Hyperspectral Raman Microscopic Imaging Using Powell Lens Line Illumination

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Abstract
The design and characterization of a simple and robust hyperspectral Raman line imaging illumination system with the use of a Powell lens is reported. The generated line uniformity is ±5% of total intensity with a laser power density of 12 mW/μm2 at the sample with a 50×/0.8 NA (numerical aperture) objective. Similar results were obtained by using other objectives. Linewidths remained near the diffraction limit for all objectives tested. Significant decreases in image acquisition time are also reported with the use of a Powell lens-illuminated hyperspectral Raman line imaging microscope equipped with an intensified charge-coupled device (CCD) detector. Hyperspectral images (100 × 350 pixels) were acquired in as little as 8 with a corresponding signal-to-noise ratio of 24.