Q-switched Neodymium Laser Research Articles

External-signal control of the emission spectrum of a Q-switched neodymium laser

The radiation emitted from a neodymium laser, which was Q-switched by a Kerr cell, was locked by the narrow-band radiation emitted from a neodymium laser operating under free-oscillation conditions. The frequency-locking band was measured. The width of the line emitted by the Q-switched laser was reduced by a factor of 5?103. The system employed made it possible to tune the frequency within the locking band (~40 cm?1).

Laser-induced deformation modes in thin metal targets

Thin metal targets were irradiated with a Q-switched neodymium laser. The absorption of the laser energy produced a high-temperature and -pressure plasma which drove stress waves into the targets. In some cases the plasma was confined using the technique developed by Anderholm and it was found that the magnitude of the stress increased with confinement. The histories of the deformations were measured using quartz and single-slit diffraction gauges and two distinct deformation modes were discovered. The first occurred on a time consistent with the acoustic transit time through the target and the second occurred in terms of transit times, up to an order of magnitude later. This latter late-time deformation mode resulted in the permanent deformation of the targets.

Multi-quantum photoconductivity in Cdln2S4

A study has been made of photoconductivity in Cdln2S4 induced by 1.17 eV photons from a Q-switched neodymium laser. Both three-photon absorption, and two-photon absorption involving the emission of a phonon, have been investigated. The experimental data are in satisfactory agreement with the theory of multi-quantum transitions which takes into account the peculiarities of crystal zone structure.

Singly resonant proustite parametric oscillator tuned from 1.22 to 8.5 μm

A singly resonant parametric oscillator based on proustite has been operated for the first time. The device was pumped by a Q-switched neodymium (1.065 μm) laser in a noncollinear phase-matching geometry. The output has been tuned over the wavelength range 1.22–8.5 μm. The idler power was typically ∼100 W in a bandwidth of ∼1 cm−1.

Time-resolved direct-reading spectrochemical analysis using a laser source with medium pulse-repetition rate

This paper describes the use of a Q-switched neodymium laser with a pulse-repetition rate of 6.25 pulses per second as a spectrochemical source. The detection system comprises a two channel gated integrator for time-resolution and integration of multiple samplings. By pre-lasing the sample it was found that surface effects could be eliminated. Precisions of 2 per cent were obtained for analysis of aluminium alloys. Third partner effects were found to exist. A study of the crater formation suggested a high degree of absorption of laser energy in the partly trapped plasma after initial crater formation.

Effects of F - centers on laser-induced breakdown in KC l single crystals

Breakdown in KCl by Q-switched ruby and neodymium lasers was investigated by varying the concentration of F-centers. Breakdown field for neodymium laser decreased remarkably with increasing F-centers. Decrease of breakdown field for ruby laser, however, was rather gradual.

Many-quantum absorption in gallium phosphide

A study has been made of photoconductivity in GaP induced by 1.78 and 1.17 eV photons from Q-switched ruby or neodymium lasers. Many-quantum processes were observed with 2 to 7 photons participating simultaneously. Double-photon absorption with a phonon participating has also been investigated. The observed many-quantum transitions confirm the recent ideas about GaP zone structure. Based on a generating function method, the theory of many-quantum transitions is developed which takes into account the peculiarities of crystal zone structure. The experimental data are in satisfactory agreement with the theory. Both the many-quantum theory and the experimental method reported in the present paper permit one to study the zone structure of various crystals and to obtain new or supplementary information on fundamental optical constants of solids.

Chemical kinetics at the micro level: A laser micro temperature jump apparatus for relaxation studies in micro samples

The kinetics of chemical reactions at equilibrium can be investigated in samples of very small size with a giant laser pulse shifting the state of equilibrium by a temperature jump. The output of a Q-switched neodymium laser is fired into a microcavity of 5 μl. The solvent, which absorbs part of the laser energy, is heated instantaneously and the kinetics of the chemical processes leading to the new state of equilibrium can be followed up. The principles of the present design are based on the particular properties of a giant laser pulse—high energy and short duration, small beam divergence, emission at wavelengths where many solvents already absorb—and permits thereby (a) a very high time resolution, (b) a very small sample size (⩾ 5 μl), and (c) the use of polar as well as apolar solvents, since heating occurs by means of electromagnetic energy absorption instead of Joule-heating due to ionic conduction. The design of the instrument is such that reaction kinetics even in such integrated biological structures as single cells or cell organelles can be studied.

Electric strength of some liquid dielectrics subjected to a Q-switched laser pulse

A concentrated Q-switched neodymium laser beam was used to break down the following dielectric liquids: doubly distilled water, xylene, cyclohexane, and benzene. The threshold value for each liquid was determined by taking the average for ten exposures for each sample, the five highest for which breakdown did not occur, and the five lowest for which breakdown did occur. Measurement of the laser power density in each sample was used to calculate the field strength of the beam by use of the Poynting vector.

The effect of the laser on cellular respiration.

A frequency of 5300 A, derived from a frequency-doubled Q-switched neodymium laser was observed to produce progressive injury and death of cells from a culture of newborn rat cerebellum. A subsequent observation that the green laser frequency (but not 6943 A of the same intensity from a Q-switched ruby laser) could reduce the rate of oxygen consumption of rat brain cell suspensions suggested that the cytochromes may serve as chromophores. This hypothesis was confirmed by a demonstration that cytochromes c+c1 failed to act as hydrogen acceptors following 10 impacts of 1 Mw/cm2 each of the green laser frequency and cytochromes a+a3 showed a similar response when a brain cell suspension was irradiated (200 kw) with frequencies of 6096 and 6013 A. These data illustrate the principle that laser frequencies which are appropriately matched to the absorption characteristics of target molecules can selectively inhibit specific molecular components in intact cells, if a controlled energy density range is used.