CN107664482B - Grating measuring device - Google Patents
Grating measuring device Download PDFInfo
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- CN107664482B CN107664482B CN201610616981.1A CN201610616981A CN107664482B CN 107664482 B CN107664482 B CN 107664482B CN 201610616981 A CN201610616981 A CN 201610616981A CN 107664482 B CN107664482 B CN 107664482B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
Abstract
The invention discloses a kind of grating measuring devices, comprising: light source module, for generating the different two light beams of frequency；Grating；Signal processing module and grating measuring probe, enter optical module including double frequency, horizontal direction detecting module, with reference to detecting module and two symmetrically arranged retroreflector, double frequency enters optical module and is used to receive two light beams and project it onto grating surface and with reference to detecting module, two light beams, which are projected, to be interfered to be formed with reference to interference signal with reference to detecting module, in grating surface diffraction occurs for two light beams, diffraction light is projected to corresponding retroreflector respectively, re-diffraction occurs through retroreflector retroeflection to grating surface, the convergence of re-diffraction light projects horizontal direction detecting module and interferes to form horizontal direction displacement interferometer signal；Signal processing module detect horizontal direction displacement interferometer signal and it is described refer to interference signal, and calculate grating horizontal direction displacement.The present invention can be directed to same measurement point, realize horizontal plane X, the two dimension of Y-direction detects simultaneously.
Description
Technical field
The present invention relates to IC manufacturing field, in particular to a kind of grating measuring device.
Background technique
Nano measurement technology is the basis in the fields such as nanoprocessing, nanometer manipulation, nano material.IC industry, precision machinery,
MEMS etc. requires high-resolution, high-precision displacement sensor, to reach nano-precision positioning.With integrated circuit
It develops by leaps and bounds towards extensive, high integration direction, the alignment precision requirement of litho machine is also higher and higher, correspondingly, obtains
Work stage, the precision of the six-degree of freedom position information of mask platform is taken also to increase accordingly.
Interferometer has higher measurement accuracy, up to nanometer scale, in a lithography system, be employed for measurement work stage,
The position of mask platform.However, the measurement accuracy of interferometer nearly reaches the limit at present, while interferometer measurement precision is by ring around
Border is affected, and measurement repeatable accuracy is not high, even if environment is fine, error also can be more than 1nm, therefore, the measurement of conventional dry interferometer
System, which is difficult to meet, further increases the requirement of alignment precision, with high precision, the micromicron measurement scheme of high stability compels to be essential
It wants.
Optical grating measuring system is affected by environment smaller at work, there is preferable repeatable accuracy, in New Generation Optical etching system
In started to gradually replace interferometer, undertake high-precision, high stability micromicron precision measure task.Publication No. US7389595
United States Patent (USP) propose it is a kind of based on optical fiber transmission two-dimensional grating measuring system, light source and detectable signal light are all made of optical fiber
Transmission.In the patent formula, light source is semiconductor laser, and the position between grating and read head is measured using zero-difference detection mode
It moves.However the mode anti-interference ability of zero-difference detection is weaker, position data is easy dry by external stray light, electromagnetic field and vibration
The influence disturbed.Application No. is the Chinese patents of CN201210449244 to propose a kind of double frequency heterodyne optical grating measuring system, this is
System can effectively improve measurement accuracy.But it only has detectable signal to transmit by optical fiber, and laser light source and grating reading head are placed on one
It rises, volume is big, is not suitable for the usage scenario of spaces compact；In addition, when grating is relative to having Rx, Ry angular deflection between read head
When, measuring system interference performance can reduce, and measuring system is caused to fail, and the resetting difficulty of grating and read head is too big in the invention,
Install and use inconvenience.
The United States Patent (USP) of Publication No. US8300233B2 proposes a kind of optical grating ruler measurement system, it uses beam orthogonal
Incident grating, prism of corner cube obtain two-dimensional position data horizontally and vertically after returning to diffracted beam.Due to level
To when measurement, the measurement point of X-direction and the position of Y-direction measurement point are different, cause measurement error larger, and needed for grating scale
Light pass surface size is big, at high cost.
Summary of the invention
The present invention provides a kind of grating measuring device, to realize the horizontal direction displacement measurement to grating.
In order to solve the above technical problems, the present invention provides a kind of grating measuring device, comprising: light source module, for generating
The different two light beams of frequency；Grating；Signal processing module；And grating measuring is popped one's head in, including double frequency enters optical module, horizontal direction
Detecting module, with reference to detecting module and two symmetrically arranged retroreflector, wherein it is described for receiving that the double frequency enters optical module
Two light beams, and the two light beams are projected into the grating surface and refer to detecting module, the two light beams project
Described to interfere to be formed with reference to interference signal with reference to detecting module, in the grating surface diffraction occurs for the two light beams,
Diffraction light is projected to corresponding retroreflector respectively, and re-diffraction, two beams occur through the retroreflector retroeflection to the grating surface
The convergence of re-diffraction light projects the horizontal direction detecting module and interferes to form horizontal direction displacement interferometer signal；The signal
Processing module detect the horizontal direction displacement interferometer signal and it is described refer to interference signal, and calculate the horizontal direction position of the grating
It moves.
