Optical imaging through turbid media with a degenerate four wave mixing correlation time gate

Journal Article · Tue Dec 20 00:00:00 EST 1994 · Applied Optics; (United States)

DOI:https://doi.org/10.1364/AO.33.008346· OSTI ID:6873467

Sappey, A D ^[1]

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1. Formerly with the Los Alamos National Laboratory, CST-2, MSJ565, Los Alamos, New Mexico 87545 now with the ADA Technologies, Inc., 304 Inverness Way South, Suite 110, Englewood, Colorado 80112 (United States)

A novel method for detection of ballistic light and rejection of unwanted diffusive light to image structures inside highly scattering media is demonstrated. Degenerate four wave mixing (DFWM) of a doubled YAG laser in Rhodamine 6G is used to provide an ultrafast correlation time gate to discriminate against light that has undergone multiple scattering and therefore lost memory of the structures inside the scattering medium. We present preliminary results that determine the nature of the DFWM grating, confirm the coherence time of the laser, prove the phase-conjugate nature of the signal beam, and determine the dependence of the signal (reflectivity) on dye concentration and laser intensity. Finally, we have obtained images of a test cross-hair pattern through highly turbid suspensions of whole milk in water that are opaque to the naked eye. These imaging experiments demonstrate the utility of DFWM for imaging through turbid media. Based on our results, the use of DFWM as an ultrafast time gate for the detection of ballistic light in optical mammography appears to hold great promise for improving the current state of the art.

• OSTI ID: 6873467
• Journal Information: Applied Optics; (United States), Vol. 33:36; ISSN 0003-6935
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
IMAGE PROCESSING
FREQUENCY MIXING
MAMMARY GLANDS
BIOMEDICAL RADIOGRAPHY
CORRELATIONS
GRATINGS
NEODYMIUM LASERS
RHODAMINES
TURBIDITY
AMINES
BODY
CARBOXYLIC ACIDS
DIAGNOSTIC TECHNIQUES
DYES
GLANDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
LASERS
MEDICINE
NUCLEAR MEDICINE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANS
PROCESSING
RADIOLOGY
REAGENTS
SOLID STATE LASERS
550602* - Medicine- External Radiation in Diagnostics- (1980-)