Temperature profile measurements of near-field optical microscopy fiber tips by means of sub-micronic thermocouple

• Published in: International journal of thermal sciences Vol. 39; no. 4; pp. 519 - 525
• Main Authors: Thiery, Laurent, Marini, Nathalie, Prenel, Jean-Pierre, Spajer, Michel, Bainier, Claudine, Courjon, Daniel
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Paris Elsevier Masson SAS 2000; Elsevier
• Subjects: Exact sciences and technology; fiber tips; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; micro-thermocouple; microscopy; near-field; Near-field scanning optical microscopes; optical fiber; Physics; Scanning probe microscopes, components and techniques; temperature; temperature; optical fiber; fiber tips; microscopy; near-field; micro-thermocouple; Optical fibers; Temperature measurement; Microscope tips; Thermocouples; Measuring methods; Experimental study; Scanning near field optical microscopy
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/S1290-0729(00)00231-3

The present paper deals with the experimental measurement of temperature along various shapes of fiber tips used as near-field optical microscope probes. An ultra-small thermoelectric couple makes it possible to detect the tip temperature as far as the junction dimension remains smaller than the local investigated area. The couple is a 0.5 μm Pt and Pt–Rh 10 % welded wires, whose dynamic and dimensional characteristics allow the investigation of the thermal behaviors of tapers under steady-state and periodic excitation modes (bandwidth near 1 kHz). Temperature profiles along these fiber tips (up to 400 μm from the apex) are shown and discussed. Confirming some authors' results, dramatic temperature increases due to an internal heating can occur for some configurations. Such temperatures can play a key role in the imaging process, because of the resulting behaviors of the apex, mainly due to its thermal expansion. Indeed, variation of the aperture diameter and thermoelastic interaction with the sample surface could explain some artefacts in the resulting images.