Preferably, the grating measuring probe further include: vertical measurement module and vertical detecting module, through the double frequency
The light beam entered in the two light beams of optical module outgoing is projected to the grating surface through the vertical measurement module, through described
Another light beams in the diffraction light of grating surface diffraction and the two light beams are projected to the vertical detecting module and occur to do
It relates to form vertical deviation interference signal, the signal processing module receives the vertical deviation interference signal, and in conjunction with the ginseng
Examine the vertical deviation that interference signal calculates the grating.
Preferably, the optional prism of corner cube of retroreflector.
Preferably, the light source module includes: laser, isolator, optical splitter, frequency shifter, the first coupler and
Two couplers；The light beam that the laser issues is two beams by optical splitter light splitting, respectively enters the frequency after isolator
It moves device and generates the different two light beams of frequency, the two light beams are sent to after the coupling of the first, second coupler respectively
The grating measuring probe.
Preferably, the laser uses gas laser.
Preferably, the frequency shifter is Zeeman frequency divider, birefringence element or two acousto-optic frequency shifters.
Preferably, the grating is one-dimensional grating or two-dimensional grating.
Preferably, the horizontal direction detecting module includes optical splitter, X to measurement coupler and Y-direction measurement coupler, pass through
Two light beams after the optical grating diffraction are surveyed by the X to measurement coupler and the Y-direction respectively after optical splitter light splitting
Measure coupler coupling.
Preferably, the optional polarization splitting prism of optical splitter.
Preferably, the light splitting direction of the polarization splitting prism is identical as the pitch direction of the grating.
Preferably, it includes the first beam splitter and the second beam splitter that the double frequency, which enters optical module, in the two light beams
It is a branch of to be incident to the grating respectively after the first beam splitter beam splitting and described with reference to detecting module, in the two light beams
Another Shu Jing described in the grating is incident to after the second beam splitter beam splitting respectively and described with reference to detecting module.
Preferably, the double frequency, which enters optical module, includes the first beam splitter, the second beam splitter and third beam splitter, it is described to hang down
It include vertical measurement coupler to detecting module, the light beam in the two light beams is by after the first beam splitter beam splitting points
It is not incident to the vertical measurement module and described with reference to detecting module, another light beams in the two-beam book are by described the
The third beam splitter is incident to after two beam splitter beam splitting respectively and described with reference to detecting module, the third beam splitter will receive
Beam splitter after be incident to the vertical measurement module and the grating surface respectively, the vertical measurement coupler will be through institute
The light beam for stating vertical measurement module outgoing closes beam.
Preferably, the vertical detecting module further includes the 4th beam splitter, the third beam splitter is by received light beam
The 4th beam splitter and the grating surface are incident to after beam splitting respectively, is incident to the light beam of the 4th beam splitter and through institute
It is coupled after stating the light beam conjunction beam of vertical measurement module outgoing by the vertical measurement coupler.
Preferably, it includes: first collimator, the second collimator and angle of wedge piece pair that the double frequency, which enters optical module, wherein institute
It states first collimator and the second collimator respectively collimates the two light beams, appointing in the two light beams after collimation
Anticipate it is a branch of be incident to the angle of wedge piece to carry out angle control.
Preferably, further including the mirror assembly turned to for realizing light beam.
Preferably, realizing signal transmitting by polarization maintaining optical fibre between the light source module and grating measuring probe.
Preferably, the X passes through multimode fibre and transmits signal to measurement coupler and Y-direction measurement coupler
To the signal processing module.
Preferably, the vertical measurement module includes: the second polarization splitting prism, the second prism of corner cube and Polarization Control
Device, vertical measuring light beam are first transmitted through second polarization splitting prism, by Polarization Controller rotatory polarization direction, projection
A diffraction occurs on to grating, the zero-order diffraction light of a diffraction enters behind Polarization Controller rotatory polarization direction again
It is incident upon second polarization splitting prism, is returned to after second polarization splitting prism reflexes to second prism of corner cube
Second polarization splitting prism, is again incident on the grating later and re-diffraction occurs, the zero level in re-diffraction light
Diffraction light projects the vertical detecting module after second polarization splitting prism.
Preferably, the tilt controller uses Faraday rotator or half wave plate.
Preferably, being incident to polarization direction and the institute of the light beam of second polarization splitting prism in the two light beams
Stating the polarization directions of another light beams in two light beams, there are the first angle, the correspondingly placements of second polarization splitting prism
Direction rotates the first angle, and the polarization direction for the light beam being emitted after the Polarization Controller also rotates the first angle.
Preferably, first angle is 45 degree.
Preferably, there are for the polarization direction and the grid direction of the grating that are incident on the light beam of the grating surface
Two angles.
Preferably, second angle is 45+k*90 degree, wherein k is natural number.
Preferably, signal is passed to the signal processing module by multimode fibre by the vertical detecting module.
Preferably, described pass to the signal processing module for signal by multimode fibre with reference to detecting module.
Compared with prior art, the invention has the following advantages that
1, the achievable all -fiber transmission of the present invention, have strong antijamming capability, measurement accuracy are high, duplicate measurements precision is high,
Without error influences, structure is simple and installs and uses convenient feature, is extremely applicable to the micromicron essence of high-stability requirement
Spend multidimensional measure field.
