What are some of the principles of mechanical, galvanometer, and laser scanners?

天文望远镜

What are some of the principles of mechanical, galvanometer, and laser scanners? [Copy link]

In order to protect the galvanometer, a lens is added. The laser will be refracted when passing through the lens. So does this refraction need to be handled by software? If the lens moves, then the software will fail. How does the scanner handle this? The picture is for reference (because one is a marking machine, which is different from a scanner)

chunyang

"In order to protect the galvanometer, a lens is added, and the laser will be refracted when passing through the lens." This statement is completely wrong, and the basic concept is wrong.

The galvanometer is a reflector, and protecting the galvanometer has nothing to do with the number of lenses.

The function of the galvanometer is to make a laser beam circulate in a straight line through reciprocating or rotational motion, that is, to achieve line scanning. By using two galvanometers in appropriate positions, the laser can be circulated in a plane area, that is, to achieve surface scanning. The movement speed of the galvanometer corresponds to the scanning frequency, and the deflection angle range corresponds to the scanning area, which of course needs to be controlled. However, for the sake of simplicity and reliability, the galvanometer usually does not use software for direct motion control, and at most performs start and stop control, but the software needs to read the motion state of the galvanometer, that is, the scanning process must be synchronized with the movement of the galvanometer. For the surface scanning system, the movement of the two galvanometers must also be synchronized.

chunyang

Regarding the issue of protecting the galvanometer:

No mirror reflection can achieve 100% reflectivity, which means that the reflector will absorb the energy of the incident light, which will cause the temperature of the reflector to rise. If the temperature rise is too high, the mirror material may be damaged. The laser converges into a very narrow beam of light. If the power is high and it shines on a certain point on the reflector for a long time, the mirror surface will not be able to bear it. Even in this case, other lenses in the optical path will not be able to bear it. Therefore, once the laser is turned on, the galvanometer must be kept moving to disperse the laser energy. If the galvanometer stops moving, the laser must be turned off in time. Protecting the galvanometer will naturally protect other lenses in the optical path. That is why I said in the previous post "For the sake of simplicity and reliability..."

天文望远镜

chunyang published on 2020-8-6 16:53 About protecting the galvanometer: Any mirror reflection cannot achieve 100% reflectivity, which means that the reflector will absorb the energy of the incident light, which will...

Thank you for your answer. I will study the principle of the process after get off work today.