- Dec 30, 2016
Yes that's exactly what i did ! I'm using the strong bi concave from my other home made BE and a wider longer FL exit lens, With the longer FL the beam is expanded to fill the exit lens at around 85%.......Did you keep your same primary and just add a wider longer FL exit lens?
I don't know the focal lengths of the lenses, I focus it by sliding the large black section fore and aft, I made this BE through trial and error using scavenged lenses from a hand full of sources...Since the spot a few feet away is tiny then you have the expander focused. Is that correct? What are the focal lengths of the lenses?
When you have time measure the focal length of both lenses.I don't know the focal lengths of the lenses, I focus it by sliding the large black section fore and aft, I made this BE through trial and error using scavenged lenses from a hand full of sources...
This is one of two lenses i got out of a set of binocular's, i'm using the other one as the exit lens in the BE.....
Yes, but there's only one focal length for any lensDo you mean the distance from the lens to it's tightest point?
This will allow us to calculate how wide the spot will be over a distance.
If it's 10 feet across the room and the dot is a pin head wide at it's tightest focus, then at 20 feet it's going to be 2 pin heads wide and so on.
Rather than sensor/film insert wall/ceiling fan.
No. In this case the beam will be collimated for lowest divergence when a given positive focal length lens is place at its focal length from the emitter. You can then measure the separation to get the focal length.Right, the distance from an emitter at which it reproduces an equal size image of the emitter, is that correct?