The ultrafast laser polishing technology is a new surface processing technology in recent years. Because this technology has the characteristics of the polishing quality and less heat effect, it is very suitable for high precision polishing for hard brittle materials. This paper from the ultrafast laser polishing system structures, experimental design, and data analysis, etc., studies the ultrafast laser polishing principle and processing technology of single crystal silicon. In the experiment, the system with femtosecond laser (λ=515nm, f=4kHz) and picosecond laser (λ=532nm, f=200kHz) polishing materials, after processing, system using digital microscope and surface profiler tests the surface roughness and surface morphology of the region. This paper analyzes the laser energy density, the spot overlap and scanning mode for ultrafast laser polishing quality. The orthogonal experiment design can be clearly analyzes the importance of factors are in polishing effect. And the single factor experiment design can be clearly analyzes the parameter level changes on the polishing effect. Combining with two methods of experiment, parameters can be optimized scientifically and comprehensively.
Laser polishing technique using thermal effect of the interaction of light with matter to achieve removal of material, it is a non contact polishing techniques. In recent years, ultra fast laser polishing techniques got great progress, when ultra fast laser matter interaction, no thermal effect or thermal effect is very small, the removal of material is achieved primarily through momentum transfer. In the material removal process will appear the phenomenon of surface atoms in the redistribution, using this effect, we are likely to achieve the manufacture of the ultra smooth surface of atomic scale magnitude. This article has discussed and analyzed the mechanism of ultra fast laser semiconductor materials, based on this, parameters and their influence on the influence of ultra fast laser polished monocrystalline silicon effects were studied. Used the orthogonal experiment method to optimize the main parameters of the laser polishing, it can reach to a better combination of optimized parameter values. Used self-built picosecond laser polishing system and did monocrystalline silicon polishing experiment, got a good polishing effect.
Microchannel plates（MCPs）are the key component of the image intensifier. Compared with the traditional MCPs, the Si MCPs which are fabricated by micro-nanofabrication technologies have a high gain, low noise and high resolution etc. In this paper, the lithography process is studied in the process of fabricating periodic micropore array with 10 um pores and 5 um pitch on Si. The effects of exposure time, reversal bake temperature and development time on the lithography quality are focused. By doing a series of experiments the better result is got: the photoresist film is obtained at a low speed 500/15(rpm/s) and a high speed 4500/50(rpm/s); the soft bake time is 10min at 100℃; the exposure time is 10s; the reversal bake time is 80s at 115℃; the development time is 55s. By microscope observation and measurement, the pattern is complete and the size of the pattern is accure, it meets the requirement of lithography process for fabricating Si-MCP.
A method of encoding eight objects simultaneously in a detour computer generated hologram(CGH) is
proposed. In the method, we divide eight objects into two groups and multiple objects are encoded
through synthesized spectrum. The simulation demonstrated the effectiveness of the method. In the
reconstruction two groups of objects were reconstructed around the same diffraction order along x, y directions, respectively. The result showed that the method can improve the information capacity in
a CGH efficiently.
It is important to accurately obtain micro displacement in industry, especially in numerical controlled
machine. But traditional methods encountered some difficulties in high-precision measurement. A new
approach based on moiré fringes digital image processing technique (DIP) is proposed in this paper. A
smartly designed experiment is done to grasp moiré fringes from two same gratings, so complicated
equipments are not necessary which has obvious advantages. A CCD is used to acquire digital images.
Then the images are done by digital image processing, including filtering and gray-scale transformation,
fringes identification. A smart way to calibrate the distance represented by each pixel is given in this
paper with DIP technique. The distance of a certain fringe between two images is obtained to display
the micro displacement of any object. The result of this approach is compared with a higher accurate
micro displacement, their similarity identify the correct of this method. We are sure that the result will
be more satisfactory if higher accurate equipment is applied in inspection.
Optical transfer function (OTF) of optical system is an important character to show optical system's
imaging quality. It is important to accurately obtain the OTF in optical measurement. But traditional
methods encountered some difficulties in high-precision measurement. A new approach based on
digital image processing technique (DIP) is proposed in this paper. An experiment is done to acquire
the image of a pill and a CCD is used to acquire digital images. Optical-electronic focal plane fixing
technology is adopted to obtain a more accurate image. Then the images are done by digital image
processing, including filtering and Fast Fourier Transform, and the 2-dimension modulated transfer
function (MTF) is obtained. The MTF of this detected lens derived from this way is compared with a
higher accurate equipment to measure the OTF of the same lens, the results have some differences.
