Page 214 - Optofluidics Fundamentals, Devices, and Applications

Adaptive Optofluidic Devices 189

Cham.4
Cham.1
1
A
2

3
z Functional
y 4 B Cham.2-3 area
3 mm
x
(a) (b)

0.5 mm 0.5 mm 0.5 mm 1 mm 1 mm 1 mm
(c) (d) (e) (f) (g) (h)

FIGURE 8-4 A set of cylindrical orthogonal lenses [69]: (a) conceptual drawing of
the device; (b) measured beam profi les show independent two-axis beam shaping;
(c) through (e) demonstration of imaging and optical signal processing: (c) image of
a target taken under a microscope; (d) image of the target projected on the CCD by
the device; (e) Fourier transform of the target (diffraction pattern) projected on the
CCD; (f) through (h) demonstration of beam shaping with a CCD camera placed at
z = 200 mm behind the device. The fi gures show patterns of light on the CCD.
(L. Pang, U. Levy, K. Campbell, A. Groisman, and Y. Fainman, “Set of two orthogonal
adaptive cylindrical lenses in a monolith elastomer device,” Opt. Express, 13,
9003–9013, 2005.)

(neglecting the thickness of the wall) that defines the focusing prop-
erties of the lens (see Fig. 8-3).
Much early work on polymer-based lenses focused on micro-
lenses and lens arrays with constant focus [120,121]. Refractive micro-
lenses with lens diameters of a few to several hundred micrometers
are extensively used in optical devices such as detectors and emitters
to boost the optical efficiency. They are also likely to be combined
with other micro-optical structures in optical sensor arrays, in high-
definition display and projection systems, in biomedical systems, and
in optical interconnection technology. Many fabrication techniques
have been developed [70,94,111,122–141], and micro-lens arrays can
now be tailored and fabricated in high volumes.
Tunable polymer-based lenses can be actuated thermally
[95,97,142] or pneumatically [71]. For thermally tuned lenses both
planar [142] and free space [95] configurations were demonstrated.
In the free-space configuration, thermally actuated polymeric lens