Biomedical Engineering Reference
In-Depth Information
Resolution
target
Fireball without
laser illumination
Laser illumination
through fireball
FIGURE 2.39
Laboratory demonstration of single-VCSEL illuminator.
2.11.4 High-Brightness Imaging
The system developed is intended for a wide variety of illumination sce-
narios. The VCSEL can be pulsed and operated uncooled for the duration of
short events (e.g., 150-200 ms), as was the case with previous work in laser
illuminators, where the light source determined the temporal sample size
for the event. For longer event applications, it can be operated CW and in a
cooled configuration. In CW operation, the temporal characteristics of high-
speed capture are determined by the camera.
For imaging applications involving the liner collapse, jet formation, and
progression of a detonated shaped charge, some camera timing capabilities
may not be fast enough to fully characterize the event. Typical jet velocities
approach 10-12 km/s [85, 92]. In these cases, one might consider, for instance,
the Imacon 200 ultra high-speed camera, with frame rates up to 200 million
frames per second, or 5-ns samples.
Use of VCSELs for laser illumination applications shows great promise as
a versatile, readily implemented approach to a host of current challenges for
high-speed imaging. A technology demonstration phase utilizing a single-
VCSEL array has been performed in the author's laboratory. A view from
the demonstration is shown in Figure 2.39. This illustrates the ability to see
through a fireball using laser illumination and narrow bandpass filtering.
The utility of the VCSEL illumination is readily apparent. A fielded brass
board 9-VCSEL model, shown below in Figure 2.40, is now in testing in live
fire applications.
2.12 VerticalCavitySurfaceEmittingLaserTechnology
Princeton Optronics (PO), in Trenton, New Jersey, is the leader in commercial
VCSEL technology. The following information (Section 2.12) is courtesy of
PO and Dr. Chuni Ghosh.
 
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