JPS60133381A - Light wave distance measuring apparatus - Google Patents

Abstract

PURPOSE:To remove the effect due to uneven phase with respect to the angle of radiation by moving a reflecting member into and out of the optical path between a light emitting section and an object lens to enable the use of light which is almost the same in the range of radiation angle as correcting light. CONSTITUTION:When a measuring light is selected, a radiation light from a light emitting section 1 passes through a through hole 5 of a shutter 2, then, reflected on the reflecting surface 6a of a light beam splitter 6 and radiated as parallel flux passing through an object lens 7. The radiation light is reflected with a corner cube 8 at the measuring point to be distance measuring information via a light receiving section 9. When a correcting light is selected, a radiation light from the light emitting section 1 passes through the through hole 5, a light with the range of angle of radiation almost the same as the measuring light containing the optical axis of the light emitting section 1 is reflected from a reflecting member 4 to form a parallel flux with a condenser lens 10 for the correcting light. Then, it is focused with a condenser lens 11 via reflecting members 12 and 13 and enters the light receiving section 9 to offer correcting information for measuring errors based on a phase deviation between the optical path length and an electronic circuit section in the apparatus.

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 measurement point. The distance is measured by emitting light and focusing the light returned from the reflector on a light receiving element using a light receiving optical system, converting it into an electrical signal, and detecting the phase delay of the reflected modulated light with respect to the reference modulated light. It is a device. In the case of such a light wave distance measuring device, 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 over time in the mechanical setting position of the optical path or the temperature characteristics of the light emitting element.
There is a problem that the distance measurement error increases. This phase unevenness is small and within an acceptable range near the optical axis in a highly directional light emitting element, which is very effective in that a large amount of light can be emitted from a light wave ranging device. At radiation angles that are far from the optical axis, phase unevenness with respect to angle tends to be very large.

Conventional methods for reducing the influence of phase unevenness on the radiation angle include a method of coupling a light emitting element and an optical fiber and bending this optical fiber to arrange it in the optical path; There are ways to use less.

However, it is difficult to achieve the purpose of bending the optical fiber without extreme bending, and the bending can lead to the optical fiber breaking, impairing the reliability of the optical rangefinder over time, and also causing radiation In order to use 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 since such a light emitting element is omnidirectional, it is difficult to actually The light output in the narrow radiation angle range used is small, and when used optically coupled with optical fibers, etc., the coupling efficiency with them is very poor, and more power is required to compensate for the coupling loss. The disadvantage is that the amount of emitted light must be increased by supplying

The purpose of the present invention is to solve the drawbacks of the above-mentioned conventional methods,
The object of the present invention is to provide a light wave distance measuring device that eliminates the disadvantages caused by phase unevenness, and its features are as follows.

In the present invention, a shutter is provided on the optical path between the light transmitting part and the objective lens to switch the light incident on the light receiving part into measurement light and correction light, and the light is reflected on the shutter at the shutter position when switching to the correction light. By attaching the member and condensing the reflected light with a condensing optical system, and using as correction light the light with a radiation angle range that is almost the same as the measurement light including the optical axis of the light transmitting unit, the optical axis of the light transmitting unit can be focused. On the other hand, unlike the case where light at a large angle is used as correction light, it is not affected by phase unevenness with respect to the radiation angle that leads to measurement errors. Then, it becomes 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 using omnidirectional light-emitting elements, which have little phase variation with respect to the radiation angle but are inefficient as light wave ranging devices. This inconvenience will no longer occur.

Embodiments of the present invention will be described in detail below with reference to the drawings. In addition to 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 distance measurement error. It is already known that by using this method, the phase unevenness caused by the location of the light emitting surface can be mixed evenly, and this problem can be solved.

Therefore, in consideration of this fact in the embodiments of the present invention, a combination of a light emitting element and an optical fiber or an optical rod is considered as a light transmitting section. here,
It is clear that an optical fiber or an optical rod is not necessary for a light emitting element that has no phase unevenness depending on the location of the light emitting surface, and the light emitting element may be placed as it is as a light transmitting section.

FIG. 1 is a diagram showing an embodiment of the present invention regarding the optical structure of a light wave distance measuring device, in which l is a light transmitting unit, 2 is a shutter for switching between measurement light and correction light, and 3 is a shutter 2. A driving device, 4 is a reflecting member provided on the shutter 2, 5 is a light transmission optical path through hole, 6 is a light beam splitter, 6a and 6b are reflective surfaces of the light beam splitter 6, 7 is an objective lens, 8 is a corner In the cube, 9 is a light receiving section, 10 and 11 are lenses for correction light, and 12 and 13 are reflection members for correction light.

FIG. 2 is a diagram showing an embodiment of the light transmitting section l in FIG. 1, in which 14 is a light emitting element, 15 is a condenser lens,
1G is an optical fiber, 16a is an input end face of the optical fiber 16, and 1 (3b is an output end face of the optical fiber 16).This optical fiber may be an optical rod.

