Support: LS Series Lens Spectrographs

Support Topics

How should I select external optics to bring light into my spectrometer? [+][-]

Q: Can you provide some information on selecting external optics to bring the light into my spectrometer?

A: Below are some comments on lens selection.

Make sure the lenses are optimized for transmission over the full wavelength region of interest. For example, some lenses are optimized for visible wavelengths so the AR-coatings are not optimized for NIR wavelengths.

Wavelength Range:
The range specified is 550-920nm.

Make sure the lenses are chromatically-corrected for the wavelength region of interest. You don’t want a large change in focus at different wavelengths.

Spectrometer Aperture (f/#):
Make sure you don’t overfill the optics. This will only contribute to potential stray light. If anything, it is okay to slightly under fill the optical system.

If the lens has an integrated f-stop, the lens iris can be adjusted to match the spectrometer.

In some instances it might be a good idea to use a lens pair to accomplish the object-image transfer from the sample to slit.

The first lens collects and collimates light from the sample.
The second lens takes the collimated beam and focus this on the slit.
We normally recommend a 1:1 lens arrangement (equal focal lengths), however this could be changed if required to optimize the light collection. For example, collect at f/2 from a fiber and focus at f/4 to match the spectrometer.



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