A method for improving the coating capability of low dielectric layer is disclosed. The side wall and floor bound a chamber. A control circuit may be configured to convert the measurement value into a control value. The command execution section generates, at one time, one or more control signals of a value or values corresponding to the one or more pieces of the control data received from the register at one time at a timing predetermined for the one or more pieces of the control data. The light trap includes an elongated housing through which the polarized beam passes, and light absorptive material within the elongated housing.