光谱仪测量窄带宽光源光谱分布的七点修正法

针对光谱仪在测量窄带宽光源的光谱分布时出现的光谱变形现象，提出了一种带宽修正方法—七点修正方法。首先，利用泰勒级数和相关的导数公式，得到了七点修正公式的数学解析式;其次，用光谱线型为正弦函数的模拟光谱对七点修正法进行验证，采用正弦函数来模拟真实光谱，通过光谱仪的带宽函数计算出测量值，然后应用七点修正公式，对测量值进行修正;最后利用中心波长为365 nm的LED光源对七点修正法进行了实验验证，用双光栅单色仪来测量LED光源的光谱辐射照度，光谱仪带宽分别选为5与0.5 nm，将七点修正公式应用于测量值，得到修正值。模拟结果表明： 在选定的模拟条件下，修正后得到的中心波长处的峰值可以达到真实值的99%以上;实验结果表明： 修正后中心波长处的峰值可以达到真实值的95%以上。由模拟结果和实验结果可知，七点修正法与三点修正法和五点修正法相比，修正效果有明显提升，这种带宽修正方法可以广泛应用在光谱测量领域。

Seven-Point Correction Approach for Spectrum Measurement of Light Source with a Narrow Bandwidth

The finite bandwidth of spectroradiometers always causes significant errors when the measured light source has a nar ‐row bandwidth compared to that of spectroradiometers .In order to solve this problem ,an improved correction approach which is called seven‐point correction approach is proposed .Firstly ,the seven‐point correction formula is obtained with Taylor’s series and related derivative formula .Secondly ,the effect of seven‐point formula is validated through a simulated spectrum with a sine function shape .Considering the sine function as true spectrum ,we calculate the measured spectrum with the bandpass function of spectroradiometers .We also correct the measured spectrum with the seven‐point formula .At last ,we validate the seven‐point formula experimentally with a LED lamp whose center wavelength is 365 nm . Using a double grating monochromator ,we measure the irradiance of LED lamp when the bandwidth of spectroradiometer is 5 and 0.5 nm .We also obtain the corrected spectrum by applying seven‐point formula to measured spectrum .The simulated results show that ,the corrected value at the center wavelength could be above 99% of the true value .The experimental results show that ,the corrected value at the center wavelength could reach above 95% of the true value .Above all ,the proposed seven‐point approach has an improved correction effect compared with three‐point and five point approach .This correction approach could be widely applied in the field of spec‐trum measurement .