TW201905438A - Heterodyne interferometric configuration for measuring dynamic phase change wherein calculations of the phase delay and the optical axis angle are independent to each other - Google Patents

Abstract

Provided is a heterodyne interferometric configuration for measuring dynamic phase change, which sequentially penetrates a core structure of a first polarization state conversion element, a to-be-tested birefringence element, and a second polarization state conversion element through a signal light wave. The polarization state conversion elements adjust the polarization state of the light wave to be circularly polarized through a phase delay function, and the optical axes of the two polarization conversion elements are perpendicular to each other, so as to generate an interfering signal of a linearly polarized horizontal electric field and an interfering signal of a linearly polarized vertical electric field. The amplitudes of the two interfering signals are proportional to cos([Phi]/2) and sin([Phi]/2), respectively, and the phase difference between the two interfering signals is equal to 2 times the optical axis angle [beta], so that calculations of the phase delay [Phi] and the optical axis angle [beta] are independent to each other. Due to phase subtraction, common mode phase noise can be eliminated, and amplitude common mode noise, such as mild variations in light source power, can also be eliminated.

Description

 Measured dynamic phase change heterodyne interference architecture  

The invention relates to a measurable dynamic phase change heterodyne interference architecture, which is a set of heterodyne interference architecture for measuring dynamic birefringence parameters, and by means of fast sampling, calculating the instantaneous amplitude and phase of the interference signal with a computer, The dynamic change of the phase delay Φ and the optical axis angle β of the birefringent material to be tested can be recorded, and the measurement range of the phase delay can reach [0, 4π], and the optical axis angle measurement range is [0, π].

Birefringence is a feature exhibited by an anisotropic material. This feature shows that when a polarized light wave penetrates such a material, the polarized light wave is split into two paths, and the polarization states of the two paths are perpendicular to each other. And the refractive index of the material experienced is different; this phenomenon is due to the special symmetry of the molecular structure of the anisotropic material, so that the material itself has two mutually perpendicular axes, one called the extraordinary axis (Extraordina _r y Axis, whose refractive index is n _e , the other axis is called the Ordinary axis, and its refractive index is n _o ; when n _e <n _o , this kind of material is called negative birefringent material, and vice versa. When n _e >n _o , it is called a positive birefringent material.

Birefringent materials such as quartz, which are resistant to high temperature and corrosion, have been widely used in semiconductor, optical, communication, chemical and other industrial fields; for example, calcite, metallurgy, cement, plastic, glass, ceramics, rubber, paper, synthetic fiber The liquid crystal is also a birefringent material. Because its birefringence property can be manipulated by an applied electric field, it has been widely used in various display and light wave control devices. In addition, biological materials such as muscle fibers, nerve tissue, etc., also show some degree of birefringence; while the isotropic material, which does not have birefringence, has a slight arrangement of crystal molecules under the influence of stress or electromagnetic field. The change will also produce a weak birefringence phenomenon.

Due to the physical properties of the optical axis of the birefringent material, two birefringence parameters are defined from the optical angle, one is the phase delay Φ generated when the polarization state of the light wave is parallel to the two axial directions and the two axial directions are transmitted. d is the thickness of the birefringent material, λ is the wavelength of the light wave; if the extraordinary axis is defined as the optical axis of the material, the other parameter is the angle between the optical axis and the reference coordinate - the optical axis angle β.

For non-destructive detection, the phase delay Φ and the optical axis angle β will cause the light wave that penetrates the light wave or is reflected by such material to change its polarization state, and quantitatively analyze the change amount of the polarization state of the light wave, thereby calculating Φ and β, can deeply understand the physical properties of birefringent materials, or quantitatively calibrate components made of such materials, such as optical wave plates (Wave plates), liquid crystal panels; and detect and analyze the birefringence parameters of reflected light waves of biological materials, Understand the physiological or pathological mechanism for reference as a medication or treatment; and by measuring the weak birefringence parameter distribution of industrial products such as glass, tantalum, and tantalum wafers by polarized light waves, the stress distribution of the product can be analyzed to judge the product.窳, service life, etc. Therefore, it is an important technical field to use a polarized light wave to non-destructively detect a birefringent material and analyze the amount of change in the polarization state of the transmitted light wave.

