As variation of light sources such as Solid State Lighting (SSL) increases, it is becoming more important to evaluate luminous intensity distribution and total luminous flux with goniophotometry. To reduce uncertainty and increase efficiency of total luminous flux evaluation with goniophotometry, we compare several existing calculation methods for total luminous flux evaluation. For the comparison, some incandescent lamps and LED lamps that differ with regard to luminous intensity distribution have been measured by a goniophotometer, and those total luminous flux values have been evaluated using the existing methods. The comparison results show that optimization for the angular measurement step taking into account not only beam spread angle but also details of luminous intensity distribution is required for reducing the measurement time and the measurement uncertainty simultaneously. To optimize the angular measurement step, modulation of the step in accordance with the 2nd derivative of the luminous intensity distribution is required.
Illuminance and exposure time are controlled to avoid rapid deterioration of museum objects. However, it is possible that the effect of harmful ultra-violet rapiation and visible light on objects is evaluated incorrectly by integrated illuminance. In this report, an evaluation method for light exposure levels for museum objects is discussed. Exposure tests of textiles with different light sources were conducted, and the progress of deterioration of the textiles was evaluated with two different light exposure level indexes : integrated illuminance and effective radiant exposure. The results show that effective radiant exposure can be used to evaluate light exposure levels causing damage to textiles more accurately. Furthermore, this paper proposes a new method that corrects illuminance and integrated illuminance. The new method easily improves the precision of evaluating light exposure levels with conventional integrated illuminance.
The authors designed a lighting system that expresses the characteristics and traditional landscape elements at night in Ozeki Park in Kaneyama Town, Yamagata Prefecture. By distributing small lights along the water surface, trees, and a wooden wall, it was considered that each landscape element would be individually conspicuous at night. It was also considered that the reflection in the water surface increased, and this encouraged people to walk around at night. As a result of implementing the landscape lighting for half of year 2014, the total amount of light flux was reduced to about 50% of the previous amount. Furthermore, it was confirmed that local residents could walk without anxiety and the lighting environment became harmonized with the surrounding landscape. The lights put in a row at suitable intervals showed that the landscape, walking, and energy saving could coexist.