A modified Michelson interferometer is described that allows calibration and measurement simultaneously. The method is used to detect displacements down to 1 nm with a time resolution of 40 nsec. These values are close to theoretical resolution limits for the experimental arrangement. The probing beam is focused onto the investigated sample, allowing measurements with a lateral resolution of 1.5 microm. The method has been applied to investigate the deformation behavior of pulsed diode lasers.
The deformation behavior of pulsed double−heterostructure diode lasers at both mirror and contact surfaces was investigated by means of an interferometric technique. The diodes, which were only supported by the pressure of a wire connection, showed at the end of a current pulse an elongation and deflection behavior. Longitudinal and flexural vibrations of the diodes were measured after the application of a single current pulse and for the flexural vibrations a resonance behavior was observed during a current pulse train.
769Infolge strahlungsloser fJberg/inge, Lichtabsorption und ohmscher Verluste tritt eine Erw/irmung der Laserdioden auf, die zu einer Verformung des Diodenk6rpers ffihrt. Der 5rtliche und zeitliche Verlauf der Verformung wurde bei verschiedenen Stromdichten und einer Pulsl/inge von 150 ns bestimmt. Die Messung wurde mit einem Michelson-Interferometer an GaAs-GaAIAs-Heterostrukturen durchgeftihrt. Der Diodenlaserspiegel bildete den einen Spiegel des Interferometers, dessen anderer Spiegel auf einer Piezokeramik mittels einer S/igezahnspannung gleichf6rmig bewegt wurde. W/ihrend des Anstiegs des S/igezahns wurde die Diode gepulst. Aus dem auf photoelektrischem Weg ermittelten zeitlichen Verlauf der Intensit/it der beiden tiberlagerten Lichtstrahlen wurde die Verformung des Diodenlaserspiegels bestimmt. Bei vierfacher Schwellstromdichte wurden L/ingen/~nderungen am pn-/3bergang in der GrSssenordnung yon 100 A mit einer Abklingzeit von einigen Millisekunden gemessen.On the Emission Spectrum of Atomic N in Solid N2: Vibrational Relaxation Rates of N2by O. OEHLER and K. DRESSLER (Laboratorium fiir physikalische Chelnie, ETH Zflrich)The emission spectrum of atomic nitrogen in a matrix of pure molecular nitrogen at low temperature has been investigated extensively by Broida, Peyron, HSrl, Brown and others El, 21. The excitation of the low lying metastable states of atomic N can be ascribed to the quenching of triplet excitons N 2 (A 327~+, v = 0) via the energy tranSfer processes The experimental lifetimes Ell of the ~ and ~' emissions (v~ -40 s) and of ~ and <5' (z, < 1 s) can be taken as the lifetimes of the atomic 2D and ~P states, resp., in the N2 matrix. The short lifetime found for the sharp lines of the cr group Ell, on the other hand, indicates that the high vibrational levels responsible for these lines ZAMP 22/49
Conditions were presented which the holographic procedure must satisfy if diagnostic quality is to be preserved in recording and reconstruction. The resolution of the reconstruction must be comparable to that of the original film. Resolution was examined in relation to holographic record size and signal-to-noise ratio. The latitude of contrast in the original should not be reduced; consideration of the characteristics of various recording media showed that faithful contrast reproduction can be approached by suitable developing techniques and recording procedures. A hologram of high diffraction efficiency was shown to be desirable since the reconstructed image must be of sufficient brightness for useful observation. The inherent problem of speckle and its minimization was examined. The physical and mathematical aspects of these considerations as they relate to clinical roentgenograms were presented.
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