  Confocal microscopy is the backbone of cellular research labs across the
world but unfortunately, the imaging is restricted to a single plane. Chromatic
confocal microscopy offers the possibility to image multiple planes
simultaneously thus providing a manifold increase in the imaging speed whereas
eliminating the need for z-axis scanning. Standard chromatic confocal systems
have a limited imaging range of the order of a few hundreds of micrometers
which limits their applications. In this work, using a single zinc selenide
lens, we demonstrate a chromatic confocal tomography system that has an imaging
range of 18 mm with an average lateral resolution of 2.46 microns and another
system with a 1.55 mm imaging range with 0.86 microns average lateral
resolution. Doing so, we have pushed the imaging range of chromatic confocal
systems from micrometer to centimeter regime, an improvement of approximately
two orders of magnitude. The proposed approach can be a powerful tool for
confocal imaging of biological samples or surface profiling of industrial
samples.
