Biomedical subjects

Nelly Cap

Publications and source records attributed to Nelly Cap.

3 recordsLinked to original sources

PubMed2006

Speckle activity images based on the spatial variance of the phase.

We propose the display of the local spatial variance of the temporal variations of the phase as an activity descriptor in dynamic speckle images. The spatial autocorrelation of the speckle intensity is calculated in sliding windows, and an estimation of the variance of the phase variations in each region of the sample is determined. The activity images obtained in this way depict some interesting features and in some cases they could be related to physical magnitudes in the samples. A simulation is presented, and examples corresponding to usual study cases are also shown, namely, fruit bruising and paint drying.

Journal Article↗

PubMed2003

Holodiagrams in birefringent media.

The modifications to the holodiagram concept to describe free propagation (the extraordinary ray) inside birefringent materials are described. Holodiagrams are graphs showing the loci where the sum or the difference in the optical path from a generic point to two foci is the same. The holodiagrams obtained in this way give the shape of the surfaces that satisfy Fermat's principle, conjugate by reflection of one focus into the other, and represent the interference fringes obtained if both points are coherent sources. The reflection law in birefringent media is investigated in relation to this diagram. One direction for the optical axis is considered: parallel to the line joining the source and the observation point. Quartz-type and calcite-type crystals are studied.

Journal Article↗

PubMed2003

The projection diagram.

We describe a diagram, named the projection diagram (PD), that can be used for the interpretation of fringe projection operations in a similar way as the Holodiagram is used in holography and other branches in optics. It is obtained as a Moiré pattern between two spoke targets that mimic central projections, the same as those in a projection and observation system or two projection systems. N. Abramson [Academic, London (1981)] has already proposed its use in systems with two observation points (i.e., stereoscopic observation). By using this PD, several interesting features dealing with fringe projection are highlighted. Information on the sensitivity vector and the geometry of the contouring surfaces can be straightforwardly obtained in a graphical way. The effect of defocusing can also be included in the diagram.

Journal Article↗