XIII Congress of the 
International Society for Photogrammetry 
Helsinki, 1976 
Commission V 
Working Group V/3 
Invited Paper 
J. W. C. GATES 
National Physical Laboratory 
Teddington, Middlesex 
England 
Three-Dimensional Location and 
Measurement 
by Coherent Optical Methods 
Formulations and techniques are presented for measuring the 
positions and movements of three-dimensional objects by 
employing both coherent light and holographic recording. 
INTRODUCTION 
( tonnes and its effects began to be 
provements in temporal coherence and fre- 
quency stability suggest that advances may 
be made in the measurement of position in 
studied in the earliest days of the dis- 
three dimensions, and in recording methods. 
covery of the interference of light, from the 
time of Isaac Newton onwards, but curiosity 
was the main motivation until intensive study 
of the imaging of fine detail by Abbe and 
MEASUREMENT TECHNIQUES 
The basis of classical optics in relation to 
  
ABSTRACT: The availability of lasers with high coherence and stability 
suggests ways of recording spatial relationships and of making posi- 
tional measurements with greater precision. Examples are quoted of 
optical measurements made with coherent light in real-time experi- 
ments, and the extension to the photographic recording of holograms 
for measurement is shown. Measurement via holography has been 
carried out for transilluminated, three-dimensional arrays of spheres, 
moving and measurable in three dimensions, and of solid three- 
dimensional bodies, also moving and measurable in three dimensions. 
Current work is introduced by means of an example of a photofabri- 
cated optical element capable of identifying positions in a three- 
dimensional space. 
  
others led to the formulation of theories of 
coherence. Application to practical studies 
remained somewhat incomplete until the ad- 
vent ofthe laser as a practically perfect source 
of coherent light. Progress in new ways of 
measuring length has been rapid and im- 
PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING, 
Vol. 41, No. 11, November 1975, pp. 1349-1354. 
optical measurement is the concept of a 
“ray.” In order to proceed very far, however, 
it soon becomes necessary to consider the 
spreading of the effect of information carried 
by finite amounts of energy along "rays." We 
find that diffraction is the essential process by 
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