A spatial filter assembly comprising of a focusing lens, a pinhole and a collimating lens is usually to clean up the output from a laser beam. But as the wavelength of the laser source is varied, the focal planes of the lenses would also change which would mean that the pinhole and the collimating lens would have to be moved axially to get a clean, collimated output beam. Additionally, the size of the pinhole would also have to be adjusted to avoid clipping of the focused beam.
Are there any ideas on how to spatially filter a beam from a tunable wavelength source (450-650nm, 0.5W-5W) without having to move any optic?
I think it would suffice to axially position the pinhole and one of the lenses in the spatial filter system (either the collimating lens or the focusing lens). I was trying to understand if there was a way to avoid moving any of the lens. Yes, if I am going ahead with a refractive system I would have to use lenses that perform well over the entire visible wavelength band.
You are right, using mirrors instead of lenses would be a good option. Thank you for the suggestion.
Another option would be Reflective Bragg grating used for spatial filtering (http://www.optigrate.com/BragGrate_Spatial.html). But they have a bandwidth of only 50nm within which it spatially filters the input beam. I was trying to find out if there are other options out there that I may use.
I also have the same problem, I need to spatially filter two wavelengths (532 nm, 660 nm) of laser light at the same time, if I don't move the optics, is it just the loss of laser power at one of the wavelengths, does the other have any effect? ?
Sarka Nemcova Thank you for your answer. Is it possible to select a suitable pinhole to achieve better results by spatially filtering two wavelengths at the same time? I plan to use an aspherical lens here.
Sarka Nemcova Thank you very much, I think this method is a more appropriate method, and it is not perfect to spatially filter lasers of different wavelengths at the same time. One downside of my system is that the 532 nm laser is elliptical and the beam diameter is larger than the 660 nm laser, which makes it difficult for me to choose a pinhole, and recently I'm going to do a test to choose the right one. In addition, the website https://www.edmundoptics.cn/company sells achromatic aspheric lenses, but they are aimed at low-power lasers and are expensive.
- Badges
- Science topic
- Similar topics
- Medicine
- Public Health