Response time of F 4000 biplanar photocell in various holders

Abstract

The problem of designing a holder for use with the ITT F4000 (or FW114) biplanar photocell is discussed together with the intrinsic properties of the photocell. The intrinsic photocell rise time combined with that of the simple holder described gives a 10-90% rise time of 280 ps. This is virtually as fast as previously published designs for this photocell but also gives over twice the current (up to 4 A into 125 Ω) for the same cathode current, thus increasing the useful dynamic range. The response of the photocell in its holder is combined with the response of a Tektronix type 519 cathode-ray oscilloscope to give an overall response and curves of true and observed pulse lengths which can be used to measure pulse lengths and peak powers for pulses down to 300 ps half-width.