I have been looking for this for a year! I remake old toys using those 5v green laser diodes and sometimes it's night er have a slightly thicker laser beam. But I just couldn't figure out which type of lenses to get! Now I do. Thank you.
Very nice video! What I was wondering, are abberations like spherical abberations relevant for beam expanders? Would abberations disturb the beam or would the magnification just change a little?
Yes, I think aberration is important. If the expander is not being used with infinite conjugates, then there will be a minimum spot size due to spherical aberration. Even with infinite conjugates, the outer portions of the beam won't be focused at infinity with spherical aberration. So it seems that the beam should eventually become narrower over a long distance due to spherical aberration. So, aberration, as well as diffraction, continue to be issues with afocal systems. With a laser source, it's my understanding that spherical aberration is the dominant aberration since the rays are incident at essentially zero field (other than the incoming beam divergence angle). And of course, with broad spectrum light, chromatic aberration is as much an issue as with any imaging system.
I have been looking for this for a year! I remake old toys using those 5v green laser diodes and sometimes it's night er have a slightly thicker laser beam. But I just couldn't figure out which type of lenses to get! Now I do. Thank you.
Very nice video! What I was wondering, are abberations like spherical abberations relevant for beam expanders? Would abberations disturb the beam or would the magnification just change a little?
Yes, I think aberration is important. If the expander is not being used with infinite conjugates, then there will be a minimum spot size due to spherical aberration. Even with infinite conjugates, the outer portions of the beam won't be focused at infinity with spherical aberration. So it seems that the beam should eventually become narrower over a long distance due to spherical aberration. So, aberration, as well as diffraction, continue to be issues with afocal systems. With a laser source, it's my understanding that spherical aberration is the dominant aberration since the rays are incident at essentially zero field (other than the incoming beam divergence angle). And of course, with broad spectrum light, chromatic aberration is as much an issue as with any imaging system.