In phase-shifting metrology, the accuracy of phase measurement is directly affected by the phaseshifting
error, Accurate calibration of phase-shifter is very important if good measurement results are expected. A new
in-line high accuracy phase-shifting calibration method based on Damped-Least-Square algorithm which provides
stable convergence and accurate phase distribution is presented. By intercepting a line on the same position from a
series of interferograms associating with the phase-shifter's characters and constructing the mathematic model for
intensity of the line on each interferogram, the correlative coefficients of the mode's function can be solved, one of
which is the wrapped phase. Then the voltage-unwrapped phase curve is obtained through unwrapping technique.
Results of computer simulation show a high accuracy after several fast iterations. In addition, taking an experiment for
example in our interferometer, the characteristic curve of phase shift over voltage change is presented in the end.
Experiment results show it can be an in-line calibration method for phase-shifer in PSI.
The characteristics of pulse laser transmitting in atmosphere were analyzed. An experiment setup was introduced to
measure the impacts of fog produced by ultrasonic-nebulizer on time delay characters of the laser pulse transmission in
atmosphere. The experimental results show that the width of laser pulse becomes wider while the laser pulse transmits in
fog. The value of width broadened increases with the enhancement of fog thickness. The value of width broadened is
substantially proportional to the extinction coefficient. The R-square of curve fitting is 0.9777. This relation may be used
to estimate the atmosphere extinction.
Method of computer digital image processing was utilized to measure non-circularity of single mode fiber. The two end
faces were polished, the faces come into plane, and which are perpendicular to fiber axis. Laser beam was thrown on one
end of the fiber, and an inerratic spot was formed from light beam put out at another end of the fiber. The spot was shot
by a digital camera with 5.1x106 pixels. The image was processed with a computer. The process includes full color
picture being translated into gray one, contrast enhancement, median filtering, and picking-up contour line. The every
different three points on the contour line were taken out to determine one circular radius, average of many radiuses was
calculated, The maximum radius and the minimum radius are picked out to calculate the fiber no-circularity in according
to definition. Visual C++ and Matlab were used to programme. The results of experiment show that measurement
precision is independent of the sampling number, but dependence of gray value, and average standard deviation is about
A lidar system was constructed to operate in the initiative state as well as passive state, with atmosphere component
inspecting and elements of weather. The lidar system consists of laser transmit system, receiving telescope system,
subsequence optics system, signals detecting and processing system. Tuned output laser from the system made up of
SL-III-10-YAG laser and ND6000 tunable dye laser is employed as probing light beam. Its wavelength takes 270-900
nm. Optical axis of laser transmit system is in parallel with one of receiving telescope system. The telescope is made into
Cassegrainian type, and efficient aperture is 400mm. Dispersion spot of the focus point is about 0.5mm. A spatial
resolution of 3.0m was provided in the lidar system.
Tops of optical fiber are polished to be detectable, the tops come into plane, which are perpendicular to fiber axis. A
cirque pattern is formed on the out top of fiber by skew rays in the fiber. The pattern is shot with a digital camera. A
bitmap format cirque pattern is obtained. The inside and outside boundaries are taken out with digital image processing
method. Three different pels on the boundaries are picked out to define a circle at every space. The maximum and the
minimum diameter are picked out from many circles acquired to calculate the fiber core no-circularity in according to
definition. A quartz fiber core no-circularity was measured, with numerical aperture 0.22, and diameter 100 micron.
When the optical fiber was placed straight, periphery of the pattern on the out top appear regular denotation, the core no-circularity
is less than 4.0%. But the fiber is made into a spiral cord in diameter 20cm, the periphery of the pattern is
smooth, measured the no-circularity is about 1.7%, the result is identical to which obtained by microscope measurement.
The result indicates that no-circularity measured is almost independent of wavelength of laser with modes being
Micrometric displacement sensor with optical fiber was employed to inspect deformation of membrane box with air pressure changing, in order to avoid the defects in inspecting deformation, or improve and optimize performances of the sensors. A multi-path optical fiber sensor was utilized to measure the displacement, so that sensitivity is increased, and a little changing in air pressure may be measured. The relation between optical fiber sensor output changes and atmospheric pressure changes was standardized with a standard air pressure gauge. A setup for measuring atmospheric pressure was formed, the experiment results indicate that measurement range is 500-1060hpa, resolution is 0.2hpa, and accuracy is ±0.2hPa.
Polyaniline membrane is a conductive polymer, widely used as a current carrier for electrochemical and biological matters, and as a sensor. It is important to control the thickness of polyaniline membrane in measuring current of electrochemical reaction and beneficial to evaluate the quality and thickness of the membrane by using laser confocal scan microscope. After inputting 0.5ml of aniline and 355mg of Na2SO4 into 25ml of pH2.0 buffer solution compound with HCl/KCl, a polyaniline membrane is deposited on a Pt wire of Φ0.8mm in diameter with the constant potential anode oxidation method in the CHI660b set, at a voltage of 0.75 Volt, the process of which takes 240 seconds. The polyaniline membrane is inspected with laser confocal scan microscope, at respective wavelengths of 488nm and 633nm. Then the various images are taken at 40×objective lens and different focal lengths. There are many light and shade stripes on the images, parts of which are closed, while others are unclosed curves. The polyaniline membrane is evaluated in terms of its width intervals of the stripes, thickness and uniformity, by means of image analyzing using the laser confocal scan microscope.
In the paper, a set for measuring terrain atmospheric visibility is put forward. Principle of the set operating is discussed. The processing of the signals in the set is analyzed. Optical fiber beams are utilized. The fiber beams act as both a field stop and a spatial filter. The errors caused by the limit of the end faces of fiber are smaller than 3.0 % in the set.The errors can be eliminated by means of adjusting the instrument constant of the set. The effect by the forward scattered light on the measuring of transmission light is cut down due to the spatial filter. The measuring of angular scattering coefficient is not affected by the change in the intensity of probing beam, and change in the properties ofpropagation by the depositing of dust. The set can be used in the real-time measuring of visibility. The relative error is about 3.7 % between the total scattering coefficient and that by the transmission light method.
In this paper, a testing method for optical polished surface in level instrumentation and supersmooth surface in soft x- ray system using Atomic Force Microscope (AFM) is presented, and some testing results reached to nanometer RMS are listed. In the paper it is indicated that, different size of polished platforms are formed as difference of optical polished method and period. Important applications of AFM testing method for improving optical polished technology and obtaining supersmooth surface are introduced in the paper.
In this paper, the new method on testing and evaluating of optical surface microprofile using Atomic Force Microscope (AFM), which has both good vertical and lateral resolution. The nanometer-grade microprofile of super-smooth optical surface can be obtained using AFM method, but can't by classical interferometer, as the latter has a poor lateral resolution. Some tested examples of optical surface are shown in the paper. The microprofile images are viewed in monitor and printed in microcomputer.