2, the leveling module in grating measuring device of the invention can control two light beams and realize horizontal direction displacement
Measurement, horizontal direction detecting module can detect horizontal direction displacement signal and reference optical signal, realize that horizontal direction (X/Y) two dimension is visited
It surveys, the measurement of X-direction can be made identical with the measurement point of Y-direction, effectively reduced because of measured point difference bring measurement error；
Light pass surface size needed for also significantly reducing grating reduces grating cost.Furthermore the present invention can also make grating measuring pop one's head in
Size it is more compact, compress installation space.
3, the present invention is directly measured using the zero order light reflected of grating, and vertical measurement distance not will receive spot size
Limitation, the vertical measurement of any distance may be implemented.
4, the present invention can also effectively merge horizontal direction (X/Y) and vertical (Z) measurement scheme, realize that multiaxis is surveyed
Amount.And vertical (Z) when using horizontal direction (X/Y) to measure when measuring the zero order light reflected that can't use realize,
Improve the capacity usage ratio of optical grating ruler measurement system.In the case where not increasing incident beam power, the measurement number of axle is increased.
5, the present invention can produce very high three axis of integrated level or multiaxis reading head, suitable for wanting to space and size
It asks very high, while measurement accuracy and repeatability is required in high sports platform multiaxis Measurement and Control System.
6, the double frequency heterodyne grating measuring transmitted based on all -fiber can be achieved in the present invention.
7, for the present invention using gas laser as light source, coherence length is long, it is ensured that pops one's head in grating and grating measuring
Inclination or deflection it is larger when, can also effectively interfere.
8, the present invention can also realize the separation of laser light source and grating reading head, and read head is small in size, and it is tight to be applicable to space
The usage scenario gathered.
9, the present invention uses double frequency optical detection, and stability is higher, anti-interference ability is stronger, and measurement accuracy and repeatability are more
It is excellent.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of grating measuring device in the embodiment of the present invention 1；
Fig. 2 is the hot spot distribution schematic diagram in the embodiment of the present invention 1 on grating；
Fig. 3 is the structural schematic diagram of grating measuring device in the embodiment of the present invention 2；
Fig. 4 is the polarization state variation schematic diagram that light beam passes through vertical measurement module in the embodiment of the present invention 2；
Fig. 5 is the structural schematic diagram of grating measuring device in the embodiment of the present invention 3.
It is as shown in the figure:
100- grating measuring probe,
110- double frequency enters optical module, 111- first collimator, the second collimator of 112-, 113- angle of wedge piece pair；
The vertical measurement module of 120-, 121- polarization splitting prism, 122- prism of corner cube, 123- Polarization Controller；
The vertical detecting module of 130-, the 4th beam splitter of 1301-, the 5th beam splitter of 1302-, the 4th remote couplings device of 1303-；
140- horizontal direction measurement module, 141, the first prism of corner cube of 142-；
150- horizontal direction detecting module, the first beam splitter of 151-, the second beam splitter of 152-, 153- the first polarization spectro rib
Mirror, the first remote couplings of 154- device, 155- the second remote couplings device；156- third remote couplings device, 157- reflecting mirror, 158-
Three beam splitters；
200- grating；
300- light source module, 301- laser, 302- isolator, 303- beam splitter, 304- reflecting mirror, the first frequency displacement of 305-
Device, the second frequency shifter of 306-, the first coupler of 307-, the second coupler of 308-；
701~703- measurement point；
Specific embodiment
In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, with reference to the accompanying drawing to the present invention
Specific embodiment be described in detail.It should be noted that attached drawing of the present invention is all made of simplified form and uses non-essence
Quasi- ratio, only for the purpose of facilitating and clarifying the purpose of the embodiments of the invention.
Embodiment 1
As shown in Figure 1, the grating measuring device of the present embodiment includes:
Light source module 300, for generating the different two light beams of frequency；
Grating 200；
Multiple detector (not shown),
Signal processor (not shown)；
And
Grating measuring probe 100, including double frequency enter optical module, horizontal direction detecting module, right with reference to detecting module and two
The retroreflector for claiming setting, in the present embodiment, the retroreflector is preferably prism of corner cube 141,142, wherein double frequency enters optical module use
In the reception two light beams, and the two light beams are projected into 200 surface of grating and refer to detecting module, two-beam
On 200 surface of grating diffraction occurs for beam, and diffracted ray projects corresponding retroreflector, through the retroreflector retroeflection to grating
Re-diffraction occurs for 200 surfaces, and the convergence of two beam re-diffraction light projects the horizontal direction detecting module and interferes, and forms water
It puts down and is detected after displacement interferometer signal by detector, the two light beams project the detecting module that refers to and interfere, shape
It is detected at after reference interference signal by detector, the signal processor is according to the horizontal direction displacement interferometer signal and the ginseng
Examine the horizontal direction displacement that interference signal calculates the grating 200.It includes that third is long-range that detecting module is referred to described in the present embodiment
Coupler 156 is connected between third remote couplings device 156 and detector by multimode fibre.
