Copper Bromide Vapor Research Articles

Mass spectrometric study of laser‐induced pyrolytic decomposition of TMA

AbstractThe composition of the gaseous phase during pyrolytic laser‐induced chemical vapour deposition (LCVD) of aluminium from trimethylaluminium (TMA) was determined. The analysis was carried out in situ by means of a quadrupole mass spectrometer (QMS) in a closed reaction cell. The decomposition of the aluminium alkyl was induced by a copper bromide vapour laser on the surface of (111) silicon monocrystalline wafer at 0.22 GW m−2 average power density, 120 μm s−1 scanning speed and 100 Pa (1 mbar) partial pressure of TMA. The detected gaseous products of the pyrolysis of TMA were ethane, ethylene, methane and hydrogen. The presence of ethane and ethylene was probably due to the unconventional way of decomposition caused by pulsed laser irradiation. The mass peak dynamics of the created pyrolytic products at m/e = 28, 16 and 2 indicated significant production of ethane + ethylene, methane and hydrogen in the ratio 1:5:1.75.

Active optical systems with a copper bromide vapor amplifier

An experimental demonstration was made of the feasibility of using the active medium of a copper bromide vapor laser with hydrogen admixtures as an image amplifier in active optical systems. Images of microobjects located several meters from the amplifier were obtained in this way. Large (~ 7 cm) fields of vision were achieved in the telescopic system. The power of a beam carrying a negative image exceeded 0.5 W, so that it was possible to project independent images on a screen of more than 5 m2 in area.

Investigation of optical inhomogeneity of the active medium in a CO2laser with hf excitation

An investigation was made of the optical inhomogeneity of the active medium in a fast-flow closed-cycle CO2 laser with a transverse hf capacitative discharge and a 5-liter active volume. A lateral-shear interferometer employing a pulse-periodic copper bromide vapor laser was used in the measurements. Optical inhomogeneity of the wedge type in the flow direction and of the positive lens type in the transverse direction was found to be present at the start of the discharge, and there was a 2-mm-thick layer at the electrodes. The inhomogeneity was considerably smoothed out toward the end of the discharge zone along the flow direction. The gain and gas temperature distributions in the active medium were measured in the discharge current direction. The results obtained prove that the active medium homogeneity in a laser with an hf capacitative discharge is higher than that when a self-sustained discharge is pumped by a dc current.

Relaxation of metastable copper atoms in a copper bromide vapor laser under regular pulse conditions

An experimental investigation was made of the relaxation of the populations of 2D5/2 and 2D3/2 metastable states of the copper atom in the interpulse period in the active medium of a copper bromide vapor laser under near-optimal lasing conditions. Measurements were resolved over the cross section of the discharge zone. The processes responsible for the observed decay of the metastable state populations were considered. An investigation was made of the influence of hydrogen on the lasing characteristics, the excitation power, and the decay of the metastable-state populations. The reasons for an increase in the output power of a copper bromide vapor laser with added hydrogen are discussed.

Investigation of the factors limiting the service life of a copper bromide vapor laser

An experimental study was made of the factors limiting the service life of a sealed pulsed copper bromide vapor laser. In the operating regime, the entire laser discharge tube was heated in such a way that the lowest temperature of 430 °C was maintained in side arms containing the active substance. The discharge tube was operated for a period of 335 h, after which it was opened up and subjected to an investigation. During the operating period the laser output power fell from 3.6 to 2.0 W, mainly due to the deposition of copper on the exit windows. Gross discharge and lasing instabilities were observed toward the end of the operating period and these were explained by the observed increase in the bromine concentration in the tube during the laser operation.

Comparison of the characteristics of copper, copper chloride, and copper bromide vapor lasers

The results are given of a comparative study of the characteristics of copper and copper halide vapor lasers, excited by regular pulses. It was found that the lasing characteristics of copper chloride and copper bromide vapor lasers were practically identical, both under excitation conditions which correspond to the optimal efficiency and under other excitation conditions, and that they differed from those of a copper vapor laser. An average output power of ~13 W was obtained and an efficiency of 1% were obtained for all these lasers. The indications are that the advantage of employing a particular type of laser will be mainly determined in practice by the convenience of using the given design to solve a specific problem.