In the past 20 years, the use of polarized light detection to analyze birefringent elements or materials, or to detect analytical stress distribution, there are numerous research results and patents, such as US 3177761A, US 3434786A, US 5644562A, US 6157448A, US 20030090673A1, US 72122891B1, WO 2004003652A1 , US 6697157 B2, WO 2004036260A3, US 6947140 B2, US 6940595B1, US 8264675B1, CN 102998283A, WO 2016025278A3, but these architectures and technical features can only measure the phase delay Φ of [0, 2π], and part of the architecture, for the double The optical axis angle β of the refractive element is limited, or the phase delay Φ must be completely measured under the condition of β, and some optical structures must adjust the azimuth of some optical components during the measurement process. As a result, the requirement for real-time measurement of birefringence parameters cannot be achieved.

The object of the present invention is to provide a non-difference interference structure capable of measuring [0, 4π] dynamic phase change to measure dynamic birefringence parameters, and the optical component does not need to be adjusted during the measurement process, and does not need to be considered. The optical axis angle of the birefringent material to be tested, by means of rapid sampling, and the computer calculates the instantaneous amplitude and phase of the interfering signal (for example, using Fourier transform, or maximum similarity), the phase delay Φ of the birefringent material to be tested is recorded. The dynamic change of the optical axis angle β, and the measurement range of the phase delay Φ can reach [0, 4π], and the measurement range of the optical axis angle β is [0, π].

To achieve the foregoing objective, the present invention can measure a dynamic phase change heterodyne interference architecture comprising: an incident light wave of linear polarization coherent single-frequency laser light, the linear polarization direction of the incident light wave being adjusted to be α degrees with the horizontal X-axis, And splitting the light wave into two directions through an incident spectroscopic device, wherein the incident light splitting device is a signal light wave, and the incident light splitting device reflects a reference light wave; the signal light wave is slightly adjusted after the frequency is guided And sequentially passing through a first polarization conversion component, a to-be-measured birefringence component, and a second polarization conversion component, and the optical axes of the first polarization conversion component and the second polarization conversion component are perpendicular to each other; After the reference light wave is slightly adjusted by another frequency, it is guided to penetrate a linear polarizing element, and the incident reference light wave is converted into a linearly polarized light wave, and the linear polarization angle is 45 degrees with the X-axis; the signal light wave and the reference light wave are in one The beam splitting device overlaps, and the beam splitting device guides the mixed light wave to a polarization beam splitting device in a coaxial transmission manner, the polarizing beam splitting device allows horizontally polarized light waves to penetrate but The vertically polarized light wave reflects, the horizontally polarized light wave that penetrates the polarization beam splitting device is incident on a first sensing device, and the vertically polarized light wave reflected by the polarizing beam splitting device is incident on a second sensing device, after being in the signal, The calculation of the birefringence parameter phase delay Φ and the optical axis angle β of the birefringent element to be tested can be calculated.

Wherein, the incident light wave linear polarization angle α is 0 or 90 degrees, the interference signal amplitude of the horizontally polarized light wave penetrating the polarization beam splitting device, and the interference signal amplitude of the vertically polarized light wave, respectively, and |sin(Φ/2 )| or |cos(Φ/2)| is proportional.

In practice, when the incident light wave selects a dual-frequency coherent laser, and the polarization states thereof are perpendicular to each other, the signal light wave reference light wave after splitting the light wave into two directions through an incident beam splitting device does not need a device for slightly adjusting the frequency, and is structurally The device for adjusting the frequency is omitted. The incident beam splitting device can be changed to a device having the same function as the polarizing beam splitting device, and the first frequency adjusting device and the second frequency adjusting device are not required, and only the signal light wave after passing through the incident beam splitting device is corrected in advance. The linear polarization angle is 0 degree or 90 degree, and the rest of the optical frame purchase and signal processing methods are completely the same as the foregoing.

