TY - JOUR

T1 - Laser calorimetric absorptance testing of samples with varying geometry

AU - Balasa, Istvan

AU - Jensen, Lars O.

AU - Ristau, Detlev

PY - 2014/7/1

Y1 - 2014/7/1

N2 - Laser calorimetry is based on the measurement and evaluation of the temperature increase caused by absorption in the sample exposed to laser radiation. A temperature distribution develops in the irradiated sample as a result of dependence on the thermal diffusivity of the sample. Therefore, finding a correlation between the temperature increase and absorption becomes a complex task. This challenge was met by keeping the sample geometry at a standard size and simulating the thermal distribution for a number of optical materials. Using this method, Laser Zentrum Hannover e.V. (LZH) developed a calorimetric test setup that offers fully calibrated absorptance values for sample diameters of 25 mm (or 1 in.) with a total error of below 13% and a relative measurement error of below 5%. However, this technique is limited to the above-mentioned sample geometry. This work presents an approach to adjust the measurement configuration to numerous sample sizes for standard circular laser components. Finite element analysis and experimental verification are presented for exemplary values of the samples' diameters. Based on the different sample mount concept, this procedure allows utilizing flexibility in test wavelength and angle of incidence, combined with the sensitivity level sufficient for current optical materials.

AB - Laser calorimetry is based on the measurement and evaluation of the temperature increase caused by absorption in the sample exposed to laser radiation. A temperature distribution develops in the irradiated sample as a result of dependence on the thermal diffusivity of the sample. Therefore, finding a correlation between the temperature increase and absorption becomes a complex task. This challenge was met by keeping the sample geometry at a standard size and simulating the thermal distribution for a number of optical materials. Using this method, Laser Zentrum Hannover e.V. (LZH) developed a calorimetric test setup that offers fully calibrated absorptance values for sample diameters of 25 mm (or 1 in.) with a total error of below 13% and a relative measurement error of below 5%. However, this technique is limited to the above-mentioned sample geometry. This work presents an approach to adjust the measurement configuration to numerous sample sizes for standard circular laser components. Finite element analysis and experimental verification are presented for exemplary values of the samples' diameters. Based on the different sample mount concept, this procedure allows utilizing flexibility in test wavelength and angle of incidence, combined with the sensitivity level sufficient for current optical materials.

KW - absorption

KW - contamination

KW - high power laser

KW - laser calorimetry

KW - metrology

KW - optical thin films

KW - substrates

KW - ultrafast laser optics

UR - http://www.scopus.com/inward/record.url?scp=84940258703&partnerID=8YFLogxK

U2 - 10.1117/1.oe.53.12.122503

DO - 10.1117/1.oe.53.12.122503

M3 - Article

AN - SCOPUS:84940258703

VL - 53

JO - Optical Engineering

JF - Optical Engineering

SN - 0091-3286

IS - 12

M1 - 122503

ER -