A New Logarithmic Photometer
A commonly used logarithmic photometer chassis employs 4 cut-in diodes to convert the quasilogarithmic function to a true logarithmic function. With 4 cut-in diodes this conversion can only be completely accomplished at 5 points in the complete dynamic range. A technique was developed allowing conversion of quasilogarithmic data to true logarithmic form to 21 points over the dynamic range. The circuitry described is applicable to multiple phototubes and photographic photometry. (Author).
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application bias supply bias voltage calibration cathode follower circuitry complete system constant control box control varies converter correction circuit correction signal correction tap correction voltage applied corresponding Densitometer designed difference amplifier dynamic range dynode voltage Ensminger filament flux level four cut-in diodes full-wave rectifier Gain Adjustment gain control gain factor Hence high voltage supply horizontal axis impedance input signal log cycle logarithmic form LOGARITHMIC PHOTOMETER Richard long term low voltage supplied M.P. anode current maximum measuring circuit millivolts Multiplier Phototube Servo networks operator oscillator photometer chassis Phototube Servo Unit position potentiometers are connected power supply power transformer quasilogarithmic function recorder pen recorder scale rection reference voltage regulated with zener resistor response servoed multiplier phototube Silicon diodes stability straight line approximation supply consists switch tapped potentiometer techniques tion transfer function transistors true logarithmic tubes twenty-one point utilized voltage is monitored zener diodes zero