Orthogonal Polarization Spectral (OPS) Imaging represents a major innovation over conventional intravital microscopy because of its portability and elimination of the need for special preparations. Here's how it works:

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1. Light from a source is converted to a wavelength of 550 nanometers, the isobestic point for hemoglobin. Hemoglobin becomes the contrast agent allowing for optimal imaging of the microcirculation.
   
   
2. The light passes through the first polarizer.
   
   
3. The polarized light is directed towards the tissue by a set of lens.
   
   
4. As the light hits the tissue, it is reflected back through the lens. Most of the light reflecting off the tissue and returning through the lens will remain polarized. Ten percent or less of the light will penetrate deeply into the tissue and go through multiple scattering events becoming depolarized. The depolarized light is reflected back through the lenses to a second polarizer or analyzer.
   
   
5. The analyzer, orthogonal (90 degrees) to the first polarizer, eliminates the reflected polarized light and allows the depolarized light to pass through to the CCD (Charged Couple Device), videocamera. The depolarized light forms an image of the microcirculation on the CCD, which can be captured through single frames or on videotape. The image produced is as if the light source is actually placed behind the desired target or transilluminated.

OPS-based image

Conventional