Optical configurations for oceanographic applications of eHolography

John Watson, Hongyue Sun, David Cyril Hendry, Michael Player

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

eHolography (electronic or digital holography) has been used for observing and measuring particle size and distribution in biomedicine, sedimentology and oceanology. In these areas, eHolography possesses advantages over other imaging techniques in terms of its capability for recording live organisms (e.g. plankton) or events (e.g. sediment erosion) in a non-disturbed environment. Compared with classical holography, an eHologram is recorded digitally on an electronic imaging sensor and reconstructed numerically, to produce a three-dimensional map of the scene. In this paper, we present our progress in developing an electronic Holographic Camera for high-resolution imaging, both subsea and in air (eHoloCam). Many optical configurations have been successfully used in classical (photographic) holography, including a back-flluminating inline beam with and without a separated reference beam, and side/front illuminated object with an off-axis reference beam. For eHolography, it is necessary to reexamine these and other optical geometries with specific reference to the constraints of reduced resolution and recording area of current CCD or CMOS imaging sensors. For example, using a divergent beam in recording back-illuminated in-line eHolograms can give an improvement in image resolution over the more usual collimated beam geometry. Furthermore, when using an off-axis beam in eHolography considerable limitations are encountered in obtaining useable holograms, such as the need to record at small reference beam angles. In this paper, we will discuss the various geometries we have used to overcome these difficulties.
Original languageEnglish
Title of host publicationOceans 2005
Subtitle of host publicationEurope
Place of PublicationLos Alamitos, CA, USA
PublisherIEEE Press
Pages1214-1219
Number of pages6
Volume2
ISBN (Print)0780391039
DOIs
Publication statusPublished - 3 Oct 2005
EventOceans 2005 Europe International Conference - Brest, France
Duration: 20 Jun 200523 Jun 2005

Conference

ConferenceOceans 2005 Europe International Conference
CountryFrance
CityBrest
Period20/06/0523/06/05

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Keywords

  • geometrical optics
  • high-resolution imaging
  • holographic optical components
  • holography
  • image resolution
  • optical imaging
  • optical recording
  • optical sensors
  • oceanographic equipment
  • oceanographic techniques

Cite this

Watson, J., Sun, H., Hendry, D. C., & Player, M. (2005). Optical configurations for oceanographic applications of eHolography. In Oceans 2005: Europe (Vol. 2, pp. 1214-1219 ). IEEE Press. https://doi.org/10.1109/OCEANSE.2005.1513232