The imaging plane’s illumination nonuniformity is an important parameter for wide FOV and short-focus optical imaging
system.But now the imaging plane’s illumination nonuniformity measurement device can not meet the requirements of
wide FOV, high uniformity and wide dynamic range.A new device combined with assymmetric double-hemisphere
technology was set up. It was composed of the special integrating sphere, CCD camera, precision displacement
mechanism, image acquisition, and testing software.The CCD was pre-calibrated and the testing software realized a
auto-correction,image acquisition, display and the illumination nonuniformity calulation.The light source was calibrated
by the national standard color temperature lamp.The device can provide a Lambert object surface .The advantages of the
device were that the FOV was as largely as 100°,and a wide illumination range of (10-3~103)Lx was achieved. An
optimal simulation of assymmetric double-hemisphere was calculated by LightTools,it was proved that the illuminace
nonuniformity at the outlet was better than 1.7%.Finally, the illumination nonuniformity of the integrating sphere and a
wide FOV and short-focus lens were respectively measured.The results show that, the illumination uniformity of the
integrating sphere is less than or equal to 1.49%,and the imaging plane’s illumination nonuniformity of the lens is
An advanced fiber point diffraction interferometer (FPDI) is built for measuring spherical mirror surface and spherical
lens wave front aberration with high precision. This new interferometer is based on point diffraction technique. Using
short coherence length laser as light source, the perfect spherical wave diffracts from fiber point resource as reference
wave. And the spherical wave is interfered with object wave to achieve higher accuracy. A phase shifting point
diffraction interferometer with one single-mode-optical-fiber is built for measuring concave spherical mirror surface. A
concave spherical mirror is measured by the experimental facility. The interferograms are collected by CCD and
analyzed by computer. The PV values and RMS values of resulted surface error are compared with the result acquired by
digital wave front interferometer. The measured surface is fitted and represented by Zernike polynomials. The results
compared with Zygo GPI interferometer are proximately the same. Finally the differences between them are discussed in
detail. To measure the aberration of spherical lens, a two single-mode-optical-fibers point diffraction interferometer is
built by adding another single mode optical fiber. A convex lens is measured. The interferograms is presented.
Due to the phasing effects, the measurements of Minimum Resolvable Temperature Difference (MRTD) for Staring
array thermal imagers often get abnormal results when the targets approaching system Nyquist frequency (fn). To
simulate the relations between MRTD values and four-bar targets' frequencies, this paper introduces the concept of best
contrast. Clearly, the MRTD results are inversely proportional to the best contrasts under optimum phases, higher
contrast corresponding to a lower MRTD. On the other hand, with the spatial frequencies increasing, the target's
opening area shrinking and leads the effective infrared eradiation decreasing, this means the MRTD results are inversely
proportional to the opening area of the target. Based on these two assumptions, and through numerical simulations, this
paper depicts the tendency chart of MRTD under optimum phases to the four-bar targets' spatial frequencies. The
tendency chart adequately explains the hump curve happens at frequencies between 0.6fn and fn. From the simulations,
the maximum of MRTD values can be predicted at the frequency of 0.89fn. The tendency chart illustrated by numerical
simulation is consistent with the MRTD results get in laboratory. While in Dynamic Minimum Resolvable Temperature
Difference (DMRTD) testing, moving the four-bar targets introduces temporal effects not present in static MRTD test.
Simulation reveals that DMRTD test can get more realistic shape of the curve between 0.6fn and fn, the characteristic
hump in the static MRTD curve between 0.6fn and fn is not seen.
An absolute measurement method of spherical lens with Fiber Point Diffraction Interferometer (FPDI) was developed.
To achieve a high accuracy, several key techniques are discussed such as: short coherence length laser, interferogram
collecting, experiment set up, and reconstruction of wave front. Through these techniques an experiment system has been
built. The 5-step phase shifting interferograms are collected. The wave front is fitted by Zernike polynomials and
reconstructed. The repeated measurement result has a good performance compared to a Zygo GPI interferometer.
