Laser cleaning of alumina particles on glass and silica substrates: Experiment and quasistatic model

Abstract

Silica and microscope slides that had been pretreated with a variety of wet chemical, ultrasonic and laser irradiation surface preparation methods were contaminated with alumina particles of around 3 μm. The samples were prepared and processed without delay so as to avoid capillary condensation in a high humidity environment and thus ensuring that the process is dry laser cleaning. They were then irradiated with a pulse of 248 nm radiation from a KrF excimer laser, over a range of fluences. The laser cleaning results show that, in this case, the surface preparation method appears to have little effect on the laser cleaning efficiency. They also demonstrate that the threshold fluence for particle removal of silica is approximately eight times higher than that for microscope slides, when so prepared. In contrast, application of Arnold et al.’s thermal expansion model of laser cleaning in the quasistatic limit to this material system predicts that the threshold fluence for silica will be about 15 times greater than that for glass. One possible explanation for this discrepancy may be that the particle’s absorptivity (0.16) is inaccurate. A value of 0.35 gives good agreement between theory and experiment.

Laser Grinding of Single-Crystal Silicon Wafer for Surface Finishing and Electrical Properties

“…The laser beam with high energy density is absorbed by the surface oxide layer, which forms a rapidly expanding plasma and produces shock wave. The shock wave causes the pollutants to fragment and be removed [ 19 ]. While the next step is laser melting due to thermal accumulation.…”

Pulsed laser cleaning: comparing science with art and cultural heritage applications

“…Figure 2 shows a bark painting of an eel mounted on a background plate which in turn is mounted on a computer controlled translation stage for laser treatment and which allows precise positioning for low magnification imaging (off-line). High resolution imaging is completed with the in-line optical microscopy unit in the foreground of fig.2, which has been described in [8][9][10][11]. …”

“…This will soon be augmented with a Nd:YAG laser system. The KrF laser system and in-line optical microscopy system used to record before and after images of micro-scale regions of interest has been described fully elsewhere [8][9][10][11][12][13][14][15][16][17][18]. The scale of most artifacts for processing in laser conservation is macroscopic, and the resolution of most interest is that of human vision.…”

“…All of our studies have measured the laser cleaning result affected by a single laser pulse. Excellent removal efficiencies of alumina particles (0.3µm -tens of microns) and silica/glass microspheres (0.3 µm ->100 µm) from various glass surfaces using (i) high beam quality UV-copper vapour lasers [3], (ii) a XeCl excimer laser [4][5][6] and (iii) a KrF excimer laser [7][8][9][10][11][12][13][14][15][16][17] have been obtained. Single-laser-pulse fluence of the order of a few hundred mJ/cm 2 is required for laser cleaning.…”

Cleaning of mildew on the optical lens with an economical and ordinary Diode laser

“…In order to improve optical transmittance of lenses, the makers of lenses usually deposit one or more layers of optical coating which is made up of inorganic or organic materials. [1]But they are difficult to clean in many industrial applied fields [2]. Due to humid and warm environment a variety of mildews would breed on these optical coatings.…”