TW440682B - Phase difference measuring apparatus and heterodyne interference measuring system using this apparatus - Google Patents

Abstract

This invention provides a kind of phase difference measuring apparatus and the heterodyne interference measuring system that using this apparatus. In particular, the invention is about the non-contact polarized-light heterodyne interference phase real-time measuring system that can reach the real-time measuring effects. The main characteristic of this invention is that the optical signal from the heterodyne interferometer is subtracted and amplified by a differential amplifier so as to have the output signal that is obtained by transforming the phase modulation of input optical signal into the form of amplitude modulation. By direct measuring the magnitude of vibration amplitude, the phase variation can be determined so as to effectively increase the measuring speed and sensitivity.

Description

V. Description of the invention (10 15 A7 B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 20 The present invention provides -box phase # ¥ θ 差 + ,, + # ϋ Μ 4 differential measurement device and the application of this device is十 #Measuring system, especially refers to a non-contact polarization that can achieve instant measurement results. The time difference of the interferometric interference _, the system. Second: precision level In the field of measurement, the change of the measured phase (―) is usually based on the wavelength of light and the reference of light-Γ: degree, speed, length, vibration, or other relevant physical quantities:. High homogeneity, so laser is used as the light source in such interferometers. Optical heterodyne interferometers have matured in the precise measurement of physical quantities such as displacement, angle, speed, length, and vibration. Changes in environmental factors, such as temperature, will cause the phase measurement accuracy of the optical heterodyne interferometer to decrease. Therefore, the architecture of the optical heterodyne interferometer must meet the optical common path (optical common path). Keep the same State, the phase can be protected from interference from the external environment. Even so, as shown in the first figure, the common optical path heterodyne interference vibrator of the polarization optics in the invention patent owned by the applicant and published in Patent No. 35725 " The path configuration not only uses Mach-Zehnder interferometers, but also breaks through and improves conventional techniques. However, when the phase difference is finally sensed, a phase lock loop such as a phase detector is used. , Phase-locked amplifier (10ck-in amplifier) and other methods to measure the phase size, resulting in slower measurement phase or doppler (doppler) frequency response speed, etc., so the high precision required for phase measurement And the ability to respond quickly cannot be taken into account at the same time, which seriously limits the function of such heterodyne interferometers. In view of the conventional laser heterodyne interferometers encountered in the phase measurement, please read the precautions before reading this and then fill out this Page binding page 4 This paper size is applicable to China National Liangs ratio (CNS) 8 4 grids (210X297 mm) 4406 8 2 A7 B7 V. Description of the invention (10 15 20 Speed limit, causing The inconvenience when using this technology, the present inventors have experienced and actively researched, and the invention of the "phase difference amount, phase amplifier is phase difference measurement device and heterodyne interference measurement system using the device". The purpose is to provide a real-time phase difference measurement device. The optical signal from the laser heterodyne interferometer is processed by a differential amplifier and output in an amplitude modulation manner to obtain a rapid response effect. The purpose is to provide a non-contact polarized light heterodyne interference phase instant measurement system that uses the above-mentioned phase difference real-time measurement device to achieve the effect of real-time measurement of surface accuracy. Yet another object of the present invention is to provide a non-contact polarized light heterodyne interference phase instant measurement system using the above-mentioned phase difference instant measurement device. When the measured phase change amplitude is large, K can be simply quantified. Measure the change. J Another object of the present invention is to provide a non-contact polarized light heterodyne interference phase instant measurement system using the above-mentioned phase difference instant measurement device, which can clearly distinguish between the measured phase change in the direction of increasing or decreasing. The main feature of the present invention is that the optical signal from the heterodyne interferometer is subtracted and amplified by a differential amplifier, so that the output signal is converted from the phase modulation of the incident optical signal to an amplitude modulation form, which can be directly measured by The amplitude is small and the phase change is defined so as to effectively improve the measurement rate and sensitivity. To achieve the above-mentioned purpose, the phase difference measuring device of the present invention is used to measure two components of a polarized optical heterodyne interferometer. Beams perpendicular to each other (orthogonal) linearly polarized optical signals are respectively converted into two telecom daring '' at least one of the two optical signals of the heterodyne interferometer, which is booklet page 5 This paper is universal China National Standard (CNS) A4 (21 × 297 mm) V. Description of the invention (10 15 A7 B7 Printed by Shelley Consumer Cooperative of Intellectual Property Bureau of the Ministry of Economic Affairs 20: Reflected light obtained by shooting to a test object And the light of each of the optical signals is a large J phase 胄 i is a function including a product of frequency difference and time, and a subtraction term, respectively. The measuring device includes:-a differential amplifier for H-electricity input and phase Minus ii iu νϋ & sub-amplification to obtain the sine function including the product of the frequency difference and the inter-product, η Fingans. & v ^ and its product with the phase difference sine function; and a signal processing device for County # ^ is used to measure the amplitude of the phase difference function and / or avoid its variation. Regarding the technical means adopted by the present invention to achieve the above objectives and features and its effectiveness, the preferred embodiments are illustrated in conjunction with the drawings The description is as follows: The first figure shows the contamination intention of the conventional polarized optical common-path heterodyne interference vibrometer; the second figure shows the single-frequency stable frequency laser polarization of the first preferred embodiment of the present invention. Schematic diagram; the third diagram is a schematic diagram of the second preferred embodiment of the present invention, a dual-frequency mutual vertical line off-lane optical heterodyne interferometer; the fourth diagram is a polarized light analysis sheet of the third diagram causing p-wave and S-wave interference涔 Schematic diagram; The fifth circle is a schematic diagram of a single-frequency stable frequency laser polarized clip common path ring heterodyne interferometer of the third preferred embodiment of the present invention; the sixth diagram is a fourth preferred embodiment of the present invention dual-frequency mutual Vertical line depolarization optical ring heterodyne interferometer Intent; The seventh diagram is a schematic diagram of the fifth preferred embodiment of the present invention, a single-frequency stabilized laser polarizer common path ring optical fiber heterodyne interferometer; and the sixth comparative example of the present invention " 1N & . Frequency Lei Xianzhu polar • —: gutter (please read the notes on the back before filling this page) Page 6 The private paper method scale is applicable to China National Standards (CNS) from the specifications (21〇 > < 297 Public product) Α7 ----------- B7___ V. Description of the invention () 4 (Mlcheirony-T ^^ ll ^ ~~ »Drawing number component comparison table: 10, 20 ... Single-frequency stable frequency line bias Laser 11 '21 ... # wave plate 2 5 231, 232, 23 3, 431, 432 ... beam splitter 241, 242 ... acousto-optic modulator 251, 252 ... driver 261, 262, 263 , 461, 462 ... pole 4 beam splitters 271, 272, 273 '274, 275, 471, 472, 473, 474 10 reflectors 281, 282, 481, 482 ... light detectors 291, 292, 491, 492 ... band-pass filters 30, 50 ... differential amplifier 31 ... signal processing device 15 310,51 ... amplitude modulation signal demodulator 311 ... phase comparator 312 ... electronic counters 32, 521, 522 ... back Grant circuit 40 .. Double Frequency stabilized and mutually perpendicular polarized lasers 20 421, 422 ... Polarized light analysis sheet 60 .. Polarized light state retention single-mode fiber 90 ... Test sample The phase difference measuring device of the present invention can be used to cooperate with The first page 7 of the aforementioned paper size is in accordance with the Chinese National Standard (CNS) A4 (210X297 mm). Flat (please read the precautions on the back before filling this page). Printed by the Shellfish Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. Figure 5 of the system ο-* 5 A7 B7 Printed by the Shellfish Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs ο 2. Description of the invention (5) The common optical path heterodyne interferometer works together to form the heterodyne interference measurement system of the present invention In the first preferred embodiment, please refer to the second figure, and a polarized light emitted from a light source (in this embodiment, a linearly polarized single-frequency stable frequency helium-neon laser is taken as an example) passes through a pole Angle adjustment device, such as the half-wave plate (λ / 2 wave plate) 21 in this example to adjust its polarization angle; and then the laser beam is divided into a signal beam μ incident to the object 90 by the beam splitter 231, and With reference to the reference beam L2. " ίσ beam and reference beam pass through a frequency adjusting device, respectively, in this example, an acousto-optic modulatoi AOM 241, 242, each acousto-optic modulator 241, 242 is subject to Its drivers 251 and 252 are actuated, so that the frequency of the signal beam 1 ^ passes through the acousto-optic modulator 241 and the frequency is changed; the frequency of the signal beam l2 passes through the acousto-optic modulator 242 and is changed to ω2; The frequency code of the two beams after the splitting produces a slightly different frequency difference Δω »Of course, as is well known to those skilled in the art, the frequency adjustment device here can be achieved by electro-optic modulation or any other similar device. The signal beam 1 ^ passes through a beam splitter 232 and a polarized beam splitter 261 to separate the Pi wave and S wave which are perpendicular to the oscillating direction of the electromagnetic field, and at least one of the beams is reflected by the object 90 (in this embodiment The middle system irradiates P! To the object to be measured 90 and takes its reflected light, SJi is reflected by the plane mirror 272), and then reflected and turned by the polarization beam splitter 261 and the beam splitter 232, and reflected by the simple mirror 271. The P2 and S2 waves of the reference beam coincide at the beam splitter 233. To the polarized light beam splitter 262, the heterodyne interference P-wave (PβPζ) signal and the heterodyne interference 3-wave (si + s2) signal are linearly polarized and perpendicular to each other. Page 8 ----- --- ^ ------, order ------ 0 {Please read the notes on the back before filling in this page) This paper size applies to Chinese national standards (CNS > A4 size (210X297 mm) )

