CN104237987A - Grating groove bending automatic control and correcting method - Google Patents

Abstract

The invention provides a grating groove bending automatic control and correcting method and relates to the technical field of grating ruling. The automatic control and correcting method solves the problems that improvement design and installation debugging need to be repeatedly carried out on the mechanical structure of a grating ruling machine in a mechanical design method in the existing grating groove bending correction technique, the design process is complex, efficiency is low and the groove bending correction effect is poor. The method includes the steps of (S101) building a grating average groove bending mathematical model, (S102) conducting grating pre-ruling to obtain a pre-ruling grating, and calculating grating average groove bending of the pre-ruling grating, (S103) designing an automatic control scheme of the grating ruling machine, (S104) building a work table displacement compensation mathematical model of the grating ruling machine, and (S105) correcting grating groove bending in an automatic control method. By means of the grating groove bending automatic control and correcting method, grating groove bending can be effectively reduced, grating diffraction wavefront quality is improved, and operation precision and work efficiency of the grating ruling machine are improved.

Description

A kind of grating line is bending controls bearing calibration automatically

Technical field

The present invention relates to grating ruling technical field, particularly relate to and a kind ofly reduce that the bending grating line of grating line is bending controls bearing calibration automatically.

Background technology

The plane grating adopting mechanical scratching method to make is due to the impact of the adamas icking tool rail direct linear error of optical grating graduating machine scoring system and the factor such as rigidity is limited, adamas icking tool can be caused to run along curvilinear path, thus make mechanical scratching grating produce curve tendency.The groove that curve tendency shows as each groove of grating is bending, and when the stable performance of optical grating graduating machine scoring system, curved shape and the amplitude of each groove of grating comparatively repeat.Grating line bending error affects optical grating diffraction beam quality.Changchun Inst. of Optics and Fine Mechanics, Chinese Academy of Sciences is carrying out finding in the development of large scale grating, and when increasing raster size, curve tendency error is one of principal element affecting optical grating diffraction beam quality.Reduce grating line to bend, contribute to improving optical grating diffraction beam quality, reduce the aberration of grating image system, improve preparing grating precision and application level.

Prior art adopts the method improving Design of Mechanical Structure to reduce the curve tendency of grating.Although by repeatedly repeatedly to design optical grating graduating machine scoring system physical construction and after a large amount of debugging tests, can reduce the bending amplitude of grating line to a certain extent, but to be undoubtedly efficiency lower for said method.

Summary of the invention

The present invention adopts the repetitious Curve guide impeller of optical grating graduating machine physical construction and Installation and Debugging for solving existing grating line curvature correction method, there is the problems such as the low and curve tendency calibration result of design process complexity, efficiency is poor, the invention provides that a kind of grating line is bending controls bearing calibration automatically.

A kind of grating line is bending controls bearing calibration automatically, and it comprises the steps:

S101, set up the average curve tendency mathematical model of grating;

S102, carry out grating prescribed, obtain prescribed grating, calculate the average curve tendency of grating of described prescribed grating;

The automatic control scheme of S103, design optical grating graduating machine;

S104, set up optical grating graduating machine worktable displacement compensate mathematical model;

S105, carry out grating ruling, adopt automatic control methods calibration grating curve tendency.

In the present invention one better embodiment, step S101 comprises further:

S1011, derive grating line error under grating conical diffraction mounting, mathematic(al) representation between grating substrate face shape error and optical grating diffraction wavefront;

S1012, from described grating line error, remove the integral position error of grating pivot angle and grating line, obtain the relational expression between the average curve tendency of grating and grating line error.

In the present invention one better embodiment, method of geometrical optics in step S1011, is adopted to derive grating line error under grating conical diffraction mounting, mathematical relation expression formula between grating substrate face shape error and optical grating diffraction wavefront.

In the present invention one better embodiment, the average curve tendency of described grating, according to step S1011 and step S1012, indirectly extracts and obtains from optical grating diffraction wavefront.

In the present invention one better embodiment, step S102 comprises further:

Before the order of symmetry time diffracted wave of described prescribed grating measured by S1021, employing optical grating diffraction wavefront measurement instrument, and therefrom extract grating line error;

S1022, according to the relational expression between the average curve tendency of described grating and grating line error, calculate the average curve tendency value of grating of described prescribed grating.

