The quality of X-ray optics on beamline is a key factor that limits the performance of the beam line to play. For X-ray mirror surface characterization with high accuracy, long trace profiler and NOM for flat or slight curved mirror have been developed. However, these two kind of instruments cannot measure the highly curved mirror since requirement of high precision and that of large range contradict each other. In this paper, we proposed a novel wavefront-coding-based surface slope metrology technique. Four-dimension information of the optics under test, including x-y position and sagittal/tangential angle, is provided. Due to the focused beam used and the high speed DMD (Digital Mirror Device), high spatial resolution of the measurement is obtained. In experiment, we demonstrated this technique by measuring bend-based high energy monochromator developed in BSRF.
The third generation synchrotron radiation source like High Energy Photon Source (HEPS, Beijing) requires X-ray optics
surface with high accuracy. It is crucial to develop advanced optics surface metrology instrument. The Long Trace
Profiler (LTP) is an instrument which measures slope in the long dimension of an optical surface. In order to meet the
accuracy requirements for synchrotron optics, a number of researches have been carried out to improve the LTP during
the last decades. Many variations have been installed worldwide. As a part of the advanced research of HEPS, the
metrology laboratory at Beijing Synchrotron Radiation Facility (BSRF, Beijing) has been conducting work of building a
new LTP since 2012. The accuracy of the instrument is expected to be <0.1μrad rms for component up to 1m in length.
In this paper, we present some design consideration for nano-accuracy LTP. Two error sources, including the
deformation of the granite structure and imperfect optical surface, are studied. We report our optimized configuration of
the granite structure and the dependences of the measurement error on the surface error. The results are considered as an
important instruction for the proper choice of each component in the profiler. We expect to bring the profiler into
operation in 2015.
A classical iterative Lucy-Richardson (LR) inversion algorithm used for recovering particle-size distributions (PSD) from light-scattering data is proposed. The convergence of iteration is validated in the numerical simulation for three different distributions: the gamma, the log-normal, and the Rosin-Rammler. The accuracy of the inversion is checked graphically against the exact distribution with good results, even for the synthesized intensity data of a signal-noise-ratio smaller than 20 dB. Finally, an experiment with linear charge coupled device as the detector is carried out, and the PSD is recovered successfully by the LR inversion method.
Image restoration for constructing high-spatial-resolution images in an imaging system which realizes indirectly far-filed
imaging by integrating the microlenses array with LCD is reported. We have investigated the indirectly far-field imaging
condition where adjacent sampling points contribute the detected signal. Experimental setup with microlens of 500 μm
diameter and 8 mm focal length is built to prove this condition by studying performance of image restoration using
modified point spread function (PSF). Since any one iterative method is not optimal for all image deblurring problems,
some deblurring algorithms including direct deconvolution and iterative deconvolution are applied to our imaging system
and we compared the effectiveness of these iterative procedures to choose right one for our use.
This paper presents an improvement approach to realize tracking on smooth glass surface based on
subjective speckle. The scattering mechanism on glass surface is analyzed and the affection on tracking
precise and range for tracking with subjective speckle is researched. The speckle captured by CCD just
from the upper surface of the glass is achieved by grazing incidence of the laser beam and the noise
mixed with the signal is eliminated by a barrier above the surface. Based on the apparatus of subjective
speckle tracking, the speckle contrast is improved from 0.25 to 1.25 by non-Gauss effect and the range
of the tracking has been increased from 200 μm to 400 μm compared with the objective speckle
method on the same condition.
We firstly propose the technique to realize far-filed image by integrating the microlenses array with LCD. This technique
is expected to resolve eye-gazing problem in common teleconferencing system without affecting the display performance
of LCD. The characteristics of far-field diffraction image and geometric image formed by single microlens are simulated
and analyzed. The simulation shows that the quality of image is seriously reduced by geometric aberration and
diffraction of the small aperture diameter for aspherical and spherical surface profile refractive microlens. The main
problem of image acquisition with high resolution is that the signal obtained by cell detector is contributed not only by
the sampling point in the axis of the corresponding cell microlens but also sampling points nearby. In simulation,
Microlenses of 300μm diameter same with pixel size of LCD were used in orthogonal array at 1mm pitch, which is also
the sampling interval in object space. These microlenses array with unit number 213x246 are placed up to 600mm away
from object surface. Monte Carlo optimization algorithm is adopted to give accurate inversion results. The typical results
are presented with our main conclusions.