External PMT amplifier


We have used a high-speed op-amp (LT1355, Linear Technology, http://www.linear.com/) to construct the amplifier for the external PMT.  A simple-minded non-inverting DC amplifier (see figure below) circuit was built with two resistors (R1=1.0kW & R2=7.5W).  Two serially connected 9Vbatteries were used as the power supply to the op-amp, to avoid 60Hz main noise.  Being a very fast nano-second event, the pulse signal generated by a single photon event was amplified by approximately 5 fold.  Some negative deflection was seen in the amplified signal in the end-phase of the pulse signal, however, it was relatively smaller in amplitude.  Since the amplified pulse signal is integrated by the confocal controller to compute the intensity of a pixel we anticipate that the effect of the negative deflection is negligible. 



Hajime Hirase   hajime@osiris.rutgers.edu