In FIG. 2, the modulated light from the light emitting element 14 is transmitted to the optical fiber 1 via the condenser lens 15.
The image is formed on the incident end surface 16a of No. 6. The modulated light that has entered the input end face 16a is transmitted by the optical fiber 16 and is emitted from the output end face 16b. This is light transmitting section 1
It becomes radiation light from. In FIG. 1, the shutter 2 is
This is a switching shutter that switches the light incident on the light receiving section 9 to either measurement light or correction light. A reflecting member 4 is attached to the shutter position when the correction light is selected, and the reflecting member 4 is attached to the shutter position when the measuring light is selected. Therefore, the light passes through the shutter 2 and reaches the light beam splitter 6. At this time, the first reflecting member transmits light, but no light enters it. Further, when the correction light is selected, the emitted light from the light transmitting section 1 is reflected by a reflection member 4 such as a mirror provided on the shutter 2 and guided to the correction light optical path.

At this time, the measuring light is not present because the reflecting member is set in the light transmission optical path and the measuring light optical path is blocked. That is, considering the case where the measurement light is selected now, the emitted light from the light transmitting section 1 passes through the light transmitting optical path through hole 5 of the shutter 2, and then is reflected by the reflecting surface 6a of the light beam splitter 6. The light passes through the objective lens 7, becomes a parallel light beam, and is emitted to the outside.

This emitted light is reflected by a corner cube 8 installed at the distance measurement point, and the reflected light passes through the objective lens 7 again, is reflected by the reflective surface 6b of the light beam splitter 6, and enters the light receiving section 9. This becomes distance measurement information. In addition, when the correction light is selected, the emitted light from the light transmitting section 1 passes through the light transmitting optical path through hole 5 of the shutter 2 and is converted into measurement light including the optical axis of the light transmitting section by the reflecting member 4. Light in almost the same radiation angle range is reflected, becomes a parallel beam of light that enters the correction light condensing lens 10, is reflected by the first reflecting members 12 and 13, is condensed by the condensing lens 11, and enters the light receiving section 9. However, this information serves as correction information for measurement errors based on the optical path length within the device and the phase shift of the electronic circuit section.

In this embodiment, the reflecting member 4 is attached to the shutter 2, and this shutter is rotated by the driving device 3, 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 I can't blame you. FIG. 3 shows one example of this, in which one reflecting member 4 is rotated by a drive shaft 17 of a drive device 3 in accordance with the measurement light and the correction light, and is moved in and out of the optical path. As described above, the reflecting member 4 can be driven by any method as long as the measuring light and the correction light can be switched. Furthermore, in this embodiment, the parallel light velocity produced by the condensing lens 10 is transmitted by the reflecting members 12 and 13, but an optical fiber is used for this portion, and the condensing lens 10 connects the reflecting member 4 to the incident end of the optical fiber. The reflected light from the optical fiber is collected by the 1m optical lens 11, and the light is sent to the light receiving section 9.
It may be a structure in which the light is incident on the

As explained above, according to the present invention, a reflecting member is moved in and out of the optical path between the light transmitting unit and the objective lens according to the measurement light and the correction light, and the reflected light is focused by the focusing optical system, By using light with almost the same emission angle range as the correction light,
Unlike the case of using light at an angle far away from the optical axis of the light transmitter, the influence of phase unevenness on the radiation angle can be removed, and a large amount of radiation can be obtained, so it is not suitable for application to light wave rangefinders. It becomes possible to use a highly directional light emitting element that is immediately effective. Therefore, the inconvenience of securing the necessary amount of emitted light by selecting a light emitting element with small phase unevenness with respect to the radiation angle and supplying a large amount of power to that light emitting element to compensate for its poor emission efficiency is eliminated. It is possible to obtain a greater amount of emitted light with a few minutes of the supplied power compared to a device. Therefore, it is a very effective device for reducing power consumption and reducing electrical errors in a light wave distance measuring device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the optical structure of a light wave distance measuring device, FIG. 2 is a diagram showing an example of the light transmitting section, and FIG. 3 is a diagram showing an example of the driving section of the reflecting member. It is a figure showing an example. 1... Light transmitting section 2... Shutter 3... Shutter drive device 4... Reflection member 5...
・Light transmission optical path through hole 6...Light beam splitter 6a, 6b・
・Reflecting surface 7 of the light beam splitter 6 ・Objective lens 8 ・
... Corner cube 9 ... Light receiving section IQ, 11 ...
Tip lens for correction light 12.1.3... Reflection member for correction light 14... Light emitting element 15... Condenser lens 1
6...Optical fiber 16a...Incidence end surface 1 of optical fiber 16
6b... Output end surface 17 of optical fiber 16
... Drive shaft of drive device 3

Claims (1)

[Claims] The modulated radiation light from the light emitting section is emitted toward a reflector using a light transmitting optical system, and the reflected modulation from the reflector is focused on the light receiving section using a receiving optical system, so that the modulated radiation light and In a light wave distance measuring device that measures distance by a phase difference with reflected modulated light, a reflecting member is provided on the optical path between the light transmitting section and the light transmitting optical system, and is moved in and out according to the measurement light and the correction light, By arranging a single-beam optical system that focuses the correction light on the correction light optical path, the radiation modulated light having approximately the same radiation angle range as the measurement light is used as the correction light, and the radiation of the radiation modulated light is A light wave ranging device characterized in that the influence of phase unevenness with respect to angle is removed.