I have been studying the design of a spectrometer using a transmission diffraction grating. I stumbled upon this link, https://ibsen.com/technology/spectrometer-design-guide/. It explains a Transmission grating-based spectrometer. Additionally, at the end of the page, it mentions that "transmission gratings are generally used in the Littrow configuration". However, on further doing research on the internet I am unable to find details on transmission grating being used in a Littrow configuration. Resources point out to reflection gratings.

So, my question is: Is a Littrow configuration spectrometer uses transmission or reflection grating or it can use both.

I am trying to understand the location of specific wavelengths on the screen/detector after passing through the focusing convex lens when transmission grating is used. For reference, see the image below.

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1 Answer 1


It can use both. One of the benefits of the Littrow configuration is that it does not cause astigmatism in the diffracted optical beam. (I think it also gives you the maximum spreading of the wavelengths, but I'm not sure now.) Therefore, although the Littrow configuration is defined as having the incident angle so that the light would come straight back with a reflective grating, one can still use the same incident angle with a transmission grating.


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