The Multi Mode Spectrometer

The Multi Mode Spectrometer enclosures both an Echelle and a Long Slit spectrograph in one single instrument.

The rapid switch* between this two operating modes let you to register both a high resolution echelle and a high signal-to-noise ratio long-slit spectra sequentially.

*Provided each focus is equipped with a dedicated CCD, otherwise switching CCD is necessary.


Optical design of the instrument.

Main features

Entrance slit

Entrance slit is adjustable from 0 to 1 mm and accomodate a dekker for height limiting in echelle mode. The mirrored surface of the slit reflects the field around the analyzed star onto a camera for pointing and guiding. Typical imaged field diagonal is 5 arcmin for 0.6 m telescope and 8 arcmin for 0.4 m telescope.

Entrance beam

Spectrograph entrance focal ratio is F/20 and telescope faster focal ratios can be easily adapted to the spectrograph using a Barlow lens (2X for F/10 telescopes). Long entrance focal ratio allows the use of polarizers for spectropolarimetry and all-reflective optics for collimator.

Echelle mode

Standard echelle spectrum covers the range 3900-8800 Å without gaps onto a focal surface 18x13 mm wide, that matches popular CCDs like Kodak KAF-8300. Spectral resolution R=15'000 in the range 4200-6800 Å with 120 micrometer wide entrance slit (equivalent to 2 arcsec with 0.6 m telescope). Prism cross disperser avoids overlapping of second orders.

Long Slit mode

Standard reflection grating gives the full spectral range 3900-8600 Å on KAF-8300 CCD with R=1000. A wedge prism in the optical beam avoids second order overlapping. Other gratings and dispersions are available upon request, for example for the GAIA range.

Carbon enclosure

The case of the spectrograph is completly made in carbon fiber for optimal thermal stability and mechanical stiffness. Size of the box is 340x300x140 mm and appoximate weight without CCD is 5 kg.

Remote operation

All spectrograph operations are fully motorized for remote use. Remote operations include: slit opening, decker selection, focusing, long-slit/echelle switching. Internal and external temperatures are recorded during operation.

Calibration spectral lamp

The reference lamp box contains both Th[Ar] hollow cathode lamp for spectral calibration and tungsten lamp for flat field. The box is connected with fiber optics to the spectrograph. Th[Ar] HCL produces about 500 unblended lines that can be used in echelle mode. Ar lines are used for calibration of long slit low resolution spectra.


A dedicated software for windows/linux environment performs spectrograph control and automated flat/bias/dark correction, extraction, wavelength and flux calibration of the echelle and long slit spectra.

Find out more:

Echelle mode

Long Slit mode

Technical specs

Example targets