CN115390265A - Optical device thermal noise compensation system based on liquid crystal phase delayer - Google Patents

Optical device thermal noise compensation system based on liquid crystal phase delayer Download PDF

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CN115390265A
CN115390265A CN202210330485.5A CN202210330485A CN115390265A CN 115390265 A CN115390265 A CN 115390265A CN 202210330485 A CN202210330485 A CN 202210330485A CN 115390265 A CN115390265 A CN 115390265A
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oven
temperature
liquid crystal
polarization
crystal phase
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王卓
朱骏
刘祀浔
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Beihang University
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/64—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image
    • G02B27/646—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image compensating for small deviations, e.g. due to vibration or shake
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0012—Optical design, e.g. procedures, algorithms, optimisation routines
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
    • G02B27/0068—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration having means for controlling the degree of correction, e.g. using phase modulators, movable elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/44—Grating systems; Zone plate systems

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Abstract

A liquid crystal phase retarder-based optical device thermal noise compensation system utilizes a liquid crystal phase retarder (LCVR) as a controllable spatial light modulator, and the liquid crystal phase retarder enables specific light to vertically penetrate through the surface of glass and can modulate the polarization state of the light according to actual requirements. The invention carries out compensation based on the optical field, meets the design requirement, has the characteristic of convenient engineering realization, compensates the influence of the change of the refractive index of the optical device caused by the high temperature of the oven, improves the measurement precision of the system, is suitable for solving the problem of the temperature drift of the optical device caused by the high temperature, and has very wide application prospect.

Description

Optical device thermal noise compensation system based on liquid crystal phase delayer
Technical Field
The invention relates to the field of system temperature compensation, in particular to a thermotropic noise compensation system of an optical device based on a liquid crystal phase delayer, which can be applied to thermotropic noise of the optical device, can meet pure optical temperature measurement and is particularly suitable for all-optical thermotropic noise compensation of an alkali metal gas chamber.
Background
Optics are key components of many scientific devices, especially for quantum measurement instruments, which are core sensitive components. Optical devices typically operate over a wide temperature range, where temperature changes affect optical system temperature gradients in many ways, causing optical element strain and increasing system aberrations. Unless simplifying assumptions are made about the temperature distribution through the optical system, such effects are generally unpredictable. Considering only uniform temperature changes and simple radial temperature gradients, a uniform temperature rise will result in an increase in radius, element thickness and air space, and the refractive index of the optical element will vary with the refractive index of the optical medium, which is typically air. The temperature inevitably affects the performance of the optical device, and any error can cause great influence on the ultrahigh-sensitivity device, so that the realization of high-precision measurement and stable control of the temperature of the optical device has important significance.
Currently, the study on the temperature of the optical device is mainly focused on analyzing the degree of influence of the temperature on the optical device, the temperature distribution when the optical device is subjected to heat radiation. There has been little research on methods for temperature compensation of optical devices, which mainly focus on servo-controlled movement of components and bimetallic supports with reciprocating motion, which require mechanical control with low precision.
In conclusion, with the development and popularization of the light beam modulation technology and the light beam synthesis technology, a system designed for the thermal noise compensation of the optical device has a wide prospect, and research and practical research in the aspect is still relatively lacked. This patent, based on the general idea of the design of a compensation system for thermally induced noise in liquid crystal phase retarder (LCVR) based optics, will provide guidance and reference to similar optical systems.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the optical device thermal noise compensation system based on the liquid crystal phase retarder, which can be applied to the thermal noise of the optical device, can meet the requirement of pure optical temperature measurement, and is particularly suitable for the all-optical thermal noise compensation of the alkali metal gas chamber.
The technical solution of the invention is as follows:
the thermotropic noise compensation system is characterized by comprising a window mirror, wherein the window mirror is arranged between a light incidence side of an oven and a light emergence side of the liquid crystal phase retarder and comprises a second 1/2 wave plate and a temperature sensing chip resistor, the temperature sensing chip resistor is connected with a light path compensation control signal input end of the liquid crystal phase retarder through a controller, one surface of the temperature sensing chip resistor is pasted on the second 1/2 wave plate, and the other surface of the temperature sensing chip resistor faces the oven to directly sense radiant heat generated when the oven heats a gas chamber.
The temperature sensing chip resistor is a platinum resistor, the controller is connected with an upper computer, and the upper computer monitors light path compensation control signals, light beam deviation data caused by radiation heat influence of the window mirror, the heat radiation temperature of the oven and the working temperature of the oven.
The liquid crystal phase retarder is connected with the laser device sequentially through the first polarization beam splitter and the first 1/2 wave plate, the laser device is connected with the upper computer through the frequency and power stabilizing module, the light emitting side of the oven is connected with the second polarization beam splitter, the transmission side of the second polarization beam splitter is connected with the first photoelectric detector, the reflection side of the second polarization beam splitter is connected with the second photoelectric detector, the first photoelectric detector and the second photoelectric detector are connected with the signal processor respectively, and the signal processor is connected with the upper computer.
The periphery of the oven is provided with a magnetic compensation coil, and the magnetic compensation coil and the oven are respectively connected with an upper computer.
The controller controls the liquid crystal phase delayer based on early-stage data calibration of the window mirror and the oven, and the early-stage data calibration adopts the following structure: the light emergent side of oven sets up polarization analysis appearance, polarization analysis appearance with be located oven light incident side the window mirror connects the host computer respectively, the host computer is connected the oven, the window mirror avoids liquid crystal phase delay ware is directly through first polarization beam splitting prism and first 1/2 wave plate connection laser instrument.
The early-stage data calibration comprises the following steps:
step 1, setting a plurality of spaced set temperatures for the oven through the upper computer, wherein a signal detected by a temperature sensing patch resistor in the window mirror is a temperature signal;
and 2, linearly polarized light is generated after laser generated by the laser passes through the first 1/2 wave plate and the first polarization beam splitter prism, the linearly polarized light enters the polarization analyzer after passing through the window mirror and the oven, the current temperature signal is transmitted to the upper computer by the temperature sensing patch resistor in the window mirror, the received polarization signal is transmitted to the upper computer by the polarization analyzer, and the upper computer reads and stores the temperature signal and the polarization signal so as to calibrate the window mirror and the oven for early-stage data.
The set temperatures in the step 1 are 25 ℃,160 ℃,170 ℃,175 ℃,180 ℃,185 ℃,190 ℃ and 200 ℃, the working temperature range of the oven is 160 ℃ to 200 ℃, each set temperature corresponds to one temperature signal, and each temperature signal corresponds to one polarization signal received by the polarization analyzer.
The change in refractive index of the optical material in the window mirror with temperature follows the following Sellmeier equation:
Figure BDA0003575124260000021
where Δ n is the refractive index change, n 0 The glass refractive index is 20 ℃, delta T is the variation of the glass temperature, and lambda is the wavelength of the light transmitted through the glass; a. The 0 ,A 1 ,A 2 ,B 0 ,B 1 ,λ TK Being constant, it needs to be determined by fitting an equation to the refractive index obtained from the measurements or given by the window mirror manufacturer; (Δ T) 2 Is a second order term for temperature change;
because of the change in the refractive index, the light rays no longer travel in a straight line but in a curve, and therefore, the optical glass exhibits anisotropy and non-uniformity, which affect the refraction of light rays and the polarization state of light rays within the optical lens, and the relationship between the refractive index, stress, and optical path difference is:
δ x ＝dn x -dn y ＝d(P-Q)(σ x -σ y )
δ y ＝dn y -dn z ＝d(P-Q)(σ y -σ z )
δ z ＝dn x -dn z ＝d(P-Q)(σ x -σ z )
wherein delta x ，δ y ，δ z The optical path difference of the triaxial stress along the x, y and z axes; n is a radical of an alkyl radical x ，n y ，n z Is the refractive index of triaxial stress along the x, y, z axes; sigma x ，σ y ，σ z The main stress of the triaxial stress along the directions of x, y and z axes; p and Q are respectively the transverse and longitudinal stress constants of Vertamer stress optics.
The invention has the following technical effects: the invention relates to an optical device thermal noise compensation system based on a liquid crystal phase retarder, which utilizes the liquid crystal phase retarder (LCVR) as a controllable spatial light modulator, and the characteristics of the liquid crystal phase retarder, such as the liquid crystal phase retarder, that specific light vertically penetrates through the surface of glass, the polarization state of the light can be modulated according to actual requirements, and the like, aiming at the temperature drift of the optical device caused by the high temperature of an oven, a compensation scheme for realizing the thermal noise of the optical device by utilizing the LCVR is established by combining the platinum resistance temperature measurement with the influence of the thermal noise of the LCVR compensation optical device, and the design effect of utilizing the LCVR to solve the temperature drift of the optical device caused by the oven is realized. The invention carries out compensation based on the optical field, meets the design requirement, has the characteristic of convenient engineering realization, compensates the influence of the refractive index change of the optical device caused by the high temperature of the oven, improves the measurement precision of the system, is suitable for solving the problem of temperature drift of the optical device caused by the high temperature, and has very wide application prospect.
Drawings
Fig. 1 is a schematic diagram of a thermal noise compensation system for an optical device based on a liquid crystal phase retarder according to the present invention.
Fig. 2 is a schematic diagram of a system for performing data calibration on the window mirror in fig. 1.
The reference numbers are listed below: 1-a laser; 2-a first 1/2 wave plate; 3-a first polarization splitting prism; 4-liquid crystal phase retarder (LCVR); 5-window mirror (second 1/2 wave plate + temperature sensing chip resistor); 6, an oven; 7-air chamber; 8-magnetic compensation coil; 9-a second polarization beam splitter prism; 10 — a first photodetector; 11 — a second photodetector; 12-frequency and power stabilizing module; 13-a controller; 14-a signal processor; 15-an upper computer; 16-polarization analyzer.
Detailed Description
The invention is explained below with reference to the figures (fig. 1-2) and examples.
Fig. 1 is a schematic structural diagram of a thermotropic noise compensation system for an optical device based on a liquid crystal phase retarder, which implements the present invention. Fig. 2 is a schematic diagram of a system for performing data calibration on the window mirror in fig. 1. Referring to fig. 1 to 2, a thermotropic noise compensation system for an optical device based on a liquid crystal phase retarder includes a window mirror 5, the window mirror 5 is disposed between a light incident side of an oven 6 and a light emergent side of the liquid crystal phase retarder 4, the window mirror 5 includes a second 1/2 wave plate and a temperature sensing chip resistor, the temperature sensing chip resistor is connected to a light path compensation control signal input end of the liquid crystal phase retarder 4 through a controller 13, one surface of the temperature sensing chip resistor is attached to the second 1/2 wave plate, and the other surface of the temperature sensing chip resistor faces the oven 6 to directly sense radiant heat generated by the oven 6 heating an air chamber 7. The temperature sensing chip resistor is a platinum resistor, the controller 13 is connected with an upper computer 15, the upper computer 15 is used for monitoring an optical path compensation control signal, light beam depolarization data caused by radiation heat influence of the window mirror, the heat radiation temperature of the oven and the working temperature of the oven.
Liquid crystal phase delayer 4 loops through first polarization beam splitter 3 and first 1/2 wave plate 2 and connects laser instrument 1, laser instrument 1 passes through frequency stabilization power module 12 and connects host computer 15, second polarization beam splitter 9 is connected to the light outgoing side of oven 6, first photoelectric detector 10 is connected to the transmission side of second polarization beam splitter 9, second photoelectric detector 11 is connected to the reflection side of second polarization beam splitter 9, signal processor 14 is connected respectively to first photoelectric detector 10 and second photoelectric detector 11, signal processor 14 connects host computer 15. The periphery of the oven 6 is provided with a magnetic compensation coil 8, and the magnetic compensation coil 8 and the oven 6 are respectively connected with an upper computer 15.
The controller 13 controls the liquid crystal phase retarder 4 based on the preliminary data calibration of the window mirror 5 and the oven 6, and the preliminary data calibration adopts the following structure: the light outgoing side of oven 6 sets up polarization analyzer 16, polarization analyzer 16 with be located oven light incidence side window mirror 5 connects host computer 15 respectively, host computer 15 connects oven 6, window mirror 5 avoids liquid crystal phase retarder 4 directly connects laser instrument 1 through first polarization beam splitter prism 3 and first 1/2 wave plate 2.
The early-stage data calibration comprises the following steps: step 1, setting a plurality of spaced set temperatures for the oven through the upper computer, wherein a signal detected by a temperature sensing patch resistor in the window mirror is a temperature signal; and 2, linearly polarized light is generated after laser generated by the laser passes through the first 1/2 wave plate and the first polarization beam splitter prism, the linearly polarized light enters the polarization analyzer after passing through the window mirror and the oven, the current temperature signal is transmitted to the upper computer by the temperature sensing patch resistor in the window mirror, the received polarization signal is transmitted to the upper computer by the polarization analyzer, and the upper computer reads and stores the temperature signal and the polarization signal so as to calibrate the window mirror and the oven for early-stage data. The set temperatures in step 1 are 25 ℃,160 ℃,170 ℃,175 ℃,180 ℃,185 ℃,190 ℃ and 200 ℃, the operating temperature range of the oven is 160 ℃ to 200 ℃, each set temperature corresponds to a temperature signal, and each temperature signal corresponds to a polarization signal received by the polarization analyzer.
The change in refractive index of the optical material in the window mirror with temperature follows the following Sellmeier equation:
Figure BDA0003575124260000051
where Δ n is the refractive index change, n 0 The glass refractive index is 20 ℃, delta T is the variation of the glass temperature, and lambda is the wavelength of the light transmitted through the glass; a. The 0 ,A 1 ,A 2 ,B 0 ,B 1 ,λ TK Constant, it needs to be determined by fitting an equation to the refractive index obtained from the measurement or given by the manufacturer of the window mirror; (Δ T) 2 Is a second order term for temperature change; due to the variation of the refractive index, the light ray is not straight but curved, and therefore, the optical glass shows anisotropy and non-uniformity, which affect the refraction of the light ray and the polarization state of the light ray in the optical lens, and the relationship among the refractive index, stress and optical path difference is as follows:
δ x ＝dn x -dn y ＝d(P-Q)(σ x -σ y )
δ y ＝dn y -dn z ＝d(P-Q)(σ y -σ z )
δ z ＝dn x -dn z ＝d(P-Q)(σ x -σ z )
wherein delta x ，δ y ，δ z The optical path difference of the triaxial stress along the x, y and z axes; n is x ，n y ，n z The refractive index of triaxial stress along the x, y and z axes; sigma x ，σ y ，σ z The principal stress of the triaxial stress along the directions of x, y and z axes; p and Q are respectively the transverse and longitudinal stress constants of Vertamer stress optics.
The technical problems to be solved by the invention are as follows: the compensation system is used for compensating the influence of the heat radiation of a high-temperature oven on the polarization of an optical device, and provides a compensation system of thermotropic noise of the optical device based on a liquid crystal phase retarder (LCVR) so as to improve the measurement precision, and comprises an LCVR (4), a window mirror (5) attached with a platinum resistor, a controller (13), a signal processor (14) and an upper computer (15); monochromatic light generated by a laser (1) and processed by a frequency stabilization and power stabilization module (12) passes through a 1/2 wave plate (2) and is split into polarized light by a first polarization beam splitter Prism (PBS) (3), one beam of the polarized light continuously enters a gas chamber (7), and the other beam of the polarized light is used for stabilizing the frequency of the beam; the device comprises a compensation module for the noise caused by heat of light incident to a gas chamber, a compensation control module and a controller (13), wherein the compensation control module consists of an LCVR (4), a window mirror (5) and the controller (13), the influence of temperature on a system is measured through a platinum resistor, the result is fed back to the controller (13), the LCVR (4) is controlled by the controller (13) to carry out compensation, and meanwhile, the controller (13) sends data to an upper computer (15) for data monitoring; the light beam enters the air chamber module after passing through the thermal noise compensation module, the air chamber module consists of an oven (6), an atomic air chamber (7) and a magnetic compensation coil (8), wherein the oven (6) is a main thermal noise source; two bundles of light are obtained after being split by a second polarization beam splitter prism (9) after the air outlet chamber module, after the two bundles of light respectively pass through a first photoelectric detector (10) and a second photoelectric detector (11), optical signals are converted into current signals and are transmitted to a signal processor (14), the two paths of input signals are compared by the signal processor (14), and finally the signals are transmitted to an upper computer (15) for a director to observe.
And the LCVR (4), the window mirror (5) and the controller (13) in the optical path are used for compensating and controlling the thermal noise of the optical device.
The oven (6) is a main thermal noise source, and the window mirror (5) is closer to the oven (6) and is subjected to heat radiation close to the oven.
A system for LCVR based optical device thermally-induced noise compensation, comprising: the oven (6) can generate heat radiation outwards in the working process, the resistance value of a platinum resistor adhered to the surface of the window mirror (5) can be changed due to the action of the heat radiation, the generated electric signal can be processed by the controller (13), the processed voltage signal is used as a feedback quantity and is sent back to the LCVR (4) to control the LCVR (4), and the LCVR (4) compensates an optical path;
through window mirror (5), oven (6) two parts carry out earlier stage calibration data, obtain the relation between the heat radiation temperature of oven (6), the back deviation that window mirror (5) produced by the temperature influence, promptly: the signal detected by a platinum resistor in the window mirror (5) is defined as a temperature signal, the temperature of the oven (6) is defined as a set temperature, and the signal received by the polarization analyzer (16) is a polarization signal.
Data calibration step, as shown in fig. 2:
(1) Placing the window mirror (5) at a distance L from the oven (L is smaller); because the glass gas chamber can deform due to temperature rise, and the light beam is deflected, the gas chamber is taken out of the oven (6); a polarization analyzer is placed behind the oven, and the change of polarization is recorded by using an upper computer (15).
(2) The temperature of the oven is set by an upper computer (15).
(3) The laser generated by the laser (1) passes through the 1/2 wave plate (2) and the PBS to generate linearly polarized light; linearly polarized light enters a polarization analyzer (16) after passing through a window mirror (5) and an oven (6), wherein a platinum resistor on the window mirror (5) transmits a current temperature signal to an upper computer (15); the polarization analyzer (16) transmits the received polarization signal to the upper computer (15); the upper computer (15) reads and stores the temperature signal and the polarization signal for calibrating data.
(4) The window mirror (5) is respectively calibrated under the distances L1 and L2 from the oven, and the set temperatures are respectively the temperature signal and the polarization signal at room temperature (25 ℃), 160 ℃,170 ℃,175 ℃,180 ℃,185 ℃,190 ℃ and 200 ℃ of the laboratory where the window mirror is located. The working temperature range of the oven is 160-200 ℃.
(5) The control system is set by the relationship between the temperature signal and the polarization signal.
Temperature changes affect the window mirror (5) performance changes, causing stress changes, polarization/light intensity attenuation.
Temperature changes affect optical system temperature gradients in many ways resulting in optical element strain and increased system aberrations. Unless simplifying assumptions are made about the temperature distribution through the optical system, such effects are generally unpredictable. We only consider uniform temperature variations and simple radial temperature gradients. A uniform temperature rise results in an increase in radius, element thickness and air space, and the refractive index of the optical element changes as the refractive index of the optical medium, typically air, changes. The Sellmeier equation of the optical lens material as a function of refractive index with temperature is:
Figure BDA0003575124260000061
wherein Δ n is the refractive change rate; n is 0 Glass refractive index at 20 ℃; Δ T is the amount of change in glass temperature; λ is the wavelength of light transmitted through the glass; a. The 0 ,A 1 ,A 2 ,B 0 ,B 1 ,λ TK Constant, it needs to be determined by fitting an equation to the refractive index obtained from the measurement (given by the manufacturer of the window mirror); (. DELTA.T) 2 A second order term for temperature change.
Due to the change in refractive index, the light rays are no longer straight but propagate with a bend. Therefore, the optical glass exhibits anisotropy and non-uniformity, which affect the refraction of light rays within the optical lens and the polarization state of the light rays. The relationship between refractive index, stress and optical path difference is:
δ x ＝dn x -dn y ＝d(P-Q)(σ x -σ y )
δ y ＝dn y -dn z ＝d(P-Q)(σ y -σ z )
δ z ＝dn x -dn z ＝d(P-Q)(σ x -σ z )
wherein delta x ，δ y ，δ z Is the optical path difference of the triaxial stress along the x, y and z axes. n is a radical of an alkyl radical x ，n y ，n z Is the refractive index of the triaxial stress along the x, y, z axes. Sigma x ，σ y ，σ z The principal stress of the triaxial stress along the x, y and z directions. P and Q are respectively the transverse and longitudinal stress constants of Vertamer stress optics.
From the above equation, it can be seen that the optical polarization of the window mirror (5) changes with changes in its surface temperature, and the changes in polarization can introduce polarization errors into the high-precision system.
(1) The relationship between temperature and optics is:
temperature changes affect the window mirror (5) performance changes, causing stress changes, polarization/intensity attenuation. The refractive index of the optical element changes with the change in the refractive index of the optical medium, which is typically air. The Sellmeier equation of the optical lens material with the change of the refractive index is as follows:
Figure BDA0003575124260000071
wherein Δ n is the refractive change rate; n is 0 Glass refractive index at 20 ℃; Δ T is the amount of change in glass temperature; λ is the wavelength of light transmitted through the glass; a. The 0 ,A 1 ,A 2 ,B 0 ,B 1 ,λ TK Constant, it needs to be determined by fitting an equation to the refractive index obtained from the measurement (given by the manufacturer of the window mirror); (. DELTA.T) 2 A second order term for temperature change.
Due to the change in the refractive index, the light rays are no longer straight but propagate curvedly. Therefore, the optical glass exhibits anisotropy and non-uniformity, which affect the refraction of light rays within the optical lens and the polarization state of the light rays. The relationship between refractive index, stress and optical path difference is:
δ x ＝dn x -dn y ＝d(P-Q)(σ x -σ y )
δ y ＝dn y -dn z ＝d(P-Q)(σ y -σ z )
δ z ＝dn x -dn z ＝d(P-Q)(σ x -σ z )
wherein delta x ，δ y ，δ z Is the optical path difference of the triaxial stress along the x, y and z axes. n is x ，n y ，n z Is the refractive index of the triaxial stress along the x, y, z axes. Sigma x ，σ y ，σ z For the three-axis stress along the x-axis,principal stress in the y, z-axis direction. P and Q are respectively transverse and longitudinal stress constants of Vertamer stress optics.
From the above equation, it can be seen that the optical polarization of the window mirror (5) changes with changes in its surface temperature, and the changes in polarization can introduce polarization errors into the high-precision system.
(2) Window mirror (5), oven (6) two parts carry out earlier stage calibration data, obtain the relation between the thermal radiation temperature of oven (6), the retroflection that window mirror (5) produced by the temperature influence, promptly:
the signal detected by a platinum resistor in the window mirror (5) is defined as a temperature signal, the temperature of the oven (6) is defined as a set temperature, and the signal received by the polarization analyzer (16) is defined as a polarization signal.
A data calibration step:
A. placing the window mirror (5) at a distance L from the oven (L is smaller); because the glass air chamber can be deformed due to temperature rise, the light beam is deviated, and the air chamber is taken out of the oven (6); a polarization analyzer is placed behind the oven, and the change of polarization is recorded by using an upper computer (15).
B. The temperature of the oven is set by an upper computer (15).
C. The laser generated by the laser (1) passes through the 1/2 wave plate (2) and the PBS to generate linearly polarized light; linearly polarized light enters a polarization analyzer (16) after passing through a window mirror (5) and an oven (6), wherein a platinum resistor on the window mirror (5) transmits a current temperature signal to an upper computer (15); the polarization analyzer (16) transmits the received polarization signal to the upper computer (15); the upper computer (15) reads and stores the temperature signal and the polarization signal for calibrating data.
D. The temperature of the window mirror (5) is respectively calibrated to be the temperature signal and the polarization signal of the laboratory room temperature (25 ℃), 160 ℃,170 ℃,175 ℃,180 ℃,185 ℃,190 ℃ and 200 ℃ at the distances L1 and L2 from the oven. The working temperature range of the oven is 160-200 ℃.
E. The control system is set by the relationship between the temperature signal and the polarization signal.
(3) Monochromatic light generated by the laser (1), processed by the frequency stabilization and power stabilization module (12) passes through the 1/2 wave plate (2), is split into polarized light by the first polarization beam splitter Prism (PBS) (3), one beam of the polarized light continuously enters the air chamber (7), and the other beam of the polarized light is used for stabilizing the frequency of the beam; the light incident to the air chamber passes through the compensation module of heat induced noise, the compensation control module comprises LCVR (4), window mirror (5), controller (13), LCVR (4) in the light path, window mirror (5), controller (13) triplex for the compensation control of optical device heat induced noise, measure the influence of temperature to the system through platinum resistance, and feed back the result to controller (13), LCVR (4) are controlled in controller (13) and are compensated, controller (13) send data for host computer (15) and carry out data monitoring simultaneously.
(4) The light beam enters the air chamber module after passing through the thermal noise compensation module, the air chamber module is composed of an oven (6), an atom air chamber (7) and a magnetic compensation coil (8), wherein the oven (6) is a main thermal noise source. The window mirror (5) is close to the oven (6) and is subjected to heat radiation of the oven close to the oven. Due to the action of heat radiation, the resistance value of a platinum resistor adhered to the surface of the window mirror (5) is changed, the generated electric signal is processed by a controller (13), the processed voltage signal is used as a feedback quantity and is sent back to the LCVR (4) to control the LCVR (4), and the LCVR (4) compensates an optical path.
(5) Two bundles of light that get after going out air chamber module behind second polarization beam splitting prism (9) beam splitting, two bundles of light are after first photoelectric detector (10) and second photoelectric detector (11) respectively, and light signal is converted into current signal and is carried for signal processor (14), and signal processor (14) compare two way input signal, and final signal transfer is to host computer (15) and supply the director to observe.
In a word, the method considers the influence of a high-temperature oven on an optical device, and compensates the influence through a controller, so that the method has great practical value for the ultrahigh-sensitivity inertia and magnetic field measuring device based on the atomic spin effect; the study of temperature compensation methods for optical devices is relatively lacking; the method is suitable for temperature compensation scenes of various optical devices, and temperature drift generated by the optical devices at low temperature can be compensated by using the method. Compared with the existing control method using a metal bracket with reciprocating motion, the method has higher precision. And the polarization information of the optical device, which is influenced by the temperature, is directly acquired by utilizing the optical information instead of the information obtained by calculation, so that the calculation error is reduced.
Those skilled in the art will appreciate that the invention may be practiced without these specific details. It is pointed out here that the above description is helpful for the person skilled in the art to understand the invention, but does not limit the scope of protection of the invention. Any such equivalents, modifications and/or omissions as may be made without departing from the spirit and scope of the invention may be resorted to.

Claims (8)

1. The thermotropic noise compensation system is characterized by comprising a window mirror, wherein the window mirror is arranged between a light incidence side of an oven and a light emergence side of the liquid crystal phase retarder and comprises a second 1/2 wave plate and a temperature sensing chip resistor, the temperature sensing chip resistor is connected with a light path compensation control signal input end of the liquid crystal phase retarder through a controller, one surface of the temperature sensing chip resistor is attached to the second 1/2 wave plate, and the other surface of the temperature sensing chip resistor faces the oven to directly sense radiant heat generated by the oven for heating an air chamber.
2. The liquid crystal phase retarder-based optical device thermal noise compensation system according to claim 1, wherein the temperature sensing chip resistor is a platinum resistor, the controller is connected to an upper computer, and the upper computer monitors an optical path compensation control signal, beam depolarization data of the window mirror caused by the radiation heat, the oven heat radiation temperature and the oven operating temperature.
