ENHANCED HIGH-SPEED LOGARITHMIC PHOTO-DETECTOR FOR SPOT SCANNING SYSTEM

• Main Authors: DONDERS PAUL, MACKAY DEREK, CAO KAI, SULLIVAN JAMIE, CHEN GRACE, WOLF RALPH
• Format: Patent
• Language: English; Korean
• Published: 25.07.2014
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; SEMICONDUCTOR DEVICES; TESTING

Disclosed are apparatus and methods for inspecting or measuring a specimen. An incident beam is directed across a plurality of consecutive scan portions of a specimen so that an output beam profile from each scan portion is consecutively collected by a photomultiplier tube (PMT), and the scan portions include at least one or more first scan portions and a next scan portion that is scanned after the one or more first scan portions. After or while the incident beam is directed to the one or more first scan portions of the specimen, an output signal for each first scan portion is obtained based on the output beam profile that is collected by the PMT for each first scan portion. An expected output beam profile for the next scan portion is determined based on the output signal that is obtained for each one or more first scan portions. As the incident beam is directed towards the next scan portion, a gain input to the PMT for the next scan portion is set based on the expected output beam profile so that the gain for such next scan portion results in a measured signal at the PMT that is within a predefined specification of the PMT or other hardware components that receive a measured signal from the PMT.