My son has a question for his science class and I am not knowledgable about the subject so I am looking for some help.

 

Can a microscope make the beam from a laser more powerful?

A lens can focus the beam onto a smaller point, but it can't make it more powerful - you'd have to somehow add more energy to it to do that.

A lens can focus the beam onto a smaller point, but it can't make it more powerful - you'd have to somehow add more energy to it to do that.

 

Well, you increase the intensity, since you have the same power in a smaller area, and you could interpret that as making it more powerful. The region getting the light has seen an increase in power.

It would focus the beam (and therefore make it more intense but in a smaller area) right by the eyepiece, but it would spread out after that. It would no longer be a "beam," just like a regular flashlight the color of the laser.

It would focus the beam (and therefore make it more intense but in a smaller area) right by the eyepiece, but it would spread out after that. It would no longer be a "beam," just like a regular flashlight the color of the laser.

 

That's true of a single lens. With a microscope/telescope setup, i.e. the lenses separated by the sum of their focal lengths, you'd change beam sizes but the beam would have its normal divergence. A collimated beam would not diverge, and the size will change by the ratio of the focal lengths. We do this in the lab — collimate a beam coming out of a fiber, and then expand it to fill the window of the vacuum chamber (about 37mm), and also take a free-space beam and make it smaller to fit into a small aperture on an optoelectrical component. In both cases the beams continue to propagate with very little divergence (or convergence).