Yeah, it really depends on your light sensors responce, most common light sensors have response times of a couple miliseconds or micro seconds.
Neither datasheet (SFH205 and SFH203a) gives data on the reproducibility of the switching time. Would it really matter what the switching time was (within the limits of pulse frequency), if it were very reproducible (i.e., the s.d for switching time was << than the difference in arrival times)? Is that data available?
As I read the OP's question, he seems to mean voltage as a logic/digital signal, not as something that is quantitated.
I used the SFH203FA as detector, using a LD163 904nm laser diode in my commercial range finders.
The laser units had to be calibrated to to correct for the variance in 'sum total' response time of the laser diode, SFH and following amplifiers.
Once calibrated the laser unit were very stable.
The laser measured 'range' had to be corrected also for the 'strength' of the returned echo.
The stronger the echo, the faster the rise time and the 'apparent' shorter range.
Great. Now I have a winter project.
Thanks for the information. I suspected intensity, temperature, and ambient light(?) might be factors. It is easy to see how echo intensity might be corrected for. Is temperature a factor too?