Confocal microendoscopy with chromatic sectioning

Placing a spatial light modulator, such as the Texas Instruments Digital Micromirror Device (DMD), in the light path of a microscope enables a variety of novel applications. One application enables reflectance in vivo confocal imaging of cells and tissue structure through a fiber-optic image guide. While multi-wavelength reflectance confocal microendoscopy with optical sectioning is a requirement for a clinically useful device, some form of axial scanning is also necessary. This is readily achieved using a multi-element lens system with some form of mechanical translation, however, this generally results in large probes and high cost. These limitations can be overcome using a two-element GRIN lens system in which the traditionally undesirable chromatic aberration of such a system can be exploited to allow for color-encoded optical sectioning. In our system a wavelength encoding range of 200 nm permits a sectioning range of 40 μm from the tip of the probe into the tissue.