Specifically, with continued reference to Fig. 1, the light source module 300 includes laser 301, isolator 302, optical splitter, frequency displacement
Device and coupler, optical splitter include beam splitter 303 and reflecting mirror 304.
The laser 301 is using any wavelength between 400~1500nm, such as 633nm, 780nm, 980nm.Into one
Step, it is additionally provided with wavelength monitor system on the laser 301, for the situation of change to 301 wavelength of monitoring laser, and
Implementation compensation is carried out to wavelength.Further, gas laser, such as He-Ne Lasers can be directly used in the laser 301
Device has the characteristics that line width is extremely narrow, frequency stabilization performance is good.The laser 301 is for generating laser beam, the laser beam
For linearly polarized light, polarization direction can be P polarization, be also possible to S-polarization.
The exit of the laser 301 is arranged in stop echo reflection in the isolator 302；The isolator 302
It can also be substituted by the optic fibre end with inclined surface, can equally reduce echo reflection influence, be installed on laser 301
The stability of laser 301 can be improved in isolator 302 or optic fibre end with inclined surface.
The frequency shifter uses acousto-optic frequency shifters, electric light frequency shifter, Zeeman frequency divider or birefringence element, in the present embodiment
Frequency shifter and coupler be two groups, frequency shifter use acousto-optic frequency shifters, to show that difference is referred to as the first, second frequency displacement
Device 305,306 and the first, second coupler 307,308.The light beam that laser 301 issues is divided into two bundles through the beam splitter 303,
A branch of to project after first frequency shifter 305 generates certain frequency shift amount through the first coupler 307, another light beam is through reflecting mirror
304 enter second frequency shifter 306 and project after generating the frequency shift amount different from previous light beam through the second coupler 308.
Further, the two beams frequency is different, has the light beam of certain frequency difference, using polarization maintaining optical fibre remote transmission to grating
Measuring probe 100.
With continued reference to Fig. 1, it includes: first collimator 111, the second collimator 112 and angle of wedge piece that the double frequency, which enters optical module,
To 113, wherein the first collimator 111 and angle of wedge piece are used to carry out a wherein incident beam collimation and angle control to 113
System, second collimator 112 is for collimating another incident beam, and the angle of wedge piece is to the 113 control two-beams
The opposite depth of parallelism of beam.The double frequency enter optical module further include the first beam splitter 151, the second beam splitter 152, reflecting mirror 157 with
And third beam splitter 158；
For convenience of description, measuring beam will be known as through light beam of the angle of wedge piece to 113 outgoing, be emitted through the second collimator 112
Light beam be known as reference beam；
Measuring beam is divided to through first beam splitter 151 measures beam splitting for two, wherein a measurement beam splitting projects grating 200
Surface, another measurement beam splitting are transmitted through third remote couplings device 156 through third beam splitter 158 after the reflection of reflecting mirror 157；
Reference beam is divided to through second beam splitter 152 for two with reference to beam splitting, wherein one projects grating 200 with reference to beam splitting
Surface, it is another to be reflected into third remote couplings device 156 through the third beam splitter 158 with reference to beam splitting.
It continues to refer to figure 1, optical module two light beams adjusted is entered by double frequency, is respectively perpendicular and projects on grating 200,
It is projected on corresponding prism of corner cube 141,142 respectively after diffraction occurs on grating 200, after the reflection of prism of corner cube 141,142
It is projected on grating 200 again, again after 200 diffraction of grating, the convergence of two light beams projects the horizontal direction detecting module.
The horizontal direction detecting module includes: that the first polarization splitting prism 153, the first remote couplings device 154 and second are remote
Journey coupler 155, it is remote that the two light beams after re-diffraction respectively enter first after 153 beam splitting of the first polarization splitting prism
Journey coupler 154 and the coupling of the second remote couplings device 155, are transferred to detector for coupled signal by multimode fibre later.
As shown in Fig. 2, the hot spots that grating measuring probe 100 generates, distribution arrangement above grating 200 relative to
The pitch direction cant angle theta angle of grating 200, wherein θ can be any angle of 0 to 360 degree and 0 to 360 degree multiple.Such as Fig. 2
It is shown, measure the 2-d position measurement of horizontal direction, it can the displacement of X, Y-direction are integrated together detection, so that grating is surveyed
Amount probe 100 it is compact-sized, and X to the measurement point 701~703 with Y-direction in the same point, can be to avoid because of X, Y-direction
The not identical bring error of measurement point, can also make hot spot distribution on grating 200 compact, and reduction 200 detection area of grating improves light
200 surface utilisation of grid, reduces cost.
Incident beam on grating 200 can be same polarization direction, and the first, second remote couplings device 154,155 can be straight
Detection is connect, is not required to increase polarizing film, the power loss of whole system can be reduced, improve the efficiency of light energy utilization.
The present invention uses double frequency optical detection, and stability is higher, anti-interference ability is stronger, and measurement accuracy and repeatability are more excellent.
Preferably, grating can be used to substitute in first, second, third beam splitter 151,152,158, light beam is realized
Separation.
