CN104483098A - Real-time correction method for offline measurement error of crystal matching angle - Google Patents

Abstract

The invention discloses a real-time correction method for an offline measurement error of a crystal matching angle. The real-time correction method comprises the following steps of monitoring an incident laser drift angle in a crystal matching angle measurement process by virtue of a laser autocollimator; if the laser drift angle is greater than a preset threshold 0.4'', rejecting measurement data that the angle drift is over large; monitoring a rotating angle deviation of to-be-measured crystal in the crystal measurement process by virtue of the autocollimator; plugging the reserved rotating angle deviation into matching angle calculation. The real-time correction method has the significant effects that a light path standard offset and an optical angle drift are subjected to real-time correction through the autocollimator in the measurement process, and a dynamic error in the crystal matching angle measurement process is corrected, so that the condition that correction can only be carried out aiming at the standard static error in the past is changed; the measurement accuracy of the crystal matching angle is ensured; the dynamic measurement error in a large-aperture crystal offline measurement system can be removed to the maximal extent.

Description

Crystal match angle off-line measurement error real-time correcting method

Technical field

The present invention relates to optical engineering technical field, specifically, is a kind of crystal match angle off-line measurement error real-time correcting method.

Background technology

At present, in solid high power laser system, because the optimum matching angle of KDP crystal is relevant with the factor such as the cutting technique of the optical axis of crystal, the face shape of crystal and refractive index inhomogeneity, thus cause accurately, Quick Measurement becomes hot issue in the examination of current best match angular measurement.

In the off-line system measuring process of heavy caliber crystal match angle, there are two errors, be crystal moving displacement error, incident laser angle drift measuring error, the existence of these two errors has a strong impact on the accuracy of measurement result always.

But, the domestic correction about heavy caliber crystal match angle off-line measurement error mainly rests in the Static implicit method such as laser alignment, the correction of crystal face shape influence factor, but about the effective treating method that the influence factors such as moving displacement error, laser real-time angle drift are not relevant in measuring process.

Summary of the invention

For the deficiencies in the prior art, the object of this invention is to provide a kind of crystal match angle off-line measurement error real-time correcting method, the method can eliminate the dynamic measurement error such as moving displacement error in measuring process, laser real-time angle drift to the impact of crystal match angle off-line measurement.

For achieving the above object, the present invention states a kind of crystal match angle off-line measurement error real-time correcting method, and its key is to carry out according to following steps:

Step 1: in crystal optimum matching angular measurement process, the Crystal Rotation angular deviation x ' to be measured that each measurement point occurs under different angles monitored by employing crystal autocollimator _i, wherein i is for measuring sequence number, i=1 ~ n;

Step 2: adopt Laser Autocollimator to measure the laser angular drift θ ' of incident beam _i, and with predetermined threshold value θ ₀relatively, if θ ' _ibe greater than θ ₀, then the Crystal Rotation angular deviation x ' to be measured that this measurement obtains is deleted _iwith the motor position x of Crystal-support mechanism _iif, θ ' _ibe less than θ ₀, then the Crystal Rotation angular deviation x ' to be measured that this measurement obtains is retained _iwith the motor position x of Crystal-support mechanism _i, and enter step 3;

Step 3: by the anglec of rotation deviation x ' occurred during the Crystal Rotation to be measured retained _iwith the motor position x of Crystal-support mechanism _iaccording to x _i=x _i+ x ' _icarry out matching, obtain the real electrical machinery position x of Crystal-support mechanism _iand the ratio y of energy meter 2 corresponding to this position and energy meter 1 reading _i, thus realize eliminating dynamic measurement error.

As further technical scheme, described laser angular drift predetermined threshold value θ ₀value is 0.4 ".

Incident laser drift angle in this method application Laser Autocollimator monitoring measuring process, if laser drift angle is greater than predetermined threshold value 0.4 ", cast out this angle and float excessive measurement data; the anglec of rotation deviation that in application autocollimator monitoring crystal measurement process, crystal to be measured occurs; the anglec of rotation deviation wherein retained is substituted in calculating into matching angle, at utmost can eliminate the dynamic measurement error in heavy caliber crystal off-line measurement system.