The main technical feature of the present invention is that the heterodyne interference architecture is designed to sequentially penetrate the core structure of the first polarization state conversion element, the to-be-tested birefringence element and the second polarization state conversion element through the signal light wave, and the polarization state conversion element Through the phase delay effect, the polarization state of the light wave is adjusted to become circular polarization, and the optical axes of the two polarization conversion elements are perpendicular to each other, and an interference signal of a horizontal linear polarization electric field and an interference signal of a vertical linear polarization electric field are generated, and the two groups The amplitude of the interference signal is equal to cos(Φ/2) and sin(Φ/2), respectively, and the phase difference between the two sets of interference signals is equal to 2 times the optical axis angle β, so the phase delay Φ and the optical axis The calculation of the angle β is independent of each other.

Secondly, when the Φ value is such that cos(Φ/2) or sin(Φ/2) is negative, since the signal amplitude cannot display the negative value, the phase value of the signal appears in the π value phase jump, so The π value jump of the phase is from 0 to π, or from π to 0, to determine whether the corresponding changes in cos(Φ/2) and sin(Φ/2) are less than zero, and this judgment can be obtained by calculation of the program. . The amplitude of the interference signal is changed, and after the unwrapping according to the foregoing principle, a positive and negative value is generated, and then the ratio of the two amplitudes is calculated, and the dynamic change of the Φ value can be obtained. Common-mode phase noise is eliminated due to phase subtraction, and amplitude common mode noise, such as weak variations in source power, is eliminated. The upper limit of the dynamic change of the measurement of this architecture is limited only by the modulation frequency of the optical system and the speed of the sampling speed.

100‧‧‧ incident light waves

110‧‧‧ Signal Lightwave

120‧‧‧Reference light waves

200‧‧‧ incident spectroscopic device

300‧‧‧First frequency adjustment device

310‧‧‧First guiding device

320‧‧‧First polarization conversion element

330‧‧‧Birefringent components to be tested

340‧‧‧Second polarization conversion element

400‧‧‧second frequency adjustment device

410‧‧‧Second guiding device

420‧‧‧linear polarizing elements

500‧‧‧Splitting device

510‧‧‧Polarization beam splitter

610‧‧‧First sensing device

620‧‧‧Second sensing device

Figure 1 is a schematic diagram 1 of the optical interference architecture of the present invention.

FIG. 2 is a schematic diagram of the structure of the birefringent component to be tested in the present case.

Figure 3 is a schematic diagram 2 of the optical interference architecture of the present invention.

Figure 4 is a schematic diagram of the elliptical polarization of the present case.

Figure 5 is the result of the birefringence parameter of the liquid crystal phase modulator of the present invention.

The detailed description of the present invention and the technical description of the present invention are further illustrated by the embodiments, but it should be understood that these embodiments are for illustrative purposes only and are not to be construed as limiting.

The invention is designed as a heterodyne interference architecture of a Mach-Zehnder Interferometer, which will generate an interference signal of a horizontally linearly polarized electric field and an interference signal of a vertical linearly polarized electric field, the amplitudes of the two sets of interference signals, Is equal to cos(Φ/2) and sin(Φ/2), respectively, and the phase difference between the two sets of interference signals is equal to 2 times the optical axis angle β, so the calculation of the phase delay Φ and the optical axis angle β, Independent of each other. Secondly, when the Φ value is such that cos(Φ/2) or sin(Φ/2) is negative, since the signal amplitude cannot display the negative value, the phase value of the signal appears in the π value phase jump, so The π value jump of the phase is from 0 to π, or from π to 0, to determine whether the corresponding changes in cos(Φ/2) and sin(Φ/2) are less than zero, and this judgment can be obtained by calculation of the program. . The amplitude of the interference signal is changed, and after the unwrapping according to the foregoing principle, a positive and negative value is generated, and then the ratio of the two amplitudes is calculated, and the dynamic change of the Φ value can be obtained. Common-mode phase noise is eliminated due to phase subtraction, and amplitude common mode noise, such as weak variations in source power, is eliminated.

