JPH02120816A - Method for adjusting laser light axis - Google Patents

Abstract

PURPOSE:To accurately adjust the optical axis of a laser beam even if the installation angle of a reflecting device is insufficient by estimating the deviation of the incident light of the laser beam and the setting error of the installation angle of the reflecting device from a change in the disposition angle of the reflecting device and the positions of the transmitted laser beams. CONSTITUTION:The device consisting of a mirror 1, actuators 2, 3, 5, 6, beam splitters 4, 9, lenses 7, 10, and detectors 8, 11 are used. Namely, the deviation of the incident light of the laser beam from the standard and the setting error of the installation angle of the reflecting device are estimated from the change in the installation angle of the reflecting device and the positions of plural ways of the transmitted laser beams detected by the respective detectors. The optical axis of the laser beam is adjusted in accordance with the estimated values. The adjustment and control of the installation angle are accurately executed even if the positions of the optical parts are not accurately adjusted to meet the target.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a laser optical axis adjustment method.

(Prior Art) In high-output laser devices, the laser transmission optical path tends to be long. In order to maintain the performance of this laser device, it is necessary to precisely adjust the optical axis of the transmitting laser, and if the optical path is long, adjustment becomes difficult. Further, even after the first adjustment, the optical axis may shift due to various factors.

Therefore, a method of automatically adjusting and controlling the optical axis by attaching an actuator to a mirror or the like to change its direction has been proposed.

Hereinafter, a conventionally proposed automatic adjustment and control method of the optical axis will be explained with reference to FIG. Reference numeral 1 in the figure is a mirror, and this mirror 1 reflects the optical axis p1 and reflects the optical axis I2.
shall be. Furthermore, an actuator 2 for rotating the mirror 1 around a vertical axis at the center of the front surface of the mirror 1 and an actuator 3 for rotating the mirror 1 around a horizontal axis at the center of the front surface of the mirror 1 are provided on the back surface of the mirror 1, respectively. In addition, beam splitters 4 that reflect and transmit the optical axis II2 reflected by the mirror 1 are provided at appropriate locations. On the back side of the beam splitter 4, similarly to the mirror 1, there are an actuator 5 that rotates around the vertical axis at the center of the front surface of the beam splitter 4, and an actuator 6 that rotates around the horizontal axis at the center of the front surface of the beam splitter 4. Each is provided. In addition, the optical axis j7 transmitted through the beam splitter 4
A lens 7 for adjusting 3 to a desired size, and a detector 8 for illuminating the optical axis transmitted through this lens 7 are provided at appropriate locations. This detector 8 detects the two-dimensional position of the beam spot on the detector surface, and this detected value is input to a control device (not shown) connected to the above-mentioned actuators 2 and 3. The position of the mirror 1 is adjusted by controlling the operation of the actuator 2 and the actuator 3. On the other hand, a beam splitter 9 that reflects and transmits the optical axis II4 reflected by the beam splitter is provided at an appropriate location, and a lens 10 that adjusts the optical axis g5 that has passed through the beam splitter 9 to a desired size; Detectors 11 are provided at appropriate locations to irradiate the optical axis that has passed through.

Like the detector 8, this detector 11 also detects the two-dimensional position of the beam spot on the detector surface, and this detected value is transmitted to a control device (not shown) connected to the actuators 5 and 6. ) and controls the operation of actuator 5 and actuator 6 to adjust the position of beam splitter 4.

When adjusting the optical axis, it is first assumed that the target optical axis '40 passes through the center point of the beam splitter 4 and a predetermined point on the beam splitter 9.

Then, the output of the detector 8 is fed back to the actuator of the mirror 1 and the control means (not shown) of 2.3.
5. Rotate the mirror 1 so that the optical axis I3 hits a predetermined position on the detector 8, that is, the optical axis f12 hits the center of the beam splitter 4. Furthermore, detector 1
1 output to actuators 5 and 6 of beam splitter 4.
By feeding back to the control device (not shown) and rotating the beam splitter 4, the optical axis is aligned with the detector 1.
The optical axis g4 reflected at the center of the beam splitter 4 is made to coincide with the target optical axis '40 so as to hit a predetermined position of '40.

