Figure 1: We capture the solar/skydome spectral radiance and compare state-of-the-art simulation models. (a) Our custom built solarskydome scanner, (b) relative differences between state-of-the-art simulation models and our measured samples over the hemisphere, (c) example of sample points and captured sky imagery, and (d) spectral radiance curves for different sample points in (c). AbstractThe illumination and appearance of the solar/skydome is critical for many applications in computer graphics, computer vision, and daylighting studies. Unfortunately, physically accurate measurements of this rapidly changing illumination source are difficult to achieve, but necessary for the development of accurate physically-based sky illumination models and comparison studies of existing simulation models.To obtain baseline data of this time-dependent anisotropic light source, we design a novel acquisition setup to simultaneously measure the comprehensive illumination properties. Our hardware design simultaneously acquires its spectral, spatial, and temporal information of the skydome. To achieve this goal, we use a custom built spectral radiance measurement scanner to measure the directional spectral radiance, a pyranometer to measure the irradiance of the entire hemisphere, and a camera to capture high-dynamic range imagery of the sky. The combination of these computer-controlled measurement devices provides a fast way to acquire accurate physical measurements of the solar/skydome. We use the results of our measurements to evaluate many of the strengths and weaknesses of several sun-sky simulation models. We also provide a measurement dataset of sky illumination data for various clear sky conditions and an interactive visualization tool for model comparison analysis available at
High-power, external-cavity semiconductor lasers with narrow bandwidth and fiber-coupled output are designed and constructed. An output power of 540 mW is coupled out of a 100-mum multimode fiber with coupling efficiency of 72% when the laser is operated at 1.1 A. The emission linewidth is as narrow as 22 GHz, and the wavelength is tunable from 779.7 to 793.0 nm. Application of such lasers to remote real-time Raman sensing of materials is also demonstrated.
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO WOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)12-07-1999 REPORT TYPE Final Report DATES COVERED (From -To)14 Feb 1997 to 31 May 1999 TITLE AND SUBTITLEDiode Laser Raman Scattering Prototype Gas-Phase Environmental Monitoring RY PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Process Instruments, Inc. 825 North 300 West Suite 225 Salt Lake City, UT 84103-1414 PERFORMING ORGANIZATION REPORT NUMBER SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)AFRL/DELS 3550 Aberdeen Ave SE Kirtland AFB NM 87117-5776 SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) AFRL-DE-TR-1999-1063 DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTWe proposed developing a diode-laser-based, full spectrum Raman scattering instrument incorporating a multipass, external cavity enhancement cell for full spectrum, gas phase analysis of environmental pollutants. Narrow, well-defined Raman peaks and insensitivity to moisture contamination allow for full-spectrum with detection on the order of 1 percent sensitivity with 1 to 2 minute integrations. Conventional Raman instrumentation is too expensive and not sensitive enough for industrial applications. For excitation of Raman scattering Ar-ion lasers have too short of a life and are too expensive for continuous use. Semiconductor laser diodes offer longer life than conventional lasers and now have sufficient power for rapidly obtaining Raman signals. Traditionally environmental instrumentation requires hot stack gases to be cooled prior to being measured. Cooling stack gas results in condensation and loss of water soluble species. Phase II focused on a laser power build-up of cavity design that would be stable, simple to reproduce, and cost effective. We assembled a bench prototype power build-up cavity with solid-state laser diode pumping that incorporated an efficient spectrograph (patent pending), application specific software, user interface, and calibration procedures. Although the prototype was not stable for on-line testing in industrial environmental monitoring applications, the bench prototype was extensively tested in the lab...
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