Referring to FIG. 1 and FIG. 3, when an incident light wave 100 is a linear polarization coherent single-frequency laser light, and the linear polarization direction of the incident light wave 100 is adjusted to be α degrees with the horizontal X-axis (the X-axis is parallel to the paper surface, as shown in FIG. 3 As shown, the incident light wave 100 enters an incident beam splitting device 200 that is independent of the polarization state of the light wave. The incident beam splitting device 200 splits the light wave into two directions, and penetrates the incident beam splitting device 200 to the same traveling direction as the original incident light wave 100. The light wave is referred to as a signal light wave 110, and the light wave reflected by the incident beam splitting device 200 is referred to as a reference light wave 120.

After the signal light wave 110 passes through a first frequency adjusting device 300, the light wave frequency is slightly adjusted to ω ₁ by the first frequency adjusting device 300. After the first frequency adjusting device 300 is penetrated, the signal light wave 110 passes through a first The guiding device 310 guides through a first polarization conversion component 320, a birefringent component 330 to be tested, and a second polarization conversion component 340. The first polarization state conversion element 320 adjusts the polarization state of the signal light wave 110 to circular polarization by a phase delay function; the first polarization state conversion element 320 and the second polarization state conversion element 340 have the same function, in a specific optical axis. The angle between the polarization state of the optical wave and the circular polarization state can be made, but the optical axis of the second polarization state conversion element 340 in the architecture of the present invention is perpendicular to the optical axis of the first polarization state conversion element 320. . The birefringent component 330 to be tested may be an optical phase modulator to be tested.

After the signal light wave passes through the second polarization state conversion element 340, it overlaps with the reference light wave 120 in a light splitting device 500. In addition, after the reference light wave 120 passes through a second frequency adjusting device 400, the frequency of the reference light wave 120 is slightly adjusted to ω ₂ , and the reference light wave 120 is further guided to the linear polarizing element 420 via a second guiding device 410. The linearly polarizing element 420 can convert any polarization light wave into a linearly polarized light wave, where the linear polarization element 420 converts the incident reference light wave 120 into a linearly polarized light wave having a linear polarization angle that is 45 degrees from the X-axis.

The function of the spectroscopic device 500 is the same as that of the incident spectroscopic device 200, and the optical wave is divided into two paths, and the splitting is independent of the polarization state of the optical wave. After the signal light wave 110 and the reference light wave 120 overlap the light splitting device 500, the light splitting device 500 In the coaxial transmission mode, the mixed light wave is guided to a polarization beam splitting device 510, which allows horizontally polarized light waves to penetrate but reflects vertically polarized light waves, as shown in FIG. 1, through the horizontal polarization of the polarization beam splitting device 510. The light wave is incident on a first sensing device 610, and the vertically polarized light wave reflected by the polarization beam splitting device 510 is incident on a second sensing device 620, and is amplified by a transimpedance amplifier (TIA) in the sensing device. First, the power of the horizontally polarized light wave and the vertically polarized light wave are first converted into a photocurrent, and the photocurrent is output as a voltage. After the two output voltage signals pass through the signal, the birefringence parameters Φ and β of the birefringent element 330 to be tested can be calculated.

Referring to FIG. 2 again, in the implementation of the present invention, if the incident light wave 100 source selects a dual-frequency coherent laser, the light waves of different frequencies of the light source have their polarization states perpendicular to each other, and the incident beam splitting device 200 can be changed to have The device of the same function as the polarization splitting device 510 does not need the first frequency adjusting device 300 and the second frequency adjusting device 400, as shown in FIG. 2; only the signal light wave 110 after passing through the incident beam splitting device 200 is corrected in advance. The linear polarization angle is 0 degree or 90 degree, and the rest of the optical frame purchase and signal processing methods are completely the same as the foregoing.

