Beckmann DK2A Ratio Recording Spectroreflectometer
Feb. 28, 2001

Information extracted from Adams and McCord (1970).

The Beckman DK2A is a spectroreflectometer using an integrating sphere
with three ports: one for the detector; one for the sample; and one for the
standard. Detectors are interchangable.  A photomultiplier is used for
visible wavelengths; a lead sulfide cell for infrared wavelengths. The 
detectors measure relative reflectance of the sample with respect to the standard by alternately illuminating both (via a  mirror-chopper) and 
measuring the AC voltage resulting in the detector.                                                        
                                                                              
The output is the relative reflectivity of the sample presented in two 
forms: as a plot on a stationary chart recorder; and as a sequence of 
values on punched paper tape spaced at 50 Angstrom intervals. The instrument also has an 'expanded scale' output option.                             
                                                                              
The Beckman DK2A is described in detail by Adams and McCord (1970). 

Adams, J.B. and T.B. McCord, Remote sensing of lunar
  surface mineralogy: Implications from visible and
  near-infrared reflectivity of Apollo 11 samples, Proc.
  Lunar Sci. Conf 1st, 3, 1937-1945, 1970.