JPS60195479A - Distance measuring device - Google Patents

Abstract

PURPOSE:To measure a distance with a high accuracy by irradiating a single pulse light from a light source to an object, amplifying its reflected light, irradiating it repeatedly to the object, oscillating it by a prescribed frequency, and also counting this frequency. CONSTITUTION:A pulse signal outputted from a pulse generator 21 is inputted to a laser oscillator 22, and a pulse laser light L is oscillated. Subsequently, the light L is reflected by a translucent mirror 23, made to pass through a collimator lens 24, reflected and made to ge back, also amplified by an optical amplifier 26, the object 25 is irradiated again, and it is repeated. Also, the light L is oscillated by a prescribed frequency (f) in a process of a closed loop, and a part of said light is reflected by the translucent mirror 23 and made incident on a photodetector 28, also converted to a pulse electric signal and inputted to an operating part 29, counted by a counter 30 and converted to a distance by a transducer 31. In this way, the measuring accuracy is improved by a simple device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a distance measuring device that uses light to measure the distance to an object.

[Technical background of the invention and its problems]

The first device to measure the distance to an object using light.
The one shown in the figure is known. In other words, 1 in the figure is a pulse generator, and a t-low pulse signal V4 outputted from the pulse generator 1 is amplified by an amplifier 2 and then inputted to a laser diode 3. As a result, the radar diode 3 outputs pulsed laser light, and this laser 1'Q I
, sends light to the first optical system 4 and illuminates the surface of the object 5.

The pulsed laser beam I reflected by this object 5 enters the first light-receiving element 2 through the second optical system 6;
The light is converted by the light receiving cable 7 and then input to the time measuring device 9 via the amplifier 8. On the other hand, a portion of the pulsed laser beam (1) emitted from the radar diode 3 is applied to the second light receiving element 1 through the Lt semi-transparent boundary 1o. Then, this pulsed laser beam is photoelectrically converted by the second light receiving element 1, and then amplified by the amplifier 12, and is then amplified by the time measuring device 9.
Enter. This time measuring device 9 receives a signal input manually from the second light-receiving element 1.

The time difference with the signal I input from the first light receiving element 2, that is, the time from when the pulsed laser light is output from the laser diode 3 until it is input to the second light receiving element 11 is measured. Therefore, the distance to the object 5 can be determined from the relationship between this time and the known speed of light.

By the way, according to the device 1, which measures distance from the time difference between the signals manually input to the time measuring device 9, for example, the IO
When trying to obtain a resolution of
Since it is see, 1/1s on 5ec is 1
Count. In other words, the above-mentioned time difference must be measured with a counter of approximately 611 (HIZ). However, such an ultra-high-speed counter is not only extremely expensive, but also requires delicate handling and is prone to errors, so it is difficult to measure the distance to the object. It had drawbacks such as being difficult to measure with high precision.

[Purpose of the invention]

This invention makes it possible to measure the distance to an object by oscillating pulsed light in a closed loop and using its frequency instead of using the time difference between pulse signals, making it possible to perform highly accurate measurements without the need for ultra-high-speed counters. The object of the present invention is to provide a distance measuring device that has the following features.

[Summary of the invention]

This invention aims to irradiate an object with a single pulsed light output from a light source [7, amplify the pulsed light reflected by this object with an amplifier (7) direct the pulsed light amplified by this amplifier to the upper eye [: By repeating the irradiation, the pulsed light is oscillated at a predetermined frequency, and this frequency is counted by the calculation unit to determine the distance to the object.

[Embodiment of the Invention] An embodiment of the invention will be described below with reference to FIG. 2. In the figure, 21 is a pulse generator.

This pulse generator 21 outputs a single pulse signal of several seconds, and this pulse signal is manually input to a laser oscillator 22. From this laser oscillator 22,
A pulsed laser beam of several OWX is oscillated depending on the response time. This laser light is reflected by the semi-transparent mirror 23 and enters the collimator lens 24.
Then, the object 25 is irradiated. Reflected by object 25 1. The pulsed laser beam (1) passes through the collimator lens 24 and the semi-transparent mirror 23 and enters the amplifier 26. This amplifier 26 includes a reflecting mirror 27 and a driving section 28.
is connected. The pulsed laser beam incident 17 on the amplifier 26 is optically amplified by the energy from the driving section 28, and then reflected by the reflecting mirror 27 and output from the optical amplifier 26. The pulsed laser light emitted from the optical amplifier 26 passes through the semi-transparent mirror 23 and the collimator lens 24 and irradiates the object 25.

