CN104237987B - A kind of grating line bending automatically controls bearing calibration - Google Patents

Abstract

A kind of grating line bending automatically controls bearing calibration, relate to grating ruling technical field, solve existing grating line curvature correction technique to need to use machine design method that optical grating graduating machine frame for movement is carried out repetitious Curve guide impeller and installation and debugging, the problem such as have that design process is complicated, efficiency is low and curve tendency calibration result is poor, the present invention includes: S101, set up grating average curve tendency mathematical model；S102, carry out grating prescribed, it is thus achieved that prescribed grating, calculate the average curve tendency of grating of described prescribed grating；S103, the automatic control scheme of design optical grating graduating machine；S104, set up optical grating graduating machine worktable displacement compensate mathematical model；S105, employing automatically control method calibration grating curve tendency.The bending of described grating line automatically controls bearing calibration can effectively reduce grating line bending, improves optical grating diffraction beam quality and is favorably improved optical grating graduating machine running precision and work efficiency.

Description

A kind of grating line bending automatically controls bearing calibration

Technical field

The present invention relates to grating ruling technical field, particularly relate to a kind of grating line bending reducing grating line bending and automatically control bearing calibration.

Background technology

Use plane grating that mechanical scratching method makes due to the diamond icking tool guide rail linearity error of optical grating graduating machine scoring system and the impact of the factor such as rigidity is limited, may result in diamond icking tool to run along curvilinear path, so that mechanical scratching grating produces curve tendency.The groove of each groove that curve tendency shows as grating is bending, and when optical grating graduating machine scoring system stable performance, curved shape and the amplitude of each groove of grating more repeat.Grating line bending error affects optical grating diffraction beam quality.Changchun Inst. of Optics and Fine Mechanics, Chinese Academy of Sciences finds in carrying out large scale grating development, and when increasing raster size, curve tendency error is one of principal element affecting optical grating diffraction beam quality.Reduce grating line bending, contribute to improving optical grating diffraction beam quality, reduce the aberration of grating image system, improve preparing grating precision and application level.

Prior art is to use the method improving Design of Mechanical Structure to reduce the curve tendency of grating.Although by the most repeatedly designing optical grating graduating machine scoring system frame for movement and after substantial amounts of debugging test, can reduce the amplitude of grating line bending to a certain extent, but said method is undoubtedly inefficient.

Summary of the invention

The present invention solves that existing grating line curvature correction method uses Curve guide impeller repetitious to optical grating graduating machine frame for movement and installation and debugging, the problem such as have that design process is complicated, efficiency is low and curve tendency calibration result is poor, the present invention provides a kind of grating line bending to automatically control bearing calibration.

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

S101, set up grating average curve tendency mathematical model；

S102, carry out grating prescribed, it is thus achieved that prescribed grating, calculate the average curve tendency of grating of described prescribed grating；

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

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

S105, carry out grating ruling, use and automatically control method calibration grating curve tendency.

In the present invention one better embodiment, step S101 farther includes:

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

S1012, from described grating line error, remove grating pivot angle and the integral position error of grating line, it is thus achieved that the relational expression between the average curve tendency of grating and grating line error.

In the present invention one better embodiment, step S1011 use method of geometrical optics derive the mathematical relationship expression formula between grating line error under grating conical diffraction mounting, 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 from optical grating diffraction wavefront and obtains.

In the present invention one better embodiment, step S102 farther includes:

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 grating average curve tendency value of described prescribed grating.

In the present invention one better embodiment, in step S104, the average curve tendency of grating according to optical grating graduating machine scoring system and the frame for movement of indexing system and described prescribed grating, the operation principle of optical grating graduating machine, derive described optical grating graduating machine worktable displacement and compensate mathematical model, it is thus achieved that for the workbench theory displacement of the average curve tendency of null grating.

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

Beneficial effects of the present invention: relative to prior art, the grating line bending that the present invention provides automatically controls bearing calibration and has following good effect: contribute to reducing grating line bending, improve optical grating diffraction beam quality, and be favorably improved optical grating graduating machine running precision and work efficiency.

Described above is only the general introduction of technical solution of the present invention, in order to better understand the technological means of the present invention, and can be practiced according to the content of description, and in order to above and other objects of the present invention, feature and advantage can be become apparent, below especially exemplified by embodiment, and coordinate accompanying drawing, describe in detail as follows.

