1550nm Confocal Microscopy System And The Mathematical Model For ID-201 Semiconductor Single Photon Counter

With the rapid development of laser, computer science and automation technology, microscopic imaging technology has also made considerable progress. Because of the unique advantages such as scanning speed and imaging resolution, confocal microscopy technology plays a very important role in biology, medicine and industry applications.The main purpose of this article is to build and debug a confocal microscopy system based on laser source of 1550nm and apply the system to image a series of samples. The article also focus on a research in the counting principle of a semiconductor photon counter. Via mathematical modeling, we derive the formula of the counting principle of the semiconductor photon counter and carry out experiments to verify the correctness of the formula. The following contents summarize the completed work of this article.(1) Analyze the imaging principle of the confocal microscopy. Calculate the imaging resolution of the system using Fresnel diffraction function and Rayleigh criterion. Establish preliminary design ideas of confocal microscopy system;(2) Design the optical layout, circuit module and mechanical structure of the system. Build a confocal microscopy system based on a two-dimensional scanning galvanometer to achieve rapid scanning on the sample surface;(3) Design scanning program using sawtooth signal to achieve fast scanning in X direction and stepping square wave signal to achieve the deflection of incident light in Y direction. Write driving control program using Labview software to achieve automated scanning and imaging.(4) Conduct experiments on the system and do analysis on several indicators of the imaging data. The main indexes of the system are as follows:(Ⅰ) working wavelength:1550 nm; (Ⅱ)imaging speed:3.2s/f; (Ⅲ)scanning resolution:0.9/μm;(Ⅳ)scanning step:Y direction:60 nm, X direction:1.5μm;(Ⅴ)Optical transmission efficiency:theoretical efficiency: 5.6%, experimental efficiency:3%;(Ⅵ)scanning control:high-performance automation control.(5) The confocal microscopy system use InGaAs semiconductor photon detector as the optical signal progressing device. Single photon detectors based on avalanche photodiodes are attractive, thanks to their advantages including compact sizes, broad spectrum of responses, and high detection efficiencies. This article mainly focuses on the photon counting performance of the ID-201 semiconductor photon counter, which is produced by the ID Quantique company. The purpose is to derive a photon counting formula for ID-201 and verify it using experiments. To verify the derived formula, a series of experiments are performed using the ID-201 in together with a power-adjustable fiber-optic light source that operates at 1550nm.