A high temperature camera apparatus having an elongated camera housing tube and an elongated camera support member, supporting a video camera at the interior end of the camera housing tube. The batt is laminated to at least one facing layer of film, paper or fