Laser Scanning Imaging for Increased Depth-Of-Focus

Throughout the decades, different techniques have been proposed to improve the depth-of-focus in optical microscopy. Common techniques like optical sectioning microscopy and scanning confocal microscopy have innate problems. By simply modifying the pupil function in microscope imaging system, we can also extend the depth-of-focus. The scanning system with a thin annular pupil has a high depth-of-focus and can scan the whole object, but the output light is too dim to be detected well by a photodetector. In this thesis, we propose a scanning technique employing an optical heterodyne scanning system using a difference-of-Gaussians (DoG) pupil. The object is illuminated by the combined beam which consists of two Gaussian beams with different waists, frequencies, and amplitudes. This system does not block most light like the annular pupil system and can obtain high depth-of-focus. The main objective of the thesis is to extend the depth-of-focus using the proposed system. The depth-of-focus characteristics of the DoG pupil function are examined and compared with those of well-known functions such as the circular, annular, and Gaussian pupils.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2002

Author dc:creator

• Shin, Dong-Ik

Chair dc:contributor.committeechair

• Poon, Ting-Chung

Committee members dc:contributor.committeemember

• Indebetouw, Guy J.
• Stolen, Roger Hall

• depth-of-focus
• microscopy
• difference-of-gaussians
• optical scanning holography

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-08072002-194429

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/44190