lens and Electromagnetic spectrum

[chem-art]

Can you use normal lenses outside the visible spectrum? What wavelengths can they be used with?

[swansont]

Generally they won't work as well — optics are built with a specific wavelength range in mind. You will tend to get chromatic aberration, because the index is wavelength dependent. There may also be a coating on the lens that is matched to some wavelength range, and the absorption by the lens material may be a factor. So IR optics won't work as well in the visible, and vice-versa. It's difficult to get optics that work in the deep UV.

[Klaynos]

It depends on the lenses.

 

There is nothing special about the visible spectrum.

 

But for most materials epsilon does depend on wavelength, so for things like microwaves you can't use glass because the refractive index is too different to that at 550nm.

 

Some good lens graphs can be found at:

 

http://216.182.47.188/AR_Coating_Curve.jpg

 

And having a look around people like:

 

http://www.thorlabs.com/Navigation.cfm?Guide_ID=100&Visual_ID=1650

 

Can give you some idea of the range for visible.

 

My current experiment relies on an optical train that will work over the range 200nm to 1200nm.