Accompanying drawing explanation

Fig. 1 automatically controls the flow chart of bearing calibration for the grating line bending that the present invention provides；

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 diamond icking tool displacement diagram；

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

Detailed description of the invention

Below in conjunction with the accompanying drawings and specific embodiment the present invention is further detailed explanation.

Referring to Fig. 1, present embodiment provides a kind of grating line bending to automatically control bearing calibration, and it comprises the steps:

S101, set up grating average curve tendency mathematical model.

Farther include:

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

S1012, from described grating line error, remove grating pivot angle and the integral position error of grating line, it is thus achieved that the relational expression between the average curve tendency of grating and grating line error.

Specifically, in the present embodiment, method of geometrical optics is used to derive the relational expression between the grating line error under grating conical diffraction mounting and 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, angle of incidence and the angle of diffraction is respectively θ₁And θ₂, grating constant is d.

First grating situation without Divided errors but when there is substrate face shape error is considered.As in figure 2 it is shown, grating line direction is the z-axis direction vertical with paper, when the arbitrfary point i on grating pth bar groove and grating ideal surfaced exist depth error h (x_p,y_p,z_pi) time, if the optical path difference that incident illumination and diffraction light produce is respectively δ_b1And δ_b2, then incident illumination and diffraction light produce at this point total optical path difference δ_bpiFor

δ_bpi=δ_b1+δ_b2=h (x_p,y_p,z_pi)(cosθ₁+cosθ₂)\*MERGEFORMAT (1)

When grating is without substrate face shape error but when there is Divided errors, as it is shown on figure 3, when the distance of the preferable scribe line position p of physical location p' deviation of the arbitrfary point i on grating pth bar groove is w (x_p,y_p,z_pi), if incident illumination and diffraction light are respectively δ in this produced optical path difference of point_r1And δ_r2, then incident illumination and diffraction light are in optical path difference summation δ produced by this point_rpiFor:

δ_rpi=δ_r1+δ_r2=w (x_p,y_p,z_pi)(sinθ₁+sinθ₂)\*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(sinθ₁+sinθ₂)=m λ (3)

Simultaneous formula (1), formula (2) and formula (3) can obtain, when there is substrate face shape error, Divided errors in the arbitrfary point i of grating pth bar groove simultaneously, then and optical path difference δ produced at this point_piFor:

δ_pi=δ_bpi+δ_rpi=h (x_p,y_p,z_pi)(cosθ₁+cosθ₂)+w(x_p,y_p,z_pi)mλ/d (4)

Time before employing interferometer measurement plane grating diffracted wave, the general light channel structure using monochromatic light angle of incidence equal with optical grating diffraction angle absolute value, i.e. θ₁Equal to θ₂.Now, understanding according to formula (4), interferometer records m level optical grating diffraction wavefront optical path difference and is:

Δ (m)=2H cos θ₁+Wmλ/d (5)

Wherein, the substrate face shape error on the full surface of H and W respectively grating and Divided errors quantize matrix, θ₁It it is m level optical grating diffraction angle.

Obtaining 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 by the matrix form of the Divided errors W of formula (6) calculated grating being

Formula (7) respectively arranges along grating line direction, formula (7) is removed the integral position error of grating line pivot angle and grating line, each element value b of available grating line bending matrix B_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), i.e. obtain grating average curve tendency mathematical model.

S102, carry out grating prescribed, it is thus achieved that 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 (such as 60mm), need to first carry out a grating prescribed experiment, it is thus achieved that prescribed grating.

In this example, farther include:

S1021, use optical grating diffraction wavefront measurement instrument (such as zygo interferometer etc.) measure as described in prescribed grating order of symmetry time (such 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 grating average curve tendency value of described prescribed grating.

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

In order to curve tendency average to grating is corrected, need to use autocontrol method to regulate optical grating graduating machine worktable displacement in real time, make described optical grating graduating machine worktable displacement offset grating average curve tendency value in real time, thus reduce the grating line bending that optical grating graduating machine systematic error causes.

In the present embodiment, use two-frequency laser interferometer that the displacement of workbench is measured in real time, and use piezo actuator that worktable displacement is regulated in real time.

The present embodiment in view of 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 position error are up to 5nm.Hereinafter, the automatic control scheme of optical grating graduating machine, as a example by CIOMP-2 optical grating graduating machine, is specifically introduced by this enforcement.

