the light emitting element and the light transmitting member of the light transmitting section according to the measurement light and the correction light, so that the light used as the measurement light and the By using light in the same radiation angle range or light on the optical axis as correction light, the phase with respect to the radiation angle is The effects of unevenness can be removed. Therefore, there is no need to bend the translucent material, and the large amount of emitted light can be obtained, making it possible to use highly directional light emitting elements that are very effective in application to light wave rangefinders. By selecting a light-emitting element with small phase unevenness and supplying a large amount of power to the light-emitting element to compensate for its poor emission efficiency, the inconvenience of securing the necessary amount of emitted light is eliminated, and compared to that type of light-emitting element, the number of It becomes possible to obtain a greater amount of radiated light with a supply power of -1000 yen. Therefore,
H
It is also very effective in doing so. Furthermore, since the reflective member is moved in and out of the light transmission optical path, there is no inconvenience that the amount of light is attenuated when the measurement light is selected, and the distance traveled is greater than when using a half mirror fixed on the optical path. You will also be able to get larger amounts. In addition, the optical fiber output end face of the light transmitting section is located at the focal point of the objective lens, and the measurement light is emitted.

The correction light switching shutter and its driving device, etc. are light emitting elements that are optically coupled with an optical fiber]
Since it is located close to the optical system, it is structurally advantageous compared to the case where the transmitting and receiving optical system is located in a crowded place.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention relating to a light transmitting section and its peripheral mechanism, and FIG. 2 is a diagram showing an optical system of a light wave ranging device including the light transmitting section and its peripheral mechanism shown in FIG. FIG. 3 is a diagram showing another embodiment of the driving section of the reflecting member, and FIG. 4 is a diagram showing an embodiment of the present invention regarding the light transmitting section and its peripheral mechanism in FIG. 1. It is a figure which shows another Example. ■...Light sending unit 2...Light emitting element 3 - Condensing lens 4...First optical fiber 5...Shutter 6...Reflection member 7...Through hole 8...
Drive shaft 9...Motor 10...Second optical fiber 11 Bee 11
Splitter 12 ・Objective lens 13 ・Corner cube 14 ・
Light receiving unit 15 ・Condensing lens 16 ・ND filter 17 ・Drive shaft 18.19.
20...Condensing lens

Claims (1)

[Claims] The modulated radiation light from the light transmitting part is emitted toward a reflector using a light transmitting optical system, and the modulated light reflected from the reflector is imaged on the light receiving part using a light receiving optical system. In a light wave distance measuring device that measures distance based on a phase difference between a light emitting element and a reflected modulated light, the light transmitting section is a V16 system that includes a light emitting element, a transparent member, and optical coupling between them, and the light emitting element and the light transmitting member are optically coupled. A reflecting member is provided on the light transmission optical path between the members, and is moved in and out depending on the measurement light and correction light. A light wave ranging device characterized in that the influence of phase unevenness on the radiation angle of the radiation modulated light is removed by using light in a radiation angle range as correction light.