Abstract: A substrate is electromagnetically coupled into an inductance-capacitance resonant circuit formed from (i) a member comprising a ferromagnetic material, (ii) an inductor and (iii) the substrate. The substrate is illuminated for a first time period X to cause photoconduction in the substrate. Decay in conductivity of the substrate is monitored for a second time period Y. The ratio of X to Y is greater than 1:10. Bulk lifetime of the substrate is determined from the decay.

Abstract: An apparatus includes a member including a ferromagnetic material, an inductance-capacitance resonant circuit, a substrate disposed relative to the member, and a plurality of radiation sources. The member includes a post disposed at its center and a surface extending to an outer wall. The member defines a gap between the post and the outer wall. The inductance-capacitance resonant circuit is configured to resonate at a measurement frequency. The circuit includes an inductor disposed relative to the post. The substrate is disposed relative to the member. The substrate is electromagnetically coupled to the inductor. The plurality of radiation sources is disposed radially outward from and circumferentially around the post of the member. The apparatus can be used to simultaneously measure conductance (inverse sheet resistance), steady state photoconductance, true steady state minority carrier lifetime, photoconductance build-up and photoconductance decay lifetime.

Abstract: An apparatus for measuring minority carrier lifetime is provided. The apparatus includes a resonant circuit having an inductor and a capacitor and configured to resonate at a measurement frequency. The apparatus also includes a ferromagnetic core having a first portion and a second portion. The first portion defines a gap and can be configured to direct therealong a magnetic field established by the inductor, such that lateral spreading of the magnetic field outside of the first portion is inhibited, and to direct the magnetic field generally uniformly across the gap. The second portion can be configured to direct the magnetic field therealong and, in conjunction with the first portion, into a closed loop. A radiation source can be configured to irradiate an area proximal to the gap defined by the first portion of the ferromagnetic core.

Abstract: A prepayment system for dispensing utilities using mag-stripe cards is disclosed wherein an accounting computer in a central office is used in conjunction with point-of-sale machines for encrypting a value message which is written onto the mag-stripe of a mag-stripe card. The value message contains information relating to the amount of utilities purchased by the customer, the utility rates, the site identification number, and a unique password formed by the site number, a hidden number, and the transaction number. The mag-stripe card is carried by mail or in person to the consumer's home or office and inserted into a mag-stripe card reader attached to microprocessor-based utility control device. This utility control device is capable of reading and decoding the mag-stripe card and storing the value information into memory for use in monitoring the utility usage of the customer and disconnecting or connecting the utility based on the amount of utilities purchased.

Abstract: Pivotable, reflective target elements are used to reflect infrared radiat from blackbody sources and transmit the radiation toward infrared-detecting device to test the capability of the device to detect patterns of infrared radiation under dynamic field environment.