CN1047569A - Self-scanning photorectiifier array single-frequency laser interference length measuring method and measuring instrument - Google Patents
Self-scanning photorectiifier array single-frequency laser interference length measuring method and measuring instrument Download PDFInfo
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- CN1047569A CN1047569A CN 89103380 CN89103380A CN1047569A CN 1047569 A CN1047569 A CN 1047569A CN 89103380 CN89103380 CN 89103380 CN 89103380 A CN89103380 A CN 89103380A CN 1047569 A CN1047569 A CN 1047569A
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Abstract
A kind of self-scanning photodiode array single-frequency Frequency Stabilized Lasers interference length-measuring instrument, scan with the striped of self-scanning photodiode array (SSPDA) the Michelson interference system, make the output signal of SSPDA produce frequency difference, try to achieve measured displacement (length) by frequency difference numerical value again.Since adopt frequency difference to survey length, thus stronger than the antijamming capability of general single frequency laser interferometer, owing to adopted the single-frequency frequency stabilized laser, so the general two-frequency laser interferometer of equipment is simple, the measuring accuracy height.
Description
The present invention is a length measuring instrument.
The laser interference length-measuring instrument is owing to its measuring accuracy height, and speed is fast, and measurement range is big, and applicability is developed extensively and rapidly and uses.Mainly contain two classes with laser interferometry at present as the method for linear measure longimetry, a class is the single-frequency laser interference system with the single-frequency frequency stabilized laser, and a class is the dual-frequency laser interferometer system with two-frequency laser.
The principle of work of single frequency laser interferometer is as follows: its michelson interferometer optical path commonly used is seen Fig. 1.Sending frequency from laser instrument (1) is that the light beam of f0 is divided into two-way through beam divider (2).One road directive reference mirror (3), one road directive is measured mirror (4), and the two-way light beam is joined at the D place after reflection, forms fixed interference fringe.Measure mirror (4) and be placed in the moving object, when moving object was moved with certain speed v, because Doppler effect, its frequency of light that reflects from measurement mirror (4) had an increment ± Δ f.Frequency is that the two-beam of fo and fo ± Δ f can be fashionable at the D place, can produce the phenomenon of " bat ", and Δ f is a beat frequency, make moving interference fringes.Photoelectric tube (5) receives the movable signal of interference fringe, and can convert by the quantity of calculating moving striation obtains moving object displacement (length).The interference field light distribution is constant during v=0, and photoelectric tube is received direct current signal.Horizontal metroscope by this principle is made because the amplitude of photoelectric tube output is main quantity of information, so be subjected to direct current to amplify drift, reaches the influence of factors such as light intensity attenuation, makes the antijamming capability of interference system relatively poor.
The principle of work of two-frequency laser interferometer is as follows:
Fig. 2 is the two-frequency laser interferometer schematic diagram.Add the magnetic field that is produced by permanent magnet (7) on the laser instrument (6), because Zeeman effect and pulling effect are sent a branch of left-handed and right-circularly polarized light that contains two different frequencies, its frequency is f
1And f
2This Shu Guang becomes two mutually perpendicular linearly polarized lights after by quarter wave plate (8) to be passed through parallel light tube (9) again and expands bundle and collimation.
This Shu Guang that comes out from parallel light tube reflects sub-fraction as the analyzer (11) of reference light beam by 45 ° of placements through beam divider (10), by Malus law as can be known, the projection on 45 ° of directions of the linearly polarized light of two vertical direction forms new linearly polarized light, produces beat frequency.The difference of two optical frequencies that the frequency of this bat equals laser instrument just to be sent i.e. (f
1-f
2).Enter prime amplifier (13) and computing machine (21) through photovalve (12) reception.
Remaining permeation parts is along former direction directive polarization splitting prism (15).Mutually perpendicular linearly polarized light f
1And f
2Be separated.f
2Return f behind the three-dimensional prism of directive (14)
1The light transmission polarizing prism (15) of frequency is to measuring three-dimensional prism (16), if at this moment measure three-dimensional prism (16) with speed v motion, f
1Back light just had to change and become (f
1+ Δ f).After returning, passes through this Shu Guang polarization spectroscope (15) and and f again
2Back light join, the analyzer (18) that is reflexed to 45 ° of placements by right-angle prism (17) is gone up and is produced beat frequency and received by photoelectric original (19) then, enters prime amplifier (20) and computing machine (21).
