Milton Spectronic 20D Spectrophotometer Single-beam spectrophotometer with digital wavelength and data displays. The basic wavelength of 340 to 600 nm is extended to 950 by adding an optional infrared filter and changing the phototube. Nominal spectral slit width of 20 nm is constant over the entire range. Built-in serial interface capability. 0 to 1.0 VDC serial I/O port for accessory output. Baud rates up to 9600