During my PhD program there were some concerns about the long time constant of the lock-in amplifer (SRS-844) which caused directional bluring (along the fast axis) in our laser scanning microscope. Knowing the fact that lock-in amplifers are costly I got the motivation to simulate and build an analogue circuit to overcome this. I was aware of a paper that discussed a module (tuned amplifier) to replace a lock to detect estmulated Raman scattering (SRS) signal. I basically replated their work which was also originated from a paper from 1992. Here I attach my design as a reference in case anyone wants to implement it in therir system. In my case I got a funding source to buy a faster lock-in amplifier so I did not pursue this further. To get design and PCB schematic files head over to this project.

Above is a photo of the final printed and assembled circuit. It was a great process to learn all the details of desining the circuit board and printing it.

• Paper that demonstrated tuned amplifier DOI: 10.1002/jbio.201200005