Light which has been scattered from any point in the 
surface of the scatter plate expands to over fill the 
lens aperture, and the fraction passing the aperture 
is focused down to combine on the film with the 
unscattered light from the same point of the scatter 
plate. The two components are in the relation of 
"object beam" and "reference beam" in holographic 
recording, and the record on the film is & Fourier 
holograme When reconstructed, Figure 17, 
  
  
  
  
  
Screen 
Figure 15 Contouring fringes. Spacing 5 cm 
approximately. U 
Separate negatives, bleached to produced phase records, 
are viewed in the first diffracted order, and pairs of Lens hologram 
records can be combined to yield interference contours 
of deformation, Figure 14, or, by an appropriate 
uniform movement between exposures, contours of 
surface form, Figure 15. Figure 17 System for constructing a lens hologram. 
Reference 
; two images of the aperture are produced, one rotated 
9 Forno C, "White-light speckle photography for through 180^ with respect to the other. If the 
measuring deformation, strain, and shape", reference beam has been carefully located to be 
Optics and Laser Technology, 1975, October, central, the two areas are superimposed and the 
pp 217-222. wavefronts interfere to produce a pattern showing 
the symmetrical aberrations, Figure 18. 
6 LENS HOLOGRAM TECHNIQUES FOR ANALYSING CAMERA 
SYSTEMS 
J M Burch, C Forno, L H Tanner* (10) 
Partly as the consequence of the need to explore the 
aberrations of the cameras used in the moire grid 
and white-light speckle techniques just described in 
sections 4 and 5, a novel method using a scatter plate 
to produce a holographic record of the wavefront in 
the pupil of the lens has been developed. In 
Figure 16 & beam of coherent light from a laser is 
focused down through a "scatter-plate" (a partially 
scattering plane-parallel plate) to a small spot in 
the centre of the lens aperture. This beam then 
diverges to produce a patch of light on the film in 
the camera which is conjugate with the area of the 
scatter plate covered by the convergent beam. 
  
Figure 18 Example of a reconstruction of a lens 
hologram. 
P L SP RB SB 
An important point in this method is that the 
"aberration" shown includes the effects of change of 
focus and of movement of the film, and so provides 
a relatively simple basis for examining the 
focusing and stability of the film location in 
cameras used in the normal way. 
  
Figure 16 System for producing the lens aberration 
  
holograms: Reference 
P = Polaroid, S = shutter, O = objective 
L = condenser lens, SP = scatter—plate, 10 Burch J M, Forno C, Tanner L H, "A lens hologram 
RB = reference beam, SB = scattered beams, technique for analysing symmetrical aberrations 
BS = beam-splitter, M - viewing lens, of a camera system" Optics and Laser Technology, 
C = camera lens, F = filme 1974, June, pp 109-113. 
  
93