Next, the principle of the present invention is explained. Referring to FIG. 3, it is assumed that when the signal light wave 110 (one-line polarization single-frequency coherent light wave) is incident on the optical element structure in FIG. 3, the birefringent element 330 to be tested is placed at an arbitrary optical axis angle. This arrangement is the core architecture of the present invention between two first polarization state conversion elements 320 and a second polarization state conversion element 340 having a quarter wave plate function. The incident signal light wave 110 (linearly polarized light wave) and the horizontal X-axis clip α angle, as shown on the left side of FIG. 3, the forward direction is the Z axis, and is perpendicular to the first polarization state conversion element 320 and the second polarization state conversion element 340. The optical axis angles of the first polarization conversion element 320 and the second polarization state conversion element 340 are perpendicular to each other, and are α+45 degrees and α-45 degrees, respectively, or α-45 degrees and α+45 degrees; The incident signal light wave 110 is a single-frequency coherent light wave, and both the first polarization state conversion element 320 and the second polarization state conversion element 340 and the birefringence element 330 to be tested have no depolarization effect, and the light wave power attenuation is The polarization state is independent, so a Jones matrix is used to describe the changes in the polarization of the three components with the light. Assume that the Jones matrix J _{in of the} incident light wave can be expressed as Where E _in =E _o exp[ i (ωt+ζ)] is the complex electric field amplitude of the incident signal light wave 110, ω is the optical wave angular frequency, ζ is the starting phase, i is an imaginary number; for any uniaxial phase retarder If the birefringence parameters are Φ and β , the Jones matrix can be expressed as Therefore, the Jones matrix of the first polarization conversion element 320 and the second polarization conversion element 340 are respectively when β is at α ± 45 degrees.

First, it is considered that the optical axis angles of the first polarization conversion element 320 and the second polarization conversion element 340 are α - 45 degrees and α + 45 degrees, after the linearly polarized light wave passes through the first first polarization state conversion element 320 The light wave is converted into a circular polarization state, and the circularly polarized light wave passes through the birefringent element 330 to be tested to form an elliptical polarization state, and the light wave passing through the second polarization state conversion element 340 is still elliptically polarized, according to the light wave passing through the element. Order, the Jones matrix of the output electric field Can be explained by , Indicates the component of the output electric field on the X-axis and the Y-axis, and substitutes J _Q , J _S and J _in into the above formula. In the above formula , For the electric field amplitude, , It is the phase of the electric field of the light wave component, in which the optical path difference of each component is guided by the rod, which can be absorbed into E _in without affecting the calculation result. The amplitude and phase of each component electric field are expressed as follows: To further understand the change in the polarization state of the output electric field, equation (6) can be expressed as among them Is the phase difference between the electric field components According to the foregoing description and the derivation formula, when α = [0, 90] degrees, the component electric field amplitude and phase difference are

In addition, when the optical axis angles of the first polarization conversion element 320 and the second polarization conversion element 340 in the core architecture are arranged to be α +45 degrees and α -45 degrees, the same derivation process can be obtained.

The upper right corners indicate 1, 2 indicating the optical axis angles of the first polarization conversion element 320 and the second polarization state conversion element 340, which are arranged differently. The four equations (9a), (9b), (10a), and (10b) are only available when α = 0 or 90 degrees, and other alpha angles are not available (9) and (10). Four styles.

Regardless of the arrangement, the trajectory of the synthetic electric field tip is output, and an ellipse is formed on the XY plane, and the equation (9a) is, for example, as shown in FIG. 4, which is an elliptical polarization diagram, an ellipticity angle χ and an elliptical azimuth angle ψ, Indicates the state of the ellipse. According to C.Brosseau, Fundamentals of polarized light, statistical approach , John Wiley and Sins Inc., 1998., the ellipticity angle χ and the elliptical azimuth angle 代表 representing the elliptical state, and the relationship between Φ and β is tan(2ψ)=tan (2Φ)cos(2β), sin(2χ)=sin(2Φ)cos(2β) (11)

But according to (9a) or (10a)

Or according to formula (9b) or (10b) When Φ and β are unchanged, the elliptical trajectory does not change, but the positive and negative of β changes the rotation direction of the elliptical trajectory.