Remarkable result of the present invention is: revised in real time light path standard skew in measuring process and the drift of optics angle by autocollimator, and dynamic error is revised in crystal match angular measurement process, change over only for the Static error correction situation of benchmark, ensure that the accuracy of crystal match angular measurement, at utmost can eliminate the dynamic measurement error in heavy caliber crystal off-line measurement system.

Accompanying drawing explanation

Fig. 1 is light path schematic diagram of the present invention;

Fig. 2 is method flow diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention and principle of work are described in further detail.

Crystal match angle of the present invention off-line measurement system as shown in Figure 1, this system comprises laser instrument, spectroscope 1, spectroscope 2, periscope 1, periscope 2, heavy caliber standard mirror and crystal to be measured, laser sends from described laser instrument, by described spectroscope 1, incident laser is divided into two bundles: a branch ofly incide on energy meter 1, another bundle incides on the periscope 2 after crystal to be measured through described periscope 1, by described spectroscope 2, incident beam is divided into two bundles: wherein a branch ofly incide energy meter 2 after periscope 2 reflects.

Wherein, described laser instrument is 1053nm laser instrument, and model is PL3143A-2-DPSS, and main performance index parameter is Output of laser wavelength is 1053nm; Pulsewidth is 50ps; Repetition frequency is 2Hz; Laser energy is 50mJ; Energy stability is 1.5%; The angle of divergence is 0.5mrad; Described Laser Autocollimator adopts infrared laser high precision photoelectric digital display autocollimator, and it adopts two light source design: comprise the 635nm visible red light source for slightly collimating and the 1053nm infrared laser light source for Accurate collimation.It not only can utilize self light source to carry out autocollimation or angle measurement, also can accept external infrared laser and carry out collimating or angle measurement, have automatic data collection and hold function, be easy to realize intelligentized control method.Its main performance index parameter: autocollimation precision and angle measurement accuracy are all better than 1 ", measurable angle range about 1200 ".

Described crystal autocollimator adopts Collapex AC300 type digital display photoelectric autocollimator, and this collimator has automatic data collection and hold function, is easy to realize intelligentized control method.Its main performance index parameter: autocollimation precision is better than 1 ", angle measurement accuracy is better than 0.3 ", measurable angle range about 1200 ".

As shown in Figure 2, invention have been described a kind of crystal match angle off-line measurement error real-time correcting method, carry out according to following steps:

Step 1: gather the energy meter reading of energy meter 1 and 2, the measurement of energy change value when completing Different matching horn shape state on crystal to be measured, the coordinate that order records discrete point is (x _i+ x ' _i, y _i), and adopt the Crystal Rotation angular deviation x ' to be measured that crystal autocollimator monitoring measurement point occurs under different angles _i, wherein, x _ifor the motor position of Crystal-support mechanism, i is for measuring sequence number, y _ifor the ratio of crystal energy meter 2 and energy meter 1 reading when Different matching angle, i=1 ~ n;

Step 2: adopt Laser Autocollimator to measure the laser angular drift θ ' of incident beam _i, and with predetermined threshold value θ ₀relatively, if θ ' _ibe greater than θ ₀, then the Crystal Rotation angular deviation x ' to be measured that this measurement obtains is deleted _iwith the motor position x of Crystal-support mechanism _iif, θ ' _ibe less than θ ₀, then the Crystal Rotation angular deviation x ' to be measured that this measurement obtains is retained _iwith the motor position x of Crystal-support mechanism _i, and enter step 3; θ described in this example ₀value is 0.4 ";

Step 3: by the anglec of rotation deviation x ' occurred during the Crystal Rotation to be measured retained _iwith the motor position x of Crystal-support mechanism _iaccording to x _i=x _i+ x ' _icarry out matching, obtain the real electrical machinery position x of Crystal-support mechanism _iand the ratio y of energy meter 2 corresponding to this position and energy meter 1 reading _i, thus realize eliminating dynamic measurement error.

