共聚焦生物芯片扫描仪中PMT电流增益的自动控制

根据共聚焦生物芯片扫描仪获得的图像,设计了计算机控制下的PMT电流增益自动控制系统.根据计算生物芯片图像的灰度分布与期望灰度分布的差异,得到期望灰度分布时PMT的期望电流增益,进而获得PMT的期望控制电压.一个12位数模转换器产生期望控制电压,自动控制PMT电流增益的调节,控制电压精度高达2 mV.实验结果表明,所设计的PMT电流增益自动控制系统可快速、准确地实现PMT电流增益调节,并具有稳定性高、抗干扰能力强的特点.

Auto Gain Control of the PMT used in Confocal Biochip Scanner

An auto gain control system of photomultiplier tube (PMT) used in confocal biochip scanner is designed and performed according the scanning image’s gray level distribution. The biochip image’s histogram is calculated and contrasted with the target histogram, the target gain of the PMT is obtained by the difference of the two histograms and the target control voltage is calculated by the target gain of the PMT. The target control voltage is generated using a 12-bit digital to analog converter (DAC) automatically, the precision of the control voltage is 2mV. As a result, the gain of the PMT is controled automatically too. The experiments prove that the proposed auto gain control system can control the gain of PMT quickly and accurately, at the same time, the proposed auto gain control system is very stong in stability and anti-EMI.