That is, the pulsed laser light oscillates at a predetermined frequency within a closed loop between the reflecting mirror 27 and the object 25.

On the other hand, a part of the pulsed laser light emitted from the optical amplifier 26 is reflected by the semi-transparent mirror 23 and enters the photodetector 28,
Here, it is converted into a pulse electric signal q. This photodetector 28
The pulsed electric signal from is input to the calculation section 29. This converter W section 29 is formed of a counter 30 that counts the frequency of the pulse electric signal, and a converter 31 that converts the frequency counted by the counter 30 into a distance.

Next, the operation of the device thus implanted will be explained. First, when a pulse signal output from the pulse generator 21 is input to the laser oscillator 22, the laser oscillator 22 emits pulsed laser light. This pulsed laser light is reflected by a semi-transparent mirror 23 [7], passes through a collimator lens 24, and irradiates an object 25. Then, it is reflected from this object 25 to the collimator lens 24 and the semi-transparent mirror 23.
The beam passes through the beam, enters the optical amplifier 26, is amplified here, and then irradiates the object 25 again. This process is repeated. Therefore, the pulsed laser beam oscillates at a predetermined frequency f within a closed loop of such a process. Also, part of the pulsed laser light that oscillates at frequency f.

It is reflected by the semi-transparent mirror 23 and enters the optical detector IB device 28 [2], where it is converted into a pulsed electrical signal and input to the calculation section 29 .

Then, the counter 30 of the arithmetic unit 29 calculates the pulse electric value 9 divided by -7+' (17), and this count value is converted into a distance by the converter 71 by 3. -) and the distance to the object 25 is measured.

The frequency f can be determined by the following equation. In other words, f-/2L (1) where C is the speed of light, and 3 is the distance between the reflecting mirror 27 and the object 25. Therefore, the frequency f is measured, the distance to the object 25 is calculated as j(1) by the calculation unit 29.
Served. For example, if the distance RI from the reflecting mirror 27 to the object 25 is 1 m, the frequency f will be 15QMHz. This frequency f is about 1/400 of the frequency of 60GTTz when measured using the conventional time difference.

Therefore, the counter 3 provided in the calculation section 29VC
0 may be slower than the conventional one.

F−rD″/s T,! ・・・・・・・・・・・・(2
) can be determined by the formula. Here, the reflectance of the ragged object 25, D is the diameter of the collimator lens 24, and ■ is the reflector 27.
and the object 25.

And r = 0. l, D = O, ], m, L
= 1 m, then F=IX10-'. Therefore, if the amplification factor of the amplifier 26 is set to be equal to or higher than ]X1n5, the light IA of the pulsed laser beam that oscillates once will not be attenuated.

Note that this invention is not limited to the above embodiment.

For example, as the reflector 27, a 71-nacube or a phase conjugate wavefront reflector 11 that actively returns the Pelse 1 nose light to the incident direction may be used, and if such a mirror is used, alignment of the optical index will be easy. Become. Further, the optical amplifier 26 and the reflecting mirror 27 may have an integral structure.

[Effects of the Invention] As described above, the present invention irradiates an object with pulsed light 7 and amplifies the pulsed light reflected from the object with an optical amplifier 1
7. By repeatedly irradiating the object with this amplified pulsed light, the pulsed light was oscillated at a predetermined frequency, and by counting this frequency, the distance to the object was determined. (7) Therefore, compared to the conventional method that calculates the distance 1iIII from the time difference between the pulsed light going back and forth to the object, the counting frequency can be made sufficiently lower, which reduces the cost of the device and makes handling easier. You can measure the face of

Furthermore, since the pulsed light can be oscillated by an optical system, it is possible to make the device more flexible than when the pulsed light is oscillated in a European manner.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional apparatus, and FIG. 2 is a block diagram of an apparatus R (not shown) according to an embodiment of the present invention. 22... Laser oscillator (light source), 24... Collimator lens (optical system), 25... Object, 26... Optical amplifier, 29... Arithmetic unit

Claims (1)

[Claims] A light source that outputs a single pulsed light; an optical system that irradiates an object with the pulsed light output from the light source; and a an optical amplifier that oscillates pulsed light at a predetermined frequency by repeatedly irradiating the object with pulsed light via the optical system; 1. An arithmetic unit that counts the frequency of the pulsed light oscillated by the amplifier and calculates the distance to the object based on the frequency.1. A distance measuring device characterized by: