Integral diffraction coefficients of the crystal are the essential data of a crystal spectrometer which is extensively used to measure quantitative x-ray spectra of high temperature plasmas in kilo-electron-volt regio...Integral diffraction coefficients of the crystal are the essential data of a crystal spectrometer which is extensively used to measure quantitative x-ray spectra of high temperature plasmas in kilo-electron-volt region. An experimental method has been developed to measure the integral diffraction coefficients of crystals on beamline 4B7 of Beijing Synchrotron Radiation Facility. The integral diffraction coefficients of several crystals including polyethylene terephthalate （PET）, thallium acid phthalate （T1AP） and rubidium acid phthalate （RAP） crystals have been measured in the x-ray energy range 2100-5600 eV and compared with the calculations of the ＇Darwin Prins＇ and the ＇Mosaic＇ models. It is shown that the integral diffraction coefficients of these crystals are between the calculations of the ＇Darwin Prins＇ and the ＇Mosaic＇ models, but more close to the ＇Darwin Prins＇ model calculations.展开更多
It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and mi...It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.展开更多
The optical diffraction is a major means of minute diameter measurements. Since the light intensity of the diffraction fringe, mainly distributed in the central bright stripes, and that will lead to a relatively low S...The optical diffraction is a major means of minute diameter measurements. Since the light intensity of the diffraction fringe, mainly distributed in the central bright stripes, and that will lead to a relatively low SNR for the signal of the senior stripes. The traditional dark stripes extraction algorithm affected greatly by the noise. So this paper presents an algorithm that could effectively eliminate the gross errorcaused by the noise. Than by curve fitting the local signal of the diffraction pattern with the least square principle, the system could achieve a high measurement precision.展开更多
Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditio...Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.展开更多
An optical fiber sensor for strain and temperature measurement based on long period fiber grating(LPFG) cascaded with fiber Bragg grating(FBG) structure has been proposed and realized both theoretically and experiment...An optical fiber sensor for strain and temperature measurement based on long period fiber grating(LPFG) cascaded with fiber Bragg grating(FBG) structure has been proposed and realized both theoretically and experimentally. Theoretical analysis shows that two microstructures with similar sensitivities cannot be used for double parameters measurement. The LPFG is micromachined by the CO_2 laser, and the FBG is micromachined by the excimer laser. For the validation and comparison, two FBGs and one LPFG are cascaded with three transmission valleys, namely FBG1 valley at 1 536.3 nm, LPFG valley at 1 551.2 nm, and FBG2 valley at 1 577.3 nm. The temperature and strain characteristics of the proposed sensor are measured at 45—70 °C and 250—500 με, respectively. The sensitivity matrix is determined by analyzing wavelength shifts and parameter response characterization of three different dips. The proposed optical fiber sensor based on LPFG cascaded with FBG structure can be efficiently used for double parameters measurement with promising application prospect and great research reference value.展开更多
A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approxima...A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approximately the dispersive property of single-order diffraction in far field. Its far-field diffraction pattern is experimentally verified employing a continuous terahertz source centered at 2.52 THz and a pyroelectric focal-plane-array camera, which is in good agreement with the numerical result. The device provides a new approach for direct single-shot spectral measurements of broadband terahertz waves.展开更多
A set of absorption curves was priorly prepared on transparent films to fit the background and peak intensities in continuous scanning X-ray stress measurement.It may be better to correct both background and absorptio...A set of absorption curves was priorly prepared on transparent films to fit the background and peak intensities in continuous scanning X-ray stress measurement.It may be better to correct both background and absorption of pure diffraction intensity.Experimental results revealed this to be a reliable correction method.展开更多
The scattered distribution of the lattice parameters in the Seemann-Bohlin method for stress measurement was discussed.A linear relation can be achieved by modification with the theory deduced from Kroner model.Howeve...The scattered distribution of the lattice parameters in the Seemann-Bohlin method for stress measurement was discussed.A linear relation can be achieved by modification with the theory deduced from Kroner model.However,the Seemann-Bohlin method cannot achieve good accuracy in comparison with the Bragg-Brentauo method,particularly for low stress values.展开更多
A setup of blown film machine combined with in situ synchrotron radiation X-ray diffraction measurements and infrared temperature testing is reported to study the structure evolution of polymers during film blowing. T...A setup of blown film machine combined with in situ synchrotron radiation X-ray diffraction measurements and infrared temperature testing is reported to study the structure evolution of polymers during film blowing. Two homemade auto-lifters are constructed and placed under the blown machine at each end of the beamline platform which move up and down with a speed of 0.05 mm/s bearing the 200 kg weight machine. Therefore, structure development and temperature changes as a function of position on the film bubble can be obtained. The blown film machine is customized to be conveniently installed with precise servo motors and can adjust the processing parameters in a wide range. Meanwhile, the air ring has been redesigned in order to track the structure information of the film bubble immediately after the melt being extruded out from the die exit. Polyethylene（PE） is selected as a model system to verify the feasibility of the apparatus and the in situ experimental techniques. Combining structure information provided by the WAXD and SAXS and the actual temperature obtained from the infrared probe, a full roadmap of structure development during film blowing is constructed and it is helpful to explore the molecular mechanism of structure evolution behind the film blowing processing, which is expected to lead to a better understanding of the physics in polymer processing.展开更多
In rolled strip material,the orientation of the crystallites,known as texture,is influenced by various kinds of thermo-mechanical processes,such as casting,plastic deformation,annealing and phase transformation. The m...In rolled strip material,the orientation of the crystallites,known as texture,is influenced by various kinds of thermo-mechanical processes,such as casting,plastic deformation,annealing and phase transformation. The modern industry production requires stable product performance,real-time monitoring and full controlling of the quality.The online texture measurement in metal rolling can be used to real-time monitor the whole process, and then feedback control to the production process can be implied to adjust the process parameters to ensure the stability of the products.The principles,advantages and disadvantages of related detection methods(2D X-ray diffraction,neutron diffraction,laser-ultrasonics and electromagnetic acoustic transducers(EMAT)) and the possibility of online measurement are discussed.Finally,2D X-ray diffraction and laser-ultrasonics are employed on online texture measurement,and the schemes of online texture measurement are proposed.展开更多
In this study, an improved phase-shi^ng diffraction interferometer for measuring the surface topography of a microsphere is developed. A common diode-pumped solid state laser is used as the light source to facilitate ...In this study, an improved phase-shi^ng diffraction interferometer for measuring the surface topography of a microsphere is developed. A common diode-pumped solid state laser is used as the light source to facilitate ap- paratus realization, and a new polarized optical arrangement is designed to filter the bias light for phase-shifting control. A pinhole diffraction self-calibration method is proposed to eliminate systematic errors introduced by optical elements. The system has an adjustable signal contrast and is suitable for testing the surface with low reflectivity. Finally, a spherical ruby probe of a coordinate measuring machine is used as an example tested by the new phase-shifting diffraction interferometer system and the WYKO scanning white light interferometer for experimental comparison. The measured region presents consistent overall topography features, and the resulting peak-to-valley value of 84.43 nm and RMS value of 18.41 nm are achieved. The average roughness coincides with the manufacturer＇s specification value.展开更多
A reflecting diffraction grating has been etched onto the backside of a standard cantilever for atomic force microscopy, and the diffracted light has been used to monitor the angular position of the cantilever. It is ...A reflecting diffraction grating has been etched onto the backside of a standard cantilever for atomic force microscopy, and the diffracted light has been used to monitor the angular position of the cantilever. It is shown experimentally that for small angles of incidence and for large reflection angles, the force sensitivity can be improved by few times when an appropriate detection scheme based on the position sensitive (duolateral) detector is used. The first demonstration was performed with a one micron period amplitude diffraction grating onto the backside of an Al-coated cantilever etched by a focused ion beam milling for the experiments in air and an analogous 600 nm-period grating for the experiments in air and in water.展开更多
The accurate measurement method of ultrasonic velocity by the pulse interference method with eliminating the diffraction effect has been investigated in VHF range experimentally. Two silicate glasses were taken as the...The accurate measurement method of ultrasonic velocity by the pulse interference method with eliminating the diffraction effect has been investigated in VHF range experimentally. Two silicate glasses were taken as the specimens, their frequency dependences of longitudinal velocities were measured in the frequency range 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect were calculated using A. O. Williams' theoretical expression. For the frequency dependences of longitudinal velocities, the measurement results were in good agreement with the simulation ones in which the phase advances were included. It has been shown that the velocity error due to diffraction effect can be corrected very well by this method.展开更多
The high-pressure technique is a fundamental tool for realizing novel phase transitions, chemical reactions, and other exotic phenomena. Hydrogenation is one example of a high-pressure reaction; at high pressures of s...The high-pressure technique is a fundamental tool for realizing novel phase transitions, chemical reactions, and other exotic phenomena. Hydrogenation is one example of a high-pressure reaction; at high pressures of several gigapascals, hydrogen becomes chemically active and reacts with metals and alloys to form hydrides. This paper covers a high-pressure study of the hydrogenation process and the synthesis of hydrides using a cubic-type multi-anvil apparatus. The experimental details of a hydrogenation cell assembly, high-temperature and highpressure generation, and an in situ observation technique are presented. These experiments are conducted with the aid of in situ synchrotron radiation X-ray diffraction measurements operated in an energy-dispersive mode in the conventional manner for time-resolved measurements and a newly developed angle-dispersive mode for observation of the crystal growth process during formation of metal hydrides. Two successful cases of high-pressure hydrogenation are presented: aluminum hydride, Al H3, and an aluminum-based alloy hydride, Al2 Cu Hx, which are potential candidates for hydrogen storage materials.展开更多
The scanning interference field exposure technique is an effective method to fabricate holographic diffraction grating with meter-level size and nano-level precision.The main problems of fabricating large-aperture and...The scanning interference field exposure technique is an effective method to fabricate holographic diffraction grating with meter-level size and nano-level precision.The main problems of fabricating large-aperture and high-precision grating by this technique are the high-precision displacement measurement of the stage,the high-precision control of the interference fringe and the real time compensation of the grating phase error.In this paper,the influence of grating groove error on the wavefront aberration is analyzed.In order to improve the precision of the stage with displacement range more than one meter,an integrated displacement measurement combining grating sensing and laser interferometry is proposed,which suppresses the influence of environment on measurement precision under long displacement range.An interference fringe measurement method is proposed,which combines the diffraction characteristics of the measuring grating with the phase-shifting algorithm.By controlling the direction,period and phase nonlinear errors of the interference fringe,high quality interference fringe can be obtained.Further,a dynamic phase-locking model is established by using heterodyne interferometry to compensate grating phase error caused by stage motion error in real time.A grating with the aperture of 1500mm×420mm is fabricated.The wavefront aberration reaches 0.327λ@632.8 nm and the wavefront gradient reaches 16.444 nm/cm.This research presents a novel technique for the fabrication of meter-level size and nano-level precision holographic grating,which would further promote the development of chirped pulse amplification systems,high-energy laser and ultra-high precision displacement measurement.展开更多
基金Project supported by the Foundation of National Key Laboratory of High Temperature and Density Plasma Physics(Grant No.9140C6804020704)the National Natural Science Foundation of China(Grant No.10874156)one of the authors,GanXin-Shi,was also partially supported by the School of Physical Science and Technology in Sichuan University,China
文摘Integral diffraction coefficients of the crystal are the essential data of a crystal spectrometer which is extensively used to measure quantitative x-ray spectra of high temperature plasmas in kilo-electron-volt region. An experimental method has been developed to measure the integral diffraction coefficients of crystals on beamline 4B7 of Beijing Synchrotron Radiation Facility. The integral diffraction coefficients of several crystals including polyethylene terephthalate （PET）, thallium acid phthalate （T1AP） and rubidium acid phthalate （RAP） crystals have been measured in the x-ray energy range 2100-5600 eV and compared with the calculations of the ＇Darwin Prins＇ and the ＇Mosaic＇ models. It is shown that the integral diffraction coefficients of these crystals are between the calculations of the ＇Darwin Prins＇ and the ＇Mosaic＇ models, but more close to the ＇Darwin Prins＇ model calculations.
基金This work is supported by the National Natural Science Foundation of China （Grant Nos. 60336010 ＆ 90401001）973 Program （Grant No. TG 2000036603）the Student Innovation Program of CAS （No. 1731000500010）.
文摘It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.
文摘The optical diffraction is a major means of minute diameter measurements. Since the light intensity of the diffraction fringe, mainly distributed in the central bright stripes, and that will lead to a relatively low SNR for the signal of the senior stripes. The traditional dark stripes extraction algorithm affected greatly by the noise. So this paper presents an algorithm that could effectively eliminate the gross errorcaused by the noise. Than by curve fitting the local signal of the diffraction pattern with the least square principle, the system could achieve a high measurement precision.
基金supported by the West Light Project,CAS(xbzg-zdsys-202206)the National Key Research and Development Program of China(2021YFA1401003)+1 种基金the National Natural Science Foundation of China(NSFC)(62222513,U24A6010,and U24A20317)the Sichuan Engineering Research Center of Digital Materials.
文摘Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT_16R07)the Project Plan of Beijing Municipal Education Commission for Enhancing the Innovation Capability in 2015(No.TJSHG201510772016)the Open Project of Beijing Engineering Research Center of Optoelectronic Information and Instruments(No.GD2016008)
文摘An optical fiber sensor for strain and temperature measurement based on long period fiber grating(LPFG) cascaded with fiber Bragg grating(FBG) structure has been proposed and realized both theoretically and experimentally. Theoretical analysis shows that two microstructures with similar sensitivities cannot be used for double parameters measurement. The LPFG is micromachined by the CO_2 laser, and the FBG is micromachined by the excimer laser. For the validation and comparison, two FBGs and one LPFG are cascaded with three transmission valleys, namely FBG1 valley at 1 536.3 nm, LPFG valley at 1 551.2 nm, and FBG2 valley at 1 577.3 nm. The temperature and strain characteristics of the proposed sensor are measured at 45—70 °C and 250—500 με, respectively. The sensitivity matrix is determined by analyzing wavelength shifts and parameter response characterization of three different dips. The proposed optical fiber sensor based on LPFG cascaded with FBG structure can be efficiently used for double parameters measurement with promising application prospect and great research reference value.
基金Project supported by the Foundation of Science and Technology Development of China Academy of Engineering Physics(Grant No.2011B0102023)the Foundation of Plasma Physics Laboratory(Grant No.9140C680304110C6806)
文摘A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approximately the dispersive property of single-order diffraction in far field. Its far-field diffraction pattern is experimentally verified employing a continuous terahertz source centered at 2.52 THz and a pyroelectric focal-plane-array camera, which is in good agreement with the numerical result. The device provides a new approach for direct single-shot spectral measurements of broadband terahertz waves.
文摘A set of absorption curves was priorly prepared on transparent films to fit the background and peak intensities in continuous scanning X-ray stress measurement.It may be better to correct both background and absorption of pure diffraction intensity.Experimental results revealed this to be a reliable correction method.
文摘The scattered distribution of the lattice parameters in the Seemann-Bohlin method for stress measurement was discussed.A linear relation can be achieved by modification with the theory deduced from Kroner model.However,the Seemann-Bohlin method cannot achieve good accuracy in comparison with the Bragg-Brentauo method,particularly for low stress values.
基金financially supported by the National Key R&D Plan of China(2016YFB0302501)
文摘A setup of blown film machine combined with in situ synchrotron radiation X-ray diffraction measurements and infrared temperature testing is reported to study the structure evolution of polymers during film blowing. Two homemade auto-lifters are constructed and placed under the blown machine at each end of the beamline platform which move up and down with a speed of 0.05 mm/s bearing the 200 kg weight machine. Therefore, structure development and temperature changes as a function of position on the film bubble can be obtained. The blown film machine is customized to be conveniently installed with precise servo motors and can adjust the processing parameters in a wide range. Meanwhile, the air ring has been redesigned in order to track the structure information of the film bubble immediately after the melt being extruded out from the die exit. Polyethylene（PE） is selected as a model system to verify the feasibility of the apparatus and the in situ experimental techniques. Combining structure information provided by the WAXD and SAXS and the actual temperature obtained from the infrared probe, a full roadmap of structure development during film blowing is constructed and it is helpful to explore the molecular mechanism of structure evolution behind the film blowing processing, which is expected to lead to a better understanding of the physics in polymer processing.
基金the National Natural Science Foundation of China(No.51204018)National Key Technology R&D Program of China(Nos.2011BAE23B00 and 2012BAF04B02)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China (No.20110006110027)the Fundamental Research Funds for the Central Universities(No.FRF-TP-12-167A)
文摘In rolled strip material,the orientation of the crystallites,known as texture,is influenced by various kinds of thermo-mechanical processes,such as casting,plastic deformation,annealing and phase transformation. The modern industry production requires stable product performance,real-time monitoring and full controlling of the quality.The online texture measurement in metal rolling can be used to real-time monitor the whole process, and then feedback control to the production process can be implied to adjust the process parameters to ensure the stability of the products.The principles,advantages and disadvantages of related detection methods(2D X-ray diffraction,neutron diffraction,laser-ultrasonics and electromagnetic acoustic transducers(EMAT)) and the possibility of online measurement are discussed.Finally,2D X-ray diffraction and laser-ultrasonics are employed on online texture measurement,and the schemes of online texture measurement are proposed.
基金supported by the National Natural Science Foundation of China under Grant Nos.61275096 and 51275120
文摘In this study, an improved phase-shi^ng diffraction interferometer for measuring the surface topography of a microsphere is developed. A common diode-pumped solid state laser is used as the light source to facilitate ap- paratus realization, and a new polarized optical arrangement is designed to filter the bias light for phase-shifting control. A pinhole diffraction self-calibration method is proposed to eliminate systematic errors introduced by optical elements. The system has an adjustable signal contrast and is suitable for testing the surface with low reflectivity. Finally, a spherical ruby probe of a coordinate measuring machine is used as an example tested by the new phase-shifting diffraction interferometer system and the WYKO scanning white light interferometer for experimental comparison. The measured region presents consistent overall topography features, and the resulting peak-to-valley value of 84.43 nm and RMS value of 18.41 nm are achieved. The average roughness coincides with the manufacturer＇s specification value.