Referring to Fig.1, realization process is measured the following detailed description of the horizontal direction of grating measuring device in embodiment:
It is f that He-Ne laser in light source module 300, which issues frequency,0Helium neon laser beam, after isolator 302, by
Optical splitter is divided into two-way, respectively incident first frequency shifter 305 and the second frequency shifter 306, wherein the frequency displacement of the first frequency shifter 305
Amount is Δ f1, by the helium neon laser beam of the first frequency shifter 305, frequency becomes f0+Δf1；The frequency shift amount of second frequency shifter 306 is
Δf2, by the helium neon laser beam of the second frequency shifter 306, frequency becomes f0+Δf2；This two light beams uses the first coupler respectively
307 and second coupler 308 be coupled to polarization maintaining optical fibre, remote transmission to grating measuring probe 100.
As depicted in figs. 1 and 2, frequency f0+Δf1And f0+Δf2Two beam laser beams, respectively by first collimator 111
It is collimated with the second collimator 112, and keeps two laser parallel the opposite depth of parallelism of 113 control two lasers with angle of wedge piece.For side
Just it describes, is f by frequency0+Δf1Laser beam be known as measuring beam, by frequency be f0+Δf2Laser beam be known as reference light
Beam.
The measuring beam by the first beam splitter 151 be divided to for two measurement beam splitting, one measurement beam splitting polarization direction relative to
The pitch direction cant angle theta angle of grating 200, and vertical incidence grating 200, hot spot 701 as shown in Figure 2 take -1 grade of diffraction light simultaneously
With in prism of corner cube 141 retroeflection to grating 200, hot spot 703 as shown in Figure 2 is emitted to the first polarization after diffraction occurs again
The light splitting direction of Amici prism 153, first polarization splitting prism 153 is identical as the pitch direction of grating 200.Another measurement
Beam splitting projects in third remote couplings device 156, remotely projects detector by third remote couplings device 156, believes as reference
Number.
The reference beam is divided to by the second beam splitter 152 for two with reference to beam splitting, wherein one is opposite with reference to beam splitting polarization direction
In the pitch direction cant angle theta angle of grating 200, and vertical incidence grating 200, hot spot 702 as shown in Figure 2 take+1 grade of diffraction light
And in prism of corner cube 142 retroeflection to grating 200, hot spot 703 as shown in Figure 2 is emitted to first partially after diffraction occurs again
Shake Amici prism 153.It is another to be projected in third remote couplings device 156 with reference to beam splitting, it is remotely thrown by third remote couplings device 156
It is mapped to detector, as reference signal.
For above-mentioned ± 1 grade of diffraction light after the first polarization splitting prism 153, a part of transmission-polarizing light is long-range by second
Coupler 155 couples, remote transmission to detector, detects double-frequency interference signal；Another part polarization by reflection light is remote by first
Journey coupler 154 couples, remote transmission to detector, detects double-frequency interference signal.
When grating 200 along X to when moving Δ X, detect the interference containing tested displacement through the first remote couplings device 154 and believe
Number, fringe number N1:
N1=[(f0+Δf2)T1+2ΔX/d]-[(f0+Δf1)T1- 2 Δ X/d]=(Δ f2-Δf1)T1+4ΔX/d (1)
Wherein, T1For the time used in movement Δ X displacement, d is the pitch of grating 200.Frequency is f0+Δf1Light beam exist
Diffraction, -2 Δ X/d of phase change occur twice for -1 grade of diffraction light direction of grating 200；Frequency is f0+Δf2Light beam in grating
Diffraction ,+2 Δ X/d of phase change occur twice for 200+1 grade of diffraction light direction.
The reference signal without tested displacement is detected from third remote couplings device 156, fringe number N2:
N2=(f0+Δf2)T1-(f0+Δf1)T1=(Δ f2-Δf1)T1 (2)
The fringe number that two detectors detect is subtracted each other, grating 200 can be obtained relative to grating measuring probe 100 in X
To the displacement X of movement:
Δ X=d (N1-N2)/4 (3)
When grating 200 moves Δ Y along Y-direction, that detects from the second remote couplings device 156 contains the interference of tested displacement
Signal, fringe number N3:
N3=[(f0+Δf2)T2+2ΔY/d]-[(f0+Δf1)T2- 2 Δ Y/d]=(Δ f2-Δf1)T2+4ΔY/d (4)
Wherein, T2For the time used in movement Δ Y displacement, d is the pitch of grating 200.Frequency is f0+Δf1Light beam exist
Diffraction, -2 Δ Y/d of phase change occur twice for -1 grade of diffraction light direction of grating 200；Frequency is f0+Δf2Light beam in grating
Diffraction ,+2 Δ Y/d of phase change occur twice for 200+1 grade of diffraction light direction.