X 4406 8 2 A7 B7 Printed by Shelley Consumer Cooperative of Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the invention () 6 New separation, and two optical detectors 281, 282 are used to detect linearly polarized heterodyne interference P waves ( The PfPJ signal and the heterodyne interference S-wave (SJS2) signal are converted into electrical signals and output. The electrical signals converted by this P-wave and S-wave are passed through a band-pass filter 291 with △ ω-ω, -ωζ as the center frequency, respectively. 292 'to get 5 fixed frequency interference signals and get the result of the following formula: / Ρι + Ρ2 (Δώϊ) = ^ IpIPl cos (Aiar + A ^ p) .............. .......... (1) 6, + ¾ (△ 要) = 2 > / ^ ΛΓ c〇s (Aiaf + △ A) .............. .......... (2) A differential amplifier (differential amplifier) 30 subtracts and amplifies the formed electrical signal to output 1. ^. Among them: / _ (Δ）) = y \ IΡι + Ρι (Aax)-(Δαϊ)] .............. (3) (ιΡιΛ2) are ρ The intensity of the wave and the P2 wave; (iviS2) is the intensity of the S2 wave and the S2 wave respectively; △ pain is the phase difference between the P wave and the p2 wave; 7 is differential amplification When the azimuth angle of the half-wave plate 21 is repeatedly adjusted to 0 so that ΔΛ = κ, the P-wave signal in the two sets of mutually orthogonal linearly polarized heterodyne interference signals will become : (Δώ *) = 2Kcos (A ^ ai + A ^ p) .............. ( 4) and S wave signal will become: ^ s1 + i, (A < af) = 2Kcos (A < af + Δ ^,) ......... ............. (5) Please read the note of ik first

