I am working on a project that requires me to reverse engineer a BioPhotometer and build a new one with modifications. The part where I am stuck is a photodiode that measures wavelengths between 230nm to 600nm. I know fundamentals of photodiodes, but I was not sure is a single photodiode can measure this range of wavelengths. ? Or are there special photodiodes (array) that have multiple photodiodes built into them which measure different wavelengths and hence combine to make a broad spectrum photodiode equivalent. ? Hope I have made this clear.