Recent content by jack13

Sorry, i meant f=8mm. The problem is that no tube length is indicated, so i don't really know f. The pinhole is _not_ properly sized, i need to make a spatial filter, so i need a smaller one/different objective! However i have a 1mW laser and i'd like not to lose all the energy in the spatial...

Ok, so the problem could be that the laser beam entering the spatial filter is too small! Not illuminating the whole aperture. I have a laser beam with w_0 = 0.23mm (beam radius), lambda = 632.8nm, 1.77mrad divergence. The objective legend says 20x0.40. I get the focal length doing 160mm/40 =...

My source is a 35um pinhole after a 20x0.40 objective. Now i think Gaussian beam optics (https://www.cvimellesgriot.com/Products/Documents/TechnicalGuide/Gaussian-Beam-Optics.pdf") should be used to estimate the beam size. But it's still not entirely clear to me.

Hi, i'm having the same problem. I also find experimentally that using two collimating lens with the same diameter but different focal lengths (45cm, 20cm) yields two different beam sizes (about 12mm, 6mm). The lens have been positioned so that the point source is at their front focal...