Therefore, when the Φ or β of the birefringent component 330 to be tested in the core architecture of FIG. 3 is adjusted, the polarization state of the output electric field also changes. In the interference architecture, in order to maintain the amplitude ratio and phase difference of the two interfering signals, 12), the output electric field of the core structure interferes with the electric field of the reference light wave 120 of the 45-degree linear polarization, as shown in FIG. 1 , the frequency of the linearly polarized light wave is slightly different from the frequency of the light wave passing through the core structure, thus generating an external The differential interference signal, the signal frequency Ω is equal to the difference between the two optical wave frequencies. Since the linear polarization angle of the linearly polarized light wave is 45 degrees from the horizontal X-axis, the amplitude ratio can be maintained without being affected by the power of the linearly polarized light wave during the interference.

After the reference light wave 120 electric field E _REF passes through the linear polarization element 420, the Jones matrix E _REF when overlapping with the signal light wave 110 is B is the amplitude attenuation rate of the reference light wave 120 after passing through the optical device-incident beam splitting device 200, the second guiding device 410, the linear polarization element 420, and the beam splitting device 500, E _r =E _o exp[i(ω ₂ t+ξ) ], γ is the optical path phase of the reference light wave and the residual phase after the polarization state is converted by the linear polarization element 420. Since the light wave is in a linear polarization state and is 45 degrees with the X axis, |E _{X, REF} |= |E _{Y, REF} |=|E _R | (14) The expression of the signal light wave 110 and the reference light wave 120 when the light splitting device 500 overlaps, and the expression (7) For example, it can be written as A is the amplitude attenuation rate of the signal light wave 120 after entering the beam splitting device 200, the first guiding device 310, and the beam splitting device 500 through the optical device. Since the polarization beam splitting device 510 separates the horizontally linearly polarized light wave from the vertically linearly polarized light wave, the first is incident. The electric fields of the sensing device 610 and the second sensing device 620 are respectively

At this time, the optical path phase of the signal light wave 110 is absorbed in E _in , and the optical path phase of the reference light wave 120 is absorbed in the E _r . Therefore, the output difference of the first sensing device 610 and the second sensing device 620 interferes with each other. Signal, after filtering the DC item, it can be

Ω=|ω ₁ -ω ₂ | is the heterodyne frequency, |E _in |, |E _r | and |E _R | are pure amplitudes whose phase has been absorbed in δθ due to the horizontally polarized light wave and vertical The polarized light wave is a common optical path, and δθ also includes the optical path phase difference between the signal light wave and the reference light wave. (18) and (19) consider that the optical axis angles of the first polarization conversion element 320 and the second polarization conversion element 340 are α - 45 degrees and α + 45 degrees, respectively, but if the two optical axis angles are arranged as α +45 degrees and α -45 degrees, the resulting interference signal is the same as (18), (19), except that the superscript 1 is changed to 2.

When sin( Φ /2) or cos( Φ /2) is negative due to the change of Φ value, since the amplitudes of V ₆₁₀ and V ₆₂₀ are both positive values, the change of this negative value cannot be displayed, but the interference signal The phase can be faithfully presented, and the instantaneous change in phase π represents the change in this negative value. If sin( Φ /2) or cos( Φ /2) changes from positive to negative, the corresponding interfering signal phase appears positive π phase jump; otherwise, if sin( Φ /2) or cos( Φ /2) is negative When it becomes a positive moment, the phase of the corresponding interference signal appears a negative π phase jump. Therefore, the interference signals of V ₆₁₀ and V ₆₂₀ can be expressed as

Therefore, according to the positive and negative π phase jumps of the sensing interference signal, the corresponding interference amplitude is unwrapped by signal processing, and the positive and negative amplitudes are obtained to reflect sin( Φ /2) or cos( Φ /2). The positive and negative, and then use the amplitude ratio calculation, the actual Φ value change can be obtained. After the amplitude back-winding is performed, if the linear polarization angle of the incident light wave 100 is 0 degree, the relationship between the Φ and the amplitude ratio is as follows If the linear polarization angle of the incident light wave 100 is 90 degrees, the relationship between the ratio of Φ and the amplitude is as follows The subscript _UnW indicates the amplitude after _rewinding , so V _{610, UnW} and V _{620, UnW} can be positive or negative, so the Φ value ranges from [0, 4π]. The relationship between the phase difference of the two interfering signals and the optical axis angle β of the birefringent element 330 to be tested is related to the optical axis angle arrangement of the first polarization conversion element 320 and the second polarization state conversion element 340, as in (9a), ( 9b), (10a), (10b) are shown in the four equations.

