Blue-green Laser Research Articles

Raman Scattering From TMTSF-Salts

Abstract Experimental results for Raman scattering from TSeF, TMTSF-D12, (TMTSF)2PF6 and (TMTSF)2AsF6 excited with blue-green laser light at liquid nitrogen temperature are reported. A strong resonance effect for excitation of TMTSF with 4579 Å was observed and an assignment for the ag modes was obtained by comparison with results from TTF. Methyl group modes were identified at 328 cm−1, 472 cm−1 and 916 cm−1, respectively. Charging the TMTSF molecule resulted in a strong frequency shift of -122 cm−1 and -76 cm−1 for the agu2 mode, respectively. A study of the temperature dependence of the scattering from molecular modes between 2 K and 300 K did not reveal any correlation with the phase transitions in the conducting compounds.

KRYPTON RED LASER PHOTOCOAGULATION OF THE OCULAR FUNDUS

The theoretical rationale, the histopathologic evidence, and the preliminary clinical studies related to krypton red laser (KRL) photocoagulation of the ocular fundus are reviewed. The authors report on their experience with currently available laser systems using this wavelength (647.1 nm) for photocoagulation of retinal vascular proliferative diseases and chorioretinal diseases associated with exudative manifestations. A histopathologic and clinical comparison of argon blue-green laser (ABGL), the pure argon green laser (AGL), and the krypton yellow laser (KYL), with reference to photocoagulation treatment of the ocular fundus is also discussed.

High power blue-green molecular lasers

High power blue-green molecular lasers

Naval C3applications for blue-green lasers

Naval C³applications for blue-green lasers

The Argon Laser for Cutaneous Lesions

A summary of the pathophysiology and clinical use of the argon laser in the treatment of cutaneous lesions is presented. The nonionizing blue-green argon laser light is absorbed by pigment, is converted to heat, and selectively destroys specific cutaneous lesions with sparing of adjacent dermal appendages and healing of the laser wound with minimal scarring. Vascular lesions (port wine hemangioma, capillary-cavernous hemangioma, telangiectasia), inflammatory lesions (pyogenic granuloma), nevoid lesions, tattoo lesions, and a variety of miscellaneous lesions have been successfully treated.

Multiline (480–496 nm) discharge-pumped iodine monofluoride laser

Lasing at 478.7, 484.7, 490.7, and 496.5 nm has been observed on the E→A3Π (bound→bound) band of the IF (iodine monofluoride) molecule in discharge-pumped He, Ar, CF3I, and NF3 gas mixtures. Oscillation was obtained using a stable optical cavity with output coupling mirror transmissions of 0.2 and 92%. For a 99.7%-He, 0.2%-NF3, and 0.1%-CF3I (ptotal≈1540 Torr) gas mixture and T∼92% (quartz flat), output pulse energies of ∼0.35 mJ in a ∼15-ns FWHM pulse (peak output power ≳24 kW) were measured. Optimization of the cavity output coupling and increased Ar pressures in conjunction with the use of an attaching gas (to raise the discharge E/N) are expected to improve the output energy and, consequently, the overall efficiency of this blue-green laser.

Iodine monofluoride emission spectrum and formation kinetics in electron-beam-produced plasmas

Intense blue-green fluorescence from a structured band centered at λ∼484 nm has been observed from Ar, CF3I, and NF3 (or F2) gas mixtures (T=300 K) excited by a ∼3-ns FWHM electron beam. This emission is tentatively assigned to the E→A3π1 transition of the iodine monofluoride (IF) molecule. From the temporal behavior of the IF* and I2* (342 nm) emission, it has been determined that the IF (E) level is formed primarily by excitation transfer from I* (4P) states. The fluorescence efficiency of the IF (E→A) band and the IF* (E) state radiative lifetime have been estimated to be ∼6% (in 99.83% Ar/0.13% CF3I/0.04% NF3 mixtures. PTOTAL≈2300 Torr) and ∼15 ns, respectively. The emission band structure, the short IF (E) radiative lifetime, and the Franck-Condon shift between the E and A states suggest that IF* is an attractive candidate for a blue-green laser.

