In order to assisting human vision to identify degree of injury of optical films after laser irradiation , magnified optical
films images are acquired by a CCD camera together with a microscope before and after slotted by pulsed Laser in a real time in experiments. The algorithms to judge the film damage and identify the damage morphologies are designed and texted by MATLAB. The maximum damage diameter and damage area, which are calculated using minimum external rectangle and region filling separately, are compared with state standards on damage criterion of optical film to judge the damage degree. Morphologies characters of 3 typical laser damage mechanisms to optical films are explored. Geometric features and color features parameters of damage pictures were extracted, just like the circularity of the damage area’s edge and rgb average level in the damage areas and the undamaged, through which we could deduce the main damage mechanisms. The experiment shows that the algorithms could judge the film damage and identify the damage morphologies effectively. The algorithms could be improved and used in automatic measurement and test of LIDT of optical films, also in analysis of laser damage mechanism for consideration.
Interference image processing is the key technology of optical interference measurement. Using high resolution image
sample system to recognize the interference fringe, which substituted the traditional method measured by technological
worker, is improving the measurement accuracy of thin film thickness. This paper introduced the problems on automatic
interference fringe processing in absolutely measurement based on laser interference, digital image processing
technology. The image acquisition of the SiO2 film and the pre-processing of interferogram was performed. Decimal part
of the interference fringes is obtained.
Proc. SPIE. 7658, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology
Optical Wireless Communication (OWC) adopts laser beam as the carrier to deliver the message. It combines with the
advantages of Microwave Communication and Fiber Optic Communication. The key technologies of OWC system
includes source coding, channel coding, laser diode modulation, auto-alignment and channel. In this paper, the research
progress on OWC in Xi'an University of Technology is introduced. The research on source coding involves in baseband
modulation, frequency modulation, OFDM transmission and vertical layered space-time codes. The research on channel
coding includes RS codes, Turbo codes, LDPC codes and so on. And the adaptive coding method is analyzed to meet the
different channel characteristics. Propagation performance of laser is studied and bit error rate (BER) is measured under
various weather conditions of rainy days, snowy days, foggy days, hazy days and so on. The experiment results show
that applying channel coding methods can improve the system performance of OWC, especially under rainy, snowy,
foggy weather conditions, the BER after decoding is up to 10-6. Based on many years of research, the technologies of
MIMO, OFDM and space-time coding are proved to be the key technologies that need to solve in OWC.
The technology of annular sub-aperture stitching interference used in film thickness testing is an efficient route with the
characters of high-resolution and low-cost, which don't need compensation with auxiliary components. In this
contribution, the interference methods of film thickness testing and principles of annular sub-aperture stitching are
introduced, and then a model of annular sub-aperture stitching is established on the interference phase of thin film;
finally, Sub-aperture spatial phases are unwrapped by fast Fourier transform (FFT) algorithms, and based on this, annular
image is obtained by Zernike polynomial fitting algorithm and stitching objective function. The processing algorithms
program are written and simulated by a computer. A variety of affecting the accuracy of splicing factors of the errors are
analyzed in detail, and the solutions are given to reduce the errors, and proposed changes to the existing experimental
platform. The results show that the PV value and the RMS value of phase residuals of full aperture splicing are 0.0092λ
and 0.0036λ before and after stitching respectively, and it achieves a large aperture high-precision detection of film
Proc. SPIE. 7283, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
KEYWORDS: Control systems, Signal processing, Acquisition tracking and pointing, Optical tracking, Antennas, Signal detection, Evolutionary algorithms, Servomechanisms, Laser energy, Telecommunications
Because the effect of atmospheric scattering and atmospheric turbulence on laser signal of atmospheric absorption,laser
spot twinkling, beam drift and spot split-up occur ,when laser signal transmits in the atmospheric channel. The
phenomenon will be seriously affects the stability and the reliability of laser spot receiving system. In order to reduce the
influence of atmospheric turbulence, we adopt optimum control thoughts in the field of artificial intelligence, propose a
novel adaptive optical control technology-- model-free optimized adaptive control technology, analyze low-order pattern
wave-front error theory, in which an -adaptive optical system is employed to adjust errors, and design its adaptive
structure system. Ant colony algorithm is the control core algorithm, which is characteristic of positive feedback,
distributed computing and greedy heuristic search. . The ant colony algorithm optimization of adaptive optical phase
compensation is simulated. Simulation result shows that, the algorithm can effectively control laser energy distribution,
improve laser light beam quality, and enhance signal-to-noise ratio of received signal.
For having sample spectrum, slitting is often used as characteristic objects for OTF measurement. The common measurement methods of OTF from slit image data are firstly presented in this paper. According to deep analysis of image energy distribution of tiny tilted slit, Sub-Extremum Minimum Difference Method (SEMDM) is established. The method uses the rows with energy distributions of slit image stagger one pixel exactly to determine the scale of sub-pixel segment, and LSF data with 3 to 5 times sampling frequency are achieved by several-line low sampling frequency LSF data interpolation Practical test results prove that the algorithm is correct and reliable.
A novel measurement system of digital optical modulation transfer function based on CCD is introduced. This system is mainly made of slight source , collimator, detected system, magnify object lens set, CCD, image collect card ,computer and so on. Different algorithms are proposed for two different sighting vanes of the pinhole and the slit. For pinhole sighting vane, three levels of wavelet transformation algorithm are used to denoise, and by the relation of initial point spread function and line spread function, two-dimensional pinhole image transforms two vertical direction line spread functions. Through the algorithms of Fourier transform, the test can be realized. Slit sighting vane adopts the cubic fitting interpolation algorithm to smooth the curve, and Fourier transform to realize the test. The normalized way is used to process data for the two sighting vane algorithm results. Different model photography lenses are separately measured on the test system. It is showed by the test result that the denoised signals for the pinhole sighting vane are quite smooth through three levels of wavelet transform algorithms, and the point spread function transforms to two vertical-directional line proliferation functions, which makes the Fourier frequency spectrum transform simple; and it has better effect for the slit sighting vane to employ the cubic fitting interpolation algorithm to smooth the curve. MTF test precision is 0.04mm on axis and 0.08mm out of axis.