Copper Vapor Laser Research Articles

Observation of objects under intense plasma background illumination

Experiments on the observation of a brightness-amplified image of an object through a masking arc discharge are presented. The copper-vapor laser active medium was used as an image brightness amplifier. It is shown that the image quality does not worsen under plasma background illumination.

Development of insulated gate bipolar transistor-based power supply for elemental copper vapour laser

The elemental copper vapour laser is a widely used laser from a family of metal vapour lasers for applications such as dye laser pumping, micromachining etc. In this paper, we report the development and performance of IGBT-based pulsed power supply that replaced conventional thyratron-based power supply for 4.7 cm diameter, 150 cm long copper vapour laser. The laser tube delivered an average power of 51 W, which with conventional power supply was giving 40 W. The IGBT-based power supply offers considerable reduction in the running cost of the laser. It is more user-friendly when compared with the conventional power supply.

Enhanced performance of a wide-aperture copper vapour laser with hydrogen additive in neon buffer gas

A wide-aperture copper vapour laser was demonstrated at ∼10 kHz rep-rate with hydrogen additive in its buffer gas. Maximum power in excess of ∼50 W (at 10 kHz) was achieved by adding 1.96% hydrogen to the neon buffer gas at 20 mbar total gas pressure. This increase in output power was about 70% as compared to ∼30 W achieved with pure neon at 5.5 kHz rep-rate. The 70% enhancement achieved was significantly higher than the maximum reported value of 50% so far in the literature. The enhancement was much higher (about 150%) as compared to its 20 W power at 10 kHz rep-rate using pure neon as the standard CVL operation.

Performance of hybrid, diffraction, and continuously coupled cat-eye resonators with kinetically enhanced copper vapor lasers

New resonators, namely the hybrid cat-eye resonator (HCER), diffraction-coupled cat-eye resonator (DCCER), and continuously coupled cat-eye resonator (CCCER) are demonstrated for the first time here in a kinetically enhanced copper vapor laser with high optical extraction of 70 to 80%, low beam divergence ~0.15 mrad (approximately five times the diffraction limit), and high misalignment tolerance ~5 to 6 mrad achieved simultaneously from each of these configurations. The laser used in the experiment is a 45- to 47-mm bore, 50-W kinetically enhanced copper vapor laser. In the case of HCER, the laser beam divergence reduces to about 0.12 mrad (~30-fold reduction) in an unstable direction and about 0.5 mrad (approximately seven-fold reduction) in a stable direction with average beam power of about 35 W, which is ~70% of 50-W maximum set power of the laser. In the DCCER configuration, laser power achieved is about ~37 W (75% of 50-W laser power) with beam divergence of about 0.17 mrad and misalignment tolerance of ~5 mrad. In CCCER, the output power of about 40 W (80% of 50-W laser power) is achieved with beam divergence of about 0.1 mrad (approximately three to four times the diffraction limit).

A study on the control of dye solution temperature on the line-width and wavelength stability of a copper vapour laser pumped single mode dye laser

This paper presents a study on the line-width and wavelength stability of a single mode narrow line-width (≈ 100 MHz) dye laser pumped by a copper vapour laser, with and without precision temperature control of dye solution. The single mode dye laser system was based on a specially designed SS metal dye cell and grazing incidence grating (GIG) dye resonator with intra-cavity double prism beam expander and etalon. A high precision wavelength-meter was used to record the line-width and frequency stability data. With the coarse dye solution temperature control of 23 ± 2 °C, dye laser line-width varied in a periodic fashion (in every 30 s) between 100 and 770 MHz. Frequency stability was ± 215 MHz (1 min). This is attributed to switching from single to double mode due to temperature induced cavity length change. For the precise dye solution control of 23 ± 0.1 °C, the periodic variation of the line-width was removed completely and the line-width was always ≤ 100 MHz. The frequency stability also improved to ± 42 MHz (1 min). It is established that the dye temperature control is very crucial for achieving, highly frequency stable single axial mode operation.