I 10 15 20 At this time, 'the phase in Equations (4) and (5) is transformed into ([αα + δ⑹'s phase coordinate translation]' and input into the differential amplifier 30, then Equation (4) can be rewritten Success: " page (5 |) page 9

A7 B7 V. Description of the invention (

Ipt + Pi (Awt) = 2K cos

Acat + 2 ^ p ~ A ^ s) 2K cos Δώϊ + —δ < ζ5 2 r (4,) ^ s {+ s2 (Δίΐί) = 2 AT cos (55) 10 2K cosl ΔώΤ ~ where 'phase shift contrast As far as the dynamic amplifier is concerned, its output result has nothing to do with the phase coordinate shift. The differential amplifier subtracts / ㈣ (Δ 岣 and 岣 two heterodyne interference signals and amplifies the output signal 1. ^ (△ 岣 can be written as: hut (Δώ) ί) = χ [ΐρι + ρζ (Αύχ) ~ / S + Sj (Δβ *)] = ΑγΚsin (A < ai) .............. (6) where = (^-△ &) is heterodyne interference ρ wave and heterodyne interference The phase difference of the S wave is 4 r Ksin (word) is the amplitude. According to the formula (6), it can be seen that the signal I (αα (Δ)) output by the differential amplifier 30 is an amplitude modulation (AM) signal, and its carrier frequency is Δω = ωι-ω2, where (ωbu ...) are the driving frequencies of the two acousto-optic modulators 241 and 242 in the Mach-Zehnder heterodyne interferometer. In this embodiment, an amplitude demodulator (amplitude demodulat) is used. !: AD) 3 10 The signal to be measured is instantaneously measured by the signal processing device 31 ------------ ^ ------ 1T —----- ^ (Please read first (Notes on the back, please fill out this page) Print out the magnitude of the amplitude measured by the Shellfish Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs

AjK sini ^ s is calculated ten times, that is, when the phase is j, the amplitude of the output signal is 7 K, which can be measured by the amplitude multi-tuning device 3 1 〇 real-time measurement, then = 2sin- Page 10 Therefore, when 4 This paper is reprinted with a tug (CNS) (2 丨 Gx297) ^ 4406 8 2 A7 B7 V. Description of the invention (5 10 15 Printed by the Bureau of Intellectual Property of the Ministry of Economic Affairs * Cooperatives 20 When changing, there will be a phase shift of the reflected dagger component, and this phase change will then appear in the change in the amplitude of the final output. Of course, as those skilled in the art can easily understand, if the dagger is intermodulated with the heart, Si is incident on the object to be measured, and pure reflection is also an optional implementation form. Especially, such as measuring the relative movement or vibration between different positions of the turntable of the magnetic disk drive, it is possible that? And S! Are incident on the object to be measured separately. The phase difference measurement device of the present invention includes only a differential amplifier 30 and a signal processing device 31, but in the field of heterodyne interference measurement, a differential power amplifier has always been used to reduce only two signals. Shared noise in order to remove the noise window; Disclosure of the invention, the differential amplifier is used as an optical-electric conversion processing device, which modulates the phase difference (△ and δ ^ _ in equations (1) and (2) from the amplitude of the electrical signal directly Presented, and the signal processing device 31 includes at least an amplitude modulation signal demodulation device 3 108. Accordingly, not only the phase measurement method of the passerby is converted into the measurement amplitude modulation signal, so that the phase signal to be measured is made. It is directly proportional to the amplitude, which significantly improves the sensing rate; and when the phase change is very small, the electric signal obtained from the relationship of sin xsx can be simplified as: ......... ......... (7) At this time, the magnitude of the measured amplitude is directly proportional to the knowledge, and since the size of the demodulated signal of the cap is 2γKΔ0, the sensitivity of the measurement will be the phase difference Δ-2 r Κ Compared with traditional methods such as phase-locked loop measurement of phase Δ〆, this greatly improves the sensitivity. In addition, after combining with a feedback circuit (feedback opop) 32, it is possible to use such methods as shown in this embodiment to regulate Position of the mirror 272 before and after so that the phase page11 (Please read the precautions on the back first (Fill in this page), Ding: Τ-^ Paper ΛΑϋ For towels (CNS > (21GX297 mm) V. Description of the invention (10 15 A7 B7 Printed by the Consumer Property Cooperative of the Ministry of Economics and Intellectual Property of Japan) 20 Changes Δ / Maintenance Provides a control signal (error signal) under the condition of phase nuUing. It is used in the vicinity of △ " 〇. The amplitude signal output by the differential amplifier 30 has a linear relationship with the slope of 2 r κ. Enables t to measure the smallest phase change in real time. Of course, this return-to-zero control can also use | * Note In other words, 'Because it is the phase difference of the heterodyne interference p-wave and S-wave, such as the relative position of the heterodyne interference P-wave and S-wave from the test point and the reference point, respectively | Shift, relative angle, or other physical quantities such as temperature, refractive index, electromagnetic field, etc. that cause phase changes. It can directly use the simple, fast and mature vibration page demodulation technology to obtain the magnitude of the phase known in real time in a very short time, and then obtain the corresponding physical quantities. Therefore, the present invention can be widely applied to real-time measurement of displacement, angle, speed, length, vibration, and other related optical sensors. In addition, as can be easily understood by those skilled in the art, the present invention can be applied to the measurement of relatively small displacements at two points, and naturally can also be applied to relatively small angles (smaU angles) and other related physical quantities. Instant measurement and control with minimal changes. In particular, by adding a differentiator (圊 not shown) to the signal processing device, the differential amplitude demodulated signal | d [zl ^ (t)] jf * νι —dt-, from the relationship of ω D, the present invention can Instantaneous I changes in small phases cause Doppler frequency shift ω D, and modulate the signal size by amplitude | Measuring Doppler frequency offset, its sensitivity can be increased by 2rK times, which can quickly obtain the measured phase The amount of change in time on page 12 of 11 pages in this paper (CNS > 丨 4 shape (21QX297 public envy 4406 8 2 A7 B7) V. Description of the invention (5 Measure the small vibration of the tested surface. Therefore, according to the present invention The disclosure is not only applicable to the real-time measurement of vibration and displacement, but also in combination with the feedback circuit and the use of the sensitivity of the phase change to generate a control signal, which can be accurately locked to the set initial phase state and applied to related As mentioned above, 'Because the magnitude of the amplitude modulation signal is proportional to the sine of the phase difference 10 15 Printed by the Bayer Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 20 Number sin (#)' When the phase change caused by the test object is too large , So that △ Lu can be expressed as 2τ When τη + 5, an electronic up-and-down counter 312 can also be added to the signal processing device 31, which can effectively count the n pulse signals and leave the remaining. The remaining phase 6 uses the amplitude. 4m sin $ is calculated 'where η is an integer and 0 < π. Therefore, by the parameter (n, 3), the present invention can not only effectively measure a wide range of phase changes, but also use the differential circuit to simultaneously obtain the phase The rate of change is applied to physical quantities such as speed and vibration. In order to distinguish the direction of phase change, a phase comparator 3 11 can be added to the signal processing device 31. The two optical detectors 281, 282 are The heterodyne interference signals output by the band-pass filters 291 and 292 are simultaneously input to the phase comparator 3 11 and the known positive and negative values can be measured in real time to achieve the effect of distinguishing the direction of the phase change. On the other hand, consider the feedback circuit 32 By adjusting the position of the mirror 272 to change the optical path of S, the phase difference of the heterodyne interference p wave and S wave can also be set in advance under the condition of Δout = 0) = / M. Then, the final output signal is ΑγΚsinf sin (Acjf), so the < Pre-set letter between 7Γ (please read the notes on the back before filling in this page) 7⑽ (△ 敁): Page 13 The paper size in use «Defective home rate (CNS) A4 size (210X297 mm) B7

V. Invention Description () ~ I

The phase difference value of 11 I 疋 疋 is used to measure the phase signal. In addition, as shown in the second preferred embodiment of the second figure, in addition to the aforementioned single-frequency one: helium-neon laser as the light source and the optical structure of the beam splitting, two f-binding orthogonal line deviations can also be used. Polarized (P wave and 8 wave) and different frequencies | 5 laser light (such as Zeeman laser) 40 as the light source, and the laser beam is divided into a reference beam (Pz + S2) and a signal beam (pi + Si), the j > 2 component and S2 component of the reference beam _ which were originally perpendicular to each other and could not interfere, respectively, as shown in Figure 4 ', the polarized light analysis sheet (analyzer) 422 is further divided into f Two components, therefore ,! > 2 and 82 interfere with each other in the polarized light analysis sheet 422 polarized direction components to form a reference light heterodyne interference signal, which is converted into an electrical signal by the optical 4 detector 482, and △ ω = ω ρ_ ω s is the center .. of the frequency | The band-pass wave filter 492 遽 wave is input into the differential amplifier 50. The signal beam I passes through the polarized light beam splitter 461 to S, wave, and P〗 wave splitting. In this embodiment, P is incident on the test object 91 and reflected by the test object. § 1 is reflected by the plane |

Printed by the Intellectual Property Bureau of the Ministry of Economic Affairs, the Consumer Cooperative Cooperative Society. The 15 mirrors 471 are reflected in the polarized light beam splitter 461 and the beam splitter 432 is turned, and then passed through the polarized light analysis sheet 421, which will also have the p! Component and \ component perpendicular to each other. They are respectively divided into two vertical components, and they interfere with each other in the polarization direction of the polarized light analysis sheet 421 to form a signal light heterodyne interference signal, which is also sent into the difference through the optical signal detector 481 and the band-pass filter 491. Amplifier 50. Among them, the heterodyne interference signal of the signal light 20 is as follows: / 你 (△ 欲) = / 纠 (Δ 欲) = yjw sincos (A 成 + Δ ~) ............ ........... (8) where 0 s is the polarization angle of the polarized light analysis sheet 421 in the signal beam; △ center = A is the phase difference between Si and Pi waves; △ ω- ύϋρ — 〇) s, P wave y

