Method for examination of a sample by means of the lock-in thermography

US10761039B2 · kind B2 · utility

Assignee

• DCG Systems, Inc. · US

Inventors

• Hans Heissenstein · Ebermannstadt, DE
• Peter Stolz · Fürth, DE
• Raiko Meinhardt-Wildegger · Erlangen, DE

Key dates

• Filing date: Jun 3, 2015
• Grant date: Sep 1, 2020
• Expiry date: Jun 3, 2035

Classification

• Technology area (CPC G): Physics
• CPC primary: G01J2005/0077
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Method for a non-destructive and image forming examination of a sample (1) by means of a heat flow thermography method where the examination consists of evaluating the presence of any gradients in heat flow velocity at respective depth distances from a surface of the sample (1), comprising exciting the sample (1) by means of periodic heat pulses P1 from at least one excitation source, and capturing thermal image sequences of a thermal flow originating from the heat pulses by at least one infrared camera (5), implementing relative time delays Δt between a starting point of imaging of the respective image sequences and a starting point of the periodic excitation, combining all captured image sequences to a resulting image sequence in which all images are arranged in a correct time sequence, and extracting from the resulting image sequence an indication of the existence and depth distance of a heat flow velocity transition from a surface of the sample. Exciting the sample (1) comprises applying heat pulses to the sample with a lock-in frequency equal to or higher than one fourth of the imaging frequency of the camera for exciting the sample (1), controlling an excitation period of the…