In the present invention one better embodiment, in step S104, according to optical grating graduating machine scoring system and the physical construction of indexing system and the average curve tendency of grating of described prescribed grating, the principle of work of optical grating graduating machine, derive described optical grating graduating machine worktable displacement and compensate mathematical model, obtain the theoretical displacement of the worktable being used for the average curve tendency of null grating.

In the present invention one better embodiment, in step S105, according to the automatic control scheme of the described optical grating graduating machine in step S103, and the described optical grating graduating machine worktable displacement in step S104 compensates mathematical model, adopt piezo actuator to carry out displacement to micro-positioning table to regulate in real time, the deviation of the actual displacement amount of worktable any time and the theoretical displacement of described worktable is minimized.

Beneficial effect of the present invention: relative to prior art, grating line provided by the invention bending control automatically bearing calibration has following good effect: contribute to reducing grating line and bend, improve optical grating diffraction beam quality, and contribute to improving optical grating graduating machine running precision and work efficiency.

Above-mentioned explanation is only the general introduction of technical solution of the present invention, in order to technological means of the present invention can be better understood, and can be implemented according to the content of instructions, and can become apparent to allow above and other objects of the present invention, feature and advantage, below especially exemplified by embodiment, and coordinate accompanying drawing, be described in detail as follows.

Accompanying drawing explanation

Fig. 1 is that grating line provided by the invention bends the process flow diagram automatically controlling bearing calibration;

Fig. 2 is the optical path difference schematic diagram that face shape error causes;

Fig. 3 is the optical path difference schematic diagram that Divided errors causes;

Fig. 4 is the scoring system block diagram of CIOMP-2 rose engine;

Fig. 5 is the indexing system block diagram of CIOMP-2 rose engine;

Fig. 6 is grand micro-two-stage Working table structure schematic diagram;

Fig. 7 is interferometer measurement mirror and reference mirror placement location schematic diagram;

Fig. 8 is adamas icking tool displacement diagram;

Fig. 9 is brace and connecting rod framework principle of work schematic diagram.

Embodiment

Below in conjunction with drawings and the specific embodiments, the present invention is further detailed explanation.

Refer to Fig. 1, present embodiment provides a kind of grating line to bend and automatically controls bearing calibration, and it comprises the steps:

S101, set up the average curve tendency mathematical model of grating.

Comprise further:

S1011, derive grating line error under grating conical diffraction mounting, mathematic(al) representation between grating substrate face shape error and optical grating diffraction wavefront.

S1012, from described grating line error, remove the integral position error of grating pivot angle and grating line, obtain the relational expression between the average curve tendency of grating and grating line error.

Particularly, in the present embodiment, employing method of geometrical optics derives the grating line error under grating conical diffraction mounting and the relational expression between substrate face shape error and optical grating diffraction wavefront.

Assuming that the monochromatic collimated beam that a branch of wavelength is λ is incident to plane reflection grating surface, incident angle and angle of diffraction are respectively θ ₁and θ ₂, grating constant is d.

First the situation of grating without Divided errors but when there is substrate face shape error is considered.As shown in Figure 2, grating line direction is the z-axis direction vertical with paper, when the arbitrfary point i on grating p article of groove and grating ideal surfaced exist depth error h (x _p, y _p, z _pi) time, if the optical path difference that incident light and diffraction light produce is respectively δ _b1and δ _b2, then the total optical path difference δ that produces at this point of incident light and diffraction light _bpifor

δ _bpi＝δ _b1+δ _b2＝h(x _p,y _p,z _pi)(cosθ ₁+cosθ ₂)\*MERGEFORMAT (1)

When grating is without substrate face shape error but when there is Divided errors, as shown in Figure 3, the distance departing from desirable scribe line position p as the physical location p' of the arbitrfary point i on grating p article of groove is w (x _p, y _p, z _pi), if incident light and diffraction light are respectively δ in this some optical path difference that produces _r1and δ _r2, then the optical path difference summation δ that produces at this point of incident light and diffraction light _rpifor:

δ _rpi＝δ _r1+δ _r2＝w(x _p,y _p,z _pi)(sinθ ₁+sinθ ₂)\*MERGEFORMAT (2)

If optical grating diffraction level time is m, grating constant is d, and grating uses wavelength to be λ, then from grating equation:

d(sinθ ₁+sinθ ₂)＝mλ (3)

Simultaneous formula (1), formula (2) and formula (3) can obtain, when the arbitrfary point i of grating p article of groove exists substrate face shape error, Divided errors simultaneously, then at the optical path difference δ that this point produces _pifor:

δ _pi＝δ _bpi+δ _rpi＝h(x _p,y _p,z _pi)(cosθ ₁+cosθ ₂)+w(x _p,y _p,z _pi)mλ/d (4)

When adopting before interferometer measurement plane grating diffracted wave, the light channel structure that general employing monochromatic light incident angle is equal with optical grating diffraction angle absolute value, i.e. θ ₁equal θ ₂.Now, known according to formula (4), interferometer records m level optical grating diffraction wavefront optical path difference and is:

Δ(m)＝2H cosθ ₁+Wmλ/d (5)

Wherein, H and W is respectively the substrate face shape error on the full surface of grating and Divided errors and quantizes matrix, θ ₁it is m level optical grating diffraction angle.

Obtain grating ± m level time diffraction wavefront array Δ (m) and Δ (-m) according to interferometer measurement, can obtain grating line error expression according to formula (5) is:

$W=\frac{[\mathrm{\Δ}\left(m\right)-\mathrm{\Δ}(-m)]d}{2\mathrm{m\λ}}---\left(6\right)$

If the matrix form of the Divided errors W of the grating that through type (6) calculates is

Respectively arrange along grating line direction in formula (7), in formula (7), remove the integral position error of grating line pivot angle and grating line, each element value b of grating line bending matrix B can be obtained _ijfor:

$b_{\mathrm{ij}}={\mathrm{\ϵ}}_{\mathrm{ij}}-\frac{({\mathrm{\ϵ}}_{\mathrm{aj}}-{\mathrm{\ϵ}}_{1j})(i-1)}{a-1}-{\mathrm{\ϵ}}_{1j}---\left(8\right)$

Wherein, i=1,2,3 ..., a; J=1,2,3 ..., b.

Each row of grating line bending matrix B in formula (8) are averaged, the average curve tendency B of grating can be obtained _mfor:

$B_m={[\underset{j=1}{\overset{b}{\mathrm{\Σ}}}{b}_{1j}\underset{j=1}{\overset{b}{\mathrm{\Σ}}}{b}_{2j}\underset{j=1}{\overset{b}{\mathrm{\Σ}}}{b}_{3j}\·\·\·\underset{j=1}{\overset{b}{\mathrm{\Σ}}}{b}_{\mathrm{aj}}]}^T---\left(9\right)$

According to formula (6) ~ formula (9), namely obtain the average curve tendency mathematical model of grating.

S102, carry out grating prescribed, obtain prescribed grating, calculate the average curve tendency of grating of described prescribed grating

In order to obtain the concrete numerical value of the average curve tendency of grating of certain grating line length (as 60mm), first need carry out a grating prescribed experiment, obtaining prescribed grating.

In this example, comprise further:

S1021, adopt optical grating diffraction wavefront measurement instrument (as zygo interferometer etc.) measure as described in prescribed grating order of symmetry time (as ± 1 grade etc.) diffracted wave before, and therefrom extract grating line error.

S1022, according to the relational expression between the average curve tendency of described grating and grating line error, calculate the average curve tendency value of grating of described prescribed grating.

The automatic control scheme of S103, design optical grating graduating machine.

In order to correct the average curve tendency of grating, need to adopt autocontrol method to regulate optical grating graduating machine worktable displacement in real time, make described optical grating graduating machine worktable displacement offset the average curve tendency value of grating in real time, thus the grating line that reduction optical grating graduating machine systematic error causes bend.

In the present embodiment, adopt the displacement of two-frequency laser interferometer to worktable to measure in real time, and adopt piezo actuator to regulate in real time worktable displacement.

The present embodiment consider China optical grating graduating machine be mainly CIOMP-1 to the CIOMP-5 optical grating graduating machine of Changchun Institute of Optics, Fine Mechanics and Physics, CAS, wherein CIOMP-2 optical grating graduating machine is the optical grating graduating machine that current table positions precision is the highest, and 3 σ values of its short-term positioning error can reach 5nm.Below, this enforcement, for CIOMP-2 optical grating graduating machine, is specifically introduced the automatic control scheme of optical grating graduating machine.

