LAUSR

Surface plasmon resonance imaging (SPRI) detects the changes in refractive index in close proximity to the surface of a thin metal film as variations in light intensity reflected from the back of the film and thus does not require labeling for visualization of the structures under investigation. While traditionally, the wave vector scanning is performed via angular rotations, the wave vector can also be scanned though tuning of the wavelength. Here we demonstrate that a combination of a non-monochromatic electrically tunable bandpass filter in conjunction with highly chromatically corrected imaging objectives can yield subcellular resolution for imaging of the interior refractive index of human mesenchymal stem cells.