Very nice, Ed! Mounting the lens as you have it is a definite advantage as I see it. The fewer surfaces open to air the better since my biggest problem with a separately mounted lens is dust and dirt quickly accumulating on the 2 exposed surfaces. Having just one surface exposed to open air results in half the problem, and a single surface very easy to clean. Thanks! Joe1950CN
How then do you test that your two beams are aligned correctly coming from the Bath. The reason I always use a separate mounting for the lens is so I can remove it and adjust the two beams. In addition one needs to rotating the lens a couple of deg to keep the laser reflection out of the interferogram. After the cube is rotated then the beams are no longer parallel enough and you need to adjust the side mirror. But with the lens glued to the cube you can't see one of the beams. So to me this is not simpler and make the use more complex.
Rotating the prism a few degrees will keep unwanted reflection out if the Igram but since a lens has curved surfaces a few degrees of tilt isn't enough to do that with the lens. Those reflections will be diverged and faint anyway. "But with the lens glued to the cube you can't see one of the beams." This isn't related to the lens, when you rotate the beam splitter you always have to adjust the reflected beam with the side mirror.
i read in a german forum that the beams have to cross in a distance off 77% of R. Here is the link of the thread. www.astrotreff.de/topic.asp?TOPIC_ID=210415&whichpage=6
Very nice, Ed! Mounting the lens as you have it is a definite advantage as I see it. The fewer surfaces open to air the better since my biggest problem with a separately mounted lens is dust and dirt quickly accumulating on the 2 exposed surfaces. Having just one surface exposed to open air results in half the problem, and a single surface very easy to clean. Thanks! Joe1950CN
J D,
There is an advantage to cementing it directly to the cube to
eliminate 2 air surfaces as long as you don't do too fast a mirror.
Ed
How then do you test that your two beams are aligned correctly coming from the Bath. The reason I always use a separate mounting for the lens is so I can remove it and adjust the two beams. In addition one needs to rotating the lens a couple of deg to keep the laser reflection out of the interferogram. After the cube is rotated then the beams are no longer parallel enough and you need to adjust the side mirror. But with the lens glued to the cube you can't see one of the beams. So to me this is not simpler and make the use more complex.
Rotating the prism a few degrees will keep unwanted reflection out if the Igram but since a lens has curved surfaces a few degrees of tilt isn't enough to do that with the lens. Those reflections will be diverged and faint anyway.
"But with the lens glued to the cube you can't see one of the beams." This isn't related to the lens, when you rotate the beam splitter you always have to adjust the reflected beam with the side mirror.
i read in a german forum that the beams have to cross in a distance off 77% of R. Here is the link of the thread. www.astrotreff.de/topic.asp?TOPIC_ID=210415&whichpage=6