Patent ID: 8371565

Claim:
A clamping device for clamping a substrate with a first surface and a second surface at opposite sides thereof, the clamping device comprising: a supporting plate comprising a base portion and an engaging portion, the base portion comprising a base surface, the engaging portion protruding from the base surface of the base portion and comprising an engaging surface facing away from the base surface, the supporting plate defining a through hole in the engaging surface for allowing light to pass therethrough, the supporting plate configured for supporting the substrate on the engaging surface of the engaging portion; and a plurality of clamping units configured for clamping the substrate on the supporting plate such that the engaging surface of the engaging portion is maintained substantially coplanar with the first surface of the substrate, each of the clamping units comprising: a top board; two pedestals extending from opposite ends of the top board, each of the two pedestals comprising a lateral surface, wherein the lateral surface of each of the two pedestals defines a through hole; two shafts attached to the respective pedestals, the shafts being respectively received in the through holes of the lateral surfaces of the two pedestals; and two torsional springs surrounding the respective shafts, the torsional springs each comprising a first end attached to the pedestal, and a second end attached to the engaging portion.