Abstract: An improved method and apparatus are provided for making vibration sensors, particularly of the type used in automotive applications wherein a piezoelectric element is affixed to a flexing plate which is mounted on a support stem in "umbrella" fashion. A desired resonant vibrating frequency of the sensor is obtained by progressively working a neck portion of the support stem, as by peening, to effectively decrease the vibrating radius of the plate and thus increase its resonant frequency toward and to a desired resonant frequency. The plate's frequency is monitored and the working of the stem neck portion is terminated when a desired resonant frequency is attained. An inclined support shoulder on the stem below the neck portion facilitates the aforementioned manufacture. An undercut positioned in the stem neck portion near its transition into the support shoulder further facilitates the manufacture.

Abstract: A digital storage device comprises a crystalline substrate such as silicon in which pockets of amorphous substrate material represent one of the binary logic states; the absence of amorphous material represents the other logic state. The amorphous material is formed by irradiation with a laser beam. Typically the radiation for silicon is at 347 nanometers, 2.5 nanosecond pulse length. The power density varies with crystalline orientation; for (001) silicon it is typically 0.3 J/cm.sup.2 and for (111) silicon it is 0.3 to 0.6 J/cm.sup.2. Erasure of the information is achieved by laser annealing the amorphous material back to its crystalline form.

Abstract: An integrated circuit comprises a substrate having a plurality of components electrically isolated by regions of amorphous material formed by laser irradiation. Typically the laser radiation has a wavelength less than 400 nm a pulse length between 0.1 and 10 .mu.sec, and a power density between 0.1 and 0.8 J/cm.sup.2. The substrate material may be Si, Ge, GaAs, GaAlAs, InAs, InP, InAlP.

Abstract: A laser beam diffuser for use in laser beam annealing comprises a silica laser beam guiding pipe, having a diffusing surface or layer at one end and a polished surface at the other end. The diffusing surface may be a ground surface. A bend or bends removes axial component of speckle produced by the ground surface. Adjacent the polished end the pipe may be of reduced cross section.

Abstract: Magnetic circuit apparatus for use in an electronic ignition system of a combustion engine having one or more spark ignition devices comprises a magnetically permeable frame on which is supported a field magnet and a Hall Effect pulse generator in spaced apart relation such that the field magnet and frame provide a magnetic flux path to which the pulse generator periodically is exposed to produce successive pulses in timed relation to the speed of operation of the engine. A bias magnet confronts the pulse generator at that side of the latter which is opposite to the field magnet and has a polarity opposite that of the field magnet. The flux density of the bias magnet is substantially less than that of the field magnet.