Laser Distance Measurer

Team members: Arya Chowdhury, Liu Sijin, Jonathan Wong

This project aims to build a laser interferometer that measures short distances (i.e., within a room).

Components:

• Laser diode (source)
• Function generator
• Band pass filter
• Photodiode detector
• Amplifier
• (Optional - Arduino board)

Theory / Principle: Light emitted from a laser can be used to measure distances via phase shift detection. Our setup consists of a laser diode (which serves as a light source) with a given frequency (or wavelength) and amplitude. The reflection of the light off a surface serves as a phase shift operation on the incident light. Hence, if we compare the incident light wave to the reflected light wave, we can meausre such a phase shift and therefore calculate the distance.

The detector consists of a photodiode to receive the reflecting light and a circuit to power the photodiode and output the signal. By supplying the dector with a certain voltage, we can construct the circuit as the below diagram and measure the signal via the difference in voltage.

[circuit diagram]