Because the near eye display (NED) device mainly displays its imaging effect with a unique virtual image, in essence, compared with the traditional display device, the measurement requirements and methods of brightness, light leakage ratio and other related parameters have also changed. By analyzing the imaging characteristics of optical waveguide AR display equipment, a comparative test scheme for brightness and light leakage ratio is proposed. The same type of arrayed optical waveguide NED module is experimentally measured by using equipment with different test principles, and the measurement results are compared and analyzed. The research results show that the measurement results of the ordinary aiming point luminance meter are not the luminance values in the real display. For the measurement of a certain illumination degree of the equipment, the luminance value and light leakage measured by the aiming point luminance meter have lower deviation than that measured by the two-dimensional imaging luminance meter. Therefore, in the process of testing NED, it is necessary to correctly select the measuring instrument according to its imaging characteristics, the size of the area to be tested and the test scene.
KEYWORDS: Black bodies, Light sources, Temperature metrology, Computer programming, CIE 1931 color space, Light, Radiometry, Colorimetry, Metrology, Radio optics
The color temperature and the correlated color temperature are important parameters in optical radiation measurement. In practical application, it has been a general indicator in representing illuminant color and the quality of spectrum. Starting with the source spectrum, the method via comparison has high precision, as well as a complicated process. A simplified arithmetic is needed to guarantee the veracity. Analyzing the model preliminarily on the basis of iso-color temperature line parameter given by CIE 1931, a new model can be built according to spectral power distribution. It takes steps by color temperature directly on computer programming, aiming at increasing the density of iso-color temperature line and homogeneity, and then, calculating the impact to the uncertainty of the result. By comparing with the other classical methods, it proves that high density interpolation is a programming method on calculating CCT with lesser error and better performance.
The tubing internal thread plays an irreplaceable role in the petroleum equipment. The unqualified tubing can directly lead to leakage, slippage and bring huge losses for oil industry. For the purpose of improving efficiency and precision of tubing internal thread detection, we develop a new non-contact tubing internal thread measurement system based on the laser triangulation principle. Firstly, considering that the tubing thread had a small diameter and relatively smooth surface, we built a set of optical system with a line structured light to irradiate the internal thread surface and obtain an image which contains the internal thread profile information through photoelectric sensor. Secondly, image processing techniques were used to do the edge detection of the internal thread from the obtained image. One key method was the sub-pixel technique which greatly improved the detection accuracy under the same hardware conditions. Finally, we restored the real internal thread contour information on the basis of laser triangulation method and calculated tubing thread parameters such as the pitch, taper and tooth type angle. In this system, the profile of several thread teeth can be obtained at the same time. Compared with other existing scanning methods using point light and stepper motor, this system greatly improves the detection efficiency. Experiment results indicate that this system can achieve the high precision and non-contact measurement of the tubing internal thread.
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