JPH09159874A - Alignment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust an optical axis with no loss without using a half-mirror for optical axis alignment when laser beam is transmitted to a long distance away. SOLUTION: A mirror 3 is provided at the periphery of a regular laser optical axis and if laser beam deviates from the regular optical axis, the laser beam impinges on the mirror 2 and is reflected and made incident on an optical detector, so that the optical axis deviation can be detected. Then a movable mirror device for adjusting the laser optical axis is controlled according to the output signal of the optical detector 1. Further, the optical detector 1 may be provided at the position of the mirror 3 and further a line sensor may be provided instead of the optical detector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment device used for long-distance transmission of laser light and an alignment method therefor, and an alignment device with reduced laser light attenuation and alignment using the same. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, when measuring a distance between remote places using a laser beam, an axis aligning device for aligning the optical axis of the laser beam with a target position separated by a long distance has been widely used. .

Japanese Unexamined Patent Publication No. 6-75196 (hereinafter referred to as this publication) describes a conventional axis aligning device.
The device will be described with reference to the drawings. FIG. 6 is a diagram showing a configuration of a conventional example described in this publication. This axis alignment device
The actuator 41 is arranged on the optical axis of the laser beam generated from a laser light source (not shown) and is used for adjusting the optical axis.
a first movable mirror device 41 having a, and the movable mirror device 41 disposed so as to face the first movable mirror device 41.
A second movable mirror device 42 that reflects the laser light from the optical system and has an actuator 42a for adjusting the optical axis,
The transmission side half mirror 43 arranged on the optical axis of the laser beam reflected by the second movable mirror device 42, and the transmission side half mirror 43 arranged at a predetermined transmission distance from the transmission side half mirror 43. A detection half mirror 45 that transmits laser light with a receiving half mirror 44 that reflects the laser light that has passed through the mirror 43 to an irradiation target (not shown), and that reflects and transmits the laser light reflected by the transmitting half mirror 43. And a direction detector 48 for detecting the optical axis direction of the laser light transmitted through the detection half mirror 45 via the total reflection mirror 46 and the convex lens 47, and the optical axis direction detected by the direction detector 48 is amplified. Amplifier 4
9, a first position detector 51 for detecting the optical axis position of the laser light reflected by the detection half mirror 45 via the convex lens 50, and the optical axis position detected by this position detector 51 is amplified. The amplifier 52 and the receiving side half mirror 4 detect the direction and position of the laser optical axis on the transmitting side.
A second position detector 54 for detecting the position of the optical axis of the laser beam transmitted through the optical axis 4 through the convex lens 53;
The optical axis position on the receiving side is detected by the amplifier 55 that amplifies the optical axis position detected by 4, and the data of the direction and the position of the optical axis are fetched from these amplifiers 49, 52 and 55 through the interface 56 and at the same time. A computer 57 that generates an optical axis adjustment signal based on the target value of, and the actuator 41a and the actuator 4 based on the optical axis adjustment signal.
2a for driving the actuator driver 58.

The first and second movable mirror devices 4
Reference numerals 1 and 42 have the same configuration as that of the movable mirror device 31.
The direction detector 48 is provided at the focal point of the convex lens 47 arranged in the subsequent stage of the total reflection mirror 46, and the positional deviation is Δ
Where r is the focal length and a is the focal length, the direction deviation Δθ is obtained by the equation (1), and for example, a PSD detector is used.

The position detectors 51 and 54 are, for example, four-division detectors (QPD), and the convex lens 50 is used to detect a laser beam having a diameter of about 60 mm by 10 mm.
Concentrated to 5 mm, which is half of the
And measure. The position resolution of this detector is about 40 μm
Therefore, the positional deviation of the laser beam can be measured with an accuracy of about 0.5 mm.

Here, the accuracy of the direction detector 48 is about 20 μm.
If the focal length of the convex lens 47 is 600 mm, Δθ = 3.3 × 10 ⁻⁵ , so that the laser light is 2
The accuracy when transmitted 50 m ahead is about 8.3 mm.

Next, a method of aligning such an aligning device will be described with reference to the flowchart of FIG. First, the laser light generated from the laser light source (not shown)
First movable mirror device 41, second movable mirror device 4
2. The transmission side half mirror 43 and the reception side half mirror 44 propagate the laser beam to an irradiation target (not shown) to form laser optical axes of these optical systems. Here, the angle θ indicating the direction of the laser optical axis on the transmission side, which is partially reflected by the transmission half mirror 43, is measured by the direction detector 48 (ST1.
1). The calculator 57 has an angle target value θ held in advance for this measurement angle θ. From the transmission side optical axis angle deviation | θ−θ as the transmission side optical axis direction deviation. || (ST12) and the transmission side optical axis angle deviation is the angle allowable width Δθ.
The second movable mirror device 42 is adjusted to be smaller (ST13), and the process returns to ST1 again.

