9055-DX is a motorized double 1/4m monochromator that can be switched between additive and subtractive configurations. Double monochromators have the advantage of extremely low stray light levels by virtue of using two gratings. An intermediate slit between the two units, used to define the wavelengths that pass to the second unit, also masks off light scattered within the body of the first unit. In double additive operation the 9055DX effective focal length (1/2m), dispersion and resolution (1.7nm/mm and .09nm with a 1200 l/mm grating) are doubled compared to a single unit, making this mode useful where high resolution is important. In double subtractive operation there is no dispersion in the output beam and only a single slit image appears at the output instead of a broad spread of spectral images. This allows the system to operate as a tuneable bandpass or notch filter.This system includes two manual slits (one input and one intermediate). Motorized upgrades and additional slits may be purchased separately.Gratings also need to be purchased separately, with a minimum of 2 gratings required for the system to operate. Please speak with your Sciencetech technical sales member to ensure proper grating selection.Please see the technical datasheet for additional information.