Simple camera calibration for light measurements
The availability and decreasing prices of digital photographic cameras using megapixel sensors could point to its use as high quality light measuring devices if simple and effective calibration procedures could be put to work. This paper proposes such a system, using a common digital camera combined with low cost reference color charts. The procedure to obtain the response function of the camera, the production of the color chart and its calibration is presented. In this way, it is possible to obtain light measurements otherwise only possible with sophisticated and expensive equipments.
Calibration of Camera for Light Quality Measurements of Low-Power Lamps
Environmental concerns and power efficiency point to increased use of power efficient lamps. Different manufacturers and price targets produce a wide range of light outputs, varying in intensity and spectral distribution. This type of apparatus also presents a non-linear load to the electric power supply, introducing some problems that should be taken in consideration and corrected as much as possible. To be able to measure light quality, we propose a technique that uses a conventional digital photographic camera and a set of colour-reference reflective cards. By analysis of the obtained images, a colour quality index can be computed and used to compare different type of lamps. The calibration of the set-up is crucial for the approach and some problems need to be solved for the reliability of the method.
5.63 and 5.80 MeV levels of Ne20; de-excitation branching
Abstract The ratio Г γ /Г for the 5.63 and 5.80 MeV levels of Ne 20 has been determined to be 0.077 (±0.008) and −4 , respectively, by using the C 12 (C 12 , α)Ne 20 reaction and determining the fraction of the events in which the alpha-particle and the Ne 20 recoil are present in coincidence at the kinematically correct angles. In both cases these results in themselves are shown to imply radiative E1 transition (5.63→1.63 and 5.80→0, respectively) probabilities ⪡5 × 10 −5 Weisskopf units. When taken together with the life-time for the 5.63 MeV level measured by Evans et al . values of Г( E1 ) ≲ 5 × 10 −6 and Г α ≈ 6% of the particle estimate are obtained for this state.