Single-beam spectrally encoded color imaging.

We have developed, to the best of our knowledge, a new method of conducting spectrally encoded color imaging using a single light beam. In our method, a single broadband light beam was incident on a diffraction grating, where the overlapped third order of the red, fourth order of the green, and fifth order of the blue spectral bands were focused on a line illuminating tissue. This configuration enabled each point on the line to be illuminated by three distinctive wavelengths, corresponding to red, green, and blue. A custom grating was designed and fabricated to achieve high diffraction efficiencies for the wavelengths and diffraction orders used for color spectrally encoded imaging. A bench system was built to test the new spectrally encoded color imaging method. For a beam diameter of 174 μm, the bench system achieved 89,000 effective pixels over a 70° circular field. Spectrally encoded color images of excised swine tissue revealed blood vessels with a similar color appearance to those obtained via a conventional color camera. The results suggest that this single-beam spectrally encoded color method is feasible and can potentially simplify color spectrally encoded endoscopy probe designs.