Electro-Optics - Applied Optics Fundamentals and Device Applications - page 59

self-luminosity and fireball from the image, providing excellent background
discrimination in a variety of range test scenarios.
Use of laser illumination in conjunction with narrow bandpass filtering
and electro-optic shuttered temporal filtering provides background discrim-
ination for high-resolution, high-speed digital image processing. In addition,
the characteristics of the VCSEL structures now available represent viable
lighting characteristics for other illumination events currently using flash-
bulbs and argon discharge lamps. Timing sequences for shuttering, modula-
tion, camera synchronization, exposure time, and digital image frame rate
are integrated with a high degree of accuracy, permitting high resolution,
blur- and distortion-free, quantitative video realization of high-speed events
and associated data processing. Illumination from a VCSEL array is virtually
speckle free. Measurements show that the illuminated area has speckle of
<1%. Therefore, VCSEL illumination is very desirable for many applications
where uniformity of illumination is very important.
Laser illumination can be applied in a broad range of applications. In some
it may be necessary to pulse the laser for gated imaging. This technique can
be used for 3-D imaging and also for improving the signal-to-noise ratio at
a desired depth. In gated imaging, a synchronized triggering signal is sent
to both the camera and the laser. Short pulses are then emitted from the
laser and the reflected light from the scene is accepted at desired time delays.
Other applications do not require gating.
Areas of interest may include
• Shaped charge detonations to further understand the properties of
jet formation and particulation
• Explosively formed projectile detonations to quantify launch and
flight performance characteristics
• Detonations of small caliber grenades and explosive projectiles to
verify fuse function times and fragmentation patterns
• Performance and behavior of various projectiles and explosive
threats against passive, reactive, and active target systems
• Human effects studies including body armor, helmets, and footwear
• Behind armor debris studies of large caliber ammunition against
various armor materials
• Small caliber projectile firings to study launch, free flight, and target
impact results
• Professional sporting events
Two key technologies are routinely utilized to achieve adequate scene illu-
mination for high-speed video capture: flashbulbs and discharge tubes.
Output curves for the frequently used PF-200 and PF-300 flashbulbs are
shown in Figure 2.34. The peak output of 6.0 × 10 6 lm translates to 477,465 cd.