Patent ID: 8830456

Claim:
An apparatus, comprising: a time varying beam reflector, wherein the time varying beam reflector is a rotating polygon; a radiating source that irradiates a first position on the time varying beam reflector with source radiation, wherein the radiating source is a laser; a telecentric scan lens that directs the source radiation from the time varying beam reflector onto a sample; a separating mirror that is irradiated by a first portion of reflected radiation from the sample; a first detector that is irradiated by the first portion of the reflected radiation reflected by the separating mirror, wherein the first detector generates a sum signal indicating total reflectivity of the sample and a difference signal indicating surface slope of the sample; and a second detector that receives a second portion of reflected radiation, wherein the second portion of the reflected radiation does not irradiate the separating mirror, and wherein the second detector generates a signal indicating intensity of the second portion of the reflected radiation.