Patent ID: 7604439

Claim:
A method for focusing an optical inspection device on a facing surface of a substantially flat object, the method comprising: supporting the substantially flat object over a platform having a plurality of pressure outlets and a plurality of fluid-evacuation channels, wherein the pressure outlets are connected each through a pressure flow restrictor to a high-pressure manifold which is connected through a main supply pipeline to a pressurized fluid supply, wherein the plurality of fluid-evacuation channels are connected to a low-pressure manifold which is connected through a main evacuation pipeline to a low pressure source, and wherein at least one pressure control valve is provided to regulate the pressure level of at least one of the manifolds; changing the volume of at least one manifold; and regulating the pressure level of at least one of the manifolds to adjust a gap between the platform and the object so as to focus the optical inspection device on the facing surface of the object.