TW508437B - Optical rotation angle measurement device using phase method - Google Patents

Abstract

This method can accurately measure the rotation angle and concentration of an optical solution, and it has a lot of applications. Using circular birefringence stabilized frequency laser, different wave speeds of circular polarization components in an optical solution results in the phase change of extrapolation interference signal. After the output signal passing through the low pass filter, the rotation angle measurement sensitivity can be increased by measuring the amplitude of an output phase difference signal in real time. And the output signal is the signal product between a reference beam and an extrapolation interference signal that transmits through an optical solution.

Description

508437 A7 B7 V. Description of the Invention (/) [Field of the Invention] The present invention relates to an optical rotation angle phase measurement device, and particularly to an instant measurement of optical rotation angle using dual-frequency, dual-polarization laser light. 5 [Background technology] The employee cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs prints a solution with optical activity, such as sugar water, which can rotate a linearly polarized light through the optically polarized solution to rotate an angle (Optical rotation). Therefore, the concentration of the solution and the physical quantities of optical rotation characteristics such as circular 10 birefringence can be further obtained by the magnitude of the rotation angle. However, most of the methods for measuring the rotation angle are to directly measure the intensity change of the output linearly polarized light using a polarimeter composed of a polarizer and an analyzer to obtain the rotation angle. size. This method often cannot accurately measure the rotation angle due to the unstable output intensity of the laser light source and it is also easily affected by the external environment. Therefore, some studies have proposed the use of spatial or temporal interferometers and the use of synchronous detection to improve the signal-to-noise ratio (SNR) to improve the measurement accuracy. However, these The method is more complicated in terms of optical architecture and is also easily affected by the environment. [Summary of the Invention] Therefore, an object of the present invention is to provide an optical rotation angle phase measurement device with environmental stability. ~ Another object of the present invention is to provide an optical rotation angle phase measurement device for instant measurement. Page 4 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 508437 V. Description of the invention (V) According to the above purpose, the main feature of the present invention is the use of dual-frequency, double-biased polarized mines Laser light such as Zeeman laser uses phase-sensitive (phase rhyme) methods and devices to measure the rotation angle in real time. The use of a common path optical architecture makes the scene of the ring-shaped factor; the response is effectively reduced, the stability and the detection sensitivity It is greatly improved, and real-time information can also be obtained quickly by using synchronous detection. 10 Order 15 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, a narrative angle phase measurement device of the present invention is used to test the rotation angle of an object Including: a stable frequency laser light source for outputting a signal beam and a reference beam, the signal beam and the reference beam respectively having a circularly polarized laser component with dual frequencies and polarization directions perpendicular to each other, the signal The light beam is incident on the object to be measured; a polarization beam splitting device is used to separate the p-wave and S-wave components contained in the k-number beam passing through the object; a polarized light analysis , Used to adjust the polarization direction of the reference beam from the spectroscopic element so that heterodyne interference optical signals can be generated between the P-wave and s-wave components; the first and second optical detectors respectively analyze the polarized light from the The reference optical heterodyne interference optical signal of the sheet and at least one component of the P-wave or S-wave component of the signal beam passing through the object to be measured are converted into a reference signal and a first data signal; a set of processing devices for The reference signal is shifted by 7Γ / 2 from the first data signal, and the shifted reference data is multiplied by the first data signal, and the DC signal is output to obtain the optical rotation 20 angle of the object to be measured. In order to provide a more detailed and clear understanding of the purpose, efficacy and structural features of the present invention, the preferred embodiments of the present invention are illustrated in conjunction with the illustrations below. [Brief Description of the Drawings] The first figure is the first preferred implementation of the present case. Schematic diagram of the optical structure of the example. · ___ page 5 This paper is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) I * 508437 A7 B7 Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 3) The second diagram is a schematic diagram of the rotation angle of circularly polarized light. The third diagram is a schematic diagram of the optical architecture of the second preferred embodiment of the case. The fourth diagram is the schematic diagram of the optical architecture of the third preferred embodiment of the case. The fifth diagram It is a schematic diagram of the optical architecture of the fourth preferred embodiment of the present case. 5 The sixth diagram is a schematic diagram of the optical architecture of the fifth preferred embodiment of the present case. [Detailed Description] Please refer to the first figure, the present invention uses the lightning As a light source, a stable frequency laser light source device 1 having two different frequencies and polarizing directions perpendicular to each other is used as a light source. In a first preferred embodiment, the device 1 includes a linearly polarized Zeeman laser 1 00, a half-wave plate iio, a spectroscopic element 120, and a quarter-wave plate 130. Among them, the linearly polarized laser beam emitted by the laser 100 passes through a half-wave plate, so that the two azimuth angles of the linearly polarized light P-wave and S-wave deflection angle), Parallel to the X and Y axes of the space coordinate axis, respectively. The linearly polarized light output from the light source 100 is divided into a reference beam and a signal beam by a beam splitting element (BS) 120. As shown in the second figure, because the rotation angle is generated based on the left (^ and right (R) circularly polarized light when propagating in a medium with optical rotation characteristics, the linear polarization is caused by the propagation rate being different. The light rotates, so in the first figure, a quarter-wave plate 13 with an azimuth angle of 45 is used to convert the p-wave and S-wave of the signal beam into circularly polarized r-waves and l-waves, respectively. To a solution with optical rotation characteristics, where p wave and s wave can be expressed as J wave, s, (4,%) and (A, 15) 15 20 moment broken into P wave V, S wave: 〇 · 1 respectively Amplitude and frequency of P wave and S wave, and then converted by λ / 4 wave plate. __ ^ Page ¢ The paper size is applicable to China National Standards & (CNS) A4 specifications (21〇χ 297 公 爱)-• % Tier 1 U ------ ^ --------- Line --- 1 (Please read the notes on the back before filling out this page) 508437 A7 B7 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs Fifth, the description of the invention () into R wave and L wave, which can be written as R wave · (Ι / Α) # — A. and L wave R wave and L wave pass through the solution of the object under test 140 Can be written as R, wave ·· （1 忑） Ape t + a; L 'wave ... (1 / λ / 1, Μ〆 (~ + ~) 5 where sum represents the phase change caused by the different propagation speeds of the R wave and the L wave in the optically active medium. The rotation angle of linearly polarized light can be obtained in 5 = (θκ—θ〇 / 2. When the R 'wave and L' wave pass through a 50:50 polarized light splitter (PBS), the light is split into 150, and The R 'wave and L' in the polarization direction of the P wave will be converted into (Ap / W) 10 and (As / A)% ί (ω pt + Θ R)