Frequency ωρ and the difference frequency of S-wave frequency heterodyne interference; / Λ and / J Page 14 This paper is applicable to the Chinese National Standard (CNS) A4 specification (210X297 mm) 1 ~~ '^^ 06 8 2 A7 B7 V. Description of the invention (12 10 are the light intensities of P i and S i waves respectively. Similarly, the reference light heterodyne interference signal is: Iref (Λαΐ) = / Pi + Jj (Λάχ) = sincos (△ 要 + A / re /) .............. (9) 6 &r; r is the polarized light analysis sheet in the reference beam The polarization angle 4 of 422 is the phase difference between I * 2 and S2 waves. Adjust the polarization angles 6 »s and 0 r of the polarized light analysis plates 421 and 422 in the signal light and reference light paths so that the above heterodyne interferes The amplitude of the signal satisfies the relationship of ^ 7 ^ 7 ^ ™ sin 2 ^ s = sin 2 ^. = 2χ. The above 1 ^^ (Δώ ^) and / ton (Δώ〇 can be rewritten as: ^ (△ 求) = / 料 （Δ 奴） = 2; ^ cos (Afi; r + △ heart) .............. (10) / Γβ / ( Δώ *) = Ip2 + Si (Aax)-2 ^ cos (A < ai + A ^ ref) ............ (11) Make the phase coordinates of (10) and (11) + △ ~), please read the precautions on the back before I (10) and (11) can be rewritten as: \ / / 冲 (△ 求) = / Pi + 5i (A ^) = 2 ^ cos · 1 5 (△ 欲) = 1 P1 + Sl (Δβ *) = 2 ^ C0S Acot -j (A ^ llg-A ^ ref) cos

Δ 奴 +; △ 彡 (1 0,) .2 J

2j ^ cos Acut——Δ0 (11,) V 2 J After subtracting and amplifying the input differential amplifier 50 printed by the Shelley Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economy, the output signal of the differential amplifier can be written as: L ·, (Aat) = A ^ ref (Δώ *)-Isig (Δώϊ)] = 4 ^ rsin sin (A < af) (12) where is the phase difference between the reference beam and the signal beam, 7 20 is the gain of the differential amplifier 50 (gain) . Page 15 The paper fit scale is applicable to China's national ratio (CNS) Λ4 wash case (210X297 mm)

V. Description of the invention (13 A7 B7 5 10 Of course 'You can also use a feedback circuit 52 to adjust the position of the mirror 471, change the optical path of s, and change the heterodyne interference signal wave (Pi + Si) and heterodyne. The phase difference of the interference reference wave (? 2 + Sz) is set at but (t = 〇) = such as 〇, so that the differential amplifier output signal Iout (△ slave, but can be set in the range of 0 < M < π The phase change of the phase signal such as 戎 is based on Rong; (bias), so that the direction of the phase change can be distinguished. In addition, when the heterodyne interference signal waves out + S0 and the heterodyne interference reference wave (p2 + S2) The phase difference of sini ^ U Ι0111 (Δ 奴) has an amplitude of 2 < r% times the phase signal #, and is based on the frequency of 4. The heterodyne interference signal wave (Pl + Sl) and heterodyne When the phase difference of the interference reference wave (P2 + S2) Δ0 = 2η π + (5, η is an integer and 0 < 5 < π, an electronic counter (not shown in the figure) can be added to the signal processing device to record η pulses Δφ. At 2 ', then 10111 (4 desire) = | 2; 2 ^ 3111 (monu). Amplitude modulation signal impulse signal, with the amplitude magnitude cut sin S; 2 directly measure the phase difference account I --------- ^ ------, 玎 ------ line (Please read the notes on the back before filling out this page) 15 Printed by the Shellfish Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs The range of phase measurement can be extended by the parameter (η, (5). Thereafter, as in the previous embodiment, 'the signal processing device 51 including an amplitude dephasing device 510 is placed behind the differential amplifier 50' 'The letter key of the original phase difference can be presented as the amplitude of the electrical signal, which effectively speeds up the measurement rate and improves the sensitivity of the sensor.' Furthermore, as shown in the fifth figure, when the first preferred embodiment is used, After the letter-dim beam is slightly adjusted in frequency by the frequency modulation device 241, the polarization order is made on page 16 of the I paper scale using the Chinese National Kneading Rate (CNS) Α4 specification (210X297 mm) '~~ ---- 5 2. Description of the invention (Α7 Β7 10 14 light sheet 263 separates the p! Wave component and the Si wave component of the signal beam, and enters the ring optical path component as one of the objects to be measured in opposite directions. In this embodiment, the ring optical path component is Reflected at right angles by three plane mirrors 273, 274, and 275, they form a loop for signal beam transmission. In the optical path, the signal beam? The waves and 81 waves propagate through the opposite directions of the ring optical path, respectively, and re-superimpose at the polarization beam splitter 263; and the beam splitter 233 overlaps the reference beam and the signal beam to interfere with each other. Once The ring optical path is rotated to form P [Phase phase change caused by the change of the optical path of the wave and S! Wave ', thereby forming a common path Ring Interferometer' to measure the location of the ring interferometer The environment turns or changes. With the same principle as above, the signal output by the differential amplifier can be written as: Please read the back item first and then fill in this page / ⑽ (△△) 4; © sin (字) sin (△ 敁) ....... ............ (! 3) Order 15 Printed by Shelley Consumer Cooperative of Zhithan Property Bureau of the Ministry of Economic Affairs 20 of which 'Θ For the amplitude of the heterodyne interference p-wave and heterodyne interference s-wave, — Yes! The phase change of the wave and S1 wave in the ring optical path. When j (degrees), the formula (13) can be expressed as / ⑽ (△ is called 2 丨 2々 △ and η (Δ 奴) ... (14) From this, the amplitude and measurement of the signal output by the differential amplifier 30 The phase difference is proportional to that of the phase difference, and as in the previous embodiment, a feedback signal is provided by a feedback circuit to zero the phase change at any time, thereby providing the ability to accurately control the phase change. Its detection sensitivity is enhanced compared to direct measurement2 As shown in the sixth figure, it is considered that the signal beam PfSj! In the second preferred embodiment is separated by the polarization beam splitter 462 and the s 1 wave component of the signal beam is separated and entered in opposite directions. As one of the objects to be measured, a ring-shaped optical path component is used. In this embodiment, the ring-shaped optical path component is based on a three-plane anti-furniture ratio (CNS) A4% # · (210X297 mm) 5. Description of the invention (15 A7 B7 mirrors 472, 473, and 474 reflect at right angles and form a ring optical path for signal beam transmission. The Pl wave and Sl wave in the signal beam travel through the opposite directions of the ring | shaped optical path and re-polarize. Recombination at beam splitter 462 and analysis by polarized light 421 produces heterodyne interference. Once the ring optical path | rotation causes the optical path of P〗 wave and S! Wave to change and cause the measured phase | change to form a dual-frequency polarized optical ring heterodyne interferometer. The same as above Principle, the signal output by the differential amplifier: please listen to item 5, I before