Optical grating graduating machine can be divided into scoring system and indexing system in frame for movement, and wherein scoring system is for realizing the reciprocating motion of diamond icking tool, and indexing system is for realizing the admission motion of workbench.Refer to Fig. 4, the scoring system of CIOMP-2 rose engine mainly includes delineating motor, crank connecting link, copper shoe, copper shoe guide rail, push-pull bar, delineation knife rest, quartz guide rail, its main operational principle is: driven crank to rotate by delineation motor, so that crank connecting link drives saddle slide block to move reciprocatingly on quartz guide rail by copper shoe and push-pull bar.Saddle slide block carries out CONTACT WITH FRICTION with quartz guide rail by eight shoes, saddle slide block is fixing with delineation knife rest to be connected, the bottom of delineation knife rest is provided with diamond icking tool, diamond icking tool carries out grating ruling operation with a side of vitreous silica guide rail for spigot surface in delineation knife rest drawback movement, and wherein the roll setting operation of lifting of delineation knife rest is realized automatically controlling by lifting roll setting piezoelectric ceramics.

The indexing system of CIOMP-2 rose engine uses grand micro-two-stage Working table structure, its (indexing system block diagram is as shown in Figure 5) main operational principle is: indexing motor is after decelerator slows down, take worm couple and feed screw nut secondary motion to, nut is connected by spring leaf with grand positioning table, so that indexing motor drives grand positioning table to be operated the grand positioning action of platform；The micro-positioning table physical location recorded further according to two-frequency laser interferometer and the departure of ideal position, realized micro-positioning action of workbench by Piezoelectric Ceramic micro-positioning table.

Grand micro-two grade working table concrete structures of CIOMP-2 optical grating graduating machine are as shown in Figure 6.Grating substrate 5 is placed in micro-positioning table 2, grand positioning table 1 is " basin type " structure, it is internal that micro-positioning table 2 embeds grand positioning table 1, and micro-location and grand positioning table are hung by four elastic steel sheets 3 and connect, 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 positioned.

The two-frequency laser interferometer that displacement resolution is 0.15nm that CIOMP-2 optical grating graduating machine uses U.S. Agilent (Agilent) company to produce monitors the positional information of micro-positioning table 1 in real time, in conjunction with Fig. 7, the measurement reflecting mirror 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 of micro-positioning table 1 and scoring system quartz guide rail 8 relative displacement change, above-mentioned installation site with reference to reflecting mirror 7 and measurement reflecting mirror 6 can effectively reduce optical grating graduating machine thermal expansion to scoring system quartz guide rail and the impact of micro-positioning table 1 relative displacement measurement result.Two-frequency laser interferometer employing wavelength tracker realizes the laser interferometer measurement error that environment (air refraction, temperature and humidity) change causes to external world and carries 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 frame for movement of indexing system and the operation principle of optical grating graduating machine, derive described optical grating graduating machine worktable displacement and compensate mathematical model, it is thus achieved that for the workbench theory displacement of 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 bending i.e. caused optical grating graduating machine systematic error compensates.

Specifically, as shown in Figure 8, if a length of L of grating line_g, in a groove scoring process, diamond icking tool current location D_CWith roll setting position D_ODistance be diamond icking tool displacement s, then have 0≤s≤L_g.Use method of least square that formula (9) is carried out h order polynomial matching, relational expression E (s) of the average curve tendency of grating and diamond icking tool displacement s can be obtained, if it can be expressed as

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

Grating line bending in order to cause optical grating graduating machine scoring system compensates, need to make workbench compensate with the direction that curve tendency average with grating is contrary in every grating line scoring process, and the opposite number that its offset is grating line bending value, it is-E (s).

CIOMP-2 optical grating graduating machine diamond icking tool does variable-speed motion during grating ruling, therefore before carrying out grating line bending correction, needs first to obtain the time T that diamond icking tool displacement s experiences with it_sBetween relational expression, the brace and connecting rod framework from CIOMP-2 machine scoring system is started with and is analyzed below.

As is shown in fig. 9 c, putting O correspondence crank center position, some A and some B and represent the two ends of connecting rod, some B and some C respectively and represent the two ends of push-pull bar, push-pull bar and saddle slide block are directly connected to, crank center O and push-pull bar BC not conllinear and set the two vertical dimension as h_BD。

In fig .9, BC and OD, OD ', OD " parallel, BD ⊥ OD, BD ' ⊥ OD ', BD " ⊥ OD ", ∠ AOD=θ, ∠ AOD '=θ₁, ∠ AOD "=θ₂；IfThe then maximum L of L_maxWith minima L_minIt is respectively occurring at push-pull bar away from crank center farthest with the most nearby (as shown in Fig. 9 (b) and 9 (c)), $L_{\max }=\stackrel{\‾}{{\mathrm{OD}}^{\′}}$ 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 f₀Hertz, the initial rotation phase place of crank is zero, then crank angle θ and time T_sRelation be:

θ=2 π f₀T_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 the micro-positioning table displacement that grating constant is d and the 0th article of groove is 0, then for n-th (n=1,2,3 ...) and for bar groove, it is n that micro-positioning table should have initial displacement_d.So when nth bar groove is carried out scoring operation, using piezo actuator to carry out in grating line bending makeover process, micro-positioning table displacement and the delineation time T of nth bar groove_sRelational expression be:

D(T_s)=n_d-E(s) (17)

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

S105, carry out grating ruling, use and automatically control method calibration grating curve tendency.

I.e. 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, use piezo actuator that micro-positioning table is carried out displacement to regulate in real time, the actual displacement amount making workbench any time is minimum with the deviation of described workbench theory displacement, thus realizes compensating grating line bending.

Relative to prior art, the grating line bending that the present invention provides automatically controls bearing calibration and has following good effect: contribute to reducing grating line bending, improve optical grating diffraction beam quality, improve preparing grating precision and application level, and be favorably improved optical grating graduating machine running precision and work efficiency.

The above, it is only embodiments of the invention, not the present invention is made any pro forma restriction, although the present invention is disclosed above with embodiment, but it is not limited to the present invention, any those skilled in the art, in the range of without departing from technical solution of the present invention, when the technology contents of available the disclosure above makes a little change or is modified to the Equivalent embodiments of equivalent variations, in every case it is without departing from technical solution of the present invention content, any simple modification above example made according to the technical spirit of the present invention, equivalent variations and modification, all still fall within the range of technical solution of the present invention.

Claims (5)

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

S101, set up grating average curve tendency mathematical model；

S102, carry out grating prescribed, it is thus achieved that prescribed grating；According to the grating described in step S101 Average curve tendency mathematical model, calculates the average curve tendency of grating of described prescribed grating；

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

Particularly as follows: use two-frequency laser interferometer to measure the displacement of workbench in real time, double frequency swashs The reflecting mirror of measuring of optical interferometer is arranged on the micro-positioning table of optical grating graduating machine indexing system, ginseng Examine reflecting mirror to be arranged on the quartzy guide rail of optical grating graduating machine scoring system, and use piezo actuator pair Worktable displacement regulates in real time；

S104, according to optical grating graduating machine frame for movement, the average groove of the calculated grating of step S102 Optical grating graduating machine automatic control scheme described in bending and step S103, sets up optical grating graduating machine work Platform bit shift compensation mathematical model；

S105, carry out grating ruling, compensate number according to the optical grating graduating machine worktable displacement described in S104 Learn model, use the optical grating graduating machine automatic control scheme real time correction grating line described in step S103 Bending；

Step S101 farther includes:

S1011, derive grating line error under grating conical diffraction mounting, grating substrate face shape error and light Mathematic(al) representation between before grid diffracted wave；

S1012, from described grating line error, remove the integral position of grating pivot angle and grating line by mistake Difference, it is thus achieved that the relational expression between the average curve tendency of grating and grating line error.

2. automatically control bearing calibration according to grating line as claimed in claim 1 bending, its feature It is, step S1011 uses method of geometrical optics derive grating line under grating conical diffraction mounting and miss Difference, mathematical relationship expression formula between grating substrate face shape error and optical grating diffraction wavefront.

Grating line the most according to claim 1 bending automatically controls bearing calibration, and its feature exists In, the average curve tendency of described grating is according to step S1011 and step S1012, from optical grating diffraction ripple Indirectly extract in before and obtain.

Grating line the most according to claim 1 bending automatically controls bearing calibration, and its feature exists In, step S102 farther includes:

S1021, the order of symmetry using optical grating diffraction wavefront measurement instrument to measure described prescribed grating spread out Before ejected wave, and therefrom extract grating line error；

S1022, according to the relationship expression between the average curve tendency of described grating and grating line error Formula, calculates the grating average curve tendency value of described prescribed grating.

Grating line the most according to claim 1 bending automatically controls bearing calibration, and its feature exists In, 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, piezoelectricity is used to perform Device carries out displacement to micro-positioning table and regulates in real time, make the actual displacement amount of workbench any time with The minimum deviation of described workbench theory displacement, it is achieved the correction to grating line bending.