Optical grating graduating machine can be divided into scoring system and indexing system in physical construction, and wherein scoring system is for realizing the to-and-fro movement of adamas icking tool, and indexing system is for realizing the admission motion of worktable.Refer to Fig. 4, the scoring system of CIOMP-2 rose engine mainly comprises delineation motor, crank connecting link, copper shoe, copper shoe guide rail, pull bar, delineation knife rest, quartzy guide rail, its main operational principle is: rotated by delineation motor driving crank, thus makes crank connecting link drive saddle slide block to move reciprocatingly on quartzy guide rail by copper shoe and pull bar.Saddle slide block and quartzy guide rail carry out rubbing contact by eight shoes, saddle slide block is fixedly connected with delineation knife rest, the bottom of delineation knife rest is provided with adamas icking tool, adamas icking tool is with fused quartz guide rail side for spigot surface carries out grating ruling operation in delineation knife rest drawback movement, and the roll setting operation of lifting of wherein delineating knife rest realizes automatically controlling by lifting roll setting piezoelectric ceramics.

What the indexing system of CIOMP-2 rose engine adopted is grand micro-two-stage Working table structure, its (indexing system block diagram as shown in Figure 5) main operational principle is: indexing motor is after speed reduction unit slows down, take worm couple and feed screw nut secondary motion to, nut is connected by spring leaf with grand positioning table, thus makes indexing motor drive grand positioning table to carry out the grand positioning action of worktable; The micro-positioning table physical location recorded according to two-frequency laser interferometer again and the departure of ideal position, the microposition being realized worktable by Piezoelectric Ceramic micro-positioning table operates.

Grand micro-two grade working table concrete structures of CIOMP-2 optical grating graduating machine as shown in Figure 6.Grating substrate 5 is placed in micro-positioning table 2, grand positioning table 1 is " basin type " structure, micro-positioning table 2 embedding macros positioning table 1 is inner, and microposition and grand positioning table are hung by four elastic steel sheets 3 and be connected, four symmetrical parallel placements of elastic steel sheet 3.Piezo actuator 4 is installed between grand positioning table 1 and micro-positioning table 2, and the nanoscale being realized micro-positioning table 2 by the stretching motion of piezo actuator 4 is accurately located.

The displacement resolution that CIOMP-2 optical grating graduating machine adopts U.S. Agilent (Agilent) company to produce is the positional information of the two-frequency laser interferometer Real-Time Monitoring micro-positioning table 1 of 0.15nm, composition graphs 7, the measurement catoptron 6 of two-frequency laser interferometer is installed on micro-positioning table 1, reference mirror 7 is arranged on optical grating graduating machine scoring system quartz guide rail 8, thus realize the Real-Time Monitoring that micro-positioning table 1 changes with the relative displacement of scoring system quartz guide rail 8, simultaneously reference mirror 7 and the above-mentioned installation site of measuring catoptron 6 effectively can reduce the impact of optical grating graduating machine thermal expansion on scoring system quartz guide rail and micro-positioning table 1 relative displacement measurement result.Two-frequency laser interferometer adopts wavelength tracker to realize environment (air refraction, temperature and humidity) to external world to change the laser interferometer measurement error caused and carry out real-Time Compensation.

S104, set up optical grating graduating machine worktable displacement compensate mathematical model.

In the present embodiment, according to optical grating graduating machine scoring system and the physical construction of indexing system and the principle of work of optical grating graduating machine, derive described optical grating graduating machine worktable displacement and compensate mathematical model, obtain the theoretical displacement of the worktable being used for the average curve tendency of null grating.And according to described optical grating graduating machine worktable displacement compensation mathematical model, worktable displacement is controlled in real time, the grating line namely caused optical grating graduating machine systematic error bends and compensates.

