Holographic imaging through scattering media

US5299035A · kind A · utility

Assignee

• THE REGENTS OF THE UNIVERSITY OF MICHIGAN · US

Inventors

• Emmett N. Leith · Canton, US
• David S. Dilworth · Ann Arbor, US
• Hsuan S. Chen · Midland, US
• Ye Chen · Buffalo Grove, US
• Joaquin L. Lopez · Ann Arbor, US
• Janis A. Valdmanis · Columbus, US

Key dates

• Filing date: Mar 25, 1992
• Grant date: Mar 29, 1994
• Expiry date: Mar 25, 2012

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S359/90
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An image of an object embedded in a diffusing medium is formed by propagating a coherent or equivalent light pulse through the diffusing medium and applying a reference pulse so as to gate precisely the first emerging light transmitted through the diffusing medium. An ultra-short pulse, having a duration on the order of 150 fs, insures that only the first emerging light is used to form a hologram. Instability in the diffusing medium, which may be inherent therein, as is the case with living tissue, or artificially induced therein, such as by vibrating the specimen, ensures that a subsequent hologram has a different background noise and speckle pattern. Integration of such holograms causes the background noise to average out, but time-invariant features, such as the object being imaged, become increasingly more visible as more holograms are integrated.