(Problem to be Solved by the Invention) However, when using a detector that detects only the position of the beam spot, it is difficult to determine whether the beam deviation on the detector is due to an angular deviation of the beam or a parallel deviation. It is not possible to distinguish between Therefore, for example, even if the beam hits a predetermined position on the detector, if the beam is tilted, the beam is not necessarily at the center of the beam splitter. That is, the optical axis g4 of the reflected light from the beam splitter will deviate from the desired one, and the accuracy of optical axis adjustment will deteriorate.

It is also possible to estimate the optical axis of the incident light by combining the outputs of the two detectors and adjust the optical axis by rotating the mirror and beam splitter. The calculation requires knowing the exact positions of the mirror, beam splitter and detector. However, it is often difficult to accurately target the relative positions and angles of spatially separated mirrors, beam splitters, and detectors; Otherwise, the accuracy of the estimated optical axis of the incident light will be insufficient, and it will not be possible to adjust the optical axis with high precision. For example, differences between the installation angle of mirrors and beam slivers on the device and the actual angles, ie, setting errors, often occur.

The present invention was made in view of the problems mentioned above.
Even if the positions of optical components such as mirrors and beam splitters are not precisely adjusted to the target,
It is an object of the present invention to provide a laser optical axis adjustment method that allows accurate adjustment and control of the optical axis.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a plurality of reflection devices that can reflect and transmit laser beams, a plurality of detection devices that detect the position of the transmitted laser beam from the reflection devices, and a plurality of detection devices that detect the positions of the transmitted laser beams from the reflection devices. and an actuator for adjusting the optical axis of the laser beam, the laser beam adjusting method adjusting the optical axis of the laser beam, the laser beam adjusting method adjusting the optical axis of the laser beam by changing the installation angle of the reflecting device so that each of the detection devices can transmit a plurality of transmitted laser beams. Detect the position of 17
, from the change in the installation angle of the reflection device and the position of the transmitted L nose beam detected by each of the detection devices, estimate the deviation of the incident light of the laser beam from the reference and the setting error of the installation angle of the reflection device; The optical axis of the laser beam is adjusted based on the estimated value of . Further, the present invention detects a plurality of positions of the transmitted laser beam by changing the installation angle of the reflection device and using each of the detection devices,
From the change in the installation angle of the reflection device and the position of the transmitted laser beam detected by each of the detection devices, the deviation of the incident light of the laser beam from the reference and the setting error of the installation angle of the reflection device are estimated, and these are estimated. The method is characterized in that the optical axis of the laser beam is adjusted based on these estimated values.

(Function) According to the present invention, the deviation of the incident light of the laser beam from the reference and the deviation of the incident light of the laser beam from the reference and the position of the reflected device are determined based on the change in the installation angle of the reflection device and the plurality of positions of the transmitted laser beam detected by each detection device. Since the setting error of the installation angle can be estimated and the optical axis of the laser beam can be adjusted based on this estimated value, the optical axis of the laser beam can be adjusted accurately.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a diagram showing a configuration for adjusting an optical axis 1 according to an embodiment of the present invention. Reference numeral 1 in the figure is a mirror, and this mirror 1 reflects the optical axis Ω to form an optical axis Ω2. Also, on the back surface of this mirror 1, there is a vertical axis n at the center of the surface of the mirror 1.
An actuator 2 of a gimbal mechanism for rotation around the mirror 1 and an actuator 3 of a gimbal mechanism for rotation around the horizontal axis nff1h at the center of the surface of the mirror 1 are provided.

