The input to the transmitter will be the flashgun contacts on a camera. The receiver will plug directly into the flashgun. If hardware is available - develop software algorithms. Test the effectiveness of the compressor by adding controlled amounts of noise to a communications link, and performing a phonetically- balanced speech intelligibility test. Evaluate the algorithms in a simulated communications link in the presence of Gaussian and non- Gaussian noise.
Laser rangefinders are common devices now, but they are expensive.
You will need a laser diode that can be modulated and a photodiode. Evaluate the accuracy and repeatability of your rangefinder, especially with variations in the temperature of the components. Without building a full opto-mechanical system, make measurements to demonstrate the potential improvement. Typically, electric kettles make use of a bimetallic spring to switch off when steam, being generated at a high rate, indicates boiling. However, boiling water is too hot for making instant coffee, so a kettle that switches off at 70C would be better.