Tuz Golu Blog

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Tuz Golu Campaign Blog

Tuz Golu Campaign Blog

Reflectance panel calibrations

Today was the first day of laboratory measurements. The aim here is to get a handle on any differences in the calibrations of the instrumentation and reflectance panels that are routinely used during measurements in the field. This is done by comparison to transfer standards provided by NPL that are directly traceable to primary standards. The standards used are a Transfer Standard Absolute Radiance Source (TSARS) and a calibrated reflectance panel.

Things didn't start too well as the computer that controls TSARS failed. This meant a change to the program on the first day! The reflectance panal calibration was brought forward a day to allow time for a solution to the TSARS problem to be found.

Reflectance panel comparison

All the participants panels were compared to the NPL reflectance panel using a 45°/0° source/detector geometry. The source was an NPL 1kW FEL tunsten halogen lamp and the detector was an ASD spectroradiometer that ONERA in France have kindly loaned to NPL for the duration of this campaign. The panels were measured over the full range of the spectroradiometer, 350 nm to 2500 nm.

Lamp/panel geometry  Detector/panel geometry  Andrew Deadman aligning one of the reflectance panels
Lamp/panel geometry Detector/panel geometry Andrew Deadman aligning one
of the reflectance panels

 

 I am pleased to report that the TSARS problem has been solved. Thanks must go to John Mountford at NPL who sent all the required files along with detailed installation instructions, that not even Andrew could get wrong(!), that enabled Andrew to install the required software on another computer. When tested TSARS was working well, phew!