Computing machine compares two paths of signals, and the difference ± Δ f(that calculates between them is a Doppler frequency difference).And then just try to achieve tested length value.
In two-frequency laser interferometer, " double frequency " played modulating action.It still keeps an AC signal when testee is static with respect to interferometer, the motion of testee just makes the frequency of this signal increase or reduce, thereby prime amplifier can adopt the AC amplifier of higher multiple; Avoided the zero point drift problem of direct current amplifier.The stronger reason of two-frequency laser interferometer antijamming capability that Here it is.
Though single frequency laser interferometer equipment is simpler as can be seen from top narration, owing to be subjected to direct current to amplify drift, the influence of factors such as light intensity attenuation, its poor anti jamming capability.Two-frequency laser interferometer is to utilize frequency difference to record the displacement of mobile object, and its antijamming capability is strong, but its equipment is complicated, and price is expensive.
The objective of the invention is to develop the laser interferometer that a kind of strong interference immunity, precision height, measurement range are big, cost is low.
Formation of the present invention is to scan with the interference fringe of self-scanning photodiode array (SSPDA) to the Michelson interference system, makes fixed interferometric fringe signal be transformed into the vision signal of certain frequency.When moving interference fringes, the frequency video signal of SSPDA output promptly changes, thereby produces frequency difference, utilizes the numerical value of frequency difference again, tries to achieve the displacement (length) of mobile object.
The accompanying drawings principle of work is as follows:
Fig. 3 is a light path principle figure.22 is that He-Ne laser instrument 23 is photoelectric receiving device self-scanning photodiode array for reference mirror 27 for cylinder collector lens 28 for measuring mirror 26 for beam divider 25 for beam expanding lens 24
The single-frequency laser that laser instrument (22) sends enlarges light beam through beam expanding lens (23).This light beam is divided into two-way through beam divider (24), one road directive is measured mirror (25) back backspace, another road directive reference mirror (26) back backspace, two-way backspace light beam is joined and is formed interference fringe, receive by self-scanning photodiode array (28) through cylinder collector lens (27) back, change its light signal into electric signal output.
The self-scanning photodiode array is silicon photoelectric diode array and sweep circuit, and multicircuit switch adopts to recharge sampling method with a kind of element that is integrated on the silicon chip.Fig. 4 is a self-scanning photodiode array outside drawing.29 is receive window.30 are the pipe leg.Fig. 5 is a SSPDA sweep circuit block diagram.31 is the MOS switching tube, and 32 is photoelectric tube.Be arranged with several (being 64) individual photoelectric tubes (32) in the receive window (29) of SSPDA, this photoelectric tube is operated in the charge storage mode, and when illumination increase integration time, the decay of diode both end voltage increases, and then charging current also increases.By dynamically shift register output conducting, then impressed voltage recharges each diode by sampling resistor Rs each metal-oxide-semiconductor in Fig. 5 successively successively.Thereby on the common output line of array, obtain a series of towards electric current impulse.The amplitude of these current impulses and light intensity be along the space distribution of array direction, and the mean value in illumination integration time is directly proportional.
In order to drive the work of dynamic displacement register and to scan, need the driving pulse (Φ Φ) and one road initial pulse S of two-way complementation.Reach the amplifying circuit that the output signal of photoelectric tube is amplified.When purchasing self-scanning photodiode array chip, all be furnished with corresponding driving and amplify plate.
When the self-scanning photodiode array scans fixed interference fringe, can obtain as shown in Figure 6 squiggle at its public output.Signal graph when Fig. 6 scans fixed interference fringe for the self-scanning photodiode array.Horizontal ordinate is the time, and ordinate is a magnitude of voltage, and wherein each waveform is promptly represented an interference fringe, Tcp be in the linear array each diode successively during conducting the time at interval, Ts is that the whole conductings of each diode once the time when beginning conducting again to the second time, are promptly exposed thoroughly the time in the linear array.To is time that interference fringe is required of scanning.
