How to detect low signal use MT9M001 and USB2 camera shield

Hello Arducam,

We would like to detect low fluorescence signals using the MT9M001 camera module (B0063) and USB2 camera shield (B0095). The fluorescence signal is of 670nm wavelength since this camera has a good quantum efficiency in that range we expected the camera to pick up the signal. But we are not able to do the same. The camera needed a very high-intensity light to get a clear image.
We tried changing the exposure by altering the register (0x09), we went up to a value of 10000, and we even tried changing the gain settings (register 0x35, value1000), is there a way we can improve the exposure time so that we can detect the low signal?
The camera was controlled using the GUI for windows that Arducam has provided (Link- and also tested on Raspberry PI 4 using the python program provided on the GitHub link.

We are wondering if you could provide us some support on this concerns.

Thank you.