Abstract: Scattered radiation from a sample surface is collected by means of a collector that collects radiation substantially symmetrically about a line normal to the surface. The collected radiation is directed to channels at different azimuthal angles so that information related to relative azimuthal positions of the collected scattered radiation about the line is preserved. The collected radiation is converted into respective signals representative of radiation scattered at different azimuthal angles about the line. The presence and/or characteristics of anomalies are determined from the signals. Alternatively, the radiation collected by the collector may be filtered by means of a spatial filter having an annular gap of an angle related to the angular separation of expected pattern scattering. Signals obtained from the narrow and wide collection channels may be compared to distinguish between micro-scratches and particles.

Abstract: Scattered radiation from a sample surface is collected by means of a collector that collects radiation substantially symmetrically about a line normal to the surface. The collected radiation is directed to channels at different azimuthal angles so that information related to relative azimuthal positions of the collected scattered radiation about the line is preserved. The collected radiation is converted into respective signals representative of radiation scattered at different azimuthal angles about the line. The presence and/or characteristics of anomalies are determined from the signals. Alternatively, the radiation collected by the collector may be filtered by means of a spatial filter having an annular gap of an angle related to the angular separation of expected pattern scattering. Signals obtained from the narrow and wide collection channels may be compared to distinguish between micro-scratches and particles.

Abstract: Scattered radiation from a sample surface is collected by means of a collector that collects radiation substantially symmetrically about a line normal to the surface. The collected radiation is directed to channels at different azimuthal angles so that information related to relative azimuthal positions of the collected scattered radiation about the line is preserved. The collected radiation is converted into respective signals representative of radiation scattered at different azimuthal angles about the line. The presence and/or characteristics of anomalies are determined from the signals. Alternatively, the radiation collected by the collector may be filtered by means of a spatial filter having an annular gap of an angle related to the angular separation of expected pattern scattering. Signals obtained from the narrow and wide collection channels may be compared to distinguish between micro-scratches and particles.

Abstract: Scattered radiation from a sample surface is collected by means of a collector that collects radiation substantially symmetrically about a line normal to the surface. The collected radiation is directed to channels at different azimuthal angles so that information related to relative azimuthal positions of the collected scattered radiation about the line is preserved. The collected radiation is converted into respective signals representative of radiation scattered at different azimuthal angles about the line. The presence and/or characteristics of anomalies are determined from the signals. Alternatively, the radiation collected by the collector may be filtered by means of a spatial filter having an annular gap of an angle related to the angular separation of expected pattern scattering. Signals obtained from the narrow and wide collection channels may be compared to distinguish between micro-scratches and particles.