SA-2 adaptor

The image screen adaptor SA-2 is designed to measure the background luminance on image screens and similar surfaces. It can also be used for the measurement of luminance, for instance negative viewing tables.
The adaptor consists of a housing (1) of black polyacetale, a black anodised front plate (2) with a measurement aperture (3) normally of 20mm. diameter. (Other apertures are available on request.) The front plate is covered with a black velvet cloth (4) for prevention of scratching: this also prevents ambient light from reaching the measurement aperture so that the adaptor can be used in high ambient lighting. A black plate (6) is fitted to absorb internal reflections.
On the reverse side of housing, there is a hole (7) that fits the mounting of a Hagner standard detector, which is fixed in position with washers (8).
If luminances of higher levels (from 0.1 cd/m² and higher) are to be measured, the SA-2 adaptor can be connected to the detector of any E4-X, S1, S2, S3, and S4 instrument. In this case the measured luminance can easily be calculated from the formula supplied with the adaptor.
When very low luminances are to be measured, a very sensitive detector (without cosine correction, but V_λ-filtered) could be used.