~ An electrical signal that generates heterodyne interference and is received by the second optical detector D 160 and converted into a first data signal is output. The first data signal output by Dp can be written as

Ip (Full As2 + ApAscos (Ay t + ΑΘ) · • ⑴

Wherein ΔΘ = 0R — 0L ′ =%-%; the same way ′ passes through the polarization direction of S wave R e ′ Kt + θβ and “Hachi〆 *) 〇 e i (cost + 0L). > The reference beam passes through the light analysis sheet 121 to generate heterodyne interference, and is received and converted into a reference signal by the first photodetector A 122. The A7 pages output by A are in accordance with Chinese National Standard (CNS) A4 specifications. (210 X 297 mm) — "TIT · ——! · -------- t --------- line · (Please read the notes on the back before filling this page)- 508437 Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Description of invention (Γ) The reference signal can be written as

Ir (z ^ t) = (Ap ') 2+ (As') 2 + 2Ap'As'cos (J must /) ... (2 ) Where (Ap, As') is the amplitude of the P and S waves in the reference light.

Ip (* t), and Ir (such as 0 are input to the processing device 2 respectively, and the DC signal is filtered through the band-pass filters 161 and 123 with the center frequency of 5 as the first, then Ιρ (″ Μ) = ApAscos (ztot + ΔΘ ) ............ (3) ΙΓ (ζίώ; t) = 2 Ap J As ? cos (^ 〇 ....................................... (4) where Ir (Such as t) by a tt / 2 phase shifter 124, which is shifted by π / 2 from the first data signal, so that 10 Γ (Δω t) = 2 Ap J As 5 sin (ζΐώ; /) .. ..................................... (5) Input the multiplier 190 and Ip (zto〇 again. Multiply the signals to get I1 (zi ^ i) = ApAscos (zkyi + A ^) 2Ap, As, sin (............. (6) Δ & under low concentration conditions 〇 ， Ιχ {Αωί) ^ 2I0 [cos (zky /)-A ^ sin (J ^ /)] sin (Δωϊ) 15 = I〇 [sin (2 Αωί) + A ^ cos (2 Δωί)] Λ0 ί ^ θ ............ (7) After passing a low-pass filter 200, the output DC output signal is Ιι ^ Κδ ^ Ι〇 | ^ ~ 4 | = ^ Ι〇 | 4 .............. (8) where I 〇 = ApAp, AsAs ,, 5 is the rotation angle. According to the present invention, a magnification of 21. is obtained. The signal can be calculated by the subsequent computing unit 20 processing device 210 to calculate the angle of rotation and related physical quantities. Of course, as those skilled in the art can easily understand, the signal passing through the object 140 in the foregoing preferred embodiment can be easily understood. After the beam has passed through the polarization beam splitter 15o *, the heterodyne interference generated by the polarization direction of the S wave can also be received by the third optical detector Ds 170 and converted into a second data signal, which can be written as ---: — ^ P. 8 This paper has passed the standard of 1F. “CNS” A4 (210 X 297 mm) J.— ^ 7 * 1 ^ ------------ 1 (Please read the notes on the back before filling out this page) 508437 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the invention (?)