Axicon based conical resonators with high power copper vapor laser

We report for the first time the performance of axicon based conical resonators (ABCRs) in a copper vapor laser, with novel results. The unstable conical resonator comprising of conical mirror (reflecting axicon) with axicon angle approximately pi/18, cone angle approximately 160 degrees, and a convex mirror of 60 cm radius of curvature was effective in reducing the average beam divergence to approximately 0.15 mrad (approximately 25 fold reduction compared to standard multimode plane-plane cavity) with output power of approximately 31 W. Extraction efficiency of approximately 50%-60% and beam divergence of <1 mrad was achieved in other stable ABCR configurations using flat and concave mirrors with the axicon. This is a significant improvement compared to 4-5 mrad normally observed in conventional stable resonators in copper vapor lasers. The conical resonators with copper vapor laser provide high misalignment tolerance beta approximately 4-5 mrad where beta is the tilt angle of the conical mirror from optimum position responsible for approximately 20% decline in laser power. The depth of focus d was approximately three times larger in case of conical resonator as compared to that of standard spherical unstable resonator under similar beam divergence and focusing conditions.

Photodynamic therapy of port-wine stains

Objectives: The purpose of this study was to observe the improvements of port-wine stains (PWSs) under photodynamic therapy (PDT) and to further evaluate the safety and efficacy of PDT in the dermatology clinic for the treatment of PWSs. Methods: Total of 75 PWS patients were treated with PDT. The PWS lesions were exposed to the copper vapor laser after intravenous injection of photosensitizer (Photocarcinorin, PsD-007). The lesions were photographed before each session and the therapeutic effects were evaluated by physicians based on the improvements in color, thickness and area of the photographed lesions. A follow-up visit was carried out after 2 months. The improvement rates were classified into 5 grades for quantitation of the therapeutic effects. A decision of termination or continuation of the treatment was then made according to lesion changes. Results: Patients with PWSs responded remarkably to PDT. The complete clinical remission rate was 57.33% and the effective rate was up to 94.67% in no more than four courses of treatment. Among the completely responded patients, 20.93% were treated with no more than two courses. Conclusion: PDT is safe and highly effective for the treatment of PWSs in the dermatology clinic.

The ISOLDE RILIS pump laser upgrade and the LARIS Laboratory

On account of its high efficiency, speed and unmatched selectivity, the Resonance Ionization Laser Ion Source (RILIS) is the preferred method for ionizing the nuclear reaction products at the ISOLDE on-line isotope separator facility. By exploiting the unique electronic energy level ‘fingerprint’ of a chosen element, the RILIS process of laser step-wise resonance ionization enables an ion beam of high chemical purity to be sent through the mass selective separator magnet. The isobaric purity of a beam of a chosen isotope is therefore greatly increased. The RILIS, comprising of up to three frequency tunable pulsed dye lasers has been upgraded with the installation of a Nd:YAG pump laser as a replacement for the old Copper Vapor Laser (CVL) system. A summary of the current Nd:YAG pumped RILIS performance is given. To accompany the RILIS pump laser upgrade, a new ionization scheme for manganese has been developed at the newly constructed LAser Resonance Ionization Spectroscopy (LARIS) laboratory and successfully applied for on-line RILIS operation. An overview of the LARIS facility is given along with details of the ionization scheme development work for manganese.

A study of the influence of the input electrical power on the spectral width of the 510.6 nm line of an atomic copper vapor laser

The effect of the input electrical power on the spectral width of the 510.6 nm line of an atomic copper vapor laser (CVL) is investigated. An analysis of the gas temperature inside the discharge tube and the line broadening mechanism of the CVL is reported. The input electrical power was varied from 2.0 to 4.2 kW in a cylindrical discharge tube of inner radius 2.35 cm and length 150.0 cm. A Fabry–Perot etalon and imaging camera-based setup interfaced with personal computer was used to measure the spectral width of the 510.6 nm (green) laser line. The Doppler broadened spectral profile of the laser emission varies with input electrical power and an additional broadening of almost 1 GHz at the highest operating input power was observed.

The effect of varying the hydraulic parameters of a flow cell in a dye laser pumped by a copper vapor laser

A simple method for measuring hydrodynamic parameters that influence the copper vapor laser (CVL) pumped dye laser stability is reported. A specially designed converging diverging curved flow duct is employed. The flow gap at the laser pump region is varied from 0.4 to 0.6 mm and the Reynolds number is varied from 1000 to 20,000. As a result, the channel aspect ratio and effective curvature ratio are varied from 41.6 to 62.5, and 69 to 102, respectively, at the CVL pump region. The variation in the intensity of a He–Ne laser beam transmitted through the water flowing in the test dye cell at different flow rates correlated with the numerically estimated hydrodynamic parameters. The impacts of these hydrodynamic parameters on a 5.5 kHz CVL pumped dye laser output are discussed.

