KEYWORDS: Fiber Bragg gratings, Denoising, Sensing systems, Signal to noise ratio, Wavelets, Wavelength division multiplexing, Time division multiplexing, Temperature metrology, Random lasers, Light
In this paper, a novel fiber Bragg grating (FBG) sensing system is proposed with large capacity and long transmission
distance to achieve multi-parameter measurements. Record system performances are achieved via the use of high-order
random lasing and remote optical pumping amplifications as well as the combination of time-division multiplexing and
wavelength-division multiplexing technologies. The experimental results show that the sensing distance can reach 150km
with single-end amplification and the optical signal-to-noise ratio (OSNR) is >4dB with good linearity of 0.9992 for 308
FBGs. We also proposed a new denoising method based on deep-learning, and the OSNR is enhanced to 10.2dB from
4.1dB, which is much better than the wavelet and empirical mode decomposition (EMD) methods reported, ensuring the
high accuracy of the center wavelength detection with deep-learning denoising correspondingly.
As a new generation of display technology, Laser displays a wide range of color gamut, high brightness, and other characteristics. However, as a highly coherent light source, laser speckle will be generated by the interference phenomenon of the reflected light or transmitted light of different surface elements after the incident on the surface of the object, which will seriously reduce the quality of the display image. Therefore, the suppression of laser speckle and the reduction of speckle contrast are always important problems in laser display technology. Here, we presented a speckle suppression scheme suitable for projector optical systems. Speckle suppression by spectral broadening and speckle suppression by superposition of multiple independent and unrelated speckle patterns are included in the scheme. Then, the feasibility of the scheme was verified by simulation. On this basis, the projector system was built. The speckle suppression scheme was added, and the effect of the scheme on speckle contrast was verified by actual measurement, and the speckle contrast was successfully reduced from 0.129 to 0.041, which was difficult for human eyes to distinguish.
In recent years, the Laser display has drawn wide attention due to its large color gamut and high brightness. However, the poor uniformity of color and illumination induced by the monochromatic laser has become an urgent technical problem to solve. In this work, we designed a new optical illumination frame, added a Gaussian 2° diffuser at the diffuse 1 position, expanded and shimmed the laser beam, and uniquely added an achromatic half-wave plate in front of the two red array lasers. To verify the improvement of this optical illumination frame on the illumination and color uniformity, we built a laser illumination system by using a Hitachi NUMM31 model 4*7 array laser, 639nm, 643nm 2*7 red array laser, 525nm 1*7 green array laser, and 465nm 1*7 blue array laser. Moreover, the simulation of color uniformity was conducted by lighttools. The result of color uniformity is Δx=0.08 and Δy=0.01. As a result, the color uniformity of our new optical illumination frame below 0.015 was achieved, while the color uniformity of Hisense products is 0.025. This newly developed optical illumination frame has the high potential to provide a facile pathway to realize high color and illumination uniformity by using diffusers and an achromatic half-wave plate.
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