The reason is analyzed in this paper. This method will be widely used in optical inspection.
Resolution of optical system is a critical index to judge the quality of optical system. Measuring the
resolution of optical system has become more and more important in optical measurement. But
traditionally the method to evaluate the resolution of optical system is mainly subjective because of
man's eye seeing. Although this method is simple and intuitive, it is very easy for the introduction of
the subjective error. To solve this problem, an approach based on digital image processing technique is
brought out to achieve this subjective processing in this paper. An experiment is done to grasp image of
resolving power test target formed by a teleobjective, its extreme resolution is obtained. The result
matches ideal resolution by calculation. This way has the advantage of rapid processing and objective.
It is the tendency of measuring resolution in the future.
Image target recognition plays a very important role in the areas of scientific exploration, aeronautics and
space-to-ground observation, photography and topographic mapping. Complex environment of the image noise, fuzzy,
all kinds of interference has always been to affect the stability of recognition algorithm. In this paper, the existence of
target detection in real-time, accuracy problems, as well as anti-interference ability, using lifting wavelet image target
detection methods. First of all, the use of histogram equalization, the goal difference method to obtain the region, on the
basis of adaptive threshold and mathematical morphology operations to deal with the elimination of the background error.
Secondly, the use of multi-channel wavelet filter wavelet transform of the original image de-noising and enhancement, to
overcome the general algorithm of the noise caused by the sensitive issue of reducing the rate of miscarriage of justice
will be the multi-resolution characteristics of wavelet and promotion of the framework can be designed directly in the
benefits of space-time region used in target detection, feature extraction of targets. The experimental results show that
the design of lifting wavelet has solved the movement of the target due to the complexity of the context of the difficulties
caused by testing, which can effectively suppress noise, and improve the efficiency and speed of detection.
In optical interference measurement, the standard wave provided by the standard optical flat owing to the influence of
manufacturing processes, affects seriously on the improvement of the accuracy of the test. To solve this problem, a
method brings forward based on the computer-generated hologram to achieve the reconstruction of the standard
wave-front; Secondly, on the basis of the mathematical model of standard wave-front reconstruction, the required
wave-front is reconstructed in use of the different coding to encode wave-front hologram and MATLAB; Finally, the
different coding techniques for standard wave-front have been compared. The results show that the theory based on the
standard computer-generated hologram wave-front reconstruction algorithm can achieve the standard wave-front
In the thin-film thickness wideband monitoring system, an accurate measurement of the spectral intensity signal is
critical to improving precision of coating. Because of electron gun, ion source and baking, vacuum chamber is a complex
environment with background light. Together with the inherent noise of linear CCD and quantization noise of A/D
conversion, which are main factors affecting accurate measurement of spectrum intensity. This paper uses time and
frequency multi-resolution properties of wavelet transform, adaptive threshold adjustment method is designed.
According to the different characteristics of signal and the random noise processed by wavelet transform in different
scales, the fine adjustment factor is added when the threshold is determined, on the hand, which makes the adaptive
threshold of wavelet coefficient with positive Lipschitz index decrease, this is beneficial to preserve real signals of
wavelet coefficient; on the other hand, which makes the one with negative Lipschitz index increase, this is favorable to
filter out noise signal. By this method, both rejecting true probability and false declaration probability are reduced, the
random noise is suppressed effectively, a very good filtering result is achieved, and finally the analysis accuracy of
spectrum signal and the precision of systematic decision pause are improved.
A kind of adjustment on the complicated Optoelectronic system with visible, laser, and rotative mechanical axis is
discussed in this paper. This is the adjustment of multispectral spatial rotation optical axis, the characteristics is not only
the parallelism adjustment of optical axis where relative rotaton movement occurs, but also the danger of invisible highenergy
laser, the harmful invisible laser is simulated by the visible light camera aimed at the danger; the principle and
method of the optical axis calibration finely with dual-optical wedge for guaranteeing the high parallelism depth between
laser and visible optical axis in the discretional azimuth is introduced in this paper: the special rotative adjustment
pedestal and the reference light source is designed and processed, the error of the different spatial relative position
between camera axis and visual axis is detected by turning the rotative pedestal; In this work, the mathematical model
aiming at the dual-optical wedge adjustment technique is constructed ,in which the rationality is confirmed by MATLAB
program, and the convenience, the maneuverability and the useful value of the adjustment technique is also illustrated for
the parallel precision of 0.1mrad in between laser and visible light axis.
