The 9040DS is a Double Subtractive design of the half meter 9040. Special care has been taken to design the system to minimize and eliminate stray light whenever possible.
A double subtractive monochromator operates to create a monochromatic light source by the 2nd monochromator cancelling the dispersion caused by the 1st monochromator. This allows a Double Subtractive system to operate as a tunable notch filter for Raman applications.
Please see the technical datasheet for additional information.