Page 238 - Optofluidics Fundamentals, Devices, and Applications

Bio-Inspir ed Fluidic Lenses for Imaging and Integrated Optics 213

F/# = 5 NA = 0.15
Fov = 25.1° Fov = 24.3°
1.79 MM 1.79 MM
Obj. dist. = Infinity Obj. dist. = 2 cm
(a) (b)
FIGURE 9-7 Lens View of the miniaturized unifi ed imager consisting of 3 fi xed lenses
and 1 fl uidic lens. The fl uidic lens has different shapes for objects at (a) infi nity
and at (b) 2 cm from the lens. Compared to Fig. 2.2.1, fi eld curvature and other
aberrations are greatly suppressed. (F. S. Tsai, S. H. Cho, Y.-H. Lo, B. Vasko, and
J. Vasko, “Miniaturzied universal imaging device using fl uidic lens,” Optics Letters,
vol. 33, pp. 291–293, 2008.) (See also color insert.)

48 line-pairs/mm at 100% field. Resolution is measured at a modula-
tion transfer function (MTF) of 0.3 considering C-d-F (656.3-578.6-
486.1 nm) wavelengths.
A fluidic lens was fabricated and integrated with the fixed lenses
mentioned above. The total track length of the optical system is less
than 12 mm. Figure 9-8a and b show the photographs for objects at
15 m distance and as close as 1 cm distance. The camera’s capability
of revealing details of an object invisible to human eyes is demon-
strated in Fig. 9-9. As we move the object from 14 to 1 cm, the device
can clearly resolve the fabric of a business card. The most striking
feature is that the imager can also function as a microscope. Such an
example is shown in Fig. 9-10 where lines as narrow as 2.5 μm on the
Edmund Optics 1951 Air Force Target can be resolved.

FIGURE 9-8 Demonstration of ultra-wide focusing range of the miniaturized unifi ed
imager. The device is stone bear 15 away paper mounted slide at 1 cm from device
focused at (a) the meters away, and (b) to a glass the device. (F. S. Tsai, S. H. Cho,
Y.-H. Lo, B. Vasko, and J. Vasko, “Miniaturzied universal imaging device using fl uidic
lens,” Optics Letters, vol. 33, pp. 291–293, 2008.)