Next, in ST12, the transmission side optical axis angle deviation is the angle allowable width Δθ. When it is determined that the position is smaller, the position detector 51 measures the position x of the laser optical axis partially reflected by the transmitting half mirror 43 (ST14). Calculator 57
Is a position target value x held in advance for this measurement position x. From transmission side optical axis position deviation | xx. |, And the transmission side optical axis position deviation and the position allowable width Δx held in advance. And (ST15), the transmission side optical axis position deviation is the position allowable width Δx. The position of the optical axis is adjusted so that the first and second movable mirror devices 41 and 42 are moved so as to maintain a parallel relationship so as to be smaller, and the angle θ is maintained (S).
(T16), and returns to ST4 again.

Further, in ST15, the transmission side optical axis position deviation is the position allowable width Δx. If it is determined to be smaller, the position of the optical axis is finely adjusted on the receiving side. That is, first, the position detector 54 measures the position X of the laser optical axis that has partially passed through the receiving half mirror 44 (ST17). When the measurement position X is outside the measurement range of the position detector 54, the optical axis cannot be measured, so the process returns to ST11 and the optical axis is adjusted again on the transmitting side. When the measurement position X is within the measurement range of the position detector 54, , And proceeds to the next process (ST18).

Next, the computer calculates the position target value X held in advance with respect to the measured position X on the receiving side. From the optical axis position deviation on the receiving side | XX. | Is obtained, and the optical axis position deviation on the receiving side and the position allowable width ΔX held in advance. (ST19),
The optical axis position deviation on the receiving side is the position allowable width ΔX. The first and second movable mirror devices 41, 42 are finely adjusted so as to be smaller (ST20), and the process returns to ST17 again.

After the fine adjustment, the position deviation of the optical axis on the receiving side is the position allowable width ΔX in ST19. If it is determined that the values of the transmission side measurement angle θ and the measurement position x at this time are
The angle target value θ on the transmission side held by the calculator 57. And the target position value x. The target value data is updated as
21) Then, the process returns to ST17 again to monitor the optical axis position on the receiving side.

In this way, the axis aligning device 40 can align the optical axes of the entire optical system. According to the conventional example described in the above publication, at the time of optical axis alignment, first, the laser optical axis is adjusted to the target value on the transmission side close to the laser light source, so that the laser optical axis can be rapidly roughly adjusted, After this rough adjustment, the laser optical axis is finely adjusted on the receiving side close to the irradiation target, so that the optical axis can be aligned with high accuracy.

Further, since the optical axis is first roughly adjusted on the transmitting side, which is hardly affected by the optical axis position, the optical axis can be quickly aligned even if the initial position of the optical axis is largely deviated. Further, since two detectors and two movable mirror devices are provided on the transmitting side so that the angle and position of the optical axis can be adjusted separately, the optical axis can be efficiently aligned in a predetermined procedure. It had a great effect that it could be done.

[0014]

However, the above-mentioned axis aligning device is provided with the direction detector 48 and the position detector 5.
Half mirror 4 for detecting laser light at 1, 54
Since a part of the light is extracted by using 3, 44, there is a problem that the intensity of the laser light finally output toward the irradiation target is lowered.

[0015]

According to a first aspect of the present invention, a mirror is arranged around a regular laser optical axis, and light reflected by the mirror is detected by a photodetector. The mirror is provided so that the laser light does not hit when the laser optical axis is along the regular axis, and the mirror is placed on the path of the laser light when the laser optical axis deviates from the regular axis. There is.

In the first aspect of the invention, when the laser beam is on the regular axis, there is nothing on the path that reduces the intensity of the laser beam, such as a half mirror, but when the axis is off, the laser beam is off. A mirror will be located in at least a part of the light path, and all or part of the laser light will be reflected by the mirror, and the reflected laser light will enter the photodetector and be detected.

The photodetector outputs a signal when laser light is incident, and controls the movable mirror based on this signal to restore the misaligned laser light axis to the normal axis. A second aspect of the present invention is to arrange a photodetector directly at the position of the mirror.

The second invention of the present invention is the above-mentioned first invention.
And a line sensor is used as the photodetector in the second invention. In the second aspect of the invention, when the laser light deviates from the normal axis, the photodetector is directly irradiated with a part or all of the laser light, and a signal is output from the photodetector. After that, the movable mirror is controlled in the same manner as in the first aspect of the invention to return to the normal axis. In the third invention, a line sensor is used as the photodetector.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration according to a first embodiment of the present invention. The same components as those of the conventional technique shown in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 6 of the prior art, the laser beam reflected by the second movable mirror device 42 is detected by the transmission side half mirror 43 by the partial extraction direction detector 48 and the position detector 51, and the transmission side half mirror 43 is detected. The laser beam that has passed through the mirror 43 is partially extracted by the receiving half mirror 44 and detected by the position detector 54.

In the first embodiment of the present application, the detecting section consisting of the receiving half mirror 44 and the position detector 54 is numbered as total reflection mirrors 63 and 61 shown in FIG. It is a detector.

The structure of the detector 61 is shown in FIG. FIG.
In this case, the four mirrors 3 are provided close to the sides of the square in accordance with the section of the laser beam which is square in this case, and the passage for passing the laser beam is provided in the center.