Particularly, as shown in Figure 8, if grating line length is L _g, in a groove scoring process, adamas icking tool current location D _cwith roll setting position D _odistance be adamas icking tool displacement s, then have 0≤s≤L _g.Adopt least square method to carry out the matching of h order polynomial to formula (9), relational expression E (s) of the average curve tendency of grating and adamas icking tool displacement s can be obtained, if it can be expressed as

$E\left(s\right)=\underset{q=0}{\overset{h}{\mathrm{\Σ}}}{c}_q{s}^q,q=\mathrm{1,2,3},\·\·\·,h$

Compensate in order to the grating line caused optical grating graduating machine scoring system is bending, need worktable is compensated with the direction contrary with the average curve tendency of grating in every bar grating line scoring process, and its offset is the opposite number of grating line bending value, is-E (s).

CIOMP-2 optical grating graduating machine adamas icking tool does variable-speed motion in grating ruling process, therefore before carrying out the bending correction of grating line, needs the time T first obtaining adamas icking tool displacement s and its experience _sbetween relational expression, start with from the brace and connecting rod framework of CIOMP-2 machine scoring system below and analyze.

As is shown in fig. 9 c, the corresponding crank center position of some O, some A and some B represents the two ends of connecting rod respectively, and some B and some C represents the two ends of pull bar, and pull bar is directly connected with saddle slide block, crank center O and pull bar BC not conllinear and set the vertical range of the two as h _bD.

In fig .9, BC and OD, OD ', OD " and parallel, BD ⊥ OD, BD ' ⊥ OD ', BD " ⊥ OD ", ∠ AOD=θ, ∠ AOD '=θ ₁, ∠ AOD "=θ ₂; If the then maximal value L of L _maxwith minimum value L _minoccur in pull bar respectively apart from crank center farthest and (as shown Fig. 9 (b) and 9 (c)) the most nearby, $L_{\max }=\stackrel{\‾}{{\mathrm{OD}}^{\′}}$ With $L_{\min }=\stackrel{\‾}{{\mathrm{OD}}^{\′\′}},$ And have:

$\left\{\begin{array}{c}{\mathrm{\θ}}_1=\arcsin \left(\frac{h_{\mathrm{BD}}}{L_{\mathrm{AB}}+r}\right)\\ {\mathrm{\θ}}_2=\arcsin \left(\frac{h_{\mathrm{BD}}}{L_{\mathrm{AB}}-r}\right)\end{array}\right.---\left(11\right)$

$\left\{\begin{array}{c}L=r\cos \mathrm{\θ}+\sqrt{{L_{\mathrm{AB}}}^2-{(h_{\mathrm{BD}}-r\sin \mathrm{\θ})}^2}\\ L_{\max }-L_{\min }=L_g\end{array}\right.---\left(12\right)$

Formula (11) is updated to formula (12) can obtain:

$r=\frac{L_g}{2}\sqrt{\frac{{{4L}_{\mathrm{AB}}}^2-{{4h}_{\mathrm{BD}}}^2-{L_g}^2}{{{4L}_{\mathrm{AB}}}^2-{L_g}^2}---\left(13\right)}$

If definition saddle type slider displacement s=L _max-L, as shown in Figure 9:

$s=\sqrt{{(r+L_{\mathrm{AB}})}^2-{h_{\mathrm{BD}}}^2}-r\cos \mathrm{\θ}-\sqrt{{L_{\mathrm{AB}}}^2-{(h_{\mathrm{BD}}-r\sin \mathrm{\θ})}^2}---\left(14\right)$

If the rotational frequency of crank is f0 hertz, the initial rotation phase place of crank is zero, then crank angle θ and time T _spass be:

θ＝2πf ₀T _s (15)

Simultaneous formula (14) and formula (15), can obtain saddle slider displacement s and crank times T _srelational expression be:

$s=\sqrt{{(r+L_{\mathrm{AB}})}^2-{h_{\mathrm{BD}}}^2}-r\cos \left(2\mathrm{\π}{\mathrm{fT}}_s\right)-\sqrt{{L_{\mathrm{AB}}}^2-{(h_{\mathrm{BD}}-r\sin \left(2\mathrm{\π}{\mathrm{fT}}_s\right))}^2}---\left(16\right)$

If grating constant is d and the micro-positioning table displacement of the 0th article of groove is 0, then for n-th (n=1,2,3 ...) bar groove, it is n that micro-positioning table should have initial displacement _d.So when carrying out scoring operation to n-th groove, adopting piezo actuator to carry out grating line and bending in makeover process, the delineation time T of micro-positioning table displacement and n-th groove _srelational expression be:

D(T _s)＝nd-E(s) (17)

Namely obtain optical grating graduating machine worktable displacement and compensate mathematical model.

