How to Calculate Coherence Length

By Society & Culture & Entertainment Last updated Saturday, July/06/2024

1). Determine the optical bandwidth of your laser in hertz (Hz). The optical bandwidth is the range of frequencies at which the laser operates. As an example, say the optical bandwidth is 5000 Hz.
2). Multiply the bandwidth by the number pi. To four decimal places, pi = 3.1415. This leads to 5000 Hz x 3.1415, which is 15,707.5 Hz.
3). Divide the speed of light by the product of the bandwidth and pi to get the coherence length in meters. The speed of light is 3.0 x 10^8 m/s, where "10^8" means ten to the power of 8. Continuing the example, you have (3.0 x 10^8 m/s) / (15,707.5 Hz), which gives a coherence length of 19,099.2 meters.