Fast Screening System

Certain applications in quality control and process monitoring that require no spectral information, but call for terahertz intensity measurements at “extreme” speeds. The combination of a femtosecond fiber laser, a pulsed terahertz emitter and a high-bandwidth Schottky receiver yields a setup capable of detecting individual terahertz pulses, even at repetition rates as high as 100 MHz. To handle this immense data stream, a data-processing unit converts the pulses to RMS values, producing terahertz intensity readings at sampling rates up to 500 kHz – orders of magnitude faster than any conventional terahertz system.

In a way, the system represents the world’s fastest single-pixel terahertz camera. In order to generate a terahertz transmission or reflection image, one can complement the system with fast beam-steering optics. In another application scenario, the samples themselves move – e.g. on a fast conveyor belt, or as part of a papermaking machine. In this use case, emitter and receiver remain static, and the data stream yields line scans with high spatial resolution, even for sample velocities beyond 100 m/s.