Its fringe number detected with reference signal detector is subtracted each other, grating 200 can be obtained relative to grating measuring
Displacement Y of the probe 100 in Y-direction movement:
Δ Y=d (N3-N2)/4 (5)
It should be noted that pitch direction of the hot spot distribution arrangement relative to grating 200 in the grating measuring probe 100
Cant angle theta angle, θ can be any angle of 0 to 360 degree and 0 to 360 degree multiple, survey for realizing X and/or Y-direction position
Amount.When the angle is 0,90,180,360 degree and 90 degree of multiple, the position of X or Y may detect, realize 200 water of grating
Square to one-dimensional position measure.When the angle is the angle in addition to above 0,90,180,360 degree and 90 degree of multiple,
It may detect the position of X and/or Y, realize grating scale horizontal direction 2-d position measurement.Particularly, when the angle be 45 degree,
135 degree and when 45+k*90 degree (k is natural number), groove of the grating measuring probe 100 in X and Y-direction relative to grating 200
Direction is symmetrical, and the light signal energy of X and Y-direction is evenly distributed, and can preferably realize the 2-d position measurement of horizontal direction.
Embodiment 2
The present embodiment the difference from embodiment 1 is that: the present embodiment can be realized simultaneously vertical and horizontal direction displacement measurement.
As shown in figure 3, the present embodiment is increased relative to embodiment 1: setting enters between optical module and grating 200 in double frequency
Optical path on vertical measurement module, and the vertical detecting module being correspondingly arranged with the vertical measurement module.
With continued reference to Fig. 3, the vertical measurement module includes: the second polarization splitting prism 121, the second prism of corner cube 122
With Polarization Controller 123, the measuring beam that double frequency enters optical module outgoing is first transmitted through the second polarization splitting prism 121, by polarizing
123 rotatory polarization direction of controller, projects and diffraction occurs on grating 200, and -1 grade of diffraction light in diffraction light is incident to pyramid
Prism 141, the zero-order diffraction light in diffraction light is reflected back Polarization Controller 123, again through 123 rotatory polarization side of Polarization Controller
To light beam is returning to second by reflecting when the second polarization splitting prism 121, and by the second prism of corner cube 122
Polarization splitting prism 121 is again incident on grating 200 and returns zero-order diffraction light, is finally projected to vertical detecting module.
The vertical detecting module includes the 4th remote couplings device 1303 and the 4th beam splitter 1301, and the double frequency enters optical mode
Block further include: the 5th beam splitter 1302.
The present embodiment realization is vertical, and detailed process is as follows with horizontal direction displacement measurement: measuring beam is by the first beam splitter 151
It is divided into two bundles, 200 surface of grating that a measurement beam splitting is projected through the vertical measurement module is spread out on 200 surface of grating
It penetrates, -1 in diffraction light grade diffraction light is projected to prism of corner cube 141 and measures for horizontal direction, and zero-order diffraction light is through vertical measurement mould
Block reflexes to after re-diffraction occurs for grating 200 and reflexes to the 4th beam splitter 1301 again, is transmitted to institute through the 4th beam splitter 1301
The 4th remote couplings device 1303 is stated for vertical measurement；Another measurement beam splitting is successively through the reflecting mirror 157, third beam splitter
The third remote couplings device 156 is projected after 158 to be used to form with reference to interference signal；
Reference beam is first divided to by the second beam splitter 152 for two with reference to beam splitting, wherein a reference beam splitting is by the 5th beam splitting
Mirror 1302 is again split into two beams, and a part is projected directly on grating 200 to be measured for horizontal direction, and another part is through the 4th beam splitting
Mirror 1301 projects the 4th remote couplings device 1303 for vertical measurement.Another reference beam splitting is through the third beam splitter
158, which project the third remote couplings device 156, is used to form with reference to interference signal.
Specifically, the light source module 300 issues the f that frequency is respectively0+Δf1、f0+Δf2Two-beam, to show area
It not, is f by frequency0+Δf1Light beam be known as measuring beam, by frequency be f0+Δf2Light beam be known as reference beam.Its
In, polarization state situation of change when measuring beam is by vertical measurement module is as shown in Figure 4.The polarization direction of measuring beam is opposite
There is angle α in the polarization direction of reference beam.The placement direction of second polarization splitting prism 121 also corresponding rotation alpha angle.Measure light
After beam the second polarization splitting prism 121 of incidence, polarization direction is constant, after Polarization Controller 123, polarization direction rotation alpha angle, this
When measuring beam polarization direction it is identical as the polarization direction of reference beam, all with the grid direction of grating 200 be in θ angle, when
The right measuring beam and reference beam impinge perpendicularly on 200 surface of grating.In the present embodiment, angle α is 45 degree.
Further, the light splitting direction of first polarization splitting prism 153 is identical as 200 pitch direction of grating.
When grating 200 relative to grating measuring probe 100 in Z-direction, that is, vertical mobile when, projected from vertical measurement module
It include f in 0 grade of diffraction light out0+Δf1The displacement information of+Δ Z, after closing beam with reference to beam splitting with one, the 4th remote couplings device
1303 pairs its couple, formed (Δ f2-Δf1Δ Z) interference signal, and detector is sent to by multimode fibre.Signal processing
Module calculates (Δ f2-Δf1Δ Z) interference signal detect the reference without tested displacement with from third remote couplings device 156
The difference of interference signal is it is known that grating 200 pops one's head in 100 in Z-direction displacement relative to grating measuring, to realize vertical
To measurement.
