Photothermal camera port accessory for microscopic thermal diffusivity imaging

ZALDÍVAR ESCOLA FACUNDO; DARÍO KUNIK; NÉLIDA MINGOLO; OSCAR E. MARTÍNEZ

OPTICAL ENGINEERING

SPIE-SOC PHOTOPTICAL INSTRUMENTATION ENGINEERS

Año: 2016 vol. 55 p. 1 - 10

0091-3286

Abstract. The design of a scanning photothermal accessory is presented, which can be attached to the cameraport of commercial microscopes to measure thermal diffusivity maps with micrometer resolution. The device isbased on the thermal expansion recovery technique, which measures the defocusing of a probe beam due to thecurvature induced by the local heat delivered by a focused pump beam. The beam delivery and collecting opticsare built using optical fiber technology, resulting in a robust optical system that provides collinear pump andprobe beams without any alignment adjustment necessary. The quasiconfocal configuration for the signal collectionusing the same optical fiber sets very restrictive conditions on the positioning and alignment of the opticalcomponents of the scanning unit, and a detailed discussion of the design equations is presented. The alignmentprocedure is carefully described, resulting in a system so robust and stable that no further alignment is necessaryfor the day-to-day use, becoming a tool that can be used for routine quality control, operated by a trained technician.© 2016 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.OE.55.6.064110]