AN APPARATUS AND METHOD FOR INVESTIGATING A SAMPLE

摘要

An apparatus and method for investigating a sample, the apparatus comprising: means (61) for irradiating the sample (21) with a first beam of electromagnetic radiation configured to excite an optically non-linear process within the sample; means (61) for irradiating the sample with a second beam of electromagnetic radiation; and a detector (41) for detecting a change the second beam after it has been reflected from or transmitted through the sample. If the optically non-linear process is a second order process, the detector could be used to detect a change in the polarisation of the second beam. Apparatus and method find application of samples with terahertz (THZ) radiation locally generated and detected within the sample.