Embodiment 3
The present embodiment the difference from example 2 is that: the vertical detecting module in the present embodiment does not include the 4th beam splitter
1301, the measuring beam with vertical deviation information returned by grating is using other way and through 1302 beam splitting of the 5th beam splitter
Reference beam afterwards is synthetically formed interference signal a1, realizes vertical measurement.It (is not shown in the figure and is surveyed for horizontal direction as shown in Figure 5
The part of amount), reference beam is reflected by the 5th beam splitter 1302, into the second polarization splitting prism 121, and has vertical position
The measuring beam of confidence number is exported after closing beam by the coupling of the 4th remote couplings device 1303.
For synthesizing the scheme of light beam shown in the present apparatus, specific implementation can be used various ways, can be embodiment 2
In by the 4th beam splitter 1301 realize light combination measurement, be also possible to through the 5th beam splitter 1302 and the second polarization splitting prism
Light combination measurement is realized in 121 combinations.Light combination method is not limited to the above, can also use other optical elements, such as half
Wave plate, quarter-wave plate and other auxiliary devices are realized.The structure of grating measuring probe 100 can according to demand not
Together, increase a number of polarization splitting prism and/or reflecting mirror, foldover design is carried out to optical path, to adapt to different spaces
Size requirements.
Obviously, those skilled in the art can carry out various modification and variations without departing from spirit of the invention to invention
And range.If in this way, these modifications and changes of the present invention belong to the claims in the present invention and its equivalent technologies range it
Interior, then the invention is also intended to include including these modification and variations.
Claims (23)
1. a kind of grating measuring device characterized by comprising
Light source module, for generating the different two light beams of frequency；
Grating；
Signal processing module；
And grating measuring is popped one's head in, including double frequency enters optical module, horizontal direction detecting module, symmetrically sets with reference to detecting module and two
The retroreflector set, wherein the double frequency enters optical module for receiving the two light beams, and the two light beams are projected institute
It states grating surface and with reference to detecting module, the two light beams projects the detecting module that refers to and interfere to be formed with reference to dry
Signal is related to, in the grating surface diffraction occurs for the two light beams, and diffraction light is projected to corresponding retroreflector respectively, through described
To the grating surface re-diffraction occurs for retroreflector retroeflection, and the convergence of two beam re-diffraction light projects the horizontal direction detection mould
Block interferes to form horizontal direction displacement interferometer signal；
The signal processing module detect the horizontal direction displacement interferometer signal and it is described refer to interference signal, and calculate the light
The horizontal direction of grid is displaced；
The grating measuring probe further include: vertical measurement module and vertical detecting module enter optical module outgoing through the double frequency
Two light beams in light beam be projected to the grating surface through the vertical measurement module, through the grating surface diffraction
Diffraction light and the two light beams in another light beams be projected to the vertical detecting module and interfere to form vertical position
Interference signal is moved, the signal processing module receives the vertical deviation interference signal, and refers to interference signal meter in conjunction with described
Calculate the vertical deviation of the grating；
The vertical measurement module includes: the second polarization splitting prism, the second prism of corner cube and Polarization Controller, and vertical measurement is used
Light beam first through second polarization splitting prism transmit, by Polarization Controller rotatory polarization direction, project and occur on grating
Diffraction, the zero-order diffraction light of a diffraction are incident to described second behind Polarization Controller rotatory polarization direction again
Polarization splitting prism, back to second polarization after second polarization splitting prism reflexes to second prism of corner cube
Amici prism is again incident on the grating later and re-diffraction occurs, described in the zero-order diffraction light warp in re-diffraction light
The vertical detecting module is projected after second polarization splitting prism.
2. grating measuring device as described in claim 1, which is characterized in that the optional prism of corner cube of retroreflector.
3. grating measuring device as described in claim 1, which is characterized in that the light source module includes: laser, isolation
Device, optical splitter, frequency shifter, the first coupler and the second coupler；The light beam that the laser issues is after isolator, by described
Optical splitter light splitting is two beams, respectively enters the frequency shifter and generates the different two light beams of frequency, the two light beams point
The grating measuring probe is not sent to after the coupling of the first, second coupler.
4. grating measuring device as claimed in claim 3, which is characterized in that the laser uses gas laser.
5. grating measuring device as claimed in claim 3, which is characterized in that the frequency shifter is Zeeman frequency divider, birefringent
Element or two acousto-optic frequency shifters.
6. grating measuring device as described in claim 1, which is characterized in that the grating is one-dimensional grating or two-dimentional light
Grid.
7. grating measuring device as described in claim 1, which is characterized in that the horizontal direction detecting module includes optical splitter, X
Coupler is measured to measurement coupler and Y-direction, the two light beams after the optical grating diffraction are distinguished after optical splitter light splitting
It is coupled by the X to measurement coupler and Y-direction measurement coupler.
8. grating measuring device as claimed in claim 7, which is characterized in that the optional polarization splitting prism of optical splitter.
9. grating measuring device as claimed in claim 8, which is characterized in that the light splitting direction of the polarization splitting prism and institute
The pitch direction for stating grating is identical.
10. grating measuring device as described in claim 1, which is characterized in that it includes the first beam splitting that the double frequency, which enters optical module,
Mirror and the second beam splitter, a branch of in the two light beams be incident to respectively after the first beam splitter beam splitting the grating and
It is described to refer to detecting module, it is incident to the light respectively after the second beam splitter beam splitting described in another Shu Jing in the two light beams
Grid and it is described refer to detecting module.
