Lichen Fu

Preparation and performance of silicon microchannel plate

A silicon microchannel plate (Si-MCP), with 15-25 aspect ratio of the microchannel, 6-20 microns diameter and 6-8 microns space, was prepared by Inductively Coupled Plasma (ICP) and LPCVD. The inner surface topography of microchannel was surveyed, the bulk resistance 7.3 mega ohm and electron gain 110 of MCP were tested by ultraviolet optoelectronic method. The plasma-etching lag in processing the microchannel array was analyzed and discussed. Finally, we compared the electron gain of silicon microchannel plate with traditional glass one. Our work proved the feasibility of making Si-MCP by microfabrication and semiconductor process.

New MCP reflection x-ray-sensitive film of variable-density halide

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.

New way of preparing ion barrier ultrathin film without pollution

A new technology and method preparing ions barrier film on the input face of multi-hole substratum, MCP, without carbon pollution were studied and introduced in this paper. The composition of the film and the performance of MCP coated with ion barrier film were tested by XPS and UV photoelectric emission method. The new process made the carbon content largely decrease in the film, and the characteristics of MCP unmodified.

New structure x-ray cathode for x-ray intensifier of single proximity focus

This paper introduces a new structure X-ray cathode consisting of new structure haloid coating integrated on the input surface of MCP that is applied in single proximity x-ray intensifier. The current response characteristics of different structure CsI, CsBr and KBr cathodes are compared. The conclusion of excellent output response of the dense-loose-dense three-layer new structure CsI Cathode in the energy range 40 - 50 Kev is obtained.

Soft x-ray cathode and its application in Lixiscope

In this text the photoelectric emission principle of X-ray cathode was introduced at first. Then we provided the manufacture method of CsI/MCP X-ray cathode, analyzed the quantum efficiency and noise characteristic of reflection type and transmission type X-ray cathode, proposed the improved process, provided the output characteristic and front and sectional stereoscan photograph of CsI/MCP and pointed out the development of Lixiscope and application prospect in biomedicine.

New development of low-intensity x-ray imaging scope

In this paper, proximity focus x-ray intensifier and corresponding Lixiscope system at home and abroad are introduced. The technical parameters and characteristics are given. The technical ways to improve Lixiscope and the application prospect are offered.

Numerical analysis and experimental research of output performance for Yb3+ -doped double-clad fiber lasers

In this paper, numerical analysis was investigated for the double-clad fiber lasers and experimental study on the Yb3+-doped double-clad fiber lasers was performed. The results shown that the output power increased monotonically with absorbed power, and in lossy cavity the output power is less than in the lossless cavity. The output power decreases for the lossy fiber with the reflectivity of output coupler. There was an optimum fiber length to reach a maximum output and the optimum length was mainly dependent on the loss coefficient. In experiment we obtained an output power of 21.6W, slope efficiency of 54% by using Yb3+-doped double-clad fiber and 40W LD pump source.

High-sensitivity photon-counting imaging detector

Theoretical foundation and principle programmer will be studied in this paper that special photosensitive Si-PSD (Si-Position Sensitive Detector) is rebuilt into electron bombardment mode device, which is based on minimal weak light detecting technical demands and exciting principle of high-energy electronic beam acting on silicon semiconductor. At the same time we will bring forward new concept device of electron bombardment mode PSD. According to the theoretical foundation and principle programmer, we present the practical measurement result that semiconductor gain of electron bombardment mode device is obtained. When incident electron energy is more than 4KeV, then obtained more than 103 gain. We have produced high-sensitivity photon-counting imaging detector (MCP-PSD tube) with 108~109 gain, which combined the research of microchannel plate (MCP) cascade applications with electron bombardment mode device. This paper also will present the substantial photograph of electron bombardment mode PSD device and MCP-PSD tube. Finally we will bring forward prospect realizing detection of minimal weak light photon-counting imaging.

Electron transmittance characteristics of MCP ion barrier film

The MCP ion barrier film in low-light-level imaging tube and its process techniques were introduced in this paper. The electron transmittance of this film was studied. The results of half field-of-view testing comparisons and the concept of dead voltage were presented. The dead voltage curve and the relation between dead voltage and thickness of film were tested. The composition of film was analyzed by XPS.

Silicon microhole array prepared by ICP

This paper reports on a silicon micro-hole arrays (Si-MHA) prepared by Inductively Coupled Plasma (ICP) etching, a dry etching method. By ICP etcher, we carried out several experimental researches and process exploration for micromachining Si-MHA. The mechanism of lateral etching, sidewall passivation, gas micro-transport and some process parameters in Si-MHA micromachining, such as gas switching time, flow rate, etching rate, were analyzed. The footing effect, lag effect, longitudinal strips and RIE grass effect occurred in the ICP etching process were also studied. These process problems had reappeared in the micro-hole arrays process though these problems had be solved in the field of integrated circuits process and microelectromechanical system (MEMS). The study results reported here had demonstrated a Si-MHA that the diameter was 15 μm, the center distance 30 μm, and the depth 240 μm prepared by ICP, and had led the author to believe that the deep pore structure and the deep trench with high aspect ratio were very different in etching process. The former is a closed structure for the gas transport, and the latter is an open structure, so the process of deep hole structure is a puzzle in micromachining and MEMS technology.