Is (^ t) = iAp2 + lAs2-ApAscos (^ t + A0) ......... (9) Then the first data signal Ιρ (Δα 〇 Subtract and amplify the second data signal with the input differential amplifier 180 to form a Balance detector, which can effectively reduce system noise (coimn〇n mode noise) 5 Raise the SNR value of the south, the differential amplifier i8 〇 The output signal is Id (^ 〇 = 2 r [ApAscos (zI ^ / + a ^)] .. (10) The differential amplifier 180 The output signal is input to the multiplier 190, and is multiplied by the reference signal Ir ("by") after being shifted by the redundant / 2 phase biaser 124. Similarly, after passing the low-pass filter 200, 10 12 = 2Ι0 γ | Δ ^ = 4Ι〇γ 4 .............. (11) where 7 is the gain of the differential amplifier From I〆Eq (8) and I2, Eq (l 1), it is learned that the present invention can greatly improve the detection sensitivity of the rotation angle 5 and can detect the relevant physical quantity. In addition, as shown in the fourth figure, the third one is better in this case. As shown in the embodiment, when the light source is a 15-frequency mutual circular circular polarization laser light source, such as a circularly polarized Zeeman laser 101, the stable frequency laser light source device 1 may Simplified, for the laser 101 and a beam splitter 120, the optical path of the reference beam must also be set correspondingly. The polarization direction can be adjusted in the P-wave (X-axis) direction or S-wave (y-axis) direction. Slice 121 to generate a heterodyne interference reference signal of the same quality as Eq (2). Similarly, the frequency-stabilized laser light source device in the second embodiment is replaced with the light source device in the third preferred embodiment, and becomes the first. Five pictures The sad example of the fourth preferred embodiment of this case. _ Page 9 This paper size applies Chinese National Standard (CNS) A4 (210 X 297 mm) ΊΊ M —i I · 11 ----- ^ -----— III (Please read the notes on the back before filling this page) · 508437 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 120.. 124 ... 7Γ / 2 phase shifter 140 ... DUT 180 ... Differential amplifier 200 ... Low pass filter 300 ... Phase-locked amplifier A7 B7 V. Description of the invention (7) Of course, as shown in the sixth preferred embodiment of the present invention in FIG. 6, the processing device in the first preferred embodiment is replaced by a lock-in amplifier 300, and the phase difference is measured and calculated. The size of the rotation angle 5. In summary, the present invention can indeed enlarge the rotation angle by 5 and measure it with the size of the DC signal. The detection sensitivity and the effective measurement range are greatly improved. A groundbreaking invention conforms to the novel and progressive requirements of the invention patent. However, the illustrations and descriptions disclosed above are only for understanding the embodiments of the present invention, and are not intended to limit the implementation of the present invention. All other equivalent changes or modifications should be covered by the scope of patent application below 10. The appendix is a linear graph of the changes in the concentration and phase difference of the sugar solution completed using the optical architecture of Figure 6, which can prove the feasibility of the method of the present invention. [Comparison of component numbers] 1 ··· Stable frequency laser light source device 2 ···· Processing device 15 1 〇〇 ... Linearly polarized Zeeman laser 101 ··· Circularly polarized Zeeman laser 110 ·· 二Half-wave plate 121 ... Polarized light analysis plates 123, 161 ... Bandpass filter 130 ... Quarter-wave plate 20 150 ... Polarized light beam splitter 190 ... Multiplier 210 ... Calculation and processing device page 10 This paper size applies to China National Standard (CNS) A4 specification (210 X 297 public love) —ΓΙΤ — U ---------------- ^ --- ------ (Please read the notes on the back before filling this page)

