Normally off-gated photomultiplier tube module in photon-counting mode for use in light detection and ranging measurements

In order to increase the detected range and reduce the effect of signal-induced noise in light detection and ranging (LIDAR) measurements of the high atmospheric layers, we have developed a normally off-gated photomultiplier tube module for use in the photon-counting mode. The module allows the detection of the weak backscattering signal, while at the same time rejecting the intense backscattering signal from the near range with an adjustable rejection range. The gating of our module is based on the application of positive voltage pulses on all the even dynodes of a photomultiplier head. We describe the electronic circuit design and discuss the implementation of the module. The capability of the module in rejecting intense backscattering signal from the near range was tested on our LIDAR system. The agreement between the range-corrected LIDAR signals and the standard atmospheric molecular number density up to a height of 60 km indicates a good performance by the module. Comparison between Raman and elastic backscattering signals under cloudy sky conditions indicates that the intense backscattering from near range is sufficiently suppressed and has a negligible effect on the performance of our module. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)