Non-laser Light Source Research Articles

Non-laser light divestment in conservation and preservation

Over the past 10 years, laser technologies have found acceptance for surface divestment both in industry and in art conservation. The initial endeavors in exploring and assessing the utility of this art conservation tool are recounted for investigations involving ruby, glass, ion, YAG, carbon dioxide, dye, and excimer lasers with particular emphasis on the limitations that were encountered with each (in terms of speed, cost, wavelength, spectral width, and reliability). In response to these issues, a research effort is described that was instituted to assess non-laser (viz., incoherent) light sources (e.g., flashlamps, sparklamps, arclamps, and pinchlamps) for radiation cleaning. Initial demonstration projects with these sources included Parisian textile theater seats, leather-bound books, architectural stencil designs, courthouse ironwork, and Ming Dynasty marble statues. With non-laser light generators, substrate thermal alteration and debris redeposition often present problems. These may be minimized or avoided through the incorporation of a gas jet, static liquid, liquid jet, or dry-ice blast.

Laser and non-laser light sources for photodynamic therapy.

Photodynamic therapy (PDT) is an anticancer combination therapy, which requires a photosensitiser, which tends to accumulate preferentially in the tumour, and light. Historically large, complex lasers have been used to carry out PDT treatment. Nowadays there is a wide range of coherent and non-coherent sources that can be used. This paper considers the important characteristics of light sources for PDT, including dye lasers pumped by argon or metal vapour lasers and frequency-doubled Nd:YAG lasers. Non-laser sources including tungsten filament, xenon arc, metal halide and fluorescent lamps are also discussed. New exciting developments such as LEDs and femtosecond lasers are also reviewed. The relative merits of laser and non-laser sources are critically examined.

Photodynamic Therapy of Barrett's Esophagus with Dysplasia Using Systemic Aminolevulinic Acid and a Non-laser Light Source. A Phase I/II Study

Photodynamic Therapy of Barrett's Esophagus with Dysplasia Using Systemic Aminolevulinic Acid and a Non-laser Light Source. A Phase I/II Study

Effect of photodynamic therapy on normal fibroblasts and colon anastomotic healing in mice

Photodynamic therapy as an adjuvant modality to surgical resection of colon cancer is feasible provided that it does not affect healing of the anastomosis. The aim of this study was to evaluate the effects of photodynamic therapy on the viability of normal fibroblasts and on the healing process of colonic anastomosis in mice. Both in vitro and in vivo methods were employed. For in vitro study, 2 × 10 5 human fibroblasts were incubated in triplicate with 5-aminolevulinic acid (2.5 μg/well) for 48 hours. Cells then underwent photoradiation at light doses of 50, 100, and 200 joules/cm 2 using a nonlaser light source. Viability was assessed by methylene blue dye exclusion. For in vivo studies, 60 mice were randomized into study and control groups and underwent laparotomy involving colonic anastomosis. The anastomosis underwent photodynamic therapy using 5-aminolevulinic acid (60 mg/kg) as a photosensitizer and a nonlaser light (40 joules/cm 2). On postoperative days 1, 4, 7, 14, and 21, six mice were killed and subjected to bursting pressure and histologic examinations. Results of in vitro study showed pretreatment cell viability to be 96% to 99% in both groups. Photodynamic therapy caused no significant change in fibroblast viability at all light doses. Results of in vivo studies showed that the mean bursting pressure of both groups dropped to a low peak on day 4. Subsequently there was a gradual increase in bursting pressure along the examined time points ( P <0.001). There was no difference in bursting pressure between the two groups for all time points examined. It was concluded that photodynamic therapy has no effect on viability of normal human fibroblasts and no adverse effects on healing of colonic anastomosis.

