Abstract: A TLD reader system has a laser diode that heats a thermoluminescent material causing a hemispherical photon emission that is collected by a ball lens. A filter ensures the ball lens receives and collects a predetermined transmittance value of the photons emitted within a predetermined range of wavelength. The ball lens sends the collected photons via a fiber-optic connection to a detection module. An infrared sensor senses the temperature and monitors the heating profile of the thermoluminescent material. A computer-controlled feedback loop maintains a constant output power from the laser diode.

Abstract: A thermoluminescent reader module having a hardened, durable construction has a casing which houses a filter, a ball lens and detection module. After a thermoluminscent material is heated by a laser diode, the ball lens collects the hemispherical photon emissions. The filter is positioned at the front of the casing to ensure the ball lens receives a predetermined transmittance value of the photons emitted from the thermoluminescent material within a predetermined range of wavelength. The ball lens sends the collected photons via a fiber-optic connection to the detection module. The detection module is connected to a CPU for purposes of processing the detected information. The filter, ball lens and detection module are securely attached and mounted within the interior of the casing.

Abstract: A mixer is presented which utilizes a diode bridge having a first input signal imposed across two opposite nodes of the diode bridge and having a second input signal imposed across the other two nodes of the diode bridge. A set of variable impedance devices are included in the mixer to protect the diodes in the diode bridge from overload conditions. These variable impedance devices can be included in each leg of the diode bridge or can be included in the input leads to the loop. The variable impedance devices control the current through the diodes by having a low impedance under non-overload conditions and having a high impedance under overload conditions. A particularly simple choice of the variable impedance device is a FET which has its gate shorted to its source.

Abstract: A high speed AC/DC coupler has an optical circuit for DC coupling and an AC coupler circuit, both receiving a digital input signal and both providing outputs resulting from the input signal to the same point of a clipper circuit. The response characteristic of the AC coupler circuit is faster than that of the optical coupler circuit and the output impedance of the optical coupler circuit is of such a magnitude to permit the output of the AC coupler to overdrive the output of the optical coupler. The time constant of the AC coupler circuit is set so that the signal from the AC coupler is impressed on the clipper circuit and remains impressed at least until the slower optical coupler output is also applied to the clipper circuit. The circuit provides a faithful reproduction of essentially any length input pulse, delayed a minimal time.

Abstract: A nonlinear transmission line terminator terminates a transmission line having an input from any one of a plurality of logic types. Emitter coupled logic (ECL), transistor logic (TTL), Schottky transistor logic (STTL), low power Schottky transistor transistor logic (LSTTL), complementary MOS (CMOS) and the like are accommodated by impressing the voltage representing a "0" of the logic circuitry being accommodated on one reference terminal and the corresponding "1" voltage on another reference terminal. The terminator presents a very high impedance when the input signal from the transmission line is of an amplitude falling within the "0" and "1" voltage range. When the input signal falls outside the voltage range, the impedance of the terminator matches that of the transmission line to reduce line reflections by providing a path for current to flow from the transmission line to the appropriate one of the "1" or "0" reference terminals.