A Na double-edge magneto-optic filter is proposed for incorporation into the receiver of a three-frequency Na Doppler lidar to extend its wind and temperature measurements into the lower atmosphere. Two prototypes based on cold- and hot-cell designs were constructed and tested with laser scanning and quantum mechanics modeling. The hot-cell filter exhibits superior performances over the cold-cell filter containing buffer gas. Lidar simulations, metrics, and error analyses show that simultaneous wind and temperature measurements are feasible in the altitude range of 20-50 km using the hot-cell filter and reasonable Na lidar parameters.

The Penn State Allsky imager (PSASI), a user-owned-public-access (UOPA) instrument installed at Arecibo Observatory (AO: 18.3 • N, 66.75 • W; altitude: 350 m a.s.l.; L = 1.43 at 300 km; dip angle: 46• ; geomagnetic coordinates: 29• N, 5.5• E), is a CCD-based high-resolution allsky optical imager that has been collecting ionospheric airglow data at night since May 2003. The computer controlled six-position filter wheel is equipped with three filters at 630 nm (red), 557.7 nm (green), and 777.4 nm (near-IR), respectively, which correspond to ionosphere-related oxygen emissions. The imager data, taken for more than 3.5 years now, is being used to study various ionospheric processes, such as mapped equatorial spread-F plumes, E-region gravity waves, among other, in conjunction with the AO incoherent scatter radar (ISR), mesosphere and lower thermosphere (MLT) metals lidar, and other instruments, including microbarographs. Data availability and quality as well as specific airglow events on both small/large time/spatial scales are examined, categorized, and made freely available at a data-server website. Our goal here is to briefly review the airglow science enabled by allsky imaging at AO, to describe the instrument and the data-collection methodology, and to present some of the significant results, including airglow events that correspond to ISR results.

We report the first (to our knowledge) field demonstration of simultaneous wind and temperature measurements with a Na double-edge magneto-optic filter implemented in the receiver of a three-frequency Na Doppler lidar. Reliable winds and temperatures were obtained in the altitude range of 10-45 km with 1 km resolution and 60 min integration under the conditions of 0.4 W lidar power and 75 cm telescope aperture. This edge filter with a multi-frequency lidar concept can be applied to other direct-detection Doppler lidars for profiling both wind and temperature simultaneously from the lower to the upper atmosphere. © 2009 Optical Society of America OCIS codes: 280.3640, 010.3640, 290.1310, 010.3920, 120.0280, 300.6210. Simultaneous profiling of wind and temperature from the lower to the upper atmosphere is a capability urgently needed for whole-atmosphere research and wave-coupling studies from the wave source region in the lower atmosphere to the wave impact region in the middle and upper atmospheres. Doppler lidars based on Fabry-Perot interferometers and iodine filters have achieved wind [1][2][3] or temperature [4] measurements but not both, unless a temperature channel is added to the wind lidar. This is because only one frequency is used in the lidar transmitter, leading to a single ratio for either wind or temperature derivation. In an earlier publication [5], we proposed to incorporate a Na double-edge magneto-optic filter (Na-DEMOF) into the receiver of a threefrequency Na Doppler lidar. The three frequencies of the lidar would result in three independent ratios, enabling simultaneous wind and temperature measurements from the troposphere to the stratosphere [5]. Combined with the Na Doppler lidar measurements in the mesosphere and lower thermosphere (MLT) [6], it is possible to profile both wind and temperature from the lower to the upper atmosphere. In this Letter, we implement the hot-cell Na-DEMOF that we developed and characterized in [5] into the receiver of the Colorado State University (CSU) Na Doppler lidar. The initial sky tests demonstrate the wind and temperature profiling from 5 to 50 km with this multi-frequency edge-filter technique. Illustrated in Fig. 1 6°N, 105°W). The CSU Na Doppler lidar is a dye-ring-laser-based system [6] that operates at three frequencies sequentially: f a = −651.4 MHz and f ± = f a ± 630 MHz relative to the Na D 2 line center near 589 nm. The laser beam (ϳ20 mJ per pulse at 50 Hz) is split and then transmitted to the atmosphere in three directions for vector wind measurements. Three telescopes are pointed to these three directions to collect backscattered photons. The east-pointing telescope (20°off-zenith) with a diameter of 75 cm was chosen as our test channel (ϳ17% laser power). The light collected by the telescope is coupled to a multimode fiber with a 1.5 mm core that directs the light to the Na-DEMOF receiver chain. As described in [5], the Na cell in medium magnetic field acts as a double-edge filter, so different absorptions are experienced by the left-a...

Resonance fluorescence Doppler lidars using Doppler shift and spectral broadening effects are the principal instruments to simultaneously measure wind and temperature in the middle atmosphere. Such lidars demand high accuracy, precision, and stability of the laser optical frequency. Current resonance Doppler lidars suffer various problems in frequency stabilization that limit their locking precision and stability. We have addressed these problems by developing a LabVIEW®-based laser frequency locking system. This new system utilizes wavelengthmodulation and phase-sensitive-detection techniques in conjunction with a proportional-integral-derivative feedback servo loop. It achieves better than ±1-MHz locking precision and stability over 1 h. The system also remains locked throughout a series of abrupt disturbance tests. Owing to its high locking precision, immunity to electronic and laser noise, reliability, and flexibility in adapting for various systems, we believe that this new system represents a marked improvement in resonance Doppler lidar technology. ©