Therefore, the crystal optimum matching angle computing method eliminated after dynamic error are as follows:

The fit curve equation at known crystal optimum matching angle is:

P _m(x)＝a ₀+a ₁x+…a _mx ^m

Then each discrete point (x _i+ x ' _i, y _i) point (x corresponding with in matched curve _i+ x ' _i, P _m(x _i+ x ' _i)) difference quadratic sum be:

$F(a_0,a_1,...,a_m)=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\σ}}^2=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{[y_i-P_m(x_i+{x_i}^{\text{'}})]}^2$

Only try to achieve and make above functional value reach minimum, matched curve P _m(x _i) every point function value is just closest to actual value.Make above functional value minimum, need to superior function respectively to a ₀, a ₁..., a _mcarry out differentiate:

$\frac{\∂F}{\∂a_j}=2\underset{i=1}{\overset{n}{\mathrm{\Σ}}}[y_i-P_m(x_i+{x_i}^{\text{'}})]{(x_i+{x_i}^{\text{'}})}^j=2\underset{i=0}{\overset{n}{\mathrm{\Σ}}}[y_i-\underset{k=0}{\overset{m}{\mathrm{\Σ}}}{a}_k{(x_i+{x_i}^{\text{'}})}^k]{(x_i+{x_i}^{\text{'}})}^j=0$

That is: $\underset{k=o}{\overset{m}{\mathrm{\Σ}}}{a}_k\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(x_i+{x_i}^{\text{'}})}^{k+j}\right)=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i{(x_i+{x_i}^{\text{'}})}^j,j=\mathrm{0,1,2},...,m$

Because of P _mx () most high reps is m, coefficient of correspondence is a _m, therefore m+1 system of equations can be arranged:

$\left\{\begin{array}{c}n{a}_0+a_1\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(x_i+{x_i}^{\text{'}})+...+a_m\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(x_i+{x_i}^{\text{'}})}^m=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i\\ a_0\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(x_i+{x_i}^{\text{'}})+a_1\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(x_i+{x_i}^{\text{'}})}^2+...+a_m\mathrm{\Σ}{(x_i+{x_i}^{\text{'}})}^{m+1}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i(x_i+{x_i}^{\text{'}})\\ .............................................................\\ a_0\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(x_i+{x_i}^{\text{'}})}^m+a_1\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(x_i+{x_i}^{\text{'}})}^{m+1}+...+a_m\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(x_i+{x_i}^{\text{'}})}^{2m}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{y}_i{(x_i+{x_i}^{\text{'}})}^m\end{array}\right.$

Just a can be solved according to above system of equations ₀, a ₁..., a _m, thus draw fit curve equation P _m(x _i), then to P _m(x _i) carry out differentiate, with measured data scope for field of definition (x ₁+ x ₁', x _i+ x _i') in ask its maximal value, x value corresponding to maximal value is the crystal optimum matching Angle Position after error correction.

Claims (2)

1. a crystal match angle off-line measurement error real-time correcting method, is characterized in that carrying out according to following steps:

Step 1: in crystal optimum matching angular measurement process, the Crystal Rotation angular deviation x ' to be measured that each measurement point occurs under different angles monitored by employing crystal autocollimator _i, wherein i is for measuring sequence number, i=1 ~ n;

Step 2: adopt Laser Autocollimator to measure the laser angular drift θ ' of incident beam _i, and with predetermined threshold value θ ₀relatively, if θ ' _ibe greater than θ ₀, then the Crystal Rotation angular deviation x ' to be measured that this measurement obtains is deleted _iwith the motor position x of Crystal-support mechanism _iif, θ ' _ibe less than θ ₀, then the Crystal Rotation angular deviation x ' to be measured that this measurement obtains is retained _iwith the motor position x of Crystal-support mechanism _i, and enter step 3;

Step 3: by the anglec of rotation deviation x ' occurred during the Crystal Rotation to be measured retained _iwith the motor position x of Crystal-support mechanism _iaccording to x _i=x _i+ x ' _icarry out matching, obtain the real electrical machinery position x of Crystal-support mechanism _iand the ratio y of energy meter 2 corresponding to this position and energy meter 1 reading _i, thus realize eliminating dynamic measurement error.

2. crystal match angle according to claim 1 off-line measurement error real-time correcting method, is characterized in that: the predetermined threshold value θ of the drift of laser angular described in step 2 ₀value is 0.4 ".