Relation between the absorption coefficient and the transmittance spectrum

[sounouhid]

hi every one
can you tell me how to calculate the absorption coefficient of a thin film using the absorption and the transmittance spectrum plotted as a function of the wavelength (knowing that i don't know the thickness of the film )

 

[mathman]

Since you don't know the thickness your question can't be answered. To first order the absorption is a product of the coefficient and the thickness.

 

[sounouhid]

thank you i really appreciate your help