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Extended Depth-of-focus in a Laser Scanning System Employing a Synthesized Difference-of-Gaussians Pupil

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dc.contributor.authorKourakos, Alexander Williamen
dc.contributor.committeechairPoon, Ting-Chungen
dc.contributor.committeememberBrown, Gary S.en
dc.contributor.committeememberIndebetouw, Guy J.en
dc.contributor.departmentElectrical and Computer Engineeringen
dc.date.accessioned2014-03-14T20:38:01Zen
dc.date.adate1999-05-25en
dc.date.available2014-03-14T20:38:01Zen
dc.date.issued1999-05-11en
dc.date.rdate2000-05-25en
dc.date.sdate1999-05-21en
dc.description.abstractTraditional laser scanning systems, such as those used for microscopy, typically image objects of finite thickness. If the depth-of-focus of such systems is low, as is the case when a simple clear pupil is used, the object must be very thin or the image will be distorted. Several methods have been developed to deal with this problem. A microscope with a thin annular pupil has a very high depth-of-focus and can image the entire thickness of a sample, but most of the laser light is blocked, and the image shows poor contrast and high noise. In confocal laser microscopy, the depth-of-focus problem is eliminated by using a small aperture to discard information from all but one thin plane of the sample. However, such a system requires scanning passes at many different depths to yield an image of the entire thickness of the sample, which is a time-consuming process and is highly sensitive to registration errors. In this thesis, a novel type of scanning system is considered. The sample is simultaneously scanned with a combination of two Gaussian laser beams of different widths and slightly different temporal frequencies. Information from scanning with the two beams is recorded with a photodetector, separated electronically, and processed to form an image. This image is similar to one formed by a system using a difference-of-Gaussians pupil, except no light has been blocked or wasted. Also, the entire sample can be scanned in one pass. The depth-of-focus characteristics of this synthesized difference-of-Gaussians pupil are examined and compared with those of well-knownen
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-052199-162314en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-052199-162314/en
dc.identifier.urihttp://hdl.handle.net/10919/33091en
dc.publisherVirginia Techen
dc.relation.haspartETD.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectextended depth of fielden
dc.subjectoptical scanning microscopyen
dc.subjectpupil synthesisen
dc.titleExtended Depth-of-focus in a Laser Scanning System Employing a Synthesized Difference-of-Gaussians Pupilen
dc.typeThesisen
thesis.degree.disciplineElectrical and Computer Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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