ABSTRACT
A sensitive chemical aerosol Raman detector (CARD) has been developed for the trace detection and identification of chemical particles in the ambient atmosphere. CARD includes an improved aerosol concentrator with a concentration factor of about 40 and a CCD camera for improved detection sensitivity. Aerosolized isovanillin, which is relatively safe, has been used to characterize the performance of the CARD. The limit of detection (SNR = 10) for isovanillin in 15 s has been determined to be 1.6 pg/cm3, which corresponds to 6.3 × 109 molecules/cm3 or 0.26 ppb. While less sensitive, CARD can also detect gases. This paper provides a more detailed description of the CARD hardware and detection algorithm than has previously been published.
ABSTRACT
A compact, low-threshold, multipass optical parametric amplifier has been developed for the conversion of short-pulse (360-ps) 1064-nm Nd:YAG laser radiation into eye-safe 1572-nm radiation for laser ranging and radar applications. The amplifier had a threshold pump power of as low as 45 microJ, and at three to four times this threshold pump power the amplifier converted 30% of the input 1064-nm radiation into 1572-nm output radiation.
ABSTRACT
We have observed a large variation with laser polarization in the amount of laser light resonantly backscattered from the Earth's mesospheric sodium layer located at a 90-km altitude. This variation is evidence of optical pumping of mesospheric sodium atoms.
ABSTRACT
A diode-laser end-pumped cw rotating Nd:glass disk laser that operates in the TEM(00) mode with a slope efficiency of 37% has been demonstrated to have an output power dependent on both the pumping rate and the rotation rate. As the rotation rate increases, the power increases from zero to an optimum and thereafter decreases. The initial increase is due to the lessening of the effect of medium heating on laser operation, while the decrease is due to decreased laser gain caused by sweeping of the excited-state population out of the laser cavity. At the optimum rotation rate of 2.5 Hz we obtained a cw output power of 0.55 W with 2 W of absorbed pump power; the output power was limited by the available pump power as opposed to thermal damage or thermo-optic distortion.
ABSTRACT
Laser spiking in a long pulse Nd:YAG laser has been substantially suppressed by intracavity second harmonic generation with very little loss of laser pulse energy.
ABSTRACT
We have generated pulsed, high power, sodium resonance radiation by sum frequency mixing the 1.06 microm and 1.32 microm outputs of two Nd:YAG lasers with an average power conversion efficiency of 30%. The wavelength of the sum radiation was tuned across the full Doppler width of the sodium-vapor D(2) absorption by tuning the wavelength of either Nd:YAG laser with intracavity etalons. The wavelength of the 1.32 microm Nd:YAG laser was also tuned by injection seeding with a GaInAsP/InP diode laser. We have used this sodium resonance radiation for the lidar observation of the earth's naturally occurring atomic-sodium layer at 90 km altitude.
