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Beiser L. Unified optical scanning technology (Wiley, 2003)(K)(T)(202s)_EO_.djvu |
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Size 2.0Mb Date Oct 4, 2005 |
initiated in the early 1980s [Kral,Kra2,Beil]...
A system requiring significant analytic evaluation to optimize per-
performance of several interrelated elements is represented in Figure 4.18,
the main diagram of the 17 figures in its patent [C&R]...
It is comprised of four in-
individual (plane linear grating) holographic facets mounted at 45°
in a cylindrical carrier, with the pyramidal apex facing away from
(rather than toward) the input beam...
The typical mirror mounting position places its reflecting surface
coincident with the rotating axis (Fig...
With thoughtful provision for the above
comparative factors (in electronic and system control), the resonant
scanner renders application in compact linearized scanning tasks,
including accomodation for operation in the forward and return scan
directions, for increased duty cycle...
Starting with
a standard optical fiber, the common process entails the narrowing
or tapering of its diameter by "pulling," etching, or in general micro-
machining, as conducted for near-field microscopy [Mur]...
Proper handling of the focal distance / is expressed at the
end of Section 3.4.1, taken as positive for a converging beam and
negative for a diverging beam, which is quite possible in this configu-
configuration when launched from a small D into a subsequent lens...
A similar reduction in pupil relief distance can be achieved with the
use of transmissive deflectors (or facets) instead of the above-described
reflective ones...
) and be perpendicular to
the rotating axis A of the prismatic polygon (or single mirror deflector
of Fig...
As rendered in Figure 4.22, a diffraction grating of spacing Л is
synthesized by the wavefront spacings of an acoustic wave traveling
through a block of elastic material (which is transparent to the optical
wavelength of interest)...
The modulating acoustic
drive signal is now characterized as AM, not FM.The Scophony process
is a modulation, which causes a stream of diffractive elements to travel
at the acoustic velocity...
Derived from a large diffraction region, it con-
converges and expands rapidly around focus (depending on f-number),
motivating use of a mirrored deflector such as a polygon scanner, rather
than one having substantive thickness, such as an AC) scanner...
), with a narrow r-f pulse, utilizing its central lobe
as an isolated lens traveling at velocity vs...
The rays, as the orthogonal trajectories of the wavefronts,
bend in the direction of the shorter wavelength...
Although these
techniques were developed initially for such environmentally chal-
challenging tasks as laser radar and forward-looking IR (FLIR), continued
advancement may allow their cost-effective extension to productive
commercial application...
To relieve this burden, the long wedge profile is divided into an
array of smaller wedge periods, each forming a linear phase delay of
from 0 to 2л...
[b] Synthesis of [a] with array of wedges; each width
imparts 2n phase delay over the array period, [c] Synthesis of [b] with multiple delay
elements D per 2n period)...
This may be
recognized as the [Fourier transform]2 of a uniformly illuminated
linear aperture, as described at the end of Section 2.4.1, expressed by
Equation 2-2, and illustrated in Figure 2.1...
In analog form, this scanning process is described by the
convolution or shifting function discussed in Section 2.1.3 and illus-
illustrated in Figure 2.4...
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