Optical inspector

摘要

An optical inspector includes a radiating source, a time varying beam reflector, a telecentric scan lens, a first and second lens, a field stop, and a detector. The radiating source irradiates a first position of on the time varying beam reflector with a source beam. The time varying beam reflector directs the source beam to the telecentric scan lens, which in turn directs the source beam to a sample. The first lens focuses scattered radiation from the sample to generate multiple scan lines at a first focal plane. The field stop is positioned at the first focal plane to block one or more scan lines at the first focal plane. The scan line not blocked by the field stop propagates to the second lens. The second lens de-scans the scan line and generates a point of scattered radiation at a second focal plane where the detector input is located.

主权项

1. An apparatus, comprising:
a time varying beam reflector; a radiating source that irradiates a first position of the time varying beam reflector; a waveplate that is positioned between the radiating source and the time varying beam reflector; a telecentric lens that directs the radiation reflected by the time varying beam reflector onto a sample, wherein the radiation reflected by the time varying beam reflector and directed by the telecentric scan lens produces a moving irradiated spot on the sample, wherein the irradiation of the sample causes scattered radiation to reflect from a top surface of the sample and a bottom surface of the sample; a first lens that receives scattered radiation from the sample, wherein the first lens is orientated at an oblique angle to the plane of incidence of the moving irradiated spot on the transparent sample; a field stop located at the focal plane of the first lens, wherein the field stop blocks a first portion of the scattered radiation, and wherein a majority of the first portion of scattered radiation is reflected from one surface of the sample; a de-scan lens located after the focal plane of the first lens that receives a second portion of the scattered radiation not blocked by the field stop; and a detector located at the focal plane of the de-scan lens.