Iout ^ ca) 4; Tsirt (· ^) sin (Aiai) .............. (15) 10 15 Printed by Shelley Consumer Cooperative, Bureau of Intellectual Property, Ministry of Economic Affairs 20 where Γ is the amplitude of the heterodyne interference P-wave and heterodyne interference s-wave, which is the phase change of the p-wave and S! -Wave in the circular optical path. When 丨 〇 degree j, equation (15) can be expressed as / ⑽ (△ 要) called ice △ and n (△ 叫 ......... (16) Thus, the differential amplifier 50 outputs The amplitude of the signal is proportional to the known | and can output a control signal, such as when the direction of the aircraft is stable, the control signal can be used to return to control at any time, so that the aircraft is immediately offset when the course is scheduled It is detected, and restores the predetermined heading and zeros the phase change, and provides the ability to accurately control the phase change. As shown in Figure 7, when the ring optical path in the fifth figure is kept in a single-mode ... Optical fiber (polarization maintain single m〇de 〇pticaj fibei ^ O replaced, will form a ring fiber interferometer (fiber 〇pticai ⑴ interferometer), which can also be used for real-time measurement of angular rotation, electromagnetic field strength and control, etc. Related optical sensors. Of course, the plural planar reflectors and circularly arranged optical fibers listed here are only for the purpose of explaining the circular optical path, and are not intended as a limitation. Page 18

Ms〇682 A7 B7

Claims (1)

