Abstract: The method of evaluating an optical defect in a transparent material includes irradiating the material with light to produce scattered light from the defect, rotating the material about a rotation axis passing through the defect, measuring scattered light intensity at a scattering angle (?s) to the rotation axis by means of a detector, determining the dependence of the measured scattered light intensity on rotation angle (?s) around the rotation axis and characterizing size and/or shape of the defect from that dependence. The apparatus for performing the method has a light source, a rotatable holder for the transparent material, a light sensitive receiving device and an imaging optical system for imaging scattered light from the material within a certain angular range on a detector surface of the receiving device.

Abstract: The present invention relates to a method and a device for quantitative determination of the optical quality of a transparent material. In the method, a light beam is incident on the sample made of the transparent material, in order to form a scattering volume in the sample, wherein light scattered in the scattering volume at a predefined scattering angle (?s) is imaged on a light-sensitive element and wherein signals of the light-sensitive element are integrated or added up over at least a portion of the scattering volume in order to determine a measured value representing the optical quality of the transparent material of the sample. Signal contributions which do not originate from scattering of the incident light beam at the light entry or light exit surfaces of the sample are used exclusively to determine the measured variable.