Index of Refraction Measurements Using a Laser Distance Meter

We present a simple method to determine the refractive indices of transparent media using a laser distance meter. Indices of refraction have been obtained by measuring the speed of light in materials.^1–6 Some speed of light techniques use time-of-flight measurements in which pulses are emitted by lasers and the time interval is measured for the pulse to travel from the laser to a detector. These experiments are relatively costly and use sophisticated equipment not always available in an educational institution. Our method uses a laser distance meter that can be purchased for under $80. The meter uses the accepted value of the speed of light in vacuum to determine distances based on a measured time of flight. The output is distance in meters or feet.