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High Resolution Laser Beam Profiler

IP.com Disclosure Number: IPCOM000039862D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Taubenblatt, MA: AUTHOR

Abstract

A sub-micron-sized thermocouple probe can be used to obtain a laser beam intensity profile with comparable resolution. Optical diagnostics of focused laser beams, near field optical intensities and optical fiber characteristics at a cleavage plane, are all able to be obtained using this profiler. The technique uses a thermocouple probe of small dimensions (junction area less than 0.5 mm). Light impinging on the junction is absorbed, converted to thermal energy and to a corresponding voltage by the thermocouple probe. The chopped beam produces a modulated signal which is detected by a lock-in amplifier. The probe may scan in three dimensions by using piezoelectric motion stages, to obtain the spatially resolved intensity of the focused beam.

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High Resolution Laser Beam Profiler

A sub-micron-sized thermocouple probe can be used to obtain a laser beam intensity profile with comparable resolution. Optical diagnostics of focused laser beams, near field optical intensities and optical fiber characteristics at a cleavage plane, are all able to be obtained using this profiler. The technique uses a thermocouple probe of small dimensions (junction area less than 0.5 mm). Light impinging on the junction is absorbed, converted to thermal energy and to a corresponding voltage by the thermocouple probe. The chopped beam produces a modulated signal which is detected by a lock-in amplifier. The probe may scan in three dimensions by using piezoelectric motion stages, to obtain the spatially resolved intensity of the focused beam. The spatial resolution of the technique derives from the small physical size of the probe, and from the fact that the incident radiation will illuminate mainly the end of the probe where the area is the smallest. This is especially true in the focal plane of the beam or for the beam slightly diverging, because the probe tip will then shadow the remaining portion of the sensitive area of the probe. In some cases, degradation of the resolution will occur due to the conduction of heat from other parts of the probe. This can be reduced by going to higher modulation frequencies. The sensitivity of the probe can be increased by coating with a more absorbing layer. Additional care with regard to no...