Interference No. 104,649
Page No. 12
jr
42 43'
11
50
6
P
53 53' t44
42
^48 52
5352 43 49 48 4V
45
Point U& Source
FIG. 6
Keagy '969 provides the following description of the ray diagram of Figure 6:
In FIG. 6, rays 42 and 43 emanate from a point light source 45 at angles such that
they pass through the bottom surface 44 of the plastic platen 46 and reach the
upper interface surface 50. These rays 42 and 43 happen to fall upon points on
upper surface 50 in contact with ridges of a finger, and escape the platen and are
lost as rays 42' and 43'. In contrast, rays 52 and 53 reach the top surface and
impinge upon air in the valleys between fingerprint ridges, and are jpLally
internally reflected. Their reflected versions, 53' and 52', form part of the white
portions of a working image of the user's fingerprint. Rays 52' and 53' are
refracted toward the imaging apparatus (not shown) because of the difference in
indices of refraction between the flesh in a fingerprint ridge and air.
(Keagy '969, col. 7, line 57 to col. 8, line 3). Keagy's description of Figure 6 is confusing in that
it appears to use the terms reflected and refracted to describe the same phenomenon.
F22. Keagy's description of rays that bounce off the upper surface of the platen in Figures 3
(31, 33 and 35) and 6 52' and 53') is inconsistent with the description of similar rays in Figures
5 (3a and 4a) and 7A and 7B. Although inconsistent in the specification, one skilled in the art
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Last modified: November 3, 2007