尘埃粒子计数器中光源对传感器光通量的影响分析

Influence of the Light Source in Airborne Laser Particle Counter on the Flux of Transducer

在Mie散射理论基础上,由单分散射的光强表达式导出在偏振光的入射条件下一定立体角内的散射光通量的表达式,并与自然光入射作比较。计算了在相同强度不同光源入射下,尘埃粒子计数器的两种常用散射光收集系统收集的散射光通量。结果表明:采用近前向散射光收集系统得到的光通量相等;而采用直角方向散射光收集系统时两者并不相等,且在平面偏振光入射时,收集的散射光通量还跟探测器中心与入射光偏振方向夹角有关。用MATLAB编程计算,得出了在探测器中心与偏振方向的夹角成90°或270°位置时,收集的散射光通量有极值的结论,为激光尘埃计数器传感器光学设计提供了依据。

Based on the Mie scattering theory, a formula to calculate the scattered light flux in a certain solid angle under the condition of polarized light input is derived form the formula for calculating scattered light intensity. The results are compared with the condition illuminated by a unpolarized light. The scattered light flux collected by the two common scattered light collecting systems of the airborne particle counter is calculated under the condition of different light sources but same light intensity. The result shows that the fluxe got by the near-forward scattered light collecting system is equal. On the contrary, with the right angle scattered light collecting system, they are not equal and with the lineary polarized light input, the collected light flux is related to the angle between the center of detector and the direction of polarization. Calculating results, based on MATLAB and worked out by the computer,indicate that the collected scattering light flux has extreme when the angle between the center of detector and the direction of polarization is 90°or 270°. The results may provide a reference for designing the transducer of airborne laser particle counter.