The 9030DS consists of two 100 mm scanning monochromators placed in series in subtractive mode. Bandpass is determined by the width of an intermediate slit, but the 9030DS has a net output dispersion of zero because the monochromators are optically coupled so that the dispersion of the second grating cancels that of the first. This leads to homogenized wavelengths at the output port - there is no spectrum, only a single undispersed slit image - which allows the unit to act as a tunable bandpass or notch filter.
 
 Stray light of all sorts is drastically reduced in a double monochromator, and  in the 9030DS it is further minimized by the use of concave holographic gratings. It is ideal for applications where stray light is a problem - where there may be a strong scattered background, such as in spectroradiometry, Raman or UV measurements of solar radiation.
 
 The 9030DS can be used as a tunable notch filter to remove one particular wavelength while allowing all others over the bandpass to pass through, making it an ideal instrument to pre-filter out the strong laser excitation wavelength in a Fluorescence or Raman system so that the weaker output signals can be observed.
 
 The 9030DS is a fully integrated unit with the two diffraction gratings coupled mechanically for accurate positioning, adjusted manually using a thumb-wheel. A variety of fixed slit widths is available. It can be motorized and controlled by a computer with the Sciencetech MD100 stepper motor and drive system option. Only one motor and drive unit is required for both monochromators, enabling control via Sciencetech Sci-Mono Active-X library or full featured Sci-Spec software.
 
The Model 9030DS can also be used to pass or filter out several selected wavelengths by using a custom intermediate multi-slit mask instead of a single width intermediate slit. Please contact a Sciencetech Applications Specialist for such custom wavelength filtering.