I'm building a small sensor setup that is able to measure the transmission of light through a (clouded) solution. I currently have a laser light that shines through the solution and a LDR on the other side. This works pretty well but there is quite a variation between batches of LDRs and the response is also not very linear. Therefor I started to play around with a photodiode instead of a LDR. (The output is connected to an 12bit ADC)
Currently I have VTB8440BH photodiode connected to a LTC1050 opamp. It's wired up in a current-to-voltage setup and the photodiode in photovoltaic mode as depicted in the datasheet of the opamp on page 13. The sampling frequency is very low somewhere around 1Hz.
The opamp and photodiode will be placed in an environment with a pretty constant (+/- 1C) temperature of 60C. I read in the datasheet that increasing temperatures introduce increasing amounts of noise. I was wondering what the best strategy is to build this circuit, will this circuit that I showed here already be very low noise or do I need additional components to stabilise the output?
(Another small questions, what is the purpose of the 500K resistor between pin 3 (+) of the opamp and the ground? If I check the opamp calculator of Analog Devices (www.analog.com/designtools/en/photodiode/#/photoDiode) that resistor is not present)