Colorado State University, Department of Environmental and Radiological Health Sciences, Fort Collins, Colorado 80523, USA.
J Biomed Opt. 2010 Jul-Aug;15(4):045007. doi: 10.1117/1.3477324.
Human perception of 2.0-microm infrared laser irradiation has become significant in such disparate fields as law enforcement, neuroscience, and pain research. Several recent studies have found damage thresholds for single-pulse and continuous wave irradiations at this wavelength. However, the only publication using multiple-pulse irradiations was investigating the cornea rather than skin. Literature has claimed that the 2.0-microm light characteristic thermal diffusion time was as long as 300-ms. Irradiating the skin with 2.0-microm lasers to produce sensation should follow published recommendations to use pulses on the order of 10 to 100 ms, which approach the theoretical thermal diffusion time. Therefore, investigation of the heating of skin for a variety of laser pulse combinations was undertaken. Temperatures of ex vivo pig skin were measured at the surface and at three depths from pulse sequences of six different duty factors. Differences were found in temperature rise per unit exposure that did not follow a linear relation to duty factor. The differences can be explained by significant heat conduction during the pulses. Therefore, the common heat modeling assumption of thermal confinement during a pulse may need to be experimentally verified if the pulse approaches the theoretical thermal confinement time.
人类对 2.0 微米红外激光辐射的感知在执法、神经科学和疼痛研究等截然不同的领域变得非常重要。最近的几项研究已经发现了这种波长下单次脉冲和连续波辐照的损伤阈值。然而，唯一使用多脉冲辐照的出版物是在研究角膜而不是皮肤。文献声称，2.0 微米光的特征热扩散时间长达 300 毫秒。用 2.0 微米激光辐照皮肤以产生感觉应该遵循使用 10 到 100 毫秒量级脉冲的已发表建议，这接近理论热扩散时间。因此，对各种激光脉冲组合的皮肤加热进行了研究。从六个不同占空比的脉冲序列测量了离体猪皮表面和三个深度处的温度。发现温升与占空比之间没有遵循线性关系的单位暴露差异。这种差异可以通过脉冲期间的显著热传导来解释。因此，如果脉冲接近理论热限制时间，则可能需要通过实验来验证热限制期间的常见热建模假设。
