Dear Sir. Concerning your question regarding the the use of cylindrical lenses in spectrophotometer. I think, cylindrical lenses assist in the transport of light in the spectrophotometer instrument and it can focus an ion beam, for example to make a microbeam for irradiating individual cells. Cylindrical lenses act on light to converge or expand it much like spherical lenses do, but in only one dimension. This makes them useful for altering the proportions of an image, either singly or when used in pairs. They can transform a point image into a line image or change the height of an image without altering its width (or vice versa). Applications of this type include anamorphic beam shaping and correcting the elliptical output of a laser diode to create a circular, collimated beam. Cylindrical lenses are used in the source assemblies of many systems, where they generate a line output from a laser. They are also used to gather and focus light onto a linear detector, or for coupling into a slit, as in spectroscopy applications. Cylindrical lenses can also assist in the transport of charged particles, it can guide electrons emitted from a sample to an electron analyzer.

Thanks.

Dear Peter Kapusta. How are you . Yes, I know this fact which you have mentioned very clearly, because I'm also researcher, but I want to give explanation for the question based on a background from which I have read. The assistance to our colleagues for their inquiries may be statement of just three words or any kind of help which is also based on the information obtained from others, and of course citing is very necessary and fundamental when you want to document this information in your article or any kind of manuscripts . If you are ask from the source of the mentioned information I have stated,  you can see the attached file:

Is there a throughput advantage, when using a round-to-slit fiber bundle, of a lens based fore optic versus butting the slit shaped fiber against the entrance slit?  Do you increase the amount of light hitting the grating and detector by using a cylindrical lens?

Cylindrical lenses transport and focus light in the spectrophotometer. Cylindrical lenses act on light to converge and expand it in singular dimension. They further help in regulating collimated beams. Resultant image formation is thus has clarity and doesn't look extremely altered.

This video of portable spectrophotometer (recently came across this one) uses cylindrical lens for focus and collimation and can be used as reference : https://www.youtube.com/watch?v=J0S6Q0YWapU

Thank you for the informative response

Normally they are used for correction of astigmatism introduced by an off-axis design.