不同湿度环境下可见光波段激光偏振特性研究

Laser polarization characteristics of visible light band in different humidity environments

雾霾天气严重干扰了可见光成像效果,利用可见光偏振特性可以有效提升探测效率。雾霾环境会受到气溶胶颗粒湿度的影响,湿度是雾霾环境重要物理参数。为了获得可见光在雾霾环境的偏振特性规律,分析了环境湿度对偏振特性的影响。在非偏振光气溶胶单粒子散射特性基础上,采用改进蒙特卡罗方法建立了偏振传输模型,对不同湿度水雾环境下可见波段偏振光传输特性进行研究,重点分析水雾环境湿度改变对不同可见光波段偏振光偏振特性的影响情况并建立了接近真实水雾环境,通过室内实验对偏振模型进行验证,对不同湿度环境下的450、532、671 nm线偏振光与圆偏振光的偏振度与偏振态改变进行了比较与分析,仿真模型置信度>60%。研究结果表明:偏振光的偏振度随水雾环境湿度是呈下降趋势。随着波长的增大,偏振度变化趋于平缓,出射偏振度随着波长的增加而变大,当激光波长为450、532、671 nm时,偏振度下降点的湿度值分别为50%、70%、90%;圆偏振光入射,圆偏振光的旋性对于偏振度没有影响,且高于线偏振度值。对于水雾这种容易受湿度影响较大的环境而言,在可见光波段,应该尽量选择较长波长的偏振光进行传输探测,因为湿度对较短波长的影响比较长波长的影响要大,所以,在湿度较大的环境中,较长波长的圆偏振光是偏振保持特性最好的。在湿度较大的环境中,应尽量选取波长较长的偏振光成像,以达到较好的成像效果。

Haze weather interferes with the visible light imaging effect,and the polarization characteristic of visible light can effectively improve the detection efficiency.Haze environment is affected by aerosol particle humidity,which is an important physical parameter of haze environment.In order to obtain the polarization characteristics of visible light in haze environment,the influence of humidity in haze environment on polarization characteristics was analyzed.Based on the single particle scattering characteristics of non-polarized light aerosol,the polarization transmission model was established by improved Monte Carlo method,research on transmission characteristics of polarized light in visible bands under different humidity and water mist was conducted,the influence of humidity change in water mist environment on polarization characteristics of polarized light in different visible bands was analyzed,and a near-real water mist environment was built.The polarization model was verified by laboratory experiments,the change of polarization degree and polarization state of linear polarized light on 450,532 and 671 nm was compared and analyzed under different humidity conditions,the confidence of simulation model was more than 60%.The results show that the polarization degree of polarized light decreases with the increase of humidity of water-fog environment.With the increase of the wavelength,the polarization tends to be flat,while the exit polarization degree increases with the increase of wavelength.The humidity values of the descending point of polarization degree are 50%,70%and 90%when the laser wavelengths are 450,532,671 nm,respectively.For water mist,which is easily affected by humidity,polarized light with longer wave length should be selected as far as possible for transmission detection in visible band.Because humidity has a greater influence on shorter wavelengths than longer wavelengths,circularly polarized light with longer wavelengths has the best polarization retention characteristics in environments with higher humidity.In the environment with high humidity,polarized light imaging with long wavelength should be selected as far as possible to achieve better imaging effect.