Abstract: In a process for determining the focussing of a photolithographic apparatus on a resist-coated wafer, comprising the following steps: 1) insolating, successively in various places, the resist by a test pattern, a different focussing being carried out for each insolation; 2) developing the resist; 3) observing the wafer for determing the optimal insolation and adopting the corresponding setting for the apparatus, it is provided, between steps 2) and 3), the step consisting in heating the wafer up to a temperature higher than the vitreous transition temperature of the resist.

Abstract: A gastight dynamic seal sealing the pressurized enclosure of a compressed-gas circuit interrupter to a rotatable through control shaft. Radial partition walls of a sleeve surrounding the shaft define a plurality of liquid-filled gas-trap chambers separated by small throttle passageways causing the gas leaking through elastomer joints disposed in some of said chambers to be dissolved in the liquid in degressive concentration, going from the pressurized side of the seal towards the atmospheric side thereof.