The whole set up is to observe the stress induced birefringence in glass. Light from the Natrium lamp needs to be collimated. Since the whole experiment is carried out in a normal room, there is loss of a lot of light.
How can the system on the collimation side with the lamp and the lens be improvised? Use of an iris or..?
Note: The change of lamp is possible but only in the worst case if there exists no other option.
If more information is required, feel free to ask.
Any information is appreciated. Thank you :)
Hi Winny George,
You can put the lamp into the integrating sphere, then through the fiber wire send the light to the collimating lenses. If the integrating sphere is unproper in your system, just use cossine corrector. Example accessories you can find here: https://oceanoptics.com/product-category/sampling-accessories/
Good luck!
Dear Winny,
I am not sure why you intend to use a sodium lamp to investigate birefringence of a glass instead of using a laser device. I presume you have certain wavelength(s) in mind that a laser could not provide.
Back to collimating light from an incoherent source..... in practice, it is extremely difficult if not impossible to collimate light from a source such as a sodium lamp. The best approach in my opinion is to use a concave mirror and position the lighting element of the Na lamp in between the center of curvature, 2f, and the focal point, f, such that as much light from the lamp as possible is collected and focused to a position > 2f. You should include an aperture (e.g. an iris) at the beam waist (@ > 2f) to modulate light intensity and adjust the collimation. The smaller your aperture is, the better your collimation (but the more light you waste). You can then use your 20-mm dia lens to 'collimate' the light by placing the lens about one focal distance away from the source focus. I assume you will also include polarizers in your setup to investigate birefringence.
The use of Na lamp (again, unless you are selecting an uncommon laser wavelength) is very inefficient: You won't be able to (1) collect all the light produced by the Na lamp. (2) efficiently use the source presumably you will have to introduce filters (whether broadband or line filters) at some point in your setup, and (3) truly collimate (or focus) the source because it is an incoherent source. In addition, you will likely (4) introduce chromatic aberration with any refractive elements/lens that may or may not affect your experiment depending on how sensitive it is.
Hope this helps.
Kin
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