Observation of penning ionization in Zr–Ne discharge by optogalvanic effect

The pulsed optogalvanic (OG) effect is used to observe Penning ionization in a Zr–Ne hollow-cathode discharge, which was axially irradiated by a pulsed dye laser pumped by copper vapor laser. The effect of discharge current on the temporal evolution of the OG signal is studied at 588.2, 594.5, 597.6 and 614.3 nm. The double humped temporal profile of the OG signals, corresponding to transitions of neon, and closeness of energy levels between that level of neon (Ne) and excited levels of zirconium (Zr) ions confirmed that Penning type of ionizing energy transfer collisions were taking place in the Zr–Ne discharge at lower discharge currents (≤5 mA). The disappearance of the double humped feature in the temporal profile of the OG signals indicated that the Penning contribution became negligible at higher discharge currents (≥10 mA).

Gas-discharge laser on a self-terminating thallium transition

We report an experimental study of the performance parameters of a gas discharge pumped thallium vapour laser operating on the 7s2S1/2 - 6p2P3/2o self-terminating transition at 535 nm. The switch we used, a TPI3-10k/25 cold-cathode thyratron, ensures a rise time of the load voltage pulse less than 15 ns. The laser output power is shown to increase in proportion to the energy stored in the discharge capacitor (up to the maximum voltage of the thyratron). The optimal pump pulse repetition rate for He(Ne)—Tl mixtures is ∼1.75 kHz. Even small hydrogen additions reduce the lasing energy and average output power. The addition of bismuth vapour increases the optimal pulse repetition rate (up to 3 kHz) and average output power. The factors responsible for the lower lasing efficiency in comparison with the copper vapour laser are analysed.

Efficient, high rep rate, large-bore kinetically enhanced copper vapor laser with low (&amp;lt;1 kW/l) specific input power using new thermal assembly

Large-bore kinetically enhanced copper vapor laser (CVL) based on new thermal assembly consisting of different density zones of insulation material (alumina fiber) around the discharge tube is demonstrated for the first time with efficiency eta > or = 1% at extremely low specific input power (SIP) of < or = 1 kW/l. As a result of this longitudinal profiling of the insulation material, efficiency of approximately 1.2% was achieved at lowest SIP of approximately 0.75 kW/l. Net reduction in the input power of approximately 1 kW was observed on using this thermal assembly as compared to nonprofiled thermal assembly. These results show significant improvement (25%-30%) at low input requirements of the laser on using new thermal assembly around the discharge tube with overall electro-optical efficiency eta > or = 1%. Maximum laser power achieved from the laser was approximately 78 W at approximately 9.8 kHz rep rate with efficiency of approximately 1.4%. This large-bore CVL is also capable of operating efficiently (eta approximately 1%) at high rep rate of -17 kHz with maximum laser power of approximately 50 W. Performance of the laser under various operating conditions is also presented in this short paper.

Influence of buffer gas pressure on the spectral width of the &lt;inline-formula&gt;&lt;math display="inline" overflow="scroll"&gt;&lt;mrow&gt;&lt;mn&gt;510.6&lt;/mn&gt;&lt;mtext&gt;-&lt;/mtext&gt;&lt;mi&gt;nm&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/inline-formula&gt; line of an atomic copper vapor laser

Abstract. The effect of buffer gas pressure on the intensity and thespectral width of the 510.6-nm line of an atomic copper vapor laser CVL is reported. A self-discharge heated CVL tube of internal diameter47 mm and length 1500 mm was used. The buffer gas pressure wasvaried from 5.0 to 470.0 mbar. A Fabry–Perot etalon-based setup wasused to measure and analyze the spectral width of 510.6-nm lines ofCVL. The relative intensity and spectral width of the hyperfine compo-nents changes with operating buffer gas pressure. The buffer gas pres-sure reduces the number of hyperfine components and hence overalllinewidth . © 2009 Society of Photo-Optical Instrumentation Engineers. DOI: 10.1117/1.3216574 Subject terms: copper vapor laser CVL ; hyperfine lines; linewidth; pressure . Paper 090226R received Apr. 1, 2009; revised manuscript received Jul. 1, 2009;accepted for publication Jul. 10, 2009; published online Sep. 3, 2009. 1 Introduction The copper vapor laser CVL is one of the most powerfuland efficient high-repetition-rate pulsed lasers in the visiblerange of the spectrum.

