Field demonstration of simultaneous wind and temperature measurements from 5 to 50 km with a Na double-edge magneto-optic filter in a multi-frequency Doppler lidar.

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.

Continuous-wave sodium D2 resonance radiation generated in single-pass sum-frequency generation with periodically poled lithium niobate.

With two cw single-mode Nd:YAG lasers at 1064 and 1319 nm and a periodically poled lithium niobate crystal, 11 mW of 2 kHz/100 ms bandwidth single-mode tunable 589 nm cw radiation has been detected using single-pass sum-frequency generation. The demonstrated conversion efficiency is approximately 3.2%[W(-1) cm(-1)]. This compact solid-state light source has been used in a solid-state-dye laser hybrid sodium fluorescence lidar transmitter to measure temperatures and winds in the upper atmosphere (80-105 km); it is being implemented into the transmitter of a mobile all-solid-state sodium temperature and wind lidar under construction.

Na double-edge magneto-optic filter for Na lidar profiling of wind and temperature in the lower atmosphere.

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.

Spectral structure of laser light scattering revisited: bandwidths of nonresonant scattering lidars.

It is well known that scattering lidars, i.e., Mie, aerosol-wind, Rayleigh, high-spectral-resolution, molecular-wind, rotational Raman, and vibrational Raman lidars, are workhorses for probing atmospheric properties, including the backscatter ratio, aerosol extinction coefficient, temperature, pressure, density, and winds. The spectral structure of molecular scattering (strength and bandwidth) and its constituent spectra associated with Rayleigh and vibrational Raman scattering are reviewed. Revisiting the correct name by distinguishing Cabannes scattering from Rayleigh scattering, and sharpening the definition of each scattering component in the Rayleigh scattering spectrum, the review allows a systematic, logical, and useful comparison in strength and bandwidth between each scattering component and in receiver bandwidths (for both nighttime and daytime operation) between the various scattering lidars for atmospheric sensing.

High-spectral-resolution lidar with iodine-vapor filters: measurement of atmospheric-state and aerosol profiles.

A high-spectral-resolution lidar can measure vertical profiles of atmospheric temperature, pressure, the aerosol backscatter ratio, and the aerosol extinction coefficient simultaneously. We describe a system with these characteristics. The transmitter is a narrow-band (FWHM of the order of 74 MHz), injection-seeded, pulsed, double YAG laser at 532 nm. Iodine-vapor filters in the detection system spectrally separate the molecular and aerosol scattering and greatly reduce the latter (-41 dB). Operating at a selected frequency to take advantage of two neighboring lines in vapor filters, one can obtain a sensitivity of the measured signal-to-air temperature ratio equal to 0.42%/K. Using a relatively modest size transmitter and receiver system (laser power times telescope aperture equals 0.19 Wm(2)), our measured temperature profiles (0.5-15 km) over 11 nights are in agreement with balloon soundings to within 2.0 K over an altitude range of 2-5 km. There is good agreement in the lapse rates, tropopause altitudes, and inversions. In principle, to invert the signal requires a known density at one altitude, but in practice it is convenient to also use a known temperature at that altitude. This is a scalable system for high spatial resolution of vertical temperature profiles in the troposphere and lower stratosphere, even in the presence of aerosols.

Continuous-Wave, All-Solid-State, Single-Frequency 400-mW Source at 589 nm Based on Doubly Resonant Sum-Frequency Mixing in a Monolithic Lithium Niobate Resonator.

Sum-frequency mixing of two cw single-mode Nd:YAG lasers in a doubly resonant congruent lithium niobate resonator generated two TEM(00) beams of single-frequency 589-nm radiation. The primary beam had a power of 400 mW and the secondary beam of approximately 15 mW by use of 320 mW of 1319-nm and 660 mW of 1064-nm Nd:YAG radiation incident on the lithium niobate resonator. This corresponds to an optical power conversion efficiency of more than 40%.

Daytime mesopause temperature measurements with a sodium-vapor dispersive Faraday filter in a lidar receiver.

Using a dispersive Faraday bandpass filter, we have upgraded our Na temperature lidar to be capable of 24-h operation. Along with a transmitting telescope to reduce the laser beam divergence to 0.2 mrad, the initial use of this unique narrow-band filter in a lidar receiver allowed us to reduce the detected daytime sky background to a level previously encountered at night, making routine daytime temperature measurements in the mesopause region a reality. The implementation, characterization, and results of what we believe are the first daytime mesopause temperature measurements are reported.

Doppler-free saturation fluorescence spectroscopy of Na atoms for atmospheric application.