Make fcp=1/Tcp fs=1/Ts fo=1/To
Fcp-is the sweep frequency (little sweep frequency) of self-scanning diode array.
Fs-is the initial pulse frequency (frequency exposes thoroughly) that self-scanning two swashs the pipe array.
Fo-is the modulation wave frequency of video output signals.
The following relationship formula is arranged simultaneously.Ts＝（N+No）Tcp
N-is the number that self-scanning photoelectricity two swashs photoelectric tube in the pipe array.Can be N=64.
The No-column array scanning returns required time, quite takies the number of diode.Can be No=4.
Because To=Ts/m m-is the fringe number in scan period of Ts.
∴ fo＝1/To＝m/Ts＝mfs （1）
Behind object of which movement (promptly measure mirror motion) then interference fringe to produce mobilely, establishing its movement velocity is v ', then vision signal modulation this moment wave frequency is f.
f＝fo[1±v′/（w/m·fo）] （2）
W-is the width that diode is arranged in the self-scanning photodiode array.
The striped number of gained when m-scans for the self-scanning photodiode array.
The stripe movement speed v ' with the ratio of working table movement speed V, with the ratio approximately equal of width of fringe of stripe movement and half light wave length of working table movement.That is:
v′/v＝（w/m）/（λ/2n）
∴ v′＝v w/m·2n/λ （3）
λ-for optical wavelength n-be the aerial refractive index of light.
With (3) formula substitution (2) Shi Kede:
f＝fo±V·2n/λ
If Δ f=V2n/ λ is V=± Δ f(λ/2n) then
Because of moving displacement amount s=∫ vdt
∴ S＝±∫
t oΔfλ/2n′dt （4）
This shows, obtain Δ f and can try to achieve move distance the integration of time.Be tested shift length (length).
7 explanation embodiment are as follows in conjunction with the accompanying drawings:
Fig. 7 is a SSPDA single-frequency laser interference horizontal metroscope structural representation.(vertical view)
33 is that He-Ne single-frequency frequency stabilized laser 34 is V-type support
35 is that beam expander 36 is right angle block prism (reference mirror) for beam divider 37
38 is that right angle block prism (measurement mirror) 39 is cylindrical mirror
40 are the wall of self-scanning photodiode array (CL-64) 41 for the interference head
42 is that beam expander support 43 is self-scanning photodiode array drive plate
Whole components and parts of this interference horizontal metroscope all are arranged in one except that the right angle block prism (38) of measuring mirror interferes in the head (41).Interfering head is that a rectangular box is settled two V-type supports (34) at its base plate one end (rear portion), on this support, place laser instrument (33), settle beam expander support (42) in laser instrument (33) the place ahead, place beam expander (35) thereon, beam divider (36) is settled in the place ahead at beam expander (35), settle with reference to right angle block prism (37) at the light path refractive direction of beam divider (36), the opposing party at beam divider (36) light path refractive direction settles cylindrical mirror (39), self-scanning photodiode array (40) is settled in light path the place ahead at cylindrical mirror (39), measure mirror right angle block prism (38) and interfering head (41) outside, be placed on the tested motion thing, the layout of above-mentioned all elements all must be adjusted at the tram of its light path, settles drive plate (43) on self-scanning photodiode array right side.
Fig. 8 is the structural representation of SSPDA single-frequency laser interference horizontal metroscope.(front elevation)
Same Fig. 7 of symbol among the figure.
The light path principle figure of this interferometer is seen Fig. 3.
Signal process by SSPDA output is amplified, phase locking frequency multiplying, and Pulse Subtracter, reversible counting and computing show can draw move distance (length) numerical value.
Fig. 9 is the signal processing circuit block diagram.
The advantage of interferometer of the present invention is the frequency difference that available single-frequency Frequency Stabilized Lasers interference system obtains to be similar to dual-frequency laser interferometer system.Therefore stronger than the antijamming capability of general single frequency laser interferometer, practical, because of the laser instrument that uses is a single-frequency laser, make equipment simple simultaneously, cost is low.
