Aerospace Research Technologies Inc.

Institut National D'optique

Andre Parent

Yves Taillon

Yves Painchaud

Yvan Mimeault

Michel Morin

Pierre Bernard

Pierre Galarneau

Paul Grenier

Michel Jacob

Bruno Labranche

Kevin Snell

A method of optical imaging through a scattering medium is provided in which a fit is made to an inhomogeneous diffusion model. The method facilitates good differentiation between scattering and absorption. The variation of the diffusion curve associated with the presence of an inclusion is considered rather than the diffusion curve itself. An empirical model is provided which describes the variation of the diffusion curve. A linear curve fitting process is performed to provide two parameters, one parameter associated with the scattering property of the inclusion and the other parameter associated with the absorption property of the inclusion.

Optical imaging through scattering media: fit to an inhomogeneous

The multiple emitters laser diode assembly comprises a laser diode bar for emitting a laser beam. The laser diode bar comprises a plurality of emitters aligned with respect to each other in a same plane of emission. A graded-index elongated fiber microlens is transversely set at a given distance in front of the laser diode bar for controlling the divergence of the beam. The microlens has an axis of symmetry substantially intersecting the optical axis of each emitter. A mount is provided for positioning the microlens with respect to the laser diode bar. Alternatively, the assembly may comprise a laser diode array for emitting the beam. The laser diode array comprises a plurality of substantially parallel rows of emitters with a substantially regular period between them. An array of graded-index elongated fiber microlenses is positioned substantially parallel to the rows. Each microlens corresponds to one of the rows for collimating the beam generated thereby. The GRIN fiber microlens shows less alignment sensitivity than ordinary fiber lens or aspherical fiber lens when used in a multiple emitters laser diode assembly. The GRIN lens further has the advantage of collimating a laser diode bar or array with a high degree of quality while minimizing phase aberration and distortion in the collimated transmitted beam.

Multiple emitter laser diode assembly with graded-index fiber microlens

The most common method of determining whether a breast contains cancerous tissue utilizes ionizing radiation, i.e. x-rays, which possible have tissue damaging properties. It has been found that lasers can be used as a light source in a breast tissue transillumination process. However, due to the high scattering coefficient (or diffusing properties) of breast tissue, it is not possible to obtain images having good resolution using classical transillumination techniques, even when a laser is used as the light source. When passing through a diffusing medium, a laser pulse decomposes into three classes of photons, namely ballistic, snake-like and diffuse photons. In most practical situations, the ballistic photon portion of a laser pulse, which travels in a straight line, does not pass through the tissue, i.e. only snake-like and diffuse photons pass through the tissue. It is proposed by this invention to use both the snake-like and diffuse photons in a method involving time gating and multiple field of view techniques to obtain a more precise evaluation of the scattering coefficients, i.e. a map of the interior of a region of the sample, whereby the presence (or absence) of tumors is determined. The use of multiple field of view and time gating techniques will yield a relatively clear picture of the structure of the tissue.

Method and apparatus for detecting malignancies in living tissue

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Andre Parent