Optical correlation enables the rapid identification of targets within an input signal. This is due to the inherent
Fourier-transforming property of an optical lens system. The quick development of Liquid Crystal Display (LCD) brings
opportunity to simply the optical inspection system. The most important part of the system is the joint transform
correlator (JTC). The self-correlated peaks of target image and reference image display overlapped in the center of
output plane. Its high-intensity and wide-breadth affect the correlation peak recognition. A Gaussian filter of power
spectrum processing is proposed. It can weaken the zero-order bright spot in the correlation plane, narrow the bandwidth
of the zero-diffractive peak, leach noises efficaciously and sharpen the correlated peak. This method is simple and
efficacious, adapts to real-time JTC.
The real-time on-line checkout systems are wildly required to assure the quality of products. A product optical on-line product inspection system is designed based on the principle of image cross-correlation technique. The principle of this optical product inspection method is comparing the image of products on-line with the image of references. To enhance the effectiveness of the cross correlation, a Gaussian filter is introduced to weaken the intensity of the autocorrelation peak. For angle and position detection, ten referential images under different rotation angles are put on a circle position while the image of the object is shown at the center of the circle. The information of the direction and position of the object can be obtained immediately.
Rare-earth-element-doped fibers are wildly used in fiber amplifiers, fiber lasers and fiber sensors. Fiber Bragg Gratings (FBGs) are very important optical components in optical communication and sensing. The fluorescence fiber grating consists of fiber amplifiers and fiber gratings. Some fabrication methods of the fluorescence fiber grating are proposed in this paper. After pretreated, for example, Hydrogen loading, the rare-earth-elements-doped fibers become photosensitive fiber. The FBGs can be fabricated along the rare-earth-elements-doped fiber to form the fluorescence fiber gratings. When the pump light goes through the fluorescence fiber grating, the fluorescence light emits as incoherent signal. The power spectrum can be simulated based on an effective analysis method. In experiment, the fluorescence fiber gratings is fabricated to the Erbium doped fiber after Hydrogen loading. The power spectrum of these samples are obtained.
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