Effect of the injection angle on liquid spray development in a high-speed direct-injection optical diesel engine

In this paper, the spray development and its interaction with the piston geometry were investigated in a small-bore high-speed direct-injection optical diesel engine. The effects of injection angle, injection timing, injection pressure, and injection fuel quantity were studied. The entire liquid spray cycle was visualized by a background-corrected Mie-scattering technique using a high-speed digital video camera synchronized with a high-repetition-rate copper vapour laser. For some conditions, the initial injection velocity was estimated quantitatively. The results show that the injection angle and injection timing predominantly control the spray interaction with the piston geometry and the resulting air—fuel mixing mode. Narrow-angle injection leads to a significantly different air—fuel mixing process from the traditional wide-angle injector. If properly controlled, the narrow-angle direct-injection technique offers more flexibility on injection timing control with the fuel confined in the central bowl region without wetting the cylinder liner.

A novel confocal optical pulse stretcher for laser pulses

We present an analytical and experimental study of a novel confocal optical pulse stretcher (COPS). The simple and passive pulse stretcher consists of two concave mirrors and a scraper beam-splitter and its optical configuration ensures a perfect spatial overlapping of laser pulses at the beam-splitter. The pulse stretcher is compact and suitable for laser pulses of large divergences. The confocal optical pulse stretcher is demonstrated on a pulsed copper vapour laser to convert a 40 ns (1/ e 2 % points) pulse into a 55 ns with reduction of peak power by a factor of 1.375 without loss of pulse energy.

Acoustic effects of metal vapor lasers

Some fluctuations in the output power of a copper vapor laser with a 16 mm bore were recorded by varying the excitation frequency from 13 to 33 kHz. The effect arises from the laser tube, which performs both as an optical and an acoustic resonator at the acoustic resonant frequencies. It is shown that a similar effect occurs in other metal vapor and copper halide lasers as well.

Output energy parameters of a KULON-10Cu-UV laser

The output energy parameters of an industrial KULON copper vapour laser equipped with a nonlinear frequency converter based on DKDP and BBO crystals are studied. The average and peak powers, as well as the energies and pulse durations of radiation at wavelengths of 510, 578, 255, 271, and 289 nm, are measured in the regime of high-speed pulse modulation, which is used in lasers of this series. The maximum average power was 420 mW at a wavelength of 271 nm (DKDP) and 350 and 110 mW at 255 and 289 nm, respectively (BBO). It is experimentally shown that the average energy characteristics of UV radiation can be controlled on-line by changing the pulse repetition rate of the laser.

Spectral diagnostics of vapor composition over molten Na2WO4 and Na2O-BaO-B2O3 system

The high-temperature Raman spectra recording technique was found applicable also to study luminescence of atoms and individual molecular groups in vapors over some overheated molten compounds. Sodium atomic luminescence excited with a yellow (578.2 nm) copper vapor laser line was detected in vapors over overheated molten Na2WO4 and Na2O-BaO-B2O3 system. The possibility of recording the sodium doublet spectrum by excitation with the 578.2 nm copper vapor laser line in vapors of any melts containing sodium was shown. Overheated melts in the Na2O-BaO-B2O3 system disproportionate and lose boron oxide as evidenced by the recording of luminescent spectra of BO2 molecular radicals in vapors over relevant melts.

Analysis on the laser beam pointing instability induced fringe shift and contrast dilution from different interferometers used for writing fiber Bragg grating

This paper presents an analysis on the effect of laser beam pointing instability on the fringe shift and hence the contrast dilution of superposed fringes from two beam interferometers. The interferometers analyzed are those commonly used in writing fiber Bragg grating (FBG) such as phase mask, bi-prism and phase mask based Talbot/Holographic type. The beam pointing instability is incorporated as slight change in the angle between two interfering beams. The relative immunity of different interferometers to laser beam pointing is discussed vs location of FBG writing plane from the beam splitter. The effect of the beam pointing was minimum in proximity FBG writing by phase mask. The effect, in terms of fringes contrast dilution, was worst in case of large length interferometers e.g. phase mask based-Talbot interferometer. For intermediate length prism interferometers, the effect was moderate. For a given length interferometer, the fringe shift was directly proportional to beam pointing angle and inversely proportional to fringe separation. Theoretical analysis is verified experimentally by studying the fringe instability of interference pattern formed by a bi-prism of angle 2o with the copper vapour laser (CVL, λ=510nm) beams of different beam pointing instabilities.