The well-known theory of absorption and fluorescence is briefly reviewed in a systematic manner for the Na D transitions. The resulting formalism is applied to simulation of Doppler-free saturation fluorescence spectra. With only one adjusting parameter, the nonradiative rate chosen to represent the time a thermal atom takes to move across the laser beams, the simulated Doppler-free spectra match the measured ones well for both D(1) and D(2) transitions over one decade of excitation intensities. Relative to the weighted center of the six D(2) hyperfine transition lines, the frequencies of the dominant Doppler-free features have been determined from a simulated spectrum to within ±0.1 MHz to be -651.4, 187.8, and 1068.0 MHz, respectively, for D(2a), crossover, and D(2b) resonances. These features may be used as accurate frequency references for atmospheric spectroscopy. They are essential for the operation of the newly developed narrow-band Na fluorescence lidar for wind and temperature measurements in the mesopause region.

Sodium-vapor dispersive Faraday filter.

Ultranarrow bandpass Na vapor dispersive Faraday filters at 589 nm are studied experimentally and theoretically. Their anticipated performance in the line-center operation is demonstrated experimentally with a thin Na cell in an axial magnetic field of 1750 G. A peak vapor transmission of 85%, a FWHM linewidth of 0.002 nm (or 1.9 GHz), and a background transmission of 2 x 10(-5) have been achieved.

High-spectral-resolution Rayleigh-Mie lidar measurement of aerosol and atmospheric profiles.

We report what is to our knowledge the first demonstration of simultaneous measurement of tropospheric temperature and aerosol extinction coefficient profiles using a high-spectral-resolution Rayleigh-Mie lidar. With the pressure at a single reference height independently provided, our lidar inversion is capable of deducing the vertical atmospheric profiles, including temperature, pressure, and density, as well as aerosol profiles, including backscatter ratio, extinction coefficient, and backscatter phase function.

High-spectral-resolution fluorescence light detection and ranging for mesospheric sodium temperature measurements.

The principle and practice of narrow-band light detection and ranging (lidar) for temperature measurements are discussed, with emphasis on a new two-frequency technique for measuring mesospheric Na temperature and density profiles. The uniqueness of this narrow-band lidar lies in the transmitter whose line-shape function can be measured directly. The frequency of the laser output can be monitored simultaneously during data acquisition with Doppler-free fluorescence spectroscopy by using a laboratory Na cell. These measurement techniques along with the procedures for data analysis are described in detail. At present the absolute temperature accuracy at the Na layer peak is +/-3 K (+/-4 K) with a vertical resolution of 1 km and an integration period of 5 min (2.5 min). Potential applications and furtherimprovements in this lidar technique are also discussed.

[Detecting the safety depth on human back loci by computer tomographic scanning].

The study was carried out at Tri-Service General Hospital and Mackay General Hospital. The sample population of patient was totally 120. According to their body weight and height, they were divided into six groups with various sizes, i.e. normal, over and under-weighted adults, followed by sex differences. After computer tomographic scanning results from patients' body back, the relative acupuncture loci should be measured through their anatomical position, then the distance between surface of body back and thoracic pleura could be defined as its safety depth. For each locus of the groups, the mean and its confident interval could be found. The analysis of variance (ANOVA), t-test, and multiple regression were also calculated by means of computer. The results showed that there were no significant differences on body back loci within sex differences, but for different body sizes, there appeared statistically significant differences for each locus, (P less than 0.01), so the safety depth for each back locus have actually been proved. Not only these data provided more useful information for clinical practices, but also our standard safety depth for each loci on back can then be established.

Continuous-wave Rayleigh-Brillouin-gain spectroscopy in SF(6).

We have obtained cw Rayleigh-Brillouin-gain spectra of SF(6) for both forward and backward scattering geometry with high spectral resolution. The spectral resolution is better than 4 MHz, and a Brillouin-frequency shift as small as 42 MHz is clearly resolved. Extension of the present technique to other studies is discussed.

Laboratory measurements of atmospheric temperature and backscatter ratio using a high-spectral-resolution lidar technique.

A narrow-band atomic blocking (bandstop) filter capable of high aerosol rejection has been developed for lidar applications. Using this filter, and our proposed new high-spectral-resolution lidar technique, laboratory measurementsof atmospheric temperature and backscatter ratio have been made, with an accuracy of 1 K and +/-3%, respectively.

Real-time monitoring of crystallization and structural transformation of titania films with Raman spectroscopy.

The feasibility of using Raman spectroscopy to monitor the process of crystallization and structural transformation of thin films in real time has been demonstrated experimentally. Although only amorphous titania films are investigated, the technique can be applied to other optical films and to probe the deposition of such films as well.

Two-component velocity measurements in a supersonic nitrogen jet with spatially resolved inverse Raman spectroscopy.

Using inverse Raman spectroscopy (IRS), we directly measured two perpendicular velocity components by crossing two probe laser beams symmetrically with the pump laser beam. Because of the crossing, the spatial resolution was improved by more than 1 order of magnitude compared with that obtained with previous IRS measurements. This made it possible to map out the planar velocity and temperature distributions in a supersonic N(2) jet. The measured distributions are in good agreement with theoretical calculations. Extension to the measurement of all three velocity components is discussed.