Rinehart Matthew, Zhu Yizheng, Wax Adam
Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
Biomed Opt Express. 2012 May 1;3(5):958-65. doi: 10.1364/BOE.3.000958. Epub 2012 Apr 12.
Quantitative phase spectroscopy is presented as a novel method of measuring the wavelength-dependent refractive index of microscopic volumes. Light from a broadband source is filtered to an ~5 nm bandwidth and rapidly tuned across the visible spectrum in 1 nm increments by an acousto-optic tunable filter (AOTF). Quantitative phase images of semitransparent samples are recovered at each wavelength using off-axis interferometry and are processed to recover relative and absolute dispersion measurements. We demonstrate the utility of this approach by (i) spectrally averaging phase images to reduce coherent noise, (ii) measuring absorptive and dispersive features in microspheres, and (iii) quantifying bulk hemoglobin concentrations by absolute refractive index measurements. Considerations of using low coherence illumination and the extension of spectral techniques in quantitative phase measurements are discussed.
定量相位光谱法是一种测量微观体积的波长相关折射率的新方法。来自宽带光源的光被滤光至约5nm带宽，并通过声光可调滤光器（AOTF）以1nm增量在可见光谱范围内快速调谐。使用离轴干涉测量法在每个波长处恢复半透明样品的定量相位图像，并对其进行处理以恢复相对和绝对色散测量值。我们通过以下方式证明了该方法的实用性：（i）对相位图像进行光谱平均以降低相干噪声，（ii）测量微球中的吸收和色散特征，以及（iii）通过绝对折射率测量来量化总体血红蛋白浓度。讨论了使用低相干照明的注意事项以及光谱技术在定量相位测量中的扩展。