文摘A reflecting diffraction grating has been etched onto the backside of a standard cantilever for atomic force microscopy, and the diffracted light has been used to monitor the angular position of the cantilever. It is shown experimentally that for small angles of incidence and for large reflection angles, the force sensitivity can be improved by few times when an appropriate detection scheme based on the position sensitive (duolateral) detector is used. The first demonstration was performed with a one micron period amplitude diffraction grating onto the backside of an Al-coated cantilever etched by a focused ion beam milling for the experiments in air and an analogous 600 nm-period grating for the experiments in air and in water.
文摘The accurate measurement method of ultrasonic velocity by the pulse interference method with eliminating the diffraction effect has been investigated in VHF range experimentally. Two silicate glasses were taken as the specimens, their frequency dependences of longitudinal velocities were measured in the frequency range 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect were calculated using A. O. Williams' theoretical expression. For the frequency dependences of longitudinal velocities, the measurement results were in good agreement with the simulation ones in which the phase advances were included. It has been shown that the velocity error due to diffraction effect can be corrected very well by this method.
基金partially supported by New Energy and Industrial Technology Development Organization(NEDO)under‘‘Advanced Fundamental Research Project onHydrogen Storage Materials’’‘‘Feasibility Study on AdvancedHydrogen Storage Materials for Automotive Applications(2012)’’,bythe Ministry of Education,Culture,Sports,Science and Technology(MEXT)under the‘‘Photon and Quantum Basic Research Coordinated Development Program’’,and by Japan Society for the Promotion of Science(JSPS)KAKENHI(25220911,24241032,and25420725).The synchrotron radiation experiments were performed atBL14B1 of SPring-8 with the approval of Japan Atomic EnergyAgency(JAEA)(2011B3602 and 2012B3602)
文摘The high-pressure technique is a fundamental tool for realizing novel phase transitions, chemical reactions, and other exotic phenomena. Hydrogenation is one example of a high-pressure reaction; at high pressures of several gigapascals, hydrogen becomes chemically active and reacts with metals and alloys to form hydrides. This paper covers a high-pressure study of the hydrogenation process and the synthesis of hydrides using a cubic-type multi-anvil apparatus. The experimental details of a hydrogenation cell assembly, high-temperature and highpressure generation, and an in situ observation technique are presented. These experiments are conducted with the aid of in situ synchrotron radiation X-ray diffraction measurements operated in an energy-dispersive mode in the conventional manner for time-resolved measurements and a newly developed angle-dispersive mode for observation of the crystal growth process during formation of metal hydrides. Two successful cases of high-pressure hydrogenation are presented: aluminum hydride, Al H3, and an aluminum-based alloy hydride, Al2 Cu Hx, which are potential candidates for hydrogen storage materials.
基金supported by National Key R&D Program of China(2022YFB3606100)the National Natural Science Foundation of(62435019,52275554,U21A20509,61227901)+1 种基金CAS Project for Young Scientists in Basic Research(YSBR-103)Chinese Academy of Sciences Youth Innovation Promotion Association grant(2021220).
文摘The scanning interference field exposure technique is an effective method to fabricate holographic diffraction grating with meter-level size and nano-level precision.The main problems of fabricating large-aperture and high-precision grating by this technique are the high-precision displacement measurement of the stage,the high-precision control of the interference fringe and the real time compensation of the grating phase error.In this paper,the influence of grating groove error on the wavefront aberration is analyzed.In order to improve the precision of the stage with displacement range more than one meter,an integrated displacement measurement combining grating sensing and laser interferometry is proposed,which suppresses the influence of environment on measurement precision under long displacement range.An interference fringe measurement method is proposed,which combines the diffraction characteristics of the measuring grating with the phase-shifting algorithm.By controlling the direction,period and phase nonlinear errors of the interference fringe,high quality interference fringe can be obtained.Further,a dynamic phase-locking model is established by using heterodyne interferometry to compensate grating phase error caused by stage motion error in real time.A grating with the aperture of 1500mm×420mm is fabricated.The wavefront aberration reaches 0.327λ@632.8 nm and the wavefront gradient reaches 16.444 nm/cm.This research presents a novel technique for the fabrication of meter-level size and nano-level precision holographic grating,which would further promote the development of chirped pulse amplification systems,high-energy laser and ultra-high precision displacement measurement.