ABCD, Ministry of Economic Affairs, 4th Bureau, Consumer Consumer Cooperative Printing Factory, patent application scope 17 1_ A phase difference measuring device for measuring the perpendicular line deviation of two beams by a polarized optical heterodyne interferometer A polarized optical signal is converted into an electric signal, and at least one of the two optical signals of the heterodyne interferometer includes a reflected light irradiated to a test object, and the light of each of the optical signals The magnitudes are equal and are functions including the product of frequency difference and time, and the phase difference term. The measurement device includes:,-a differential amplifier for the two electrical signals to be input and subtracted and amplified, thereby 'getting a An amplitude-modulated output signal that is proportional to the product that includes the function of the product of frequency and time and the function of phase difference; and 10 a signal processing device 'the signal processing device includes an amplitude demodulation device' to demodulate the metric The amplitude of the amplitude modulation signal and / or the amount of change of the amplitude modulation signal output by the differential amplifier. 2. The phase difference measurement device as described in item 丨 of the patent application range, wherein the signal processing device further includes a counter, thereby allowing the counter to read the phase difference when the phase difference change is more than 2 redundant. In the variation, it includes several integer multiples of 2π. 3. —A heterodyne interference measurement system is used to measure a person to be measured, including: a coherent light source; a heterodyne interferometer is used to split 20 beams from the coherent light source into one A signal beam and a reference beam. The two beams each include components of two polarization directions (P wave and S wave) perpendicular to each other. Each of the beams has a frequency difference, and at least one of the two components of the signal beam is Including the optical signals obtained by being irradiated to the above-mentioned object to be tested, and interfering with each other to generate a set of equal amplitudes, and including the product of the frequency difference and time, respectively. Page 20 This paper applies China National Standards (CNS > Α4) Grid (210 × 29? Mm) I ---------- installation ------ order ------ line (Please read the precautions on the back before filling this page} Ministry of Economic Affairs · 440B B ^ As B8 C8 printed by 4 employees 'consumer cooperatives' — ~~-~-~~ -_________ D8 VI. Application for '18 1 term and heterodyne interference signal as a function of phase difference term, light detection Detector for converting the two interference signals into an electric signal output respectively;-differential amplifier A device for inputting and subtracting and amplifying the two electrical signals, thereby obtaining an amplitude-modulated output signal that is proportional to a product including a function of frequency and time multiplied by precision and a function of phase difference, and a signal processing Device, the signal processing device includes an amplitude demodulation device for demodulating the amplitude of the amplitude modulation signal output by the differential amplifier and / or its variation amount. The heterodyne interference measurement system, wherein the light source is a single-frequency stable frequency laser; the heterodyne interferometer includes a polarization angle adjustment device, a spectroscopic device, and two sets of frequency modulation devices; and the signal processing device Including an amplitude modulation signal demodulation device, wherein: the polarization angle adjustment device includes a half-wave plate for adjusting the polarization angle of the linearly polarized beam of the single-frequency stable laser output by 15; The beam is divided into the above reference beam and signal beam by the beam splitting device, and the azimuth angle of the half-wave plate is adjusted so that the light intensity of each component of the two beams meets the requirement of 7 ^ = 77 ^ = ruler ; The frequencies of the two light beams are adjusted to be slightly different from each other by the two frequency modulation devices, causing each of the P 20 waves to interfere with each other to generate a heterodyne interference P wave signal 2 feet cos (A slave + ΔΑ), each The S waves also interfere with each other to generate a heterodyne interference S-wave signal (△ slave) = 2Kcos (A desire + ΔΑ) ', and the heterodyne interference P-wave signal and the heterodyne interference S-wave signal have the same frequency and equal amplitude. It is a function that includes the product of the frequency difference and time, and the phase difference term; page 21 of this paper applies the Chinese National Standard (CNS) Α4ί | «格 (210X297 公 嫠)辻 意 事 顼 Fill this page again s 5 10 patent application scope 19 AS B8 C8 D8 Therefore, the phase difference term included in the output signal of the differential amplifier can be obtained by the amplitude demodulation device from the magnitude of the amplitude modulation output signal. The heterodyne interference measurement system as described in item 4 of the scope of patent application, further includes a feedback circuit for changing the optical path of at least one component of the two beams, thereby interfering with the heterodyne! > The phase difference of the S wave is maintained in a range near (t = 0) = '' Rong's origin. 6_ The heterodyne interference measurement system described in item 4 of the patent application range, wherein the signal processing device It also includes a phase comparator to compare the output signals of the two optical detectors, thereby distinguishing the positive and negative of the phase difference, and discriminating the direction of change of the position of the object to be measured7, as described in item 4 of the scope of patent application. The heterodyne interference measurement system, wherein the signal processing device further includes a counter, whereby when the phase difference change / M = 2n; r + 5 is defined, the amplitude of the output signal of the differential amplifier is 4 ^ s: sin 2 It can be written as 4 ^ Tsin (£ \ 2 where 0 <with; r, η as integers, and the age of the umbrella service 'Δ% Please read the precautions and write this page again. Cooperative printed ο 2 The counter records η pulse signals, and (η, 6) reads the change of the phase difference ', thereby extending the measurement range of the phase change. The heterodyne interference measurement system, wherein the signal beam t The perpendicular dagger and \ wave are separated by a polarization beam splitting device provided in the optical path of the signal beam, and the object to be measured is a ring-shaped optical path component, wherein the polarization beam splitting device is located at the frequency Downstream of the modulation device, causing the signal beams to be perpendicular to each other. Page 22 The standard of this paper is applicable to Chinese National Standard (CNS) A4 ^ (2 丨 0X297) Λ8 B8 C8 D8 VI. Application scope 10 waves and Si Waves are separated by the polarization beam splitting device, and pass through the ring light path component formed by the ring light path component in the opposite direction, and then overlap at the polarization light splitting device. Thus, when the environment of the ring light path component is rotated, the The phase difference of the output of the differential amplifier can be obtained from the small amplitude force of the amplitude modulation signal. 