Claims (1)

Printed by 508437 A8 B8 C8 ______ _ D8 in the Consumer Standards Cooperative Standards Bureau of the Ministry of Economic Affairs 6. Scope of patent application h A phase measurement optical rotation angle device is used to test-the rotation angle of the object to be measured, including: -shed laser light Xiao Laiyu—the domain beam and a reference beam. The Lung beam and the reference beam have dual-frequency, polarized laser components that are perpendicular to each other in five directions, and the polarized component of the signal beam is based on The circularly polarized mode travels and is then incident on the object to be measured;-the polarization splitting wire 4, so that the circularly polarized light component contained in the signal wire passing through the work is distinguished into P wave and s wave direction components; A polarization first analysis sheet is used to adjust the polarization direction of the reference beam 10 from the spectroscopic element so that a heterodyne interference optical signal can be generated between the P-wave and S-wave components; the first and second optical detectors, respectively Convert at least one component of the reference beam heterodyne interference optical signal from the polarized light analysis sheet and the P-wave or s-wave component of the signal beam passing through the object under test into a reference signal and 15 a first data signal Group processing equipment Position, used to offset the reference signal by 7Γ / 2 from the first data signal, and output the reference signal after the offset with the first data signal by the DC # signal, thereby obtaining the DUT ’s Rotation angle. 2. The phase measurement optical rotation angle as described in claim 1 of the claimed patent, wherein the processing device in 20 includes a phase shifter and a multiplier, and the phase shifter is used to convert the reference Signal offset; r / 2, the multiplier multiplies the reference signal number and the first data signal output by the phase shifter and outputs them. Page 11 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) (Please read the notes on the back before filling out this page), ττ 508437 A8 B8 C8 D8 Staff of the Central Bureau of Standards, Ministry of Economic Affairs Consumer Cooperatives 6. Scope of Patent Application ^ --- 3 · —A kind of phase measurement optical rotation angle device is used as a button. The signal beam and the reference beam respectively have a polarization laser component with dual frequencies and polarization directions perpendicular to each other. The polarization component of the signal beam travels in a circular polarization manner and is incident on the target beam. _. A polarizing beam splitting device 'makes the circularly polarized light component contained in the Shinshin bundle of a phase-separated product divided into p-wave and s-wave direction components I.-Polarized light analysis > {, silk adjustment comes from Spectral element = The polarization direction of the test beam 'makes it possible to generate heterodyne interference optical signals between the P-wave and S-wave components; the first, second, and third optical servos analyze the polarized light from Sheet's reference beam heterodyne interferes with the optical signal, and passes through the The P-wave or S-wave component of the signal beam of the object under test is converted into a reference signal, a first data signal, and a second data signal; a differential amplifier for the first data signal and the second data signal to be input into the Subtraction and amplification of a differential amplifier; a set of processing means for shifting the reference signal by 7Γ / 2 from the first and second data signals, and shifting the offset reference signal to the output of the differential amplifier The difference between the first and second data signals is multiplied, and the DC signal output is taken to obtain the rotation angle of the object under test. 4. The phase measurement optical rotation angle device as described in item 3 of the patent scope of the application, wherein the processing device includes a phase shifter and a multiplier, the phase deviation Please read the note of 5 firstly. 