Each mirror is provided so that the position of this passage matches the position of the regular optical axis of the laser light. As shown in FIG. 2A, each of these mirrors is arranged at an angle with respect to the laser optical axis, and the photodetector 1 connected to the amplifier 4 corresponds to each of the mirrors on the outside thereof. It is provided.

When the laser optical axis is in the regular position,
As shown in FIG. 2A, since the laser light passes through the passage formed by four mirrors and does not hit any of the mirrors, there is no loss as compared with the conventional half mirror.

When the optical axis of the laser beam is deviated, it hits at least one of the four mirrors and is reflected by the mirror and detected by the photodetector 1. When the laser light is detected by the photodetector 1, the movable mirror devices 41 and 4 are thereafter arranged to return the laser light axis to the normal position as in the prior art.
2 is controlled.

Since the mirror shown in FIG. 2 has a square cross section of laser light, a flat mirror is provided corresponding to four sides, and the cross section of the laser light is, for example, circular. A mirror having a curved surface may be used for this, and a mirror having a shape according to need may be used.

Next, the axis aligning method of the first embodiment will be described with reference to the flowchart of FIG. Note that the control relating to this flowchart is performed for two mirrors facing each other in the mirrors shown in FIG. 2, and in the detector 61 having two mirrors facing each other, each pair is independently controlled by this flowchart. Controlled.

ST21 measures whether or not the laser light is detected by the two photodetectors. If there is no output from any of the photodetectors, it branches at ST22 and returns to ST21. If there is output, ST23
In step 2, the movable mirror device is driven and the axis is adjusted until the output from the photodetector that has output has stopped.

After that, in ST24, the presence or absence of the output of the photodetector is measured, and if there is no output from the photodetector on the opposite side in ST25, the process returns to ST21, but the output from the photodetector on the opposite side is output. For example, assuming that the movable mirror device has been moved too much, the movable mirror device is readjusted in ST26.

Then, in ST27 and ST28, the presence / absence of outputs from both photodetectors is confirmed, if there is an output, the readjustment is performed again, and if there is no output, control is performed to return to ST21. FIG. 4 shows a configuration of the second embodiment, in which a detector 62 similar to the detector 61 is provided in place of the detecting devices such as the half mirror 43 and the direction detector 48 shown in FIG. Is.

The axis alignment method of the second embodiment is described in the flow chart of FIG. Each of the movable mirror devices is controlled by the flowchart shown in FIG. 3, but first, the detector 62 performs a rough adjustment and then the detector 61 performs a fine adjustment.

Although not shown as the third embodiment, the photodetector 1 shown in FIG.
Alternatively, the photodetector 1 may be a line sensor that is generally commercially available.

In particular, when the photodetector 1 is a line sensor, it is possible to quantitatively detect the size of the deviation of the laser optical axis and use it for control. It is possible to return to the optical axis of the laser, and it is possible to simplify the control without the need to check the output of the photodetector on the opposite side after adjusting the movable mirror device as shown in the flowchart of FIG. Become.

[0034]

As described above, according to the present invention, the following effects can be obtained. In the first aspect of the invention, since the laser optical axis is adjusted without using a half mirror, there is an advantage that there is no loss of laser light and a high output can be obtained.

In the second invention, since the photodetector is arranged directly around the laser beam without using a mirror, there is an effect that the device can be downsized in addition to the effect of the first invention. In the third invention, since the line sensor is used as the photodetector, in addition to the effect of the first or second invention, there is an effect that simple control is sufficient.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of an axis aligning device according to the present invention.

FIG. 2 is a diagram showing a configuration of a detector according to the same embodiment.

FIG. 3 is a flowchart showing an axis alignment method according to the same embodiment.

FIG. 4 is a diagram showing a configuration of a second embodiment of an axis aligning device according to the present invention.

FIG. 5 is a flowchart showing an axis alignment method according to the same embodiment.

FIG. 6 is a diagram showing a configuration of a conventional axis alignment device.

FIG. 7 is a flowchart showing an axis alignment method according to the apparatus.

[Description of Reference Signs] 1 ... Photodetector, 3 ... Mirror, 4 ... Amplifier, 41 ... First movable mirror device 42 ... Second movable mirror device, 57 ... Calculator, 61, 6
2 ... Detector

Claims (3)

[Claims] 1. A movable mirror device for aligning the optical axis of a laser beam from a laser light source, and a part of the laser beam which is partially reflected or partially transmitted by a half mirror. An optical axis detection unit that detects the optical axis by the extracted laser light, and controls the movable mirror device so that the deviation between the optical axis of the laser light obtained by this optical axis detection unit and the normal optical axis is zero. In the axis aligning device including a calculator, the optical axis detection unit is composed of a mirror provided around the regular optical axis, and a photodetector that detects a laser beam reflected by the mirror and outputs a signal. The movable mirror device is controlled so that the signal from the photodetector is not output by the computer. 2. The axis aligning device according to claim 1,
An axis aligning device, wherein the optical axis detecting section is provided with a photodetector around a regular optical axis instead of a mirror. 3. The axis aligning device according to claim 1 or 2, wherein a line sensor is used as a photodetector, and the magnitude of deviation of the laser optical axis is output as a quantitative signal. Axis alignment device.