Our newest Section, it focuses on the discipline of capturing spectra from target stars using a spectrometer such as the Spectra-L200.

The design of the Littrow spectroscope, as applied in the Spectra-L200, uses a fixed, but selectable, entrance slit gap through which the light from the target object is focused (normally from your telescope). The expanding light beam is then reflected from a small precision front surface mirror to a collimating lens. This lens then transmits a parallel light bundle to the reflective diffraction grating.

The grating generates a series of spectra. The precision grating used in the Spectra-L200 has a “blazed” profile to maximise the light dispersed into the resulting spectrum. To record different target wavelengths within the spectrum, the grating can be rotated using a precision micrometer. The grating holder is set at a slight angle to the optical axis to reflect the spectrum back to the collimator. The spectrum is then re-focused by the collimating lens to the imaging camera at the focal plane.

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