Accurate three-dimensional metrology of underwater objects using replayed real images from in-line and off-axis holograms

P R Hobson, J Watson

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

In many fields of science and engineering it is important to obtain accurate high-resolution images of underwater objects and scenes to allow precision dimensional measurement and inspection. Optical holography enables true three-dimensional images, with a simultaneous high resolution and large depth of field, to be recorded. The technical challenges of recording such holograms, and their subsequent replay in the laboratory, is considerable as there are increased optical aberrations arising from the change in refractive index when an object recorded in water is replayed in air. Our detailed evaluation of these aberrations, and techniques for their compensation, are described. We have demonstrated a resolution of better than 10 mu m using in-line holography and better than 100 mu m using off-axis holography in laboratory simulations of underwater scenes. Volumes of water of 2.5 litres (in-line) and up to 100 litres (off-axis) have been recorded. An absolute coordinate accuracy of better than 1% for both in-line and off-axis holograms has been achieved. Results are presented on resolution and coordinate accuracy versus distance, replay wavelength, off-axis angle, and holographic plate misalignment. We discuss the concepts with reference to the design of an underwater holographic camera for the recording of marine organisms and the associated replay of the holograms.

Original languageEnglish
Pages (from-to)1153-1161
Number of pages9
JournalMeasurement Science and Technology
Volume10
Publication statusPublished - 1999

Keywords

  • metrology
  • optical aberration
  • holography
  • hologrammetry
  • underwater imaging
  • FRAUNHOFER HOLOGRAPHY
  • ABERRATIONS
  • RESOLUTION
  • INSPECTION

Cite this

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title = "Accurate three-dimensional metrology of underwater objects using replayed real images from in-line and off-axis holograms",
abstract = "In many fields of science and engineering it is important to obtain accurate high-resolution images of underwater objects and scenes to allow precision dimensional measurement and inspection. Optical holography enables true three-dimensional images, with a simultaneous high resolution and large depth of field, to be recorded. The technical challenges of recording such holograms, and their subsequent replay in the laboratory, is considerable as there are increased optical aberrations arising from the change in refractive index when an object recorded in water is replayed in air. Our detailed evaluation of these aberrations, and techniques for their compensation, are described. We have demonstrated a resolution of better than 10 mu m using in-line holography and better than 100 mu m using off-axis holography in laboratory simulations of underwater scenes. Volumes of water of 2.5 litres (in-line) and up to 100 litres (off-axis) have been recorded. An absolute coordinate accuracy of better than 1{\%} for both in-line and off-axis holograms has been achieved. Results are presented on resolution and coordinate accuracy versus distance, replay wavelength, off-axis angle, and holographic plate misalignment. We discuss the concepts with reference to the design of an underwater holographic camera for the recording of marine organisms and the associated replay of the holograms.",
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author = "Hobson, {P R} and J Watson",
year = "1999",
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journal = "Measurement Science and Technology",
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TY - JOUR

T1 - Accurate three-dimensional metrology of underwater objects using replayed real images from in-line and off-axis holograms

AU - Hobson, P R

AU - Watson, J

PY - 1999

Y1 - 1999

N2 - In many fields of science and engineering it is important to obtain accurate high-resolution images of underwater objects and scenes to allow precision dimensional measurement and inspection. Optical holography enables true three-dimensional images, with a simultaneous high resolution and large depth of field, to be recorded. The technical challenges of recording such holograms, and their subsequent replay in the laboratory, is considerable as there are increased optical aberrations arising from the change in refractive index when an object recorded in water is replayed in air. Our detailed evaluation of these aberrations, and techniques for their compensation, are described. We have demonstrated a resolution of better than 10 mu m using in-line holography and better than 100 mu m using off-axis holography in laboratory simulations of underwater scenes. Volumes of water of 2.5 litres (in-line) and up to 100 litres (off-axis) have been recorded. An absolute coordinate accuracy of better than 1% for both in-line and off-axis holograms has been achieved. Results are presented on resolution and coordinate accuracy versus distance, replay wavelength, off-axis angle, and holographic plate misalignment. We discuss the concepts with reference to the design of an underwater holographic camera for the recording of marine organisms and the associated replay of the holograms.

AB - In many fields of science and engineering it is important to obtain accurate high-resolution images of underwater objects and scenes to allow precision dimensional measurement and inspection. Optical holography enables true three-dimensional images, with a simultaneous high resolution and large depth of field, to be recorded. The technical challenges of recording such holograms, and their subsequent replay in the laboratory, is considerable as there are increased optical aberrations arising from the change in refractive index when an object recorded in water is replayed in air. Our detailed evaluation of these aberrations, and techniques for their compensation, are described. We have demonstrated a resolution of better than 10 mu m using in-line holography and better than 100 mu m using off-axis holography in laboratory simulations of underwater scenes. Volumes of water of 2.5 litres (in-line) and up to 100 litres (off-axis) have been recorded. An absolute coordinate accuracy of better than 1% for both in-line and off-axis holograms has been achieved. Results are presented on resolution and coordinate accuracy versus distance, replay wavelength, off-axis angle, and holographic plate misalignment. We discuss the concepts with reference to the design of an underwater holographic camera for the recording of marine organisms and the associated replay of the holograms.

KW - metrology

KW - optical aberration

KW - holography

KW - hologrammetry

KW - underwater imaging

KW - FRAUNHOFER HOLOGRAPHY

KW - ABERRATIONS

KW - RESOLUTION

KW - INSPECTION

M3 - Article

VL - 10

SP - 1153

EP - 1161

JO - Measurement Science and Technology

JF - Measurement Science and Technology

SN - 0957-0233

ER -