Question

You are working in an optical research laboratory. One of your projects involves the use of a double slit through which you pass blue laser light of wavelength 453 nm. Unfortunately, because of budget cuts, there are a lot of researchers in the same room, with lots of equipment stuffed in the room, and, in particular, lots of laser beams flying around the room. One day, you find that a second visible (400 nm to 700 nm) laser beam of unknown origin and different color is entering your double slit along with your blue beam and you are seeing an interference pattern that is the sum of those due to the two beams. You notice that the combined pattern is pretty much a mess, but wait! The

m = 3

maximum of your blue laser beam pattern is pure; there is absolutely no mixture of the other color at that point. From this fact, you determine the wavelength of the offending laser light (in nm) so that you can figure out which other researcher to ask to modify the aiming of his laser.

Answer 1