Abstract: Apparatus for measuring or detecting changes in a variety of physical or chemical parameters comprises an interferometer having a transmission frequency variable over a range of frequencies as a function of changes in the parameter. The transmission frequency is measured by beating with a coherent reference frequency.

Abstract: A record is obtained of repetitive optical phenomena having durations in the picosecond or subpicosecond range by synchronizing the deflection of the electron image in an electron-optical streaking image tube with the repetition rate of a pulse train from a continuous wave mode-locked laser which supplies such pulses to the tube. Synchronization may be effected by supplying a reference frequency signal both to the laser and to the deflection electrodes in the image tube. The signal applied to the deflection electrodes may comprise a synchronized sinusoidal voltage signal and a slowly varying bias voltage signal. An optical multi-channel analyser may be used at the output of the image tube, linked to an oscilloscope or pen recorder.

Abstract: A laser comprises a cell containing xenon at high pressure and has its walls pervious to high-velocity electrons. The cell is of cylindrical shape and constitutes the anode of a field-emission diode. The cathode of the diode is in the shape of an incomplete cylinder surrounding the anode. Electrons emitted from the cathode thus travel radially inwardly and penetrate the anode walls to excite lasing action. The external electrical connection to the anode is of planar configuration and extends radially outwardly from the anode.