Also, beam splitters 4 are provided at appropriate locations to reflect and transmit the optical axis g reflected by the mirror 1. On the back surface of this beam splitter 4, similarly to the mirror 1, there is an actuator 5 of a gimbal mechanism that rotates around the vertical axis nbSv at the center of the surface of the beam splitter 4, and an actuator 5 that rotates around the horizontal axis nbsh at the center of the surface of the beam splitter 4. An actuator 6 of a gimbal mechanism for rotation is provided respectively. Further, a lens 7 for adjusting the optical axis g3 transmitted through the beam splitter 4 to a desired size, and a detector 8 for illuminating the optical axis g3 transmitted through the lens 7 are provided at appropriate locations. This detector 8 detects the two-dimensional position of the beam spot on the detector surface, and this detected value is sent to an arithmetic and control unit (not shown) connected to the actuators 2 and 3.
is input to actuator 2 and actuator 3.
The position of the mirror 1 is adjusted by controlling the operation of the mirror 1.

On the other hand, a beam splitter 9 is provided at an appropriate location to reflect and transmit the optical axis Ω4 reflected by the beam splitter, and a lens 10 is provided to adjust the optical axis I5 transmitted through the beam splitter 9 to a desired size. A detector 11 for irradiating the optical axis transmitted through this lens 10 is provided at an appropriate location. Like the detector 8, this detector 11 also detects the two-dimensional position of the beam spot on the detector surface, and this detected value is sent to the arithmetic and control unit (
(not shown) and controls the operation of actuator 5 and actuator 6 to adjust the position of beam splitter 4.

The installation positions of the mirror 1, beam splitter 4, detector 8, beam splitter 9, and detector 11 are then adjusted to the target positions so that the optical axis g4 or the optical axis g6 coincides with a desired straight line. The optical axis g4 or the optical axis g6 during this adjustment is set as the target optical axis '40''80, respectively, and j710 is set as the reference incident light.The outputs of the detectors 8 and 11 at that time, and the outputs of the actuators 2, 3, and 5 , the feedback values for each position of the actuator 6 are stored in an arithmetic and control unit (not shown).・Then, when the incident optical axis changes, the reference optical axis and the actual incident light are A method for estimating the deviation and the deviation between the target reference position and the actual reference position of the optical components of the mirror 1, beam splitter 4, and beam splitter 9 based on the outputs of the detector 8 and the detector 11 is described below. Shown below.

In Figure 2, ``40'' is the target optical axis, and ``1''
0"20"40"50'" 80 is mirror 1,
These are reference incident and reflected optical axes such that a target optical axis is obtained when the beam splitter 4 and the beam splitter 9 are at the reference positions. And the incident optical axis '10 is mirror 1
It is reflected at the center of the optical axis '20, and the optical axis '
The beam 20 is reflected at the center of the beam splitter 4 and curved to become an optical axis '40, and further bent by the beam splitter 9 to become an optical axis '60. On the other hand, the optical axis g and the optical axis' transmitted through the beam splitter 4 and the beam splitter 9, respectively.
50 passes through lens 7° and lens 10 to detector 8.
It is assumed that this corresponds to the reference position of the detector 11.

A point v1o on the optical axis 110 is expressed as follows.

"10"v00+"l "10"'
(1) Here, 'Foo is a point on '10, tl is a parameter, and π1o is a direction vector of '10. Also,
It can be expressed as a function of the actual value as follows.

vi ”'Foo+ΔFoo+ t t-, (Tto
+Δu1o) Cabinet V (Δ'oo' 6 sun,., tl)
...(2) where Y + Δ'Foo is one point on p1, Δroo is a vector perpendicular to Ω1o, and π
10+Δu10 is a vector indicating the direction of gl, and Δ
Since u10 is taken to be perpendicular to '10, Δr
and Δ dimension. are two-dimensional, so Δ'F −
<Δr, Δp)T Go OOX OOy, ΔU
)...(3) Δu10'''' (described as Δ' IOX toy, where ) T represents transposition.

On the other hand, the reflective surface of the mirror 1 is described by the installation position of the mirror 1 and the angle of the reflective surface. The angles in the gimbal mechanism of the rotation of the mirror 1 with two degrees of freedom are α and β, and the target reference angle is α. .

IIIl βn+0'The actual reference angle is αmO+Δαmo' β
ll1o+Δβ,. Then, the point V on the actual reference reflective surface of mirror 1 can be expressed as a function of Δα, o, Δβ, 0 as follows. Here, ΔαmO′Δβmo is the difference between the installation angle of the mirror 1 on the device and the actual angle, that is, a setting error.

