APMP Pilot Study on High Transmittance Haze

Abstract This article presents the results of the Asia Pacific Metrology Programme (APMP) pilot comparison on high transmittance haze (TH), specifically TH >40 %. Various methods, including ASTM D1003, ISO 14782, the double beam method, and the double compensation method were employed. The results revealed that ASTM D1003 is still influenced by failure to compensate for sphere throughput, even in high TH artefacts. In contrast, the other methods exhibit good consistency, as expected. This article also analyses the total transmittance (TT) and diffuse transmittance (DT) obtained using the double compensation method, theoretically capable of determining accurate TT, DT, and TH, discussing the possibility of inconsistency in the reflectance between the sphere wall and the white plate affecting the agreement.