Beckman Model DU Quartz Spectrophotometer

Extremely innovative in its day, the Model DU Quartz spectrometer in both infrared and ultraviolet models was a workhorse in World War 2, assisting in research on topics as diverse as artificial rubber development and Vitamin A in food measurement.  Yet the electronics were based on the same high-gain DC amplifier circuit of the Beckman Model G pH meter, in fact using that instrument as the electronics end of the Spectrophotometer in early models, replacing the platinum electrode of the Model G with a photo-sensitive tube in the Model DU as the sensing element.  The two models in the lobby of the ISL show a completely functional unit and one disassembled to show the tungsten lamp/quartz prism/phototube light path.

DU

Spectrophotometer batteries
The Beckman Model DU was field usable, hence the sizable array of internal batteries
Spectrophotometer label
helipot DU3
Precision wound resistors and Model A Helipot
tungsten lamp
Tungsten lamp for sample illumination
tubes DU
 Four internal tubes, one of which is the detector phototube

helipot DU1
Model C Helipot

Just a thought: Dr. Beckman produced the Model A, B and C spectrophotometers, so the next model should logically be the Model D and since they worked in the ultraviolet light spectrum, calling the new unit the Model DU makes sense.  But … upon his arrival at the University of Illinois, Arnold Beckman joined the Delta Epsilon fraternity, whose members were called “DU”s.