3. The optical device thermotropic noise compensation system based on the liquid crystal phase retarder of claim 1, wherein the liquid crystal phase retarder is connected with a laser device sequentially through a first polarization beam splitter prism and a first 1/2 wave plate, the laser device is connected with an upper computer through a frequency and power stabilizing module, a light emitting side of the oven is connected with a second polarization beam splitter prism, a transmission side of the second polarization beam splitter prism is connected with a first photoelectric detector, a reflection side of the second polarization beam splitter prism is connected with a second photoelectric detector, the first photoelectric detector and the second photoelectric detector are respectively connected with a signal processor, and the signal processor is connected with the upper computer.
4. The liquid crystal phase retarder-based optical device thermal noise compensation system according to claim 1, wherein a magnetic compensation coil is disposed on the periphery of the oven, and the magnetic compensation coil and the oven are respectively connected to an upper computer.
5. The liquid crystal phase retarder-based optical device thermal noise compensation system of claim 1, wherein the controller controls the liquid crystal phase retarder based on a preliminary data calibration of the window mirror and oven, the preliminary data calibration using the following structure: the light emergent side of oven sets up polarization analysis appearance, polarization analysis appearance with be located oven light incident side the window mirror connects the host computer respectively, the host computer is connected the oven, the window mirror avoids liquid crystal phase delay ware is directly through first polarization beam splitting prism and first 1/2 wave plate connection laser instrument.
6. The liquid crystal phase retarder-based optical device thermal noise compensation system of claim 5, wherein the early data calibration comprises the steps of:
step 1, setting a plurality of spaced set temperatures for the oven through the upper computer, wherein a signal detected by a temperature sensing chip resistor in the window mirror is a temperature signal;
and 2, linearly polarized light is generated after laser generated by the laser passes through the first 1/2 wave plate and the first polarization beam splitter prism, the linearly polarized light enters the polarization analyzer after passing through the window mirror and the oven, the current temperature signal is transmitted to the upper computer by the temperature sensing patch resistor in the window mirror, the received polarization signal is transmitted to the upper computer by the polarization analyzer, and the upper computer reads and stores the temperature signal and the polarization signal so as to calibrate the window mirror and the oven for early-stage data.
7. The system of claim 6, wherein the set temperatures in step 1 are 25 ℃,160 ℃,170 ℃,175 ℃,180 ℃,185 ℃,190 ℃ and 200 ℃, the oven operates at temperatures ranging from 160 ℃ to 200 ℃, and each set temperature corresponds to a temperature signal and each temperature signal corresponds to a polarization signal received by the polarization analyzer.
8. The system of claim 1, wherein the change in refractive index of the optical material in the window mirror with temperature follows the following Sellmeier equation:
Figure FDA0003575124250000021
where Δ n is the refractive index change, n 0 The glass refractive index is 20 ℃, delta T is the variation of the glass temperature, and lambda is the wavelength of the light transmitted through the glass; a. The 0 ,A 1 ,A 2 ,B 0 ,B 1 ,λ TK Being constant, it needs to be determined by fitting an equation to the refractive index obtained from the measurements or given by the window mirror manufacturer; (Delta T) 2 Is a second order term for temperature change;
due to the variation of the refractive index, the light ray is not straight but curved, and therefore, the optical glass shows anisotropy and non-uniformity, which affect the refraction of the light ray and the polarization state of the light ray in the optical lens, and the relationship among the refractive index, stress and optical path difference is as follows:
δ x ＝dn x -dn y ＝d(P-Q)(σ x -σ y )
δ y ＝dn y -dn z ＝d(P-Q)(σ y -σ z )
δ z ＝dn x -dn z ＝d(P-Q)(σ x -σ z )
wherein delta x ，δ y ，δ z The optical path difference of the triaxial stress along the x, y and z axes; n is x ，n y ，n z Is the refractive index of triaxial stress along the x, y, z axes; sigma x ，σ y ，σ z The principal stress of the triaxial stress along the directions of x, y and z axes; p and Q are respectively the transverse and longitudinal stress constants of Vertamer stress optics.
CN202210330485.5A 2022-03-31 2022-03-31 Optical device thermal noise compensation system based on liquid crystal phase delayer Pending CN115390265A (en)

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