研究目的
To develop an uncertainty budget for the calibration of luminance meters used in road tunnels, focusing on photopic adaptation luminance measurement, and to analyze the contributions of various factors to the combined uncertainty.
研究成果
The expanded uncertainty for the calibration of luminance meters using the Type C method is 1.65% (k=2), which is sufficient for ensuring proper and energy-efficient control of road tunnel lighting systems. Key factors contributing to uncertainty include calibration of the reference photometer, instability and non-uniformity of the luminance source, stray light, alignment issues, color correction, distance measurement, and non-linearity. Improvements could involve using photocurrent multipliers or higher-resolution displays for better accuracy. The analysis provides a reliable framework for uncertainty assessment in photometric calibrations for tunnel applications.
研究不足
The calibration value is valid only for the specific measurement geometry described and may not apply to other geometries. The method is sensitive to factors like stray light, non-uniformity of the source, and alignment errors. Long-term drift of equipment could become significant, and accuracy might be limited by display resolution for small measurement values. The setup uses a cube source, which may have limitations compared to more complex integrating spheres.
1：Experimental Design and Method Selection:
The study uses Type A and Type C calibration methods for luminance meters, with a focus on the Type C method involving an integrating cube source. The mathematical model for combined uncertainty is based on equations derived from measurement geometry and illuminance measurements.
2：Sample Selection and Data Sources:
Luminance meters used in road tunnels are calibrated; specific samples or datasets are not detailed beyond the general setup.
3：List of Experimental Equipment and Materials:
Includes a uniform luminance source (cube with defined aperture and opal plate), alignment laser, linear bench, standard photometer, tube with apertures, calibrated measuring tape, calibrated gauge, and intensity standard lamps. Equipment specifications are not fully detailed.
4：Experimental Procedures and Operational Workflow:
The luminance meter under test is calibrated against a reference luminance source stabilized at 2856 K. Alignment is done using a laser beam, and measurements are taken at different luminance levels by switching light sources. Room temperature is maintained at ~24°C to minimize thermal effects, and stray light is controlled with non-reflecting surfaces.
5：Data Analysis Methods:
Uncertainty is evaluated using Type A (statistical analysis of repeated measurements) and Type B (based on available information, manufacturer specifications, etc.) methods. The combined standard uncertainty is calculated using sensitivity coefficients and expanded with a coverage factor k=2 for a 95% confidence level. Contributions of factors are analyzed using coefficients of contribution.
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