The invention is a set of heterodyne interference architecture for measuring dynamic birefringence parameters. During the measurement process, the optical component does not need to be adjusted, and the optical axis angle of the birefringent component 330 to be tested is not considered. Quick sampling, and computer calculation of the instantaneous amplitude and phase of the interfering signal (for example, using Fourier transform, or maximum similarity), can record the dynamic change of the phase delay Φ and the optical axis angle β of the birefringent material to be tested, and the phase delay Φ The measurement range is up to [0, 4π], and the optical axis angle β is measured in the range [0, π]. The upper limit of the dynamic change of the measurement of this architecture is limited only by the modulation frequency of the optical system and the speed of the sampling speed.

In order to verify the above principle description, a liquid crystal phase modulator is placed at the position of the birefringent element 330 to be tested of FIG. 1, and the birefringence parameter is measured to change as the driving voltage increases. The result is shown in FIG. 5.

Figure 5(a) shows the results of the phase measurement of the two interfering signals. Three π phase jumps can be observed, and the corresponding two sets of interference amplitudes are inversely entangled according to the three π phase jumps, as shown in (b). , where the solid line is the interference amplitude (positive and negative value) after the anti-winding, and the interference amplitude (positive value) measured by the broken line table. By calculating the amplitude ratio after the anti-winding, the measurement result of the phase delay Φ as a function of the driving voltage is obtained. As shown in (c), the phase is reduced from 383.85 degrees of 1 volt to -14.60 degrees of 10 volts, and the range of variation At 398.45 degrees, the three phase jumps are eliminated, and the optical axis angle β of the liquid crystal phase modulator is obtained, which is changed as the driving voltage increases, as shown in (d).

The functions of the above optical devices are as follows:

1. The incident spectroscopic device 200 and the spectroscopic device 500 are spectroscopic functional devices. Theoretically, the spectroscopic function is independent of the polarization state of the optical wave, and the ratio of the optical power of the split signal light wave 110 to the reference optical wave 120 power, except 0 and For any value, as long as the transmittance and reflectance of the incident beam splitting device 200 are the same as those of the spectroscopic device 500, the transmittance and the reflectance can be offset by the calculation of the formula (22), and the function and the target of the architecture of the present invention are not theoretically affected. If the incident spectroscopic device 200 and the spectroscopic device 500 have different transmittances and reflectances, they must be tested and corrected before the (23) two equations can be used to calculate the Φ value.

2. The first polarization state conversion element 320 and the second polarization state conversion component 340 convert the incident light wave 110 of the linear polarization state into a circular polarization light wave, so the device can be a conventional quarter wave plate, or other Optical elements of the same function, but the optical axis angles of the first polarization state conversion element 320 and the second polarization state conversion element 340 are known and perpendicular to each other during measurement.

3. The first frequency adjusting device 300 and the second frequency adjusting device 400 may be an acousto-optic element, which changes the frequency of the light wave by the acousto-optic effect, or an optical component assembled by other materials having the same frequency adjusting function.

4. The first guiding device 310 and the second guiding device 410 have the function of changing the traveling direction of the light wave. The function is not related to the polarization state and the optical power of the light wave, and the device can be a traditional optical plane. Reflector.

5. The first sensing device 610 and the second sensing device 620 can be traditional light sensors, whether DC coupling or AC coupling, and the response bandwidth range must include the heterodyne frequency Ω.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are all It is still within the scope of the invention patent.

