基于干涉条纹的光谱仪光谱标定方法研究

为了在光学相干层析(optical coherence tomography,OCT)系统中实现快速精准标定光谱仪的光谱带宽和确定光谱横坐标的变化规律,提出了用干涉条纹标定光谱带宽和确定波长非线性分布规律,从而实现了光谱仪光谱标定。先用单频激光确定了某一特定波长在CCD中像素点位置,然后根据光程差与干涉光谱周期数之间的关系确定了光谱仪的光谱带宽范围;再运用多项式函数拟合干涉光谱,将光谱强度平滑处理并对干涉条纹的峰值间距做了插值处理。根据峰值间距与波数的比例关系,确定了波长在横坐标的分布规律。两个对照实验结果表明,运用该方法标定的光谱带宽误差在±0.15 nm以内,标定误差优于传统汞灯等标定方法。研究结果表明:光谱横坐标校正后明显提高了系统分辨率和信噪比,因此验证该标定方法是可行的。

Spectral calibration of spectrometer based on interference fringes

In order to get fast and accurate calibration of spectrometer spectral bandwidth and to determine its spectral abscissa, in optical coherence tomography ( OCT) system, a method for calibrating spectral bandwidth and determining the nonlinear distribution law of the wave-length by interference fringes, was proposed. A single-frequency laser was employed to determine the CCD pixel position of the specific wave-length. Subsequently, according to the relationship between optical path differences and the number of interference fringe cycles, the band-width of a spectrometer was determined. Polynomial function was used to fit the interference fringes. After that, spectral intensity was smoothed and peak pitches were interpolated. Distribution disciplines of the wavelength in the abscissa was determined according to the rela-tionship between the peak pitches and the wavenumber. Two comparative tests show that the spectral bandwidth calibration error is about ± 0. 15 nm. The calibration error is better than the traditional calibration method using mercury lamp. The results indicate that the resolution and the signal-to-noise ratio of the OCT system could be greatly improved after the wavelength calibration. Hence, the feasibility of this pro-posed method for spectral calibration is verified.