An improved tomographic algorithm in the scheme of Tikhonov-Phillips regularisation method, has been employed for multi-pixel bolometric measurements in order to get as much information as possible while keeping the assumptions to a minimum. The effects of finite detector size have been taken into account with a full three dimensional treatment of the detector geometry. The application of tomog...

High sensitivity detectors for radon in air and in water have been developed. We use electrostatic collection and a PIN photodiode for these detectors. Calibration systems have been also constructed to obtain collection factors. As a result of the calibration study, the absolute humidity dependence of the radon detector for air is clearly observed in the region less than about 1.6 g/m3. The cal...

A fast and inexpensive spectrometer system has been developed to record extreme-UV impurity spectra in a magnetic-fusion-research device. To simplify the vacuum system, light is passed out of the spectrometer's vacuum to the detector with a sodium-salicylate-coated, fiber-optic coupler. This coupler is positioned so that the focal field is nearly flat over its aperture. The system's detector is...

This article compares the performance of binary turbo codes and Reed–Solomon (RS) codes in an optical communications system employing high-order pulseposition modulation (PPM) and an avalanche photodiode (APD) detector. Despite restriction of the turbo codes to binary alphabets and very simple 4or 8-state encoders, they have coding gains 0.5-dB to 0.7-dB higher than equivalent-rate RS codes whe...

This article investigates the performance of the heterodyne detection scheme for optical pulse-position modulation (PPM) communications channels when nonideal laser transmitters are employed. Two aspects of this channel will be considered. First, the limitations of unguided, turbulent channels in accommodating coherent laser communications are addressed. This is followed by an investigation of ...

Four-element modified uni-traveling-carrier (MUTC) photodiode arrays (PDA) flip-chip bonded onto transmission lines on AlN substrates are demonstrated. High RF output powers of 26.2 dBm and 21.0 dBm are achieved at 35 GHz and 48 GHz, respectively, using a PDA with 28-μm diameter photodiodes. A systematic comparison between a PDA with four 20 μm-diameter elements and a discrete detector with the...

− Light emitting diode antifuse has been integrated into a microfluidic device that is realized with extended standard CMOS technological steps. The device comprises of a microchannel sandwiched between a photodiode detector and a nanometer-scale diode antifuse light emitter. In this chapter, the device fabrication process, working principle and properties will be discussed. Change in the inter...

Compact spectrometers fabricated by placing a wedged etalon or a linear variable filter in front of a linear photodiode array typically do not exhibit the spectral resolution of a parallel filter of the same finesse. A theoretical analysis of the beam emerging from a wedged etalon is shown to predict a comalike aberration, explaining the loss in resolution. This analysis also predicts a focused...

Using FORTE photodiode detector (PDD) observations of lightning, we have determined the geographic distribution of nighttime flash rate density. We estimate the PDD flash detection efficiency to be 62% for total lightning through comparison to lightning observations by the TRMM satellite’s Lightning Imaging Sensor (LIS), using cases in which FORTE and TRMM viewed the same storm. We present here...

Avalanche photodiodes are commonly used as detectors for low energy x-rays. In this work, we report on a fitting technique used to account for different detector responses resulting from photoabsorption in the various avalanche photodiode layers. The use of this technique results in an improvement of the energy resolution at 8.2 keV by up to a factor of 2 and corrects the timing information by ...