Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19106.
Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland.
Health Phys. 2021 May 1;120(5):525-531. doi: 10.1097/HP.0000000000001376.
This study examines the nonuniform exposure to the cornea from incident millimeter waves at 94-100 GHz. Two previous studies measured temperature increases in the rhesus cornea exposed to brief (1-6 s) pulses of high-fluence millimeter waves (94 GHz), one of which also estimated thresholds for corneal damage (reported as ED50, the dose resulting in a visible lesion 50% of the time). Both studies noted large variations in the temperature increase across the surface of the cornea due to wave interference effects. This study examines this variability using high-resolution simulations of mm-wave absorption and temperature increase in the human cornea from exposures to plane wave energy at 100 GHz. Calculations are based on an earlier study. The simulations show that the peak temperature increases in the cornea from short exposures (up to 10 s) to high-intensity mm-wave pulses are 1.7-2.8 times the median increase depending on the polarization of the incident energy. A simple one-dimensional "baseline" model provides a good estimate of the median temperature increase in the cornea. Two different estimates are presented for the thresholds for producing thermal lesions, expressed in terms of the minimum fluence of incident 100 GHz pulses. The first estimate is based on thresholds for thermal damage from pulsed infrared energy, and the second is based on a thermal damage model. The mm-wave pulses presently considered far exceed current IEEE or ICNIRP exposure limits but may be produced by some nonlethal weapons systems. Interference effects due to wave reflections from structures in and near the eye result in highly localized variations in energy absorbed in the cornea and surrounding facial tissues and are important to consider in a hazard analysis for exposures to intense pulsed millimeter waves.
本研究考察了在 94-100GHz 的入射毫米波下角膜的非均匀暴露情况。两项先前的研究测量了短暂（1-6 秒）高能量毫米波脉冲照射下恒河猴角膜的温升，其中一项还估计了角膜损伤的阈值（报告为 ED50，即导致 50%时间可见损伤的剂量）。这两项研究都注意到由于波干涉效应，角膜表面的温升存在很大差异。本研究使用 100GHz 平面波能量照射人眼角膜的毫米波吸收和温升的高分辨率模拟来研究这种可变性。计算基于早期的一项研究。模拟结果表明，从短时间（最长 10 秒）暴露于高强度毫米波脉冲，角膜的峰值温升比中位数温升高 1.7-2.8 倍，这取决于入射能量的极化。简单的一维“基线”模型可以很好地估计角膜的中值温升。提出了两种不同的方法来估计产生热损伤的阈值，以入射 100GHz 脉冲的最小能量表示。第一种估计方法基于脉冲红外能量的热损伤阈值，第二种估计方法基于热损伤模型。目前考虑的毫米波脉冲远远超过了当前 IEEE 或 ICNIRP 的暴露限制，但可能由某些非致命武器系统产生。由于眼睛内和周围结构的波反射引起的干涉效应导致角膜和周围面部组织吸收的能量高度局部化变化，在对高强度脉冲毫米波的暴露进行危害分析时需要考虑这些变化。
