Biological tissue is imaged by non-damaging illumination from a coherent ht source and retroreflective radiation from a phase conjugate mirror without correction for absorption induced distortion. Optics is provided to regulate the illumination and to direct the retroreflective imaging radiation...http://www.google.es/patents/US5760388?utm_source=gb-gplus-sharePatente US5760388 - Biomedical imaging by optical phase conjugation
