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Biomedical subjects

Guy Indebetouw

Publications and source records attributed to Guy Indebetouw.

6 recordsLinked to original sources

Quantitative phase imaging with scanning holographic microscopy: an experimental assessment.

This paper demonstrates experimentally how quantitative phase information can be obtained in scanning holographic microscopy. Scanning holography can operate in both coherent and incoherent modes, simultaneously if desired, with different detector geometries. A spatially integrating detector provides an incoherent hologram of the object's intensity distribution (absorption and/or fluorescence, for example), while a point detector in a conjugate plane of the pupil provides a coherent hologram of the object's complex amplitude, from which a quantitative measure of its phase distribution can be extracted. The possibility of capturing simultaneously holograms of three-dimensional specimens, leading to three-dimensional reconstructions with absorption contrast, reflectance contrast, fluorescence contrast, as was previously demonstrated, and quantitative phase contrast, as shown here for the first time, opens up new avenues for multimodal imaging in biological studies.

Holography↗

Scanning holographic microscopy of three-dimensional fluorescent specimens.

We demonstrate experimentally the three-dimensional reconstructions of fluorescent biological specimens using scanning holographic microscopy. Three-dimensional reconstructions with transverse resolution below about 1 microm of transmission and fluorescence emission images are presented and analyzed. The limitations of the method are discussed.

Algorithms↗

Point-spread function synthesis in scanning holographic microscopy.

Scanning holographic microscopy is a two-pupil synthesis method allowing the capture of single-sideband in-line holograms of noncoherent (e.g., fluorescent) three-dimensional specimens in a single two-dimensional scan. The flexibility offered by the two-pupil method in synthesizing unusual point-spread functions is discussed. We illustrate and compare three examples of holographic recording, using computer simulations. The first example is the classical hologram in which each object point is encoded as a spherical wave. The second example uses pupils with spherical phase distributions having opposite curvatures, leading to reconstructed images with a resolution limit that is half that of the objective. In the third example, axicon pupils are used to obtain axially sectioned images.

Algorithms↗

A posteriori quasi-sectioning of the three-dimensional reconstructions of scanning holographic microscopy.

A method to obtain the axial locations of objects reconstructed by scanning holographic microscopy with submicrometer accuracy is presented and demonstrated. The method combines the holographic advantage of capturing three-dimensional (3D) information in a single two-dimensional scan, with the possibility of optically sectioning the 3D holographic reconstruction a posteriori. The method is demonstrated experimentally for pointlike features (fluorescent beads), and the limitation of the method for features of arbitrary size and shape is discussed.

Algorithms↗

Scanning holographic microscopy with transverse resolution exceeding the Rayleigh limit and extended depth of focus.

We demonstrate experimentally that the method of scanning holographic microscopy is capable of producing images reconstructed numerically from holograms recorded digitally in the time domain by scanning, with transverse and axial resolutions comparable to those of wide-field or scanning microscopy with the same objective. Furthermore, we show that it is possible to synthesize the point-spread function of scanning holographic microscopy to obtain, with the same objective, holographic reconstructions with a transverse resolution exceeding the Rayleigh limit of the objective up to a factor of 2 in the limit of low numerical aperture. These holographic reconstructions also exhibit an extended depth of focus, the extent of which is adjustable without compromising the transverse resolution.

Equipment Design↗

Three-dimensional point spread functions of an optical heterodyne scanning image processor.

We study the three-dimensional (3-D) imaging properties of an optical heterodyne scanning image processor. The image processor is a two-pupil optical system capable of 3-D imaging coherently or incoherently, depending on the detection scheme used. We derive the imaging properties in terms of the two pupils and then show an important 3-D imaging application in scanning holography by deriving its 3-D point spread functions and compare them with conventional 3-D imaging systems.

Journal Article↗