Abstract: The knowledge and data of optical properties of skin tissue are critical for optical diagnosis of dermatosis and laser dermatology.In the wavelengths of visible- and near-infrared region, the major chromorphore for light absorption in human skin is the red cells in blood.This paper presents an experimental investigation for the effect of temperature on the optical absorption of human blood.A testing system was setup for measuring the optical absorption of human blood.In experiments, the human blood was slowly heated in a water bath from room temperature to 80℃ at a heating rate of about 0.5—1.0℃·min^-1 and the blood absorption spectra were recorded every 5℃ of increase in the blood temperature for a wavelength range of 400—1000 nm.The results at the room temperature captured three major absorption peaks well known in literature, demonstrating the validity of the system.A strong dynamic variation of the blood optical absorption characteristics with temperature has been observed, showing four different patterns of change:(1) small change when the temperature is below 50℃;(2) disappearance of selectivity of the blood absorption with wavelength at 50—58℃;(3) a dramatic increase of the absorption over the most of region at 58—65℃;(4) little change when higher than 65℃.An absorption peak is observed over the wavelength from 800 nm to 1060 nm, though the peak is fairly small and broadened significantly.Such an absorption peak in the near-infrared region may lead to the development of new lasers of long wavelength with deep penetration into the skin.

Key words: blood, methemoglobin, absorbance, spectrum

摘要： 人体病变组织的光热效应是皮肤病激光疗法与光学诊断的基础,深入理解血液光吸收特性随温度变化的动态规律对利用激光来治疗葡萄酒色斑(PWS)等血管性疾病具有重要意义。设计并搭建了血液动态吸收光谱实验测量系统,利用常温水浴将血液样品缓慢加热至80℃(0.5～1.0℃·min^-1),每间隔5℃为单位对血液的光吸收特性进行测量,得到了血液在可见光及近红外范围400～1000 nm内随温度变化的动态吸收光谱。实验结果表明,加热过程中血液光吸收特性变化可分为4个阶段:常温至50℃血液吸收光谱基本无变化;50～58℃吸收特性曲线变平缓, 630 nm处吸光度增加为常温下的2倍;随着温度的进一步上升,血液光吸收特性大幅度增加;65℃后略有增加直至不再变化。整个加热过程中,血液吸光度均在970 nm处存在峰值,并且吸收性能随着温度的上升有所增加,这为今后使用该波段治疗较深的顽固病变血管奠定了坚实的基础。

关键词: 血液, 正铁血红蛋白, 吸光度, 光谱