Abstract: In order to reveal the influence of ITO film thickness on optical transmittance

and colouration，the visible transmittance， average transmittance and the transmittance

at 550 nm ( the human eyes sensitive wavelength) were calculated by mean of

TFCalc optical film design software. The influence of thickness and incident angle on the

transmittance and colouration of ITO films was investigated by the theory of film interference. The

results suggested that a series of transmission peaks appear with increasing the ITO film

thickness. With the in- crease of the film thickness，the optical transmittance of ITO films is

serrated as well as the average transmittance and transmittance at 550 nm. Accordingly，the

colouration of ITO film changes periodically. When the incident an- gle increases from 30 to 60

degree，the colouration of the ITO films with thickness of 300 nm changes from dark

purple to bright purple. The color chart of ITO films was established in this paper，which provides

technical support for industrial control and improvement of colouration of ITO films.

Key words: ITO, visible transmittance, colouration, thickness of film, incident angle