Microperforation with Laser Beam in the Preparation of Microelectrodes

Using a laser beam, spot perforations have been made in the vinyl lacquer insulation of tungsten microelectrodes. To develop the method, the effect of the diffraction of the laser beam on the diameter of the burning point and of the geometric and diffractive conditions in the focusing of the beam have been examined, taking into account the small diameter of the electrode (about 10-15 ¿m) and the thinness of the insulating layer. Using the burning method described here, it has been possible to decrease the effective divergence angle of the laser beam so that the diameters of the holes which are formed on the electrode are mostly 2 ¿m or less. The burning point of the laser beam can be localized with the developed optical method to a desired point on the electrode. The perforation has been performed in saline immersion-liquid to protect the objective and to test immediately formed holes electrolytically. The burning apparatus and method have been explained.