Detection Electronics for a Laser Scanning Microscope, Poster 17

I will be building new detection electronics for a laser scanning microscope. This specific type of microscope creates an image by focusing a laser beam on the object it wants to observe and capturing the fluorescence light... [ view full abstract ]

I will be building new detection electronics for a laser scanning microscope. This specific type of microscope creates an image by focusing a laser beam on the object it wants to observe and capturing the fluorescence light that is reemitted. Two different electronic counting systems will be built in order to accommodate varying levels of florescence. For scenarios in which the amount of incoming fluorescence is relatively low we will actually be able to count each individual photon. To do so, we will build a digital counting circuit. The microscope outputs a pulse of current for each photon it registers, so the digital circuit will amplify each pulse before using a discriminator to convert this analog pulse into a digital signal. A digital counting board will then use a voltage threshold to filter out any false signals that are present in the digital signal. In instances where the incoming fluorescence is quite high, the digital measuring technique cannot keep up with the amount of photons it is receiving and it will undercount, leading to a less accurate image reconstruction. An analog circuit, which will avoid undercounting, will use a current-voltage converter and then integrate the voltage over a set window.