Scientists use laser range-finding to measure the distance to the moon with great accuracy. A brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. A laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. In order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1km in diameter. Staying within this diameter is accomplished by using a special large-diameter laser. If λ = 534nm , what is the minimum diameter of the circular openi

Question

Scientists use laser range-finding to measure the distance to the moon with great accuracy. A brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. A laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. In order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1km in diameter. Staying within this diameter is accomplished by using a special large-diameter laser.   If λ = 534nm , what is the minimum diameter of the circular openi

anonymous · Answer

from which the laser beam emerges? The earth-moon distance is 3.84×105km . It asks for the answer in centimeters. I have no idea how to approach this. Please lead me along so I can learn how to do this type of problem.

anonymous · Answer

@theEric

theeric · Answer

I'm sorry, I don't know this one! I would research, but I'm busy with my homework. I guess there might be a formula that calculates the angle of diffraction? It would probably involve the wavelength, $\lambda$. And you have to figure out the angle you need, then which isn't so bad.|dw:1378939008114:dw|

anonymous · Answer

Yup. I researched a ton on it. I've used Chegg examples and yahoo examples but they don't really align with my problem. Thanks though, sorry about disturbing you. Good luck, Cheers, Allen