Laser light scattering detection based on sheath flow technique are well established and routinely used
in a variety of fields, ranging from ecology to medicine. Normally the width of sheath flow chamber is
assumed as a constant, but the inaccuracy during manufacture changes the inter structure of sheath flow
chamber. So the sheath flow width deviates its designed value. In our research, a novel method is
applied to research sheath flow stability. The structure of sheath flow chamber in different positions is
firstly imaged by CCD camera. The values of sheath flow width in different positions can be gotten by
image processing technologies. According to chamber width values in different positions, principle
sheath width can be calculated to be compared with the measured values. Hence sheath flow stability in
different time and different positions can be detected. By this novel method, the real width of sheath
flow forming with specific velocity rate in different positions can be measured. So the best
measurement site for dynamic individual particles scattering can be selected.
KEYWORDS: Cameras, Infrared radiation, Calibration, 3D metrology, 3D acquisition, Imaging systems, 3D vision, CCD cameras, Distortion, Stereo vision systems
Three-dimension coordinates measuring is the key technique in modern manufacturing, reverse engineering, automation,
precision measurement and computer aided surgery. In recent years, the 3D vision coordinates measurement becomes a
newly technique and has been developed rapidly. Some vision coordinates measurement machines (VCMM) were
developed. But measuring accuracy of those VCMMs is susceptible to the mal-condition and external noise, i.e. index
point brilliance and ambient light illumination. We developed a new 3D high-precise optical coordinate measuring
system based on an infrared target and two CCD cameras. Both measuring principle and linear direct reconstruction
method of binocular stereo vision based on cross optical axes are discussed. The detail design and geometric model of
the infrared target is proposed. The position and direction of the infrared target and 3D coordinates of the tip can be
directly computed according to rigid geometric transformation. Further results of calibration and measurement are
verified experimentally. A high geometrical accuracy can be reached.
Large aperture optics have been used more and more widely in modern optical system. But the testing of its surface
quality is very difficult. The circular sub-aperture stitching (CSAS) testing method can effectively extend the
interferometer's vertical dynamic range and enhance its lateral resolution, so it may be the best solution to the testing of
large aperture optics. Actually, the CSAS method can be viewed as a special workpiece localization problem. If the pose
data of all sub-apertures obtained are accurate enough, the sub-aperture data can be directly stitched together to create a
map of the full aperture. In this paper, a CSAS system will be introduced. Its motion mechanism has seven degrees of
freedom. This brings some trouble for obtaining the optics' accurate pose data along with the motion error's
accumulation. So a stereovision system is added. By exploiting appropriate scheme and algorithm, it can directly give
out the optics' accurate pose data. This provides an effective initial value for the stitching algorithm. Finally, a 150mm
flat and a 100mm convex sphere is tested using this method, and the experimental results is given to show the effect of
this method and the efficiency of the CSAS system.
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