S105, carry out grating ruling, adopt automatic control methods calibration grating curve tendency.

Namely according to the automatic control scheme of the described optical grating graduating machine in step S103, and the described optical grating graduating machine worktable displacement in step S104 compensates mathematical model, adopt piezo actuator to carry out displacement to micro-positioning table to regulate in real time, make the deviation of the actual displacement amount of worktable any time and the theoretical displacement of described worktable minimum, thus realize compensating grating line is bending.

Relative to prior art, grating line provided by the invention bending control automatically bearing calibration has following good effect: contribute to reducing grating line and bend, improve optical grating diffraction beam quality, improve preparing grating precision and application level, and contribute to improving optical grating graduating machine running precision and work efficiency.

The above, only embodiments of the invention, not any pro forma restriction is done to the present invention, although the present invention discloses as above with embodiment, but and be not used to limit the present invention, any those skilled in the art, do not departing within the scope of technical solution of the present invention, make a little change when the technology contents of above-mentioned announcement can be utilized or be modified to the Equivalent embodiments of equivalent variations, in every case be do not depart from technical solution of the present invention content, according to any simple modification that technical spirit of the present invention is done above embodiment, equivalent variations and modification, all still belong in the scope of technical solution of the present invention.

Claims (6)

1. grating line is bending controls a bearing calibration automatically, it is characterized in that, comprises the steps:

S101, set up the average curve tendency mathematical model of grating;

S102, carry out grating prescribed, obtain prescribed grating; The average curve tendency mathematical model of grating according to step S101, calculates the average curve tendency of grating of described prescribed grating;

The automatic control scheme of S103, design optical grating graduating machine;

Be specially: adopt the displacement of two-frequency laser interferometer to worktable to measure in real time, the measurement catoptron of two-frequency laser interferometer is arranged on the micro-positioning table of optical grating graduating machine indexing system, reference mirror is arranged on the quartzy guide rail of optical grating graduating machine scoring system, and adopts piezo actuator to regulate in real time worktable displacement;

S104, the average curve tendency of grating calculated according to optical grating graduating machine physical construction, step S102 and the optical grating graduating machine automatic control scheme described in step S103, set up optical grating graduating machine worktable displacement and compensate mathematical model;

S105, carry out grating ruling, the optical grating graduating machine worktable displacement according to S104 compensates mathematical model, adopts the optical grating graduating machine automatic control scheme real time correction grating line described in step S103 to bend.

2. grating line according to claim 1 is bending controls bearing calibration automatically, and it is characterized in that, step S101 comprises further:

S1011, derive grating line error under grating conical diffraction mounting, mathematic(al) representation between grating substrate face shape error and optical grating diffraction wavefront;

S1012, from described grating line error, remove the integral position error of grating pivot angle and grating line, obtain the relational expression between the average curve tendency of grating and grating line error.

3. automatically control bearing calibration according to grating line as claimed in claim 2 is bending, it is characterized in that, in step S1011, adopt method of geometrical optics to derive grating line error under grating conical diffraction mounting, mathematical relation expression formula between grating substrate face shape error and optical grating diffraction wavefront.

4. grating line according to claim 2 is bending controls bearing calibration automatically, it is characterized in that, the average curve tendency of described grating, according to step S1011 and step S1012, indirectly extracts and obtains from optical grating diffraction wavefront.

5. grating line according to claim 1 is bending controls bearing calibration automatically, and it is characterized in that, step S102 comprises further:

Before the order of symmetry time diffracted wave of described prescribed grating measured by S1021, employing optical grating diffraction wavefront measurement instrument, and therefrom extract grating line error;

S1022, according to the relational expression between the average curve tendency of described grating and grating line error, calculate the average curve tendency value of grating of described prescribed grating.

6. grating line according to claim 1 is bending controls bearing calibration automatically, it is characterized in that, in step S105, according to the automatic control scheme of the described optical grating graduating machine in step S103, and the described optical grating graduating machine worktable displacement in step S104 compensates mathematical model, adopt piezo actuator to carry out displacement to micro-positioning table to regulate in real time, the deviation of the actual displacement amount of worktable any time and the theoretical displacement of described worktable is minimized, realizes the bending correction of grating line.