npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041


Research Paper

New Physics: Sae Mulli 2015; 65: 757-762

Published online August 31, 2015

Copyright © New Physics: Sae Mulli.

Measurement of the Thermal Lens Effect in Liquid Samples

액체시료에서의 열렌즈 효과 측정

Hyunki KIM, Jaeran LEE, Sok Won KIM*

Department of Physics, University of Ulsan, Ulsan 680-749, Korea


Received: April 30, 2015; Revised: June 8, 2015; Accepted: June 12, 2015

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


When a high-power laser beam is focused into an absorbing medium, the medium is locally expanded. The phenomenon of the changing angle of convergence and divergence according to changes in the refraction of light caused by the variation in the density in the expanded region is called the thermal lens effect. The measurement methods for the thermal lens effect can be divided into a single-beam method and a dual-beam method that uses pump and probe beams. In this study, the thermal lens effect in liquids such as ethanol and methanol was measured by using a single-beam method. A Nd:YVO$_{4}$ laser beam was used as the light source, and the intensity variation of the beam transmitted through the cell that contained liquid samples was measured by using several lenses with different focal lengths as the cell was moved $\pm$3.0 cm from the focal point. The result showed that the thermal lens effect was clearly produced in ethanol and methanol that the effects for both liquids were quite similar.

Keywords: Thermal lens, Thermal expansion, Z-scan

강한 레이저 빔이 흡수 매질 내에서 집속되면 매질이 부분적으로 팽창된다. 팽창된 부분의 밀도 변화로 인해 집속되었던 빔의 진행 경로가 굴절되어 빔의 수렴각과 발산각이 달라지는 현상을 열렌즈 효과라고 한다. 열렌즈 효과를 측정하는 방법은 단일 레이저 광을 사용하는 방법과 펌프-프로브 빔을 사용하는 이중 빔 방법으로 구분할 수 있다. 본 연구에서는 단일 빔 방법을 사용하여 에탄올과 메탄올에서의 열렌즈 효과를 측정하였다. 광원으로는 Nd:YVO$_{4}$ 레이저를 사용하였고, 렌즈의 초점거리를 5$\sim$20 cm까지 변화시키며 시료를 담은 셀을 렌즈의 초점으로부터 $\pm$ 3.0 cm 지점까지 이동시켜가며 빔을 통과하는 광의 세기변화를 측정하였다. 실험결과 에탄올과 메탄올에서 뚜렷한 열렌즈 효과가 유사하게 발생함을 확인할 수 있었다.

Keywords: 열렌즈 효과, 열확산, 제트-스캔

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