Axial spectral encoding for low-cost confocal endomicroscopy

We have developed an axially spectrally-encoded confocal endomicroscope that can visualize multiple depths of the tissue in a single image frame. We developed a custom hyperchromatic objective lens (focal length = 4.8 mm; NA = 0.68) to focus different wavelengths from a broadband light source into different axial depths of the tissue. The confocal endomicroscope achieved lateral and axial resolution of 2 μm and 4 μm, respectively over a lateral field of 468 μm and an axial depth range of 100 μm. The material cost was < $1500. Preliminary confocal images of human tissues in vivo clearly visualized cellular details.