Replacing some optical vitreous reticules with digital reticule images generated by high-resolution tiny Liquid Crystal Device (LCD) can avoid repeating operations of installing, adjusting and focusing optical vitreous reticules during optical multi-parameter measurement. In this way, optical multi-parameter measurement's efficiency and precision can be enhanced obviously. For this brainchild, we designed an instrument with hardware by utilizing Field Programmable Gate Array (FPGA). The FPGA's main function is to fulfill a XGA signal driving circuit. This circuit generates 'horizontal synchronization signal', 'field synchronization signal' and 'video signal' which can drive the tiny LCD. At the same time, designing device driver programs such as external SRAM memory under embedded Linux operation system is another most important job in software aspect for the apparatus. This apparatus makes high-resolution and high-capacity digital reticule images displaying on tiny LCD accurately and rapidly. This paper mainly introduces the design method and process of 'standard XGA signals driver circuit' and 'device driver programs under embedded Linux'.
This paper presents Zernike polynomials fitting wave front which is detected by fiber point diffraction interferometer (FPDI). To confirm that Zernike polynomials are suitable for fitting concave spherical mirror surface, different orders of Zernike polynomials were used to fit several different surfaces which are produced by computer. Fitting result errors were evaluated by residual standard deviation. It is illuminated that Zernike polynomials are suitable for fitting surface which changes smoothly but not suitable for fitting surface with sharp fluctuating. When the shape changes dramatically Zernike polynomials are unable to correctly fit. Choosing appropriate term of polynomials, more terms don't mean higher precision. A metal coated concave spherical mirror, curvature radius 580mm, caliber 70mm, was measured as a sample. The five-step phase shifting interferograms of good quality were detected by an experimental FPDI which was built in lab. Measured wave front was fitted by 36 terms of Zernike polynomials from phase map which were unwrapped from five-step phase shifting interferograms. The measurement result was obtained and compared with that by Zygo interferometer when measured the same mirror. The 2 represented wave fronts have same characters such as centers bulging and marginal trough.
In biological scientific research, separating biological macromolecules or cells in liquid is always a
challenging job. Optical tweezers have been a valuable research tool since their invention in the 1980s. One of the
most important developments in optical tweezers in recent years has been the creation of two-dimensional arrays of
optical traps. In this paper, a method based on interference is discussed to form the gradient laser fields, which may cause
spatial modulation of the concentration of particles. The parameters related with the optical tweezers array are discussed
in detail and simulated by Matlab software to show the impact factor of the important parameters for the concentration
distribution of the particles. The spatial redistribution of particles in a laser interference field could be also predicted
according the theoretical analysis.
A novel means to measure optical multi-parameter is overviewed in this paper and an integrated measurement system consisting of CCD camera, LCD graph generator, testing software and computer is described. Based on this system, novel methods of measuring focal length of lens and visual magnification of infinite conjugate system are given. In addition, the measurement of other parameters such as MTF, parallax, distortion, etc. is also discussed. Three automatic focusing criteria are proposed and selectively used to locate CCD target accurately in the image plane.
The key technology that the attenuators of the continuous values are designed, manufactured and calibrated to calibrate the range of Laser Range Finder is discussed in this paper. The transmittance control technology of designing the continuous attenuator with a large caliber and 0.2dB-10dB attenuation continuously is sets forth, and the means of orthogonal polynomial surface fitting for continuous attenuation values are analyzed, the utility calibrating results are also presented.
Optical angle gauge is one of the measuring instruments standardized by the National Metrological System of Chian for verification of plane angle. In this paper a new method for verifying the optical angle gauge is described and a related photoelectric goniometer developed by ourself is introduced. As a datum instrument for measuring deviation angle of optical wedge, its maximum error is less than 0.1 inch. In addition, some examples of its application for calibrating indication error of various angle measuring devices are presented, and its distinctive advantages, especially in calibrating 2D autocollimators, are demonstrated.
A novel focus-setting technique is elaborated in terms of its theoretical analysis and experimental results. Upon the new technology a high precision instrument for measuring curvature radius of polished concave spherical surface has been developed and its practical applications are discussed. According to the appraisal made by author-itative experts, the relative measuring error of curvature radius has been reduced to the magnitude of (Delta) R/R<EQ 1/100000. The present instrument is one of key measuring devices in developing high imaging quality and large size optical instruments in advanced science and technology.