Abstract: In order to ensure the traceability of high absorption measurement,based on cavity absorber’s light trap effect,a cavity wide spectrum high absorption standard with absorption of 0.999 and spectral range of 300~1 100 nm is developed and tested.The absorption of cylindrical conical,spherical,and threaded cylindrical absorbers with different diameters were designed and simulated by Fred software based on Gouffe and Monte Carlo methods.Two sets of aluminum alloy cavity absorber with different inner wall materials of aviation black paint and electroplated nano coating were made and tested，their absorption analysis of different cavity shapes and sizes is given.Result shows that the opening diameter of the cavity is 25 mm,the inner wall coating is aviation black paint or nano copper with an absorption of 0.970,the absorption of the cylindrical conical cavity and the spherical cavity absorber is higher,and the average absorption in 300~1 100 nm is above 0.999.

Key words: High absorption, Cavity absorber, High absorption standard