Before a printing operation, printing conditions related to occurrence of mist are acquired. The trajectory of a primary beam 4 is deflected by a deflector or changed by a movable aperture such that the beam is incident on a plurality of lenses 6 and 7 off the axes thereof. The brace members are adapted to be attached to support members to form the corners of a gate box functioning as the structural portion of the gate assembly. Authorization and use of the account may be sought from an authorization agent using the account data provided on the portable device. An object reflects the terahertz pulse and the reflected pulse is detected in the transceiver using a probe pulse.