Claims (2)
1, a kind of method of measuring length with michelson interferometry, it is characterized in that scanning with the interference fringe of self-scanning photodiode array to the Michelson interference system, make fixed interferometric fringe signal be transformed into the vision signal of certain frequency, when moving interference fringes, the frequency video signal of self-scanning photodiode array output promptly changes, thereby the generation frequency difference is utilized the numerical value of frequency difference again, tries to achieve the displacement (length) of mobile object.
2, a kind of by the single-frequency frequency stabilized laser, beam expander, beam divider, the right angle block prism, cylindrical mirror, the single-frequency Frequency Stabilized Lasers interference length-measuring instrument that the self-scanning photodiode array is formed is characterized in that forming and interferes the arrangements of elements of head as follows:
Interfering head is a rectangular box, settle two V-type supports at its base plate one end (rear end), on this support, place the single-frequency frequency stabilized laser, settle the beam expander support in laser instrument the place ahead, place beam expander thereon, settle beam divider, settle with reference to the right angle block prism at the light path refractive direction of beam divider in the place ahead of beam expander, the opposing party at beam divider light path refractive direction settles cylindrical mirror, settles the self-scanning photodiode array in light path the place ahead of cylindrical mirror.Measuring right angle block prism is placed in the moving object, and all said elements all are adjusted on the tram of its light path.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89103380 CN1019416B (en) | 1989-05-25 | 1989-05-25 | Self-scanning photorectiifier array single-frequency laser interference length measuring method and measuring instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89103380 CN1019416B (en) | 1989-05-25 | 1989-05-25 | Self-scanning photorectiifier array single-frequency laser interference length measuring method and measuring instrument |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1047569A true CN1047569A (en) | 1990-12-05 |
| CN1019416B CN1019416B (en) | 1992-12-09 |
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ID=4855096
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 89103380 Expired CN1019416B (en) | 1989-05-25 | 1989-05-25 | Self-scanning photorectiifier array single-frequency laser interference length measuring method and measuring instrument |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100354599C (en) * | 2002-06-24 | 2007-12-12 | 莱特盖局股份有限公司 | Common-path frequency-scanning interferometer |
| CN102175141A (en) * | 2011-01-13 | 2011-09-07 | 清华大学 | Double-channel single-frequency laser interferometer |
| CN103075968A (en) * | 2013-01-09 | 2013-05-01 | 浙江理工大学 | High-frequency digital signal edge locking-based laser heterodyne interference signal processing method |
| CN109883362A (en) * | 2019-03-11 | 2019-06-14 | 华侨大学 | A kind of straight line degree measurement system based on grating interference principle |
-
1989
- 1989-05-25 CN CN 89103380 patent/CN1019416B/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100354599C (en) * | 2002-06-24 | 2007-12-12 | 莱特盖局股份有限公司 | Common-path frequency-scanning interferometer |
| CN102175141A (en) * | 2011-01-13 | 2011-09-07 | 清华大学 | Double-channel single-frequency laser interferometer |
| CN102175141B (en) * | 2011-01-13 | 2013-06-12 | 清华大学 | Double-channel single-frequency laser interferometer |
| CN103075968A (en) * | 2013-01-09 | 2013-05-01 | 浙江理工大学 | High-frequency digital signal edge locking-based laser heterodyne interference signal processing method |
| CN103075968B (en) * | 2013-01-09 | 2015-05-20 | 浙江理工大学 | High-frequency digital signal edge locking-based laser heterodyne interference signal processing method |
| US9797705B2 (en) | 2013-01-09 | 2017-10-24 | Zhejiang Sci-Tech University | Laser heterodyne interferometric signal processing method based on locking edge with high frequency digital signal |
| CN109883362A (en) * | 2019-03-11 | 2019-06-14 | 华侨大学 | A kind of straight line degree measurement system based on grating interference principle |
| CN109883362B (en) * | 2019-03-11 | 2024-02-02 | 华侨大学 | Straightness measurement system based on grating interference principle |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1019416B (en) | 1992-12-09 |
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