A new photolytically-pumped blue-green laser in XeF

A new photolytically-pumped blue-green laser in XeF

A new blue-green excimer laser in XeF

A new blue-green excimer laser has been demonstrated on the C-A transition in XeF, with an output energy of greater than 1 mJ. Xe*2 excimer fluorescence at 172 nm was used to photodissociate XeF2, producing XeF[B (1/2)] and XeF[C (3/2)]. The B (1/2) state was collisionally relaxed to the C (3/2) state with an Ar buffer. Lasing then occurs sequentially on the B (1/2) -X (1/2) and C (3/2) -A (3/2) transitions. Measurements of the C-A laser spectrum showed a peak wavelength of 483 nm with a bandwidth of 12 nm. This new laser is potentially highly efficient and scalable and should be tunable over a bandwidth greater than 40 nm.

Blue-Green Lasers for Ocean Optics

This paper discusses the present status and future possibilities of blue-green laser technology. Laser developments that are potentially most useful for ocean optics are emphasized. Historically, argon ion lasers have been used for virtually all underwater experiments requiring coherent cw sources, while frequency doubled Nd: YAG lasers have provided pulsed blue-green radiation. Neither of these lasers is appropriate for high-average-power field use. The best present candidate for appli-cations where high pulse energy is of primary importance is the flashlamp pumped dye laser. For range-gated applications, where 5-20 nsec pulses are needed, the copper vapor laser is the best immediate choice. A single pulsed laser that is suitable for both applications is not yet available. A cw laser with reasonable efficiency is also unavailable. With recent UV/visible molecular gas laser developments, it is likely that a single blue-green source capable of satisfying most ocean optics needs will be available within three to five years. Promising possibilities include KrF laser and XeF laser pumping of a blue-green dye laser and Raman downshifting of XeF laser output. Several longer term possibilities for in-band blue-green molecular gas lasers have been identified.

Determination of Underwater Plate Dynamics Using Laser Beams

Underwater plate vibration and its associated noise are of interest for the analysis of ship structures, propeller blades, and other areas of underwater acoustics. In order to analyze the relationship between a plate vibrating underwater and the acoustic pressure in the near-field, optical interferometric holography, using a blue-green laser beam, was used to determine surface displacement for the vibrating plate, which was excited through a fluid-coupled system. Acoustic measurements of the same source were made in a water tower concurrently with the holography and later at a precision acoustic testing facility. This method permits prediction of underwater plate modal frequencies and shapes with high accuracy.

Quasicontinuous emission from ion lasers in electrodeless high-frequency discharges

The generation conditions were investigated and the output characteristics were determined for the blue–green laser radiation emitted by xenon ions and for the ultraviolet radiation emitted by oxygen ions. These ions were excited in an electrodeless high-frequency discharge using excitation pulses of ~1.5 msec duration. The total pulse output power of the xenon ions was ~120 W under quasicontinuous conditions and the corresponding output power of the O II (λ = 374.95 nm) and O III (λ = 375.98 and 375.48 nm) oxygen lines was 5 W. It was found that these lines could be emitted continuously.

Application of an airborne pulsed laser for near shore bathymetric measurements

A feasibility investigation of the deployment of a pulsed blue-green laser as an airborne bathymetric sensor for near-shore beach reconnaissance has been performed. Preliminary transmission measurements were made in a water tank using AVCO Corporation's new high-powered 3-nsec pulsed neon laser. These results were used in the design of the airborne tests. The laser transmitter/receiver system was installed in a Turbo Commander and flown over the shores of Lake Ontario. Water depths up to 26 ft were recorded. The maximum depth capability, which is determined by the turbidity of the water, is limited in the present system to approximately four attenuation lengths at a platform altitude of 500 ft. In fairly clear water ( α = 0.1 m −1) this amounts to a depth-measuring capability of 120 ft. The shallow water resolution is ± 1.5 ft. An operational system employing a high-power high-pulse rate laser (100–1000 pps) could operate from either a helicopter or a high-performance aircraft and sweep out a broad area coverage. An aircraft flying at 300 miles/hr could obtain data points every 20 ft over an area of 5–50 sq miles/hr.