Comparative Analysis Of Far Field And Near Field Photometric Measurement Systems

With the improvement of people's living standard,people have more and more requirements on lighting quality.In order to improve the lighting quality,it is necessary to get more detailed and accurate photometric and colorimetric information of the light source.In the optical designing of LED,two models are generally used to simulate and evaluate the light source.They are "far field model of light source" and "near field model of light source".Most of traditional photometric measurements are based on the far field model,but the "far field model of light source" regards the light source as a point source,which is not accurate enough while in the application of short distance lighting case.In the case of "near field model of light source",the photometric data is too large and complex to apply it in actual lighting engineering.A small photometric measurement system was set up in this thesis.The measurement system mainly includes a photometric measurement equipment and a two-dimension rotary stage that control the horizontal and vertical rotation of the luminaire.The control and coordination of the rotary stage and measuring equipment are performed with LabVIEW software,so that they can perform automatic measurement and acquisition of the optical information of luminaire in full space.In spectrophotometric measurement,the measuring equipment such as CS2000,a spectrophotometer of KONICA MINOLTA company,was used to measure the luminance,luminous intensity,spectrum,color temperature and other information of the lamps.In the near field measurement,the measurement equipment could be a two-dimensional luminance meter(e.g.CA2000 from KONICA MINOLTA company).It would obtain complete near field photometric data by taking many luminance pictures of lamps.The measurement system also has some versatility and flexibility.It is convenient to measure various parameters by switching the measurement equipment,and it could also adjust the distance between the lamp and the equipment,so as to realize the far and near field measuring in the same measurement system.Small distributed photometric measurement system also has the ability of rapidphotometric distribution measurement.In this thesis,an XYZ photometric detector is realized.It can measure the spatial distribution of luminous intensity and color temperature simultaneously.The detector adopts AMS AS73210 as sensor and AMS AS89000 as pre-amplifier.While in case of light sources with flicker,a filter with the upper limit frequency of 16 Hz was introduced to eliminate the disturbance caused by the light source flicker.In this thesis,photometric parameters of CFL was measured with the XYZ detector.The luminous intensity distribution curve and color temperature distribution curve of the lamp were obtained.It indicates the detector performed well in the measuring of luminous intensity distribution and color temperature with a high measuring speed.In the thesis,near field photometric data of a flat panel lamp are analyzed also.Basing on analysis of near field model,analysis procedures for NF data were built.The luminous intensity distribution of FP lamp is calculated for different distance lighting application.The results indicates that for large size lamps,conventional far field of luminous distribution curve can't describe accurately the situations that the lamps were applied in really close distance.