Model D .28limited production.29 DU spectrophotometer

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quartz photoelectric spectrophotometer, cary & beckman, 1941


the a, b, , c prototype models coupled external beckman ph meter optical component obtain readouts. in developing model d, beckman took direct-coupled amplifier circuit ph meter , combined optical , electronic components in single housing, making more economical.


moving prototype production of model d involved challenges. beckman approached bausch , lomb making quartz prisms spectrophotometer. when turned down opportunity, national technical laboratories designed own optical system, including both control mechanism , quartz prism. large, high optical quality quartz suitable creating prisms difficult obtain. came brazil, , in demand wartime radio oscillators. beckman had obtain wartime priority listing spectrophotometer access suitable quartz supplies.


beckman had attempted find source of reliable hydrogen lamps, seeking better sensitivity wavelengths in ultraviolet range possible tungsten. described in july 1941, beckman spectrophotomter use hot cathode hydrogen discharge tube or tungsten light source interchangeably. however, beckman still unsatisfied available hydrogen lamps. national technical laboratories designed own hydrogen lamp, anode enclosed in thin blown-glass window. december 1941, in-house design being used in production of model d.


the instrument s design required more sensitive phototube commercially available @ time. beckman able obtain small batches of experimental phototube rca first model d instruments.


the model d spectrophotometer, using experimental rca phototube, shown @ mit s summer conference on spectroscopy in july 1941. paper cary , beckman presented there published in journal of optical society of america. in it, cary , beckman compared designs modified self-collimating quartz fery prism, mirror-collimated quartz littrow prism, , various gratings. littrow prism half-prism, had mirrored face. use of tungsten light source quartz littrow prism monochromator reported minimize light scattering within instrument.


the model d first model enter actual production. small number of model d instruments sold, beginning in july 1941, before superseded du.








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