The fiber phase shifting point-diffraction interferometer (FPS/PDI) has recently been designed to measure spherical surface with high precision. The wavefront shape emerging from the fiber, which acts as the referenced wave in FPS/PDI, must be controlled precisely in design.
The rigorous theory model of fiber point diffraction is studied for instrument realization. To execute such high accurate (10<sup>-4</sup>λ) simulation, vector diffraction method must be adopted because conventional scalar diffraction theory is unsuitable when the fiber core size is comparable to wavelength. Based on the model, the influence of fiber core diameter, end-face figure and so on is studied. Some important conclusions are inferred. Firstly, the residual aberration is reduced with decreasing of fiber core size, so that the available numerical aperture decreases. Secondly, when the end face of the optical fiber is ellipse, the effect of the ellipticity should be considered. Thirdly, the oblique fiber, like ordinary fibers cut with zero face angle, generates a high quality spherical wave, but the propagation direction changes with the oblique angle. Finally, the residual aberration of diffraction wavefront becomes larger when the surface error of the end-face figure increases. The result shows that the single mode fiber used in experiment is available for instrument design and its influence over systematic error is negligible within certain numerical aperture.
The correct monitoring of thin-film thickness is one of the main problems during the course of optical thin-film
component manufacture, in recent years, the method which is spectrum intensity measurement of thin-film component
for controlling thin-film thickness has been one of the most effective methods. When this method is used Chow
spectrum intensity is real-time, correctly measured is critical. Compared with the conventional method which is
mechanical scanning by stepper motor driving the grating of monochromator and receiving by photoelectrical multiplier
tube, in structure, the author combines the grating spectrometer with the linear CCD, which makes the problem of
spectrum intensity real-time measurement better solved, the result is satisfied. In this paper, the structure of system
affecting the spectrum intensity measurement accuracy is analyzed, By experiment, the relative parameters are
determined, the spectrum wavelength is calibrated, root-mean-square error is 0.234nm, which is up to the requirement of
monitoring wavelength resolution in the course of thin-film deposition; The algorithm is used for the real-time
compensation of spectrum intensity measurement data, which make the effect of CCD photoelectrical response
non-uniformity and nonlinear less; By changing the integral time magnitude, the rate of signal to noise of the spectrum
signal is improved, it satisfies the requirement of real-time thin film thickness control.
The fiber point-diffraction interferometer is introduced for measuring spherical surface with high precision. The
interferometer must use special laser source, the coherence length of which is no more than 10 cm. The laser source at
present can not meet the demand and the research of laser source design is performed in this paper.
The coherence length of laser source in experiment is inconsistent with that computed with general theory, which restrict
the research progress. In this paper, Mutual Coherence Function is introduced to describe the coherence of optical field.
Based on the spectral characteristic of laser source, the mode of Multi-Longitudinal Mode laser is built. Through
numerical calculation, it is discussed that how coherence degree is related with Longitudinal Mode number, spectral half
width and resonant cavity length. Some important conclusions are draw. For example, Multi-Longitudinal Mode laser
source has periodic coherence degree no matter how many longitudinal modes it contains, and the period of laser
coherence degree is always double resonant cavity length. The method for designing short coherence length laser is put
forward based on the conclusions and its coherence is measured in experiment. The result shows that the coherence
length reaches 5 cm and meets the need of the interferometer.
To characterize the spherical surface of extreme ultraviolet (EUV), the fiber phase shifting point-diffraction
interferometer (FPS/PDI) has recently been designed and implemented. The diffraction wavefront from an optical fiber
acts as the perfect referenced spherical wave and new-style interferometer configuration is used. The laboratory
apparatus has been put up to measure spherical surface in experiment. The main content of this paper is the key
technique of FPS/PDI about the method of interference image processing and the precision analysis for the
In experiment apparatus, a concave spherical surface is measured and a piezoelectric ceramics (PZT) is used for phase
shifting. The wrap phase distribution is got by five-step phase shifting method, and then the unweighted least-squares
phase unwrapping algorithm is optimized and used to obtain the unwrapped phase distribution. The error of spherical
figure is derived from the fitting method of Zernike polynomials. The data processing result is analyzed in comparison
with the measurement result of ZYGO interferometer. The repeat precision of the FPS/PDI is evaluated by multimeasurement.
Finally, the major error sources are discussed and some optimized methods for the system are
proposed.The results show that the interferometer has achieved worthy measurement precision and has great