Micro-optics and microengineering in biology and medicine

In the field of optics, as in most other domains, physical laws are dependent on the scale of observation. This has the consequence that optical devices in the sub-millimeter range must be understood and conceived differently. Similar considerations are sound for devices making use of interactions of photons with biological matter, at the cellular and tissue scale. In biological tissues, propagation of light is different at the microthan at the millimeter or centimeter scale. This has the advantage that several innovative instruments are presently in development which make use of this specific properties of light propagating at small scale. The examples of micro-endoscopy and micro-holography for tissue imaging and diagnosis are given.