Characteristics of impact driven supersonic liquid jets

Video imaging of debris clouds following penetration of lightweight spacecraft materials

: Repetitively pulsed lasers have been developed that have served as excellent illumination sources for high speed framing photography. This invited paper discusses the general subject of laser illuminators for high speed photography as well as specific capabilities of a high repetition rate Q switched ruby laser system that provides laser pulse repetition rates up to 1 MHz. Individual laser pulse energies of tilde 1 J are obtained at a laser repetition rate of 250 kHz, and proportionately lower energies as the pulse repetition rate is increased to 1 MHz. Nearly uniform pulse to pulse micropulse laser pulse energies are obtained providing for nearly constant illumination over the ~120 microsecs laser pulse envelope duration. Example images are provided illustrating the integration of the ruby laser system and camera system with a gun range to obtain high speed framing camera images of ballistic events.

MHz Class Repetitively Q-Switched, High-Power Ruby Lasers for High-Speed Photographic Applications

Some Highlights in the History of High-Speed Photography and Photonics as Applied to Ballistics

We are currently developing a high-speed photographic system that images objects engulfed in high radiance backgrounds. Using a copper vapor laser as a pulsed illuminator in conjunction with a narrow band interference filter and an electro-optic shutter as spectral and temporal filters respectively, the background radiance is diminished by eight orders of magnitude. Consequently, the back-scattered imaging photons from the laser overpower the radiant background, resulting in a sufficiently high imaging-to- background ratio. Such high levels of background discrimination is made possible by the copper vapor laser that illuminates within a spectral line of 7 GHz with great intensity centered on the 1 nm vapor laser that illuminates within a spectral line of 7 GHz with great intensity centered on the 1 nm wide transmission band of the interference filter. The laser emits 30 ns pulses with a repetition rate of 20 kHz, synchronized with an equivalent open aperture period of the electro-optic shutter. The image is captured by an electronic camera at the rate of 20,000 per second. The image is available for further digital image processing.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High-speed photographic system for objects with highly radiant backgrounds

By combining the attributes of electro-optic shuttering and pulsed laser illumination in a large format camera system, we have developed a multi-frame image converter camera with a laser illuminator that produces sequential photographs of fast phenomena with very high resolution. The combination of the large size image plane (75 mm), short exposure time per frame (minimum 12 - 15 ns), and monochromatic laser illumination provides clear, sharp, front-lit images of surfaces and shapes with no degradation by luminous air shocks or motion blur. The unique modular design of the camera and the laser allow for a variety of configurations and applications. The current camera system produces eight independent pictures or four stereo pairs. A Q-switched ruby laser with multiple pulse capability provides individual illumination for each frame. This system has photographed a variety of fast phenomena including the first stereo sequential photographs of the initial formation and early time history of high velocity shaped-charge jets.

R. D. Breithaupt

Papers

Electro-optic frame photography with pulsed ruby illumination

Electro-optic frame photography with pulsed ruby illumination