M (Δαmo'Δβ, o, vll) -0・(4)
r Therefore, by calculating the intersection of the optical axis I11 of the incident light and the mirror 1, the reflection point can be described.

Furthermore, the optical axis g2 of the reflected light can be described from the direction of the optical axis of the incident light and the angle of the mirror. The point v2 on the optical axis g2 is 7m1m (Δ'oo'Δname0.Δα..,Δβ..

. It can be expressed as However, t2)...(
5) t2 is a parametric variable.

Furthermore, the angle in the gimbal mechanism of the two-degree-of-freedom rotation of the beam splitter 4 is αbs', βbs' is the target reference angle, α, β is the actual reference bsObs.

Let the angles be α + Δα, β + ΔβbsO and bs
o bso bsO Then, the reflective surface of the beam splitter 4 is a function of the point V on the reflective surface, Δα, Δβbso, and bs
bs.

TeB (Δα, Δβ v)−〇...
(6) s bso bso ″
bs, and the reflection point at the beam splitter 4 can be described by calculating the intersection of this reflection surface and the above-mentioned reflection optical axis jl12. Here Δα
, Δβbso is the difference between the set angle and the actual angle of the beam splitter 4, that is, the setting error.

Similarly to the above, the point v4 on the optical axis Ω3 of the transmitted light of the beam splitter 4 is V-7 (ΔY Δπ Δα Δβ Δα Δβ t
)4 4 00'10' mo
'moo bsObsoゝ 4...(7
) can be expressed as Furthermore, by calculating the intersection of the transmitted light that has passed through the lens 7 and the plane of the detector 8, the position v,1 of the optical axis hitting the detector 8 can be written as 2M−v(ΔF ΔHΔa,.

,Δβ,. , ΔαbsO, AβdS□ )di d
i 00'10'=(? v )"dlx' d2y """)
Similarly, the optical axis Ω4 of the reflected light from the beam splitter 4, the reflection point on the beam splitter 9, and the optical axis ρ5 of the transmitted light from the beam splitter 9 can be described in the same way, and the position "d2" of the optical axis that hits the detector 11 is as follows. It can be written as

v=7(Δr Δπ ΔαmO'Δβ, ., ΔαbSo
, ΔβbSo) d2 d2 00° 10' ” (vd2x, vd2y) - (9) By the way, in the above description of the reflection point, reflected light, transmitted light, and irradiation point to the detector, sin (θ0+Δθ0) exists sinθ0+Δθ0'C
08cos (θ0+Δθ0)mi cosθ0−Δθo−
31nΔθ1×Δθ2)0 etc., equations (8) and (9) become Δ'
oox 'Δp, Δπ, 6 dimensions, Δα,. 7
Δβ,. .

00y fox JoyΔαbSo,
It can be described as a linear expression of ΔβbsO.

In other words, it becomes. However, a, b, (i-1~4.j-11j
J~8) is the coefficient of the above equation.

Here, assuming that the matrix of the first term on the left side of equation (10) is A1, the column vector of the second term is Δma, and the column vector of the right side is A.ΔX=...(11).

In this case, A in the first term on the left side is a constant used in the equations (2) to (9), and therefore A is a known number.

Also, of ΔX in the second term on the left side, Δvoox 'Δr
, ΔU, ΔU are 00Y of the laser beam
IOX IOY Deviation of incident light from reference (formula (3)), Δα. 0゜Δβ□. is the setting error of the installation angle of the mirror 1 (formula (4)), and Δα and Δβb8 are the setting errors of the installation angle sO of the beam splitter 4 (formula (6)). . Therefore, all ΔX are unknown quantities.

Furthermore, since each element of the incorrect column vector in equation (10) is a known number since it is the detection position of the laser beam detected by the detector 8 and the detector 11, the column vector on the right side is also known.

