The Stimulated Raman scattering spectrum of polymethyl methacrylate(PMMA) plastic fiber was measured and the characteristic of the first order Raman spectrum was studied. The threshold, spectral bandwidth was measured. The formation mechanism of stimulated Raman scattering spectrum was analyzed. The first order Raman spectral bandwidth of plastic optical fiber is less and the volume is 2.8nm or so and it is not changed with the energy of pump light. The Raman frequency shift is 2563 cm-1. Compared with silica fiber, PMMA plastic fiber has smaller spectrum width, bigger Raman frequency shift and lower threshold of energy density. The energy transfer mechanism of silica fiber is the same with PMMA plastic fiber.
Microchannel plate (MCP) is a device of two-dimension array electron multiplier. The detection ability to 40 - 60 KeV X-ray for MCP was increased by coating the halide such as CsI, CsBr and KBr on input plate of MCP, that forming a reflection X-ray sensitive film in the channel with depth of 2 - 3 times of diameter below the input plate. Experiment results show that the output response of MCP with variable density structure CsI to X-ray is about 5 - 6 times higher than that with constant density structure, and of one order of magnitude stronger than that without coating the film. Comparatively, the output response of MCP with CsI sensing film is best, CsBr medium and KBr bad. The response characteristics of MCP with CsI to X-ray related to film materials, structure, component distribution and process. Several experiment curves denoted the response characteristics to X-ray at different target voltage and current. The results basically accorded with the theory about quantum detection efficiency of reflection X-ray cathode. This new MCP reflection X-ray sensitive film of variable density halide has been successfully applied in X-ray imaging detecting devices. The corresponding detection system will find widely and potential applications in the field of medical diagnosis, nondestructive evaluation and security inspection, etc.
The theory of side pumping Nd:YAG solid state laser by high-power array-semiconductor laser cluster are discussed. On the basis ofthat, we design, construct, debugging and survey the performance ofthe laser. The solid state laser device has the following technical specifications: It adopts 3 rank and 3 line, add up to 9 continuous output LD of 20W and 808nm. Nd:YAG laser bar is ?3mm, output wavelength is 1064nm, highest output power is 52.3W, output light mode is continuous multimode, the opto-opto conversion efficiency is 29%.
High resolution and wide-angle Helmet-Mounted Display is the key technology of Virtual reality helmet. Inspired by optical laser technology, and based on the technology of laser television display, the authors suggest a new type of Helmet-Mounted Display Virtual Retinal Display (VRD)
We increase the mass and thickness of CsI film on the base of CsI/MCP (micochannel plate) reflection mode photocathode properly. A part of CsI material is evaporated into 1-1 .5 diameter depth of the channel; another part is coated onto the input surface of MCP. Thus the transmission-reflection combined new type photocathode is formed. When x-rays irradiate the cathode, they penetrate into the coated layer and cause the photoelectron emission, then the rays get into the layer on the walls of MCP, continue to interact with CsI, and produce photoelectrons again. We calculate the quantum efficiency ofthe new type on theory. We also compare the transmission-reflection mode cathode with the reflection mode cathode through experiments of the output current character. The results of the experiment indicate that, the output current of the new type is increased two times than that of CsI/MCP reflection mode photocathode under the same condition and so the quantum effective is increased.