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  • Fore Optics

    The Fore-Optics is the opto-mechanical sub-system located directly behind the focal plan of Telescope, between Galacsi, Optical Adaptative module of MUSE and spectrographs. It is designed to perform the following actions:
    - Adapt the image size and orientation of the VLT to the MUSE optics
    - Filter unwanted spectral wavelengths
    - Stabilize the image from possible misalignments between the VLT focal plane and the instrument.
    - Correct the atmospheric dispersion (in Narrow Field Mode)

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    Fore Optics
    3D model of the Foreoptics.

    The Foreoptics is composed of the following opto-mechanical elements :

    The derotator :

    The derotator compensate for the rotation of the field of view due to the telescope motion when it compensate the earth rotation.

    The Wide Field Mode (WFM) : :

    This is the main operating mode of the instrument. It has the largest field of view and we can observe simultaneously a larger number of objects.

    The Narrow Field Mode (NFM) :

    The Narrow Field Mode is a sort of “zoom” when compared to the Wide Field Mode. It will be restricted to the study of single objects at high spatial resolution. This mode incorporate an atmospheric dispersion corrector which compensate for the elongation of objects due to the atmosphere. This effect is more important when the object are seen near the horizon (because the light must then crossed a larger part of the atmopshere).