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A frequency-shift interference fringe locking system was established to enhance the contrast of holographic grating profile and to decrease the phase shift of exposure interference fringe caused by the external environment. According to the composition and the working principle of the system, the moire pattern occurrence condition in the measuring system and its dependence on the phase change of interference fringe were analyzed and the selection method for photodetectors was given. On the basis of the system accuracy, the digital control system was self-designed including A/D conversion digit. A optical frequency shifting method was used to regulate the fringe phase, and an acousto-optic modulator was taken to correct the frequency shifter of the interference fringe movement in real time. The experimental results illustrate that the system can offer a sampling frequency of 5 kHz and can restrain the interference fringe drift and low-frequency moving below 10 Hz. The 3 value of the phase shift is below 0.12 rad, which means its phase is within 0.02 interference fringe period. The system can lock the phase of the exposure interference fringe effectively in real time, and can satisfy the requirements of the holographic grating lithography better.

As traditional grating-based spectrometers can not offer fast apertures and small volume systems synchronously,this paper designs a convex grating by using holography and develops an imaging spectrometer with the convex grating as a core element.It acquires the image of target by pushbroom scanning,then obtains the data cubes of the imaging spectra.The image spectrometer has a space resolution of 2.4 nm,a spectral line bend of 0.1%,the chromatic distortion of 0.6%,and a volume of 209 mm×199 mm×110 mm.The principle of imaging spectrometer with convex grating is analyzed and its constructs are described.Then,a spectral experiment in the laboratory is carried out and the spectra of extraventricular flowers are tested.The result demonstrates that the real spectral resolution is 2.1 nm,line bend is 0.09% and the chromatic distortion is 0.6%.These data satisfy the design requirement,and obtained spectra are ideal results.

This paper analyzes the measuring results of a diffraction efficiency measuring instrument for concave gratings to improve the measuring accuracy of relative diffractive efficiency.According to the testing theory of diffraction efficiency of concave gratings,the effects of the spectral broadening of exit beam for the concave grating,section changing of diffraction beam,control of light source radiation luminance and the synchronization precision of testing wavelength on the measuring accuracy were analyzed,and several kinds of necessary equations were given.Based on regression analysis and a large number of experiment data,an optimization equation was established and programmed into a testing programming to correct automatically the test results.Experiments indicate that the tested results are correct and more precise,and the difference between optimization value and theoretical one is less than ±2.5%,which improves the testing precision effectively.This method is simpler operation,not to change the components of the instrument,and can satisfy the test requirements in strong real-time and higher precision.

The design and manufacturing of interferometric exposure systems with high wave-front flatness and structural stability is a paramount condition for development of high-quality holographic diffraction gratings.A ray-tracing was carried out on straightness of the interference fringes arisen from four kinds of interferometric exposure systems of Single Reflective Mirrors(SLR),namely,off-axis parabolic/Lloyd mirror system,single lens/Lloyd mirror system,spherical mirror/Lloyd mirror system and the separation of pairs of lens/Lloyd mirror system.A standard grating was placed in the interferometric field to make two parallel light beams for exposure incident on the grating,so that the diffractive light was superpositioned to appear Moire fringes.Then,the Moire fringes metioned above were simulated.The Zernike polynomial was used to fit the Moire fringes to get wavefront aberration of interferometric exposure systems and to compare the differrences among the four systems.The results show that the off-axis parabolic/Lloyd mirror system is the most appropriate in production of small-caliber plane holographic gratings.On that basis,the off-axis parabolic/Lloyd mirror interferometric exposure system was manufactured to fabricate plane holographic gratings with a maximum size of 110 mm×110 mm and the engraved linear density greater than 1200 l/mm.The diffraction grating wave-front aberration produced by the plane holographic grating is 0.239 6λ(λ = 550 nm),as the mirror face accuracy aberration between off-axis parabolic mirror and Lloyd mirror is λ / 8(λ = 632.8 nm).This system can be used to produce plane holographic gratings with wave-front aberration in λ/6-λ/7(λ=550 nm),if the external disturbance is overcome and finely tuned.

A spectral calibration facility consisting of a monochromator and a collimator was established to calibrate the Offner imaging spectrometer with a convex grating designed by ourselves.The self-designed software for sampling and processing spectral data was used to calibrate the Offner imaging spectrometer and analyze obtained data.Calibrated results show that the calibration facility has a compact conformation,better commonality and high calibration precision,and its spectral range is better than 400-800 nm and spectral resolution is superior to 10 nm,which can satisfy the calibration need in practice.