10 15 20 Page 12 This paper size is applicable to China National Standard (CNS) A4 (210 X 297) The shifter printed by the Consumers' Cooperative of the Ministry of Light Industry of China is used to shift the reference signal by π / 2. The multiplier shifts the reference signal output by the phase shifter and the differential amplifier output. The first and second data signal differences are multiplied with each other and output. 5. A phase measurement optical rotation angle device, which is used to test the optical rotation of an object under test, including: a stable frequency laser light source device for outputting a signal beam and a wide reference beam 'the signal beam and reference The light beams respectively have polarization laser components with dual frequencies and polarization directions that are perpendicular to each other. The polarization component 10 of the signal light beam is further moved in a circularly implanted manner and is incident on the object to be measured. Spectroscopy device, so that the circularly polarized light component contained in the signal beam passing through the DUT is divided into P-wave and S-wave direction components; a polarized light analysis sheet for adjusting the reference beam from the spectroscopic element The polarization direction is such that heterodyne interference optical signals can be generated between the ρ-wave and s-wave components; 15 ^ the first and second optical detectors, respectively, ^ test beam heterodyne interference from the polarized light analysis sheet The optical signal and at least one component of the p-wave or s-wave component of the signal beam passing through the object to be measured are converted into a reference signal and a first data signal; 20-phase demodulation device measures the reference signal and the first Information Letter Phase change 'thereby obtaining rotation angle of the analyte. 6. The phase measurement optical rotation angle device described in item 3 or 5 of the Shen Qing patent, wherein the frequency-stabilizing laser light source device includes: a linearly polarized dual-frequency frequency-stabilizing laser for outputting two different frequencies Page 13 Scope of patent application 丨 丨 (Please read the precautions on the back before filling out this page} components, and these different frequency line polarization methods are perpendicular to each other; a beam splitter element polarizes the line The light beam is divided into the signal beam and the reference beam; and a set of quarter-wave plates for adjusting the signal beam, so that the signal beam travels in a circularly polarized manner. The phase rotation optical rotation angle device described in the above item, wherein the frequency-stabilized laser light source device further includes a half-wave plate for adjusting the azimuth of the linearly polarized beam. The phase measurement optical rotation angle device according to item 3 or 5, wherein the processing device includes two sets of band-pass filters centered on the frequency difference between the P-wave component and the S-wave component, which are respectively used to filter and filter the reference signal and The first data reads the frequency of i. 9. The phase measurement optical rotation angle device described in the second and fourth items of the patent application scope, wherein the processing device further includes a low-pass filter to filter out the output signal of the multiplier. Straight The component of the flow signal. The phase rotation angle measuring device described in item 1, 3, or 5 of the patent scope of claim 2, wherein the frequency-stabilizing laser light source includes a circularly polarized dual light source for emitting mutually different frequency components. Frequency stabilized laser, and a beam splitting element from the circularly polarized dual-frequency stabilized laser beam divided into a reference beam and a signal beam. Page 14 of this paper; χ2-ϋ）) —----- 50843¾ A8 B8 C8 D8 VI. A patented circularly polarized dual-frequency stable frequency laser with frequency components and a circularly polarized dual-frequency stable frequency laser The laser beam is divided into a reference beam and a signal beam. (Please read the precautions on the back before filling out this page.) • Equipment · Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs. Page 15 This paper applies to China National Standard (CNS) A4 now available (210X297 mm)