background. Clinical experience has shown that a variety of skin lesions are treatable with rapidly pulsed yellow and green light of the copper vapor laser.

objective. To review the development, use, complications, and efficacy of the copper vapor laser when utilized for cutaneous lesions.

methods. Articles were identified through a MEDLINE search, review of these articles' bibliographies, and advice from expert physicians who have used the copper vapor laser.

results. A variety of vascular and pigmented cutaneous lesions are effectively treated with the copper vapor laser. A distinct advantage for hypertrophic or cobblestoned port-wine stains and most types of facial telangiectasia is seen when this laser's results are compared with the results of other available laser systems. Complications, including scarring, are rarely observed.

conclusion. The copper vapor laser is a useful addition to the family of lasers that are used for cutaneous conditions.

The copper vapor laser for treatment of cutaneous vascular and pigmented lesions.

Nous avons observe dans les vapeurs de terres rares (thulium, ytterbium, samarium, europium) et d'alcalino-terreux (baryum, strontium), 76 raies laser infrarouges. Les vapeurs etudiees sont excitees par des impulsions electriques breves et intenses. A l'aide d'un interferometre de Fabry-Perot et d'un dispositif de detection synchrone, nous avons mesure quelques deplacements isotopiques dans la vapeur d'ytterbium. Enfin, nous avons mis au point un laser oscillant en mode unique pour plusieurs raies des vapeurs de baryum et de strontium.

https://hal.archives-ouvertes.fr/jpa-00207104/document

Raies laser infrarouges dans les vapeurs de terres rares et d'alcalino-terreux

The high-dispersion absorption spectrum of Sr i is reported for the 1400–1900-A region. Observations include transitions from 5s2 1S0 to the J = 1° channels of Sr i associated with the excited 4d2D and 5p2P∘ ion cores of Sr ii. Autoionization and channel mixing of the observed J = 1° channels are correlated by using methods based on multichannel quantum-defect theory.

Absorption spectrum of Sr i between 1400 and 1900 Å

Publisher Summary This chapter describes the various aspects of the atomic and ionic gas lasers. Gaseous lasers employing excited atoms or their ions as the gain medium account for the largest number of lasers in operation. The simple picture of a system of energy levels in thermal equilibrium results in a distribution of level populations that decreases exponentially with increasing energy. Two distinct modes of electron-collision-excited laser oscillation have been demonstrated in the energy levels of neutral atoms. The modes include an inherently transient oscillation exhibiting very high gain and high peak output powers, but with a pulse duration substantially less than the upper level radiative lifetime, and continuous oscillations with gains ranging from low to high and output powers on the order of milliwatts. The first of the group IIA elements to exhibit cyclic laser oscillation were Ca and Sr, each with one infrared line on transitions that fit the cyclic laser description. The noble gases exhibit several transient laser lines with characteristics similar to those of the metal-vapor lasers. These lasers require fast-rising excitation pulses, possess metastable or quasi-metastable lower levels are thus self-terminating, and exhibit very high gains and output powers.

2. Atomic and Ionic Gas Lasers

Time‐resolved nsec kinetic methods are used to measure state specific electronic excitation transfer for the near‐resonant process: Ca(4s5p 1P1) +Ar ⇄k-1k1 Ca(4s5p 3P2,1,0)+Ar. In stimulated emission experiments it is found that the Ca(4s5p 3P2) level is preferentially populated. The rate constant k1 for the specific 3P2 channel is 5.2±0.5×10−11 cm3 molecule−1 sec−1. These results are discussed in terms of near‐resonant spin changing collision mechanisms. Radiative lifetimes for Ca(4s5p 1P1) and Ca(4s5p 3P1) are also determined to be 77±2 nsec and 67±2 nsec, respectively.

Laser studies of electronic excitation transfer in atomic calcium: Ca(4s5p 1P1)+Ar⇄Ca(4s5p 3P2, 1, 0)+Ar

Sr I1 1.03305 + 0,00005 1.033014 5p2P8jz0 - 4d2Da/z 460 460 Sr I1 1.09175 =t 0.00005 1.091797 5p2pl/z0 - 4d2D3!z 460 Helium or Neon at a pressure of 3 torr was used as a carrier gas, carrying t,he discharge between the cold electrodes into the vapor region within a furnace. The effective length of active medium was 9 em. The single pass gain for all these transitions has been measured and is typically 300 dB/m. At such high levels of amplification, snperradiant emission could be observed by removing the optical cavity, this radiation being distinguishable from spontaneous emission by its relatively small angular divergence.

J. Deech

Papers

New self-terminating laser transitions in calcium and strontium