11. grating measuring device as described in claim 1, which is characterized in that it includes the first beam splitting that the double frequency, which enters optical module,
Mirror, the second beam splitter and third beam splitter, the vertical detecting module include vertical measurement coupler, in the two light beams
Light beam by being incident to the vertical measurement module and described with reference to detecting module, institute respectively after the first beam splitter beam splitting
Another light beams in two-beam book are stated by being incident to the third beam splitter and described after the second beam splitter beam splitting respectively
With reference to detecting module, the third beam splitter will be incident to respectively the vertical measurement module and described after received beam splitter
Light beam through the vertical measurement module outgoing is closed beam by grating surface, the vertical measurement coupler.
12. grating measuring device as claimed in claim 11, which is characterized in that the vertical detecting module further includes the 4th point
Shu Jing, the third beam splitter will be incident to respectively the 4th beam splitter and the grating surface after received beam splitter,
It is incident to the light beam of the 4th beam splitter and after the light beam of the vertical measurement module outgoing closes beam by the vertical measurement
Coupler coupling.
13. the grating measuring device as described in claim 1,10,11 or 12, which is characterized in that the double frequency enters optical module packet
It includes: first collimator, the second collimator and angle of wedge piece pair, wherein the first collimator and the second collimator are respectively to described
Two light beams are collimated, in the two light beams after collimation it is any it is a branch of be incident to the angle of wedge piece to carry out angle control
System.
14. the grating measuring device as described in claim 10,11 or 12, which is characterized in that further include turning for realizing light beam
To mirror assembly.
15. grating measuring device as described in claim 1, which is characterized in that the light source module and the grating measuring are visited
Signal transmitting is realized by polarization maintaining optical fibre between head.
16. grating measuring device as claimed in claim 7, which is characterized in that the X is surveyed to measurement coupler and the Y-direction
Amount coupler passes through multimode fibre and signal is passed to the signal processing module.
17. grating measuring device as described in claim 1, which is characterized in that the tilt controller uses Faraday rotation
Device or half wave plate.
18. grating measuring device as described in claim 1, which is characterized in that be incident to described second in the two light beams
The polarization direction of another light beams is there are the first angle in the polarization direction of the light beam of polarization splitting prism and the two light beams,
Correspondingly the placement direction of second polarization splitting prism rotates the first angle, the light beam being emitted after the Polarization Controller
Polarization direction also rotate the first angle.
19. grating measuring device as claimed in claim 18, which is characterized in that first angle is 45 degree.
20. grating measuring device as described in claim 1, which is characterized in that be incident on the inclined of the light beam of the grating surface
There are the second angles for vibration direction and the grid direction of the grating.
21. grating measuring device as claimed in claim 20, which is characterized in that second angle is 45+k*90 degree, wherein
K is natural number.
22. grating measuring device as described in claim 1, which is characterized in that the vertical detecting module passes through multimode fibre
Signal is passed into the signal processing module.
23. grating measuring device as described in claim 1, which is characterized in that described to pass through multimode fibre with reference to detecting module
Signal is passed into the signal processing module.
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| CN109374259A (en) * | 2018-11-07 | 2019-02-22 | 暨南大学 | Holographic grating period high precision online measuring and regulating device |
| CN111457843B (en) * | 2019-04-26 | 2021-07-30 | 上海微电子装备（集团）股份有限公司 | Displacement measuring device, displacement measuring method and photoetching equipment |
| CN110261071B (en) * | 2019-07-08 | 2021-09-24 | 北京工业大学 | Laser parameter monitoring and correcting system and method |
| CN112577431B (en) * | 2019-09-29 | 2022-02-08 | 上海微电子装备（集团）股份有限公司 | Grating ruler measuring device and measuring method |
| CN112882347B (en) * | 2019-11-29 | 2022-05-10 | 上海微电子装备（集团）股份有限公司 | Grating switchable displacement measuring device, measuring method and photoetching system |
| CN111536882B (en) * | 2020-05-22 | 2021-04-13 | 复旦大学 | Reading head, two-dimensional displacement measurement system and measurement method |
| CN114111585A (en) * | 2020-08-31 | 2022-03-01 | 上海微电子装备（集团）股份有限公司 | Grating measuring device and photoetching machine |
| CN114152193B (en) * | 2020-09-07 | 2023-02-21 | 上海微电子装备（集团）股份有限公司 | Motion table grating measurement system and photoetching machine |
| CN113932909B (en) * | 2021-09-30 | 2022-06-21 | 中国科学院长春光学精密机械与物理研究所 | Online detection device for tool flutter state |
| CN114353671B (en) * | 2022-01-14 | 2022-11-01 | 西安交通大学 | Dual-wavelength diffraction interference system and method for realizing synchronous measurement of displacement and angle |
| CN117091512B (en) * | 2023-10-19 | 2024-01-02 | 中国科学院长春光学精密机械与物理研究所 | Multi-reading-head cooperative grating measuring device, measuring method, medium and equipment |
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