Diffraction light modulator based on transverse electro-optic effect in short-pitch ferroelectric liquid crystals

A diffraction modulator that exploits the transverse electro-optic effect in ferroelectric liquid crystals is proposed for applications in displays and in spatial light modulators. Experiments with a short-pitch ferroelectric liquid crystal aligned homeotropically show an achromatic contrast ratio of greater than 100:1 available with oblique readout. The sources of the contrast deterioration and the tolerance of the proposed scheme to this deterioration are analyzed. For selected directions of readout the light output obtains low sensitivity to the polarization of the readout light. Nonlaser light sources can be used in a practical display setup based on the proposed principle.

Photodynamic therapy of cancer of the esophagus using systemic aminolevulinic acid and a non-laser light source. A phase l/ll study

Institute of Gastroenterology and Department of Surgery A, Tel Aviv Sourasky Medical Center and the Sacker School of Medicine, Tel Aviv University, Tel Aviv, Israel

Evaluation of novel nonlaser light source for endometrial ablation using 5‐aminolevulinic acid

Background and Objective This research evaluated the effectiveness of a new nonlaser prototype short-arc lamp to achieve photodynamic ablation of endometrium in a rat. Study Design/Materials and Methods Thirty female Sprague-Dawley rats were divided into two groups. 5-Aminolevulinic acid (ALA), the precursor to the photosensitizer protoporphyrin IX, was injected into the left uterine horn and vehicle alone (Hyskon) was injected into the right horn of 23 rats (group 1). An additional seven rats received vehicle only into both uterine horns (group 2). Three hours later, a cylindrical diffusing optical fiber was inserted into the lumen of the uterine horns, and light treatment was delivered from either a laser or a nonlaser light source. Rats in group 1 received either 1 hour (n = 15) or 10 minutes (n = 8) of light treatment into both uterine horns. In rats in group 2, the left horn was exposed to 1 hour of light treatment. Uterine tissues were examined histologically 4 days after light treatment. Results One hour of light exposure to the uterine horns injected with ALA produced extensive necrosis of the rat uterine wall. No difference in the magnitude of destruction was seen between the groups treated with the laser and nonlaser light sources. Ten minutes of light exposure resulted in endometrial ablation that was comparable in both the laser- and the prototype-treated groups, but the destruction of the deepest layers of the uterine wall was more consistent in the group treated with the nonlaser prototype. One hour of light treatment from either light source did not result in any histological changes in the uterine horns not exposed to ALA. Conclusion The extent of endometrial ablation in the rat uterine horn achieved with the nonlaser prototype was comparable to that achieved with the laser. Thus, the nonlaser prototype may provide a less expensive approach to photodynamic endometrial ablation. Lasers Surg. Med. 25:315–322, 1999. © 1999 Wiley-Liss, Inc.

One-step two-dimensional rainbow-holographic technique with a nonlaser light source:?errata

On p. 1055 of Ref. 1, just above Eq. (1), the wavelength of the argon-ion laser should be 458 nm, not 4.58 nm. On p. 1056, in the third-to-last paragraph, the spectrum of the InGa lamp should be 320450 nm, not 3.24.5 nm.

One-step two-dimensional rainbow-holographic technique with a nonlaser light source

A technique for recording two-dimensional rainbow holograms by use of a nonlaser light source is described. Multicolor holograms are recorded in one step. The optical setup is lensless. The recording light source is an InGa lamp that provides a spectrum from UV to blue. The slit effect is generated by replication from the slit master plates.

A study of photobactericidal activity in the phenothiazinium series

The photodynamic antibacterial properties of a closely related series of commercially available phenothiazinium dyes were tested against a range of pathogenic strains of Gram-positive ( Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus) and Gram-negative organisms ( Escherichia coli, Pseudomonas aeruginosa). The photosensitisers were illuminated using a non-laser light source at a fluence of 1.75 mW cm −2 and this resulted in the enhancement of antibacterial activity in liquid culture. In several cases, illumination resulted in considerable decreases in the minimum lethal concentrations required, giving up to 100-fold increases in bactericidal activity.

A study of photobactericidal activity in the phenothiazinium series.