9. The heterodyne interference measurement system as described in item 8 of the patent application scope, which _ The ring optical path component includes a complex plane reflection 10. The heterodyne interference measurement system as described in item 8 of the scope of the patent application, wherein the ring optical path assembly includes a single-mode optical fiber with retained polarization state. 11. A heterodyne interference measurement system It is used to measure an object to be tested. (Please read the precautions on the back before filling out this page) V order 5 Printed by the Consumer Cooperative of Intellectual Property Bureau of the Ministry of Economic Affairs 2 Coherent light source; A heterodyne interference The instrument is used for splitting the light beam from the coherent light source into a signal beam and a reference beam, and the two beams include two polarization directions (P wave and s wave) components that are perpendicular to each other. Has a frequency difference, and at least one of the two components of the signal beam 'includes the reflected optical signal obtained by being irradiated onto the object to be measured' and interferes with each other to generate two sets of amplitudes of equal magnitude, and each includes the frequency difference Heterodyne interference signal as a function of time product term and phase difference term; two optical detectors for respectively converting the two interference signals into an electric signal output; a differential amplifier for the two electric signal inputs and Subtractive magnification, page 23 This paper size is applicable to China National Standards (CNS) A4 (2 丨 0X297 mm) 10 15 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 20 Patent application scope 21 Λ δ B8 C8 D8 By this, an amplitude-modulated output signal is obtained, which is proportional to the product including the function of frequency and time product and the function of phase difference; and 'a signal processing device, the The signal processing device includes an amplitude demodulation device for demodulating the amplitude of the amplitude modulation signal output by the differential amplifier and / or a variation thereof. 12. The heterodyne interference measurement system as described in item 11 of the scope of the patent application, wherein the light source is a laser with dual frequencies and mutually polarized lines to provide two beam frequencies in two mutually perpendicular directions, respectively. Slightly different linearly polarized laser beam; the heterodyne interferometer includes a spectroscopic device and a bipolar optical analysis sheet; and the signal processing device includes an amplitude modulation signal demodulation device, wherein: The light beam is divided into the above-mentioned reference beam and signal beam by the beam splitting device, so that the reference beam includes two components p2 & s2 whose linear polarization directions are perpendicular to each other and slightly different in frequency from each other, and the signal beam includes linear polarization directions to each other Two components P1 & s1 which are vertical and slightly different in frequency from each other; at least one of the two components P, S of the signal beam is irradiated onto the object to be measured, and the reference beam and the signal beam pass through Each of the corresponding polarized light analysis sheets interferes with each other of the components along the polarization direction of the polarized light analysis sheet, wherein the polarization angle of each of the polarized light analysis sheets is adjusted so that each of the components Does the light intensity satisfy the relationship of 7 ^ > Formula 1 = 2, and thus, the signal beam can generate a heterodyne interference signal wave :: ((△ 要) = + △ heart) 'The reference page 24 1 II with I nn I .t III cable (please read the precautions on the back before writing this page) This paper size is applicable to China National Standards (CNS) A4 specification (210X297 mm) 5 10 15 Patent application scope 22 Β8 The C8 D8 beam also generates a heterodyne interference reference wave / (△ 卜卜伊 以 (△ + + Δ '), and the heterodyne interference signal wave has the same frequency and equal amplitude as the heterodyne interference reference wave, and They are functions including the product of the frequency difference and time, and the phase difference term; therefore, the phase difference term contained in k number radiated by the differential amplifier can be output from the amplitude modulation by the amplitude demodulation device. The amplitude of the signal is 々 ^ sin. 13. The heterodyne interference measurement system described in item 12 of the patent application scope further includes a feedback circuit 'for changing the optical path of at least one component of the two beams, Thus, the phase difference between the heterodyne interfering agriculture and the s-wave is maintained at the original "〆 (t = 0) =" is a nearby range. 14. According to the heterodyne interference measurement system described in item 12 of the scope of the patent application, the signal processing device in Mozhong further includes a device for comparing the two optical detectors. It is a phase comparator which outputs a phase comparator to distinguish the positive and negative of the phase difference and identify the direction of change of the position of the object to be measured. 15. The heterodyne interference measurement system as described in item 12 of the patent application scope, wherein The signal processing device further includes a counter, so that when the phase difference change ττ + δ is defined, the differential amplifier output amplitude adjustment (please read the precautions on the back before filling this page) iv. Order the Ministry of Economic Affairs ’smart money. The printed signal amplitude of the employees 'cooperatives in the 4 bureaus changes the signal amplitude 4 ^ sin ά, φ can be written as 4 ^ sin where 0 < / < π' and the n pulse signals are recorded by this counter, and the phase is read by (n, 5) This allows the phase change measurement range to be extended. 16. The heterodyne interference measurement system as described in item 12 of the scope of the patent application, wherein the signal beam makes the Pi waves and Lv skins perpendicular to each other, which are applied to the middle and poor countries through the sheet-like paper on page 25. (CNS) Α4Λ4ί · (2 丨 0X297 mm) ';'--20 Β8 C8 -_____ Ρ8 6. Application for patent scope I 23 I One of the polarization beam splitting devices set in the signal beam optical path is separated, and the test is to be performed The object is a ring-shaped optical path component, so that the P! And Si waves perpendicular to each other in the signal beam are separated by the polarization beam splitting device, and pass through each other in a ring-shaped optical path formed by the ring-shaped optical path component. The polarized light splitting device is superposed, whereby the phase difference of the output of the differential amplifier is known when the environment in which the ring-shaped optical path component is rotated is obtained from the amplitude of the amplitude modulation signal 4; r sin #) . 2 Cc (j 17. Heterodyne interference measurement system according to item 16 of the scope of patent application, wherein the ring optical path assembly includes a complex plane mirror. 10 18. Heterodyne interference according to item 16 of the scope of patent application The measurement system, in which the ring-shaped optical path component includes a single-mode optical fiber that retains the polarized light state. I installed i I — order — cable (please read the precautions on the back before filling this page) The Intelligent Property Bureau of the Ministry of Economy Moderate ruler ¾ 筚 梂 家 CO26 26 I 漦 29