The available Lumonics TEA CO2 lasers (gain lengths 40 cm and 120 cm) have been mounted on an optical table and preparation of the mode-locked, line- selected output has begun. The 0.5 micro sec TEA laser pulse was considered to be too short for effective mode-locking so its pulser was modified into a simple three-element PFN to give 3 micro sec excitation. Single transverse mode operation was obtained with the 40 cm device in a folded 6m optical cavity, giving an output energy of 0.5 J in a...
Topics: DTIC Archive, TEXTRON DEFENSE SYSTEMS EVERETT MA, *CONVERSION, OSCILLATORS, OUTPUT, OPTICAL...
Topics: DTIC Archive, TEXTRON DEFENSE SYSTEMS EVERETT MA, *CARBON DIOXIDE LASERS, *TEA LASERS, MODE LOCKED...
A 15 MW. magnetohydrodynamic (MHD) power system was designed. built, and tested.
Topics: DTIC Archive, Swallom, Daniel W., TEXTRON DEFENSE SYSTEMS EVERETT MA, *ACCEPTANCE TESTS, *WEAPON...
A high quality mode locked pulse train was obtained at 9.55 microns, the CO2 wavelength chosen for frequency doubling into the atmospheric window at 4.8 microns. The pulse train consists of a 3 micro sec burst of 1.5 nsec pulses separated by 40 nsec, in a TEM(00) mode and with a total energy of 100 mJ. The pulse intensity without focussing is about 3 MW/sq.cm., already quite close to the target intensity of 10 MW/sq.cm. for frequency doubling in a AgGaSe2 crystal. The mode-locked train is...
Topics: DTIC Archive, TEXTRON DEFENSE SYSTEMS EVERETT MA, *FREQUENCY MULTIPLIERS, *MODE LOCKED LASERS,...
The duration of the mode-locked CO(2) laser pulses was measured to be 0.9 + or - nsec by the technique of (second harmonic) autocorrelation. Knowing the pulse duration, the spot size, and the harmonic conversion efficiency, a detailed fit of experiment to theory gave an estimate of the nonlinear coefficient of AgGaSe(2). d36 = 31 + or - V(1), in agreement with the most accurate literature values. A number of experiments were made with longer pulse trains in which the highest harmonic energy...
Topics: DTIC Archive, TEXTRON DEFENSE SYSTEMS EVERETT MA, *CARBON DIOXIDE LASERS, *FREQUENCY MULTIPLIERS,...
This work addresses the possibility of a high average power coherent light source in the mid-infrared, specifically in the 4.8 micrometers atmospheric window. The approach is to frequency-double the 9.55 micrometers CO2 laser line, yielding 4.775 micrometers. In order to achieve efficient conversion, the intensity of the laser is increased by intracavity resonant modulation, or modelocking. The intensity for efficient conversion in typical available lengths of doubling material is at a minimum...
Topics: DTIC Archive, TEXTRON DEFENSE SYSTEMS EVERETT MA, *INFRARED LASERS, *FREQUENCY MULTIPLIERS, *MODE...
The month has been spent in a series of harmonic generation experiments at increasing peak intensity and fluence. Second harmonic beam quality has been measured. Using the oscillator alone, with grating selection of the 9.55 micrometer line, the pulse train consisted of a spike containing about 10 pulses followed by a tail containing about 40 pulses. Both the spike and the tail contained approximately equal energy, the combined total going as high as 180 mJ. The crystal was located near to the...
Topics: DTIC Archive, TEXTRON DEFENSE SYSTEMS EVERETT MA, *CONVERSION, MIRRORS, PEAK VALUES, RATIOS, TIME...
