Are you actually trying to find the relative position of the moving object, rather than the distance to it? Over what sort of range, and in what environment, and to what resolution?
Well, i need to calculate the distance between the fixed and mobile object (relative distance would also do) within a area of 1 meter2
. A resolution upto 0.8cm will do my job..
What moves the second point? Can you measure that? An X-Y table or arm gives many options.
NO..!!! the mobile object could be placed anywhere under the mentioned area...
The only problem with this would be that the detectors would always have to stay in the same orientation to the light source so as to provide the same detection cross section (can you get detectors that this wouldn't impact? Probably)
I don't think this would help as the reading at the sensor side would greatly vary depending upon the orientation at which the mobile object is placed..