Claims (9)

A measurable dynamic phase change heterodyne interference architecture comprising: an incident light wave of linearly polarized coherent single-frequency laser light, the linear polarization direction of the incident light wave being adjusted to be α degrees with the horizontal X-axis, and transmitted through an incident The light splitting device divides the light wave into two directions, and the light beam that penetrates the incident light splitting device is a signal light wave, and the light beam reflected by the incident light splitting device is a reference light wave; the light wave of the signal is slightly adjusted after the frequency, and is guided after being guided. Passing through a first polarization state conversion element, a to-be-measured birefringence element, and a second polarization state conversion element, and the first polarization state conversion element and the second polarization state conversion element are perpendicular to each other; the reference light wave passes through another After the frequency is slightly adjusted, after guiding, a linear polarizing element is penetrated, and the incident reference light wave is converted into a linearly polarized light wave, and the linear polarization angle is 45 degrees with the X-axis; the signal light wave and the reference light wave overlap with a light splitting device. The spectroscopic device directs the mixed light wave to a polarization beam splitting device in a coaxial transmission manner, the polarization beam splitting device allows the horizontally polarized light wave to penetrate but the vertically polarized light wave is inverted The horizontally polarized light wave that penetrates the polarization beam splitting device is incident on a first sensing device, and the vertically polarized light wave reflected by the polarizing beam splitting device is incident on a second sensing device, and the signal is calculated after being in the signal. Calculation of the birefringence parameter phase delay Φ and the optical axis angle β of the birefringent element to be tested. The measurable dynamic phase change heterodyne interference structure according to the first aspect of the patent application, wherein the incident light wave linear polarization angle α is at 0 degree or 90 degrees, and the interference of the horizontally polarized light wave penetrating the polarization beam splitting device The amplitude of the signal and the amplitude of the interfering signal of the vertically polarized light wave are equal to |sin( Φ /2)| or |cos( Φ /2)|, respectively. The measurable dynamic phase change heterodyne interference architecture according to claim 2, wherein when the α is 0 degrees, and the optical axis angle of the first polarization conversion element and the second polarization conversion element is α -45 degrees and α +45 degrees, , , Δθ=2 β ; where |E _X |, |E _Y | is the electric field amplitude of the incident light wave on the X-axis and the Y-axis, and Δθ = θ _{X -} θ _Y is the electric field component of the incident light wave on the X-axis and the Y-axis The phase difference between them. The measurable dynamic phase change heterodyne interference architecture according to claim 2, wherein when the α is 90 degrees, and the optical axis angle of the first polarization conversion element and the second polarization conversion element is α -45 degrees and α +45 degrees, , , Δθ=-2 β ; where |E _X |, |E _Y | is the electric field amplitude of the incident light wave on the X-axis and the Y-axis, and Δθ = θ _{X -} θ _Y is the electric field of the incident light wave on the X-axis and the Y-axis The phase difference between the components. The measurable dynamic phase change heterodyne interference architecture according to claim 2, wherein when the α is 0 degrees, and the optical axis angle of the first polarization conversion element and the second polarization conversion element is α +45 degrees and α -45 degrees, , , Δθ=-2 β ; where |E _X |, |E _Y | is the electric field amplitude of the incident light wave on the X-axis and the Y-axis, and Δθ = θ _{X -} θ _Y is the electric field of the incident light wave on the X-axis and the Y-axis The phase difference between the components. The measurable dynamic phase change heterodyne interference architecture according to claim 2, wherein when the α is 90 degrees, and the optical axis angle of the first polarization conversion element and the second polarization conversion element is α +45 degrees and α -45 degrees, , , Δθ=2 β ; where |E _X |, |E _Y | is the electric field amplitude of the incident light wave on the X-axis and the Y-axis, and Δθ = θ _{X -} θ _Y is the electric field component of the incident light wave on the X-axis and the Y-axis The phase difference between them.  The measurable dynamic phase change heterodyne interference structure according to claim 1, wherein the first polarization state conversion component and the second polarization state transition component convert the incident light wave of the linear polarization state into a circular polarization. State light wave.    The measurable dynamic phase change heterodyne interference structure according to claim 7 is characterized in that the first polarization state conversion element and the second polarization state conversion element are 1/4 wavelength phase retarders.    For example, the measurable dynamic phase change heterodyne interference architecture of claim 1 is characterized in that, when the incident light wave is selected to be a dual-frequency coherent laser, the polarization states are perpendicular to each other, and the optical wave is divided by the incident beam splitting device. Signal light waves and reference light waves will not require a slightly frequency-adjusted device.