Patent ID: 7636164
Filing Date: 2009-12-22
Classification: G01N

Abstract:
1. A device for optically testing a zone of a specularly reflective or diffusely reflective surface of a substrate that is to be investigated, comprising: a field mirror having a substrate-side optical axis normal to the surface and a camera optical axis; at least one light source for providing bright-field illumination arranged on the camera-side optical axis, in the vicinity of the focal plane of the field mirror, that is imaged onto the zone that is to be investigated employing a telecentric optical train; and an electronic camera whose entrance pupil lies in the focal plane of the field mirror, on the camera-side optical axis, and receives part of the light emanating from the zone on the surface that is to be investigated via a telecentric optical train and transmits the images obtained to a processing device, wherein the field mirror has an aspheric, reflective surface, where the beam projected onto the surface under investigation at least covers just the zone that is to be investigated and where the camera-side optical axis is inclined at an angle of about 55° to 90° to the substrate-side optical axis and wherein a beam splitter that splits a central ray traveling along the camera-side optical axis into a transmitted ray and a ray reflected through 90° is arranged on the camera-side optical axis, and the camera is arranged on one of the pair of beam axes and the light source is arranged on the other beam axis.