Ferenc Ignacz

Repigmentation of localized vitiligo with the xenon chloride laser

Sir, Topical 5-aminolaevulinic acid (5-ALA) photodynamic therapy (PDT) has become an effective treatment option in dermatology. We report a 70-year-old man who presented with extensive erythematous patches on his abdomen and infiltrated plaques on his arms and neck. These were preceded by extensive figurate and annular erythema on his trunk and limbs for 10 years. He had a history of congestive cardiac failure, atrial fibrillation and chronic obstructive airway disease. Mycosis fungoides (MF) was confirmed histopathologically and he cleared with a course of oral 8-methoxypsoralen (8-MOP) plus ultraviolet A (PUVA). During the next year his MF progressed in extent and he also developed a solitary tumour (1 ́5 1 ́5 cm) on his left posterior thigh. The extensive patch and plaque MF cleared with a further course of oral 8-MOP PUVA, but the nodule remained and became ulcerated and painful over the next 3 months. Biopsy of this tumour showed an ulcerated epidermis with replacement of the subcutaneous tissue by a dense infiltrate of malignant CD31 T cells (Fig. 1a). There was no lymphadenopathy or organomegaly. Blood investigations were normal. Computed tomographic scans of the thorax and abdomen were negative. The tumour was treated with 5-ALA PDT: 5-ALA 20% in a cream base (Aladerm, Crawford Pharmaceuticals, Milton Keynes, U.K.) was applied, under polythene occlusion, to the tumour. Four hours later, excess 5-ALA was wiped off and fluorescence was graded as satisfactory using Woods light. He received 20 J cm at 20 mW cm using a Waldmann PDT lamp (MSR 1200; 580±740 nm). Irradiance was measured using a calibrated handheld meter (International Light 1400A and Selo33/F/W/QND52 detector with spectral shaping and neutral density filters calibrated by D.Taylor, Gloucester, U.K.). He graded pain during treatment as 8/10 but experienced no other adverse effects. The lesion cleared after five consecutive treatments over 12 weeks. Repeat biopsy showed a lymphohistocytic infiltrate but complete clearing of the original infiltrate of malignant T cells (Fig. 1b). During his course of PDT his generalized patch and plaque MF relapsed. The tumour site has remained clear on clinical examination 1 years later. He has required two courses of PUVA therapy for generalized patch and plaque MF during this period. Topical 5-ALA PDT has been proven to be effective for superficial cutaneous cancers, but there are few reports of its use in treating MF. Shanler et al. treated patch/ plaque-stage cutaneous T-cell lymphoma and showed that protoporphyrin IX accumulated within lymphocytic infiltrates; early therapeutic results were promising. Boehncke et al. using an argon laser at 630 nm showed inhibition of proliferation of malignant transformed T cells in vitro and in vivo. Wolf et al. have demonstrated the efficacy of PDT (20% 5-ALA) using a broad-spectrum source (40 J cm at 44 mW cm) in two patients with MF who cleared after four and five PDT treatments, respectively. However, Amman and Hunziker reported a poor response for an infiltrated plaque of MF to just one PDT treatment using an identical regimen. This suggests that multiple treatments are required to obtain a complete histological response. We have demonstrated the benefits of low light dose, low dose rate topical 5-ALA PDT for nodular MF, but a formal study is needed to confirm our findings.

Laser-assisted metal deposition from liquid-phase precursors on polymers

Abstract In this work, a short review is presented for results utilizing the technique of laser-assisted metallization of dielectrics. Experimental efforts and results related to the metal (palladium (Pd), copper (Cu) and silver (Ag)) deposition on polymeric materials (polyimide (PI), mylar) are reported. These polymers and metals are chosen due to their growing importance in the rapidly-developing microelectronics packaging industry. The method of laser-induced chemical liquid-phase deposition (LCLD) offers many advantages compared to other techniques such as laser-induced forward transfer (LIFT), pulsed-laser deposition (PLD) and laser-assisted chemical vapor-phase deposition (LCVD). The LCLD is time and cost effective because vacuum tools and special pre-treatments are not required. The consumed chemicals used in precursors are non-harmful and easy to handle due to the liquid phase. For the optimal physical and chemical properties of deposits, the laser and solution parameters are varied. XeCl and KrF excimer and Ar + lasers are employed for executing the palladium, Ag and/or Cu formation on the polymer substrates. Chemical and physical analyses of the formed metal patterns are performed by EDX, XRD, FESEM, SEM, resistance and adhesion measurements.

Treatment of atopic dermatitis with the xenon chloride excimer laser

Background  Narrow‐band ultraviolet B phototherapy is an effictive and safe treatment for atopic dermatitis. We have previously found that the 308 nm xenon chloride excimer laser was more effective than the narrow‐band ultraviolet B light for the treatment of psoriasis, suggesting that ultraviolet B laser might offer advantages over narrow‐band ultraviolet B.

Dynamics of excimer laser ablation of thin tungsten films monitored by ultrafast photography

The time course of laser light induced transport of tungsten films from a glass support is followed by ultrafast photography using delayed dye laser pulses. The photographs provide unambiguous evidence that the material transport in the 40–200 mJ/cm2 intensity domain takes place via removal of solid pieces from the film material. These results are consistent with heat flow calculations which predict the overall melting of the metal layer above 380 mJ/cm2. The series of photographs presented give detailed insight into the melting process and have revealed an unexpected in-flight phase separation of solid fracture pieces and molten droplets throughout the 200–900 mJ/cm2 domain. The faster propagating molten droplets form a condensed halo in front of the solid pieces, thereby providing an efficient shield between the processing laser light and the solid phase.

Transient optical properties of excimer-laser-irradiated polyimide. I: Refractive index

Reflectivity, transmission and scattering measurments in ArF (193 nm) excimer-laser irradiated polyimide are reported. The time dependence of transient changes in all three quantities were measured together for the first time, confirming a transient refractive-index change in the first 150 ns after irradiation. The relaxation time of the effect was measured and found to consist of both a fast and slow component similar to that previously reported in acoustic wave measurements. The fast decay in about 60 ns and the slow decay is 115 ns. Several potential mechanisms are examined which may explain the result.

Excimer laser ablation of molten metals as followed by ultrafast photography

Abstract Molten Sn and Bi are ablated in vacuum by an ArF excimer laser. Pictures of the surface and the ablated material are taken by ultrafast photography, with temporal resolution of 1 ns using delayed dye laser pulses. The series of snapshots covering the 0 ns–200 μs time domain contain information on the ablated plume, the development of waves on the target surface, and the initial phase of droplet formation. The velocity of the front of the ablated plume is approximately 6 km/s for both Sn and Bi at 5.5 J/cm2. While on the molten Sn surface only wave generation is observed with practically no droplet emission, the Bi surface emits a remarkable amount of material in the form of droplets originating from liquid jets. The speed of these droplets is two orders of magnitude smaller than that of the plume front. The relaxation of the whole perturbed melt pool lasts second(s) after ablation. By decreasing the fluence below 2.5 J/cm2 the Bi droplet formation can also be suppressed.

Transient optical properties of excimer-laser-irradiated polyimide. II: Carbon-cluster scattering

Experiments involving time-resolved scattering and transmission in ArF (193 nm) excimer-laser-irradiated polyimide are reported. Scattering experiments determined that constituents of the carbon layer responsible for laser-induced electrical conductivity form between 150 and 400 ns after the excimer pulse. Transmission experiments indicate that absorbing carbon is present before the formation of organized crystallites responsible for electrical conduction and scattering.

Solid state and liquid ablation of polyethylene-glycol 1000 : temperature dependence

Abstract Time-resolved investigations of solid and liquid phase ablation on the same sample (polyethylene-glycol (PEG) 1000) is presented in this paper. Because this polymer has a relatively low melting point (35°C) we could study the ablation mechanism in both solid and liquid states of matter by varying the sample temperature in the 20–80°C range. The target was irradiated by an ArF excimer laser ( λ =193 nm, FWHM=20 ns) at 1.95 J/cm 2 fluence. Pictures of the surface and the material ejection processes were taken by fast photography, with a temporal resolution of 1 ns using electronically delayed dye laser exposing pulses. It was demonstrated that plasma development and expansion (in the 0–50 ns time range), propagation parameters of shock waves and contact fronts did not depend on sample temperature in the investigated temperature range and state of matter. In contrast with this the significant material ejection (between 1–100 μs) showed a strong temperature dependence. Below the melting point (solid samples) material ejection took place in the form of dense material clouds, and in the form of squish for liquid (molten) samples. The velocity of the ejected jets depended significantly on the temperature of the molten polymer sample. This might be due to the different viscosity of PEG 1000 in the investigated temperature range.

Changes in optical properties of excimer-laser-irradiated polymers

Nanosecond resolution measurements were performed to investigate the change of reflectivity of polymers (PolyMethylMethacrylate and PolyImide) under ArF excimer laser irradiation. The temperature increase due to the irradiation was also calculated. From the results of the experiments and calculations we concluded that several processes influence the observed changes in optical properties of the irradiated polymer samples, such as the quickly expanding gas that leaves the surface immediately after the incidence of the excimer pulse, thermal decomposition of the surface layer and the decrease of the refractive index caused by the heat.

Ultraviolet light and photodynamic therapy induce apoptosis in nasal polyps

Intranasal phototherapy has been found to be effective for the treatment of nasal polyposis (NP) therefore the aim was to investigate the apoptosis inducing effect of phototherapy in NP. In this ex vivo study nasal polyp tissue was surgically collected from 21 consecutive patients with chronic rhinosinusitis (CRS) associated with NP. The removed polyps were cut into pieces and tissue samples were irradiated in vitro by different doses of combined ultraviolet and visible light (UV/VIS: 280-650 nm) and by selective ultraviolet and visible light (sUV/VIS: 295-650 nm). Photodynamic therapy (PDT) was performed by presensitizing tissue samples with 5-delta-aminolevulinic acid (DALA) then irradiated with visible light (VIS: 395-650 nm). Tunel assay was applied to detect apoptosis of epithelial and inflammatory cells in irradiated and control nasal polyp tissue samples. UV/VIS light significantly increased epithelial cell and subepithelial leukocyte apoptosis compared to control groups. PDT treatment showed the highest surface epithelial cell as well as subepithelial leukocyte apoptosis compared to all other groups. Intranasal phototherapy may serve as a new potential therapeutical method in treatment of NP.