Furthermore, the installation angle of the mirror 1 or the beam splitter 4 is adjusted by the actuator 2. Actuator 3゜Actuator 5. The actuator 6 is moved a predetermined distance mXK to change the detector 8. Detector 11
When the detected position is read, the number of the above-mentioned - following equations increases, and the rows of the above-mentioned matrix A and C can be increased.

For example, if the installation angle of the mirror 1 or the beam splitter 4 is changed and the detection positions by the detectors 8 and 11 are changed in two ways, then equations (10) and (11)
) In the formula, the rows of A and the rows of are doubled to eight rows.

When formula (11) is multiplied by the transposed matrix AT of A from the left on both sides, ATAΦΔma■AT· becomes (12), and when this is solved for ΔX, the least squares approximation solution of ΔX is obtained. That is, using the output of detector 8° and detector 1, the deviation of the incident light of the laser beam from the standard,
It is also possible to estimate the setting error of the installation angle of the mirror 1 and the setting error of the installation angle of the beam splitter 4.

Then, based on this estimated value, the optical axis II4 is set as the target optical axis.
It is possible to calculate the installation angles of the mirror 1 and the beam splitter 4 to make the optical axis I4 coincide with the target optical axis ρ4o, and drive the mirror 1 and the beam splitter 4 to make the optical axis I4 coincide with the target optical axis ρ4o. Or the optical axis g is the target optical axis' 4
It is possible to calculate the target values of the outputs of the detector 8 and the detector 1 when the output becomes 0, and it is possible to drive the mirror 1 and the beam splitter 4 to align the optical axis Ω with the target optical axis Ω4o.

In addition, in the above embodiment, the setting error of the installation angle of the mirror and beam splitter was estimated.
Assuming that there is a setting error in the installation positions of the mirror, beam splitter, lens, and detector, this setting error may be estimated. In other words, it is not easy to set a highly accurate standard, and any factor that has a large influence on the accuracy of optical axis adjustment may be arbitrarily selected and estimated in the minimum necessary amount. This simplifies the calculation of estimation and improves accuracy efficiently.

In addition, in the above embodiment, the optical axis is adjusted using the estimated setting error of the installation angle, but the estimated setting error is added to the reference value as a new reference value.
The estimation operation may be performed again. This will further improve accuracy.

〔Effect of the invention〕

As described above, the present invention detects the deviation of the incident light of the laser beam from the reference and the installation angle of the reflection device based on the change in the arrangement angle of the reflection device and the plurality of positions of the transmitted laser beam detected by each detection device. The setting error can be estimated and the optical axis can be adjusted based on this estimation. In this way, it is possible to estimate not only the deviation of the incident light but also the setting error of the installation angle of the reflection device, so even if the installation accuracy of the reflection device is insufficient, the optical axis can be adjusted with high precision. It has the effect of

Z, 11...Detector.

Claims (1)

[Claims] 1. A plurality of reflection devices that can reflect and freely transmit laser beams, a plurality of detection devices that detect the position of the transmitted laser beam from the reflection devices, and changing the installation angle of the reflection devices. and an actuator for adjusting the optical axis of the laser beam. Estimate the deviation of the incident light of the laser beam from the reference and the setting error of the installation angle of the reflection device from the change in the installation angle of the reflection device and the position of the transmitted laser beam detected by each of the detection devices, and estimate these. A laser optical axis adjustment method characterized by adjusting the optical axis of a laser beam according to a value. 2, comprising a plurality of reflection devices that can reflect and freely transmit laser beams, a plurality of detection devices that detect the position of the transmitted laser beam from the reflection devices, and an actuator that changes the installation angle of the reflection device, In the laser optical axis adjustment method of adjusting the optical axis of the laser beam, the installation angle of the reflection device is changed, and each of the detection devices detects a plurality of positions of the transmitted laser beam, and the installation angle of the reflection device is changed. Based on the change and the position of the transmitted laser beam detected by each of the detection devices, the deviation of the incident light of the laser beam from the standard and the setting error of the installation position of the reflection device or detection device are estimated. A laser optical axis adjustment method characterized by adjusting the optical axis of a beam.