The whole left side of the diagram is not important or needed to answer the question, it is just there to show a visible spectrum beam also is shone where the infrared laser fof the sensor is shone.
the sensor I'm thinking of using is VL53L0X Time-of-Flight Distance Sensor
To summarize the IR beam is aligned with the projection beam (after that is affected by a shifting lens), is reflected by a freeform (think parabolic) mirror onto a retro-reflective surface and back.
I think this should work but not sure about the freeform mirror part.
It will distort the beam profile and divergence.
I cant find enough info on how the sensor exactly works but I do know it uses a 940nm laser beam and sensor for it and use pulses to determine distance.
I can only assume from the above and from the fact that the pinhole sensor and diode are next to each other that
the visible spectrum beam shouldnt interfere with it
beam profile shouldn't matter
beam brightness loss shouldnt matter as long as it is bright enough for the sensor
the sensor and/or diode are angled a little on the chip and rely on this and/or beam divergence to make sure the beam hits the sensor for the min and max supported distances. So it should end up where it came from in this setup.
But these are just assumptions, if anyone can verify these or explain the actual working it would help.
I have no doubt whatsoever that many, many people on this forum have used that exact sensor, with a similar arrangement of mirrors, and can hardly wait to tell you about how well it worked.
When I'm feeling excessively happy or positive during the day, I come to the Arduino forums to find a regular stream of posts such as "I bought some electronic stuff, make it do something!" or "I downloaded the script/recipe/library/pre-built code and it doesn't do the custom behavior I want, write it for me!". I'm rarely disappointed. Thanks @jremington for providing a nice surprise for me today
so buy and try sensors until one works, all the while someone may know if it will work or not and help me save time and money?
You're more likely to get answers that tell you why a certain arrangement can not work, usually as you go against the laws of physics or outside the specs of the sensor.
For this situation, I also don't see any particular red flags. Try it out, there's nothing to lose. Either it works, or you have a nifty addition to your box of goodies! Actually, I don't know which would be the better outcome... only after three, four different attempts I'd really go for the first.
You have not answered my question about front silvered mirrors. The reason is you are reflecting IR. Glass passes very little IR and twice through a piece of glass will leave very little IR to go to the next station.