The photodynamic antibacterial properties of a closely related series of commercially available phenothiazinium dyes were tested against a range of pathogenic strains of Gram-positive (Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus) and Gram-negative organisms (Escherichia coli, Pseudomonas aeruginosa). The photosensitisers were illuminated using a non-laser light source at a fluence of 1.75 mW cm-2 and this resulted in the enhancement of antibacterial activity in liquid culture. In several cases, illumination resulted in considerable decreases in the minimum lethal concentrations required, giving up to 100-fold increases in bactericidal activity.

Confocal microscopy by aperture correlation

Most confocal microscopes do not produce images in real time with nonlaser light sources. The tandem scanning confocal microscope does produce such images but, because the pinhole apertures of the Nipkov disk must be placed far apart to reduce cross talk between neighboring pinholes, only 1% or less of the light available for imaging is used. We show that, by using aperture correlation techniques and relaxing the requirement to obtain a pure confocal image directly, one can obtain real-time confocal images with a dramatically increased (25% or even 50%) light budget.

Comparison of photodynamic therapy with cryotherapy in the treatment of Bowen's disease

The efficacy and suitability of photodynamic therapy (PDT) was compared with that of cryotherapy in the treatment of 40 lesions of Bowen's disease. Lesions were randomized to receive either cryotherapy with liquid nitrogen, or PDT using a portable desktop lamp incorporating a 300 W xenon short arc discharge source. A porphyrin precursor, 5-aminolaevulinic acid (5-ALA), was applied topically 4 h before irradiation in the PDT group. Each lesion received 125 J/cm2 at a fluence rate of 70 mW/cm2. All patients were reviewed at 2-monthly intervals and treatments repeated if required. Cryotherapy produced clearance in 10 of 20 lesions after one treatment, the remaining 10 lesions requiring two or three treatment applications. PDT resulted in clearance of 15 of 20 lesions after one treatment and of the remaining five lesions after a second treatment. The probability that a lesion cleared after one treatment was greater with PDT than cryotherapy (P < 0.01). Cryotherapy was associated with ulceration (five of 20), infection (two of 20) and recurrent disease (two of 20); no such complications occurred following PDT. PDT using a non-laser light source and topical 5-ALA appears to be at least as effective as cryotherapy in the treatment of Bowen's disease with fewer adverse effects.

Development of an alternative light source to lasers for photodynamic therapy: 3. Clinical evaluation in the treatment of pre-malignant non-melanoma skin cancer

The efficacy of a prototype non-laser light source for photodynamic therapy was assessed in clinical practice in the treatment of Bowen's disease and actinic keratoses. The light source, incorporating a 300 W short arc plasma discharge, was adjusted by appropriate filters to produce a bandwidth of 630±15 nm. Topical 5-aminolaevulinic acid was applied 4 h before irradiation to permit production within the lesion of the active photosensitizer, protoporphyrin IX. Individual lesions received 94–156 J cm−2. Twenty lesions of Bowen's disease and four actinic keratoses were treated in 12 patients. Patients were reviewed at monthly intervals and treatment repeated if residual disease was present. Clearance was achieved with a single treatment in 15 lesions and in all of the remaining nine lesions after a second treatment. The treatment was well tolerated, with pain absent or mild during treatment in 22 lesions, with only one lesion requiring local anaesthesia. Over the 10 days following treatment, no pain was associated with 21 treated lesions. During a 12 month follow-up period, two Bowen's disease lesions recurred. The overall complete response rate was 92%. Scarring was evident following PDT in only three lesions. Photodynamic therapy using this portable non-laser light source appears to be an effective and well-tolerated treatment for Bowen's disease and actinic keratoses.

Accumulated photon echoes by using a nonlaser light source

Accumulated photon echoes have been observed by use of a light-emitting diode. This is to our knowledge the first observation of photon echoes that are excited by a nonlaser light source. In the incoherent-light photon echo, the time resolution is equal to the inverse of the overall spectral width of the excitation light. Therefore we can easily get a high time resolution by using nonlaser light with a broad spectrum. Moreover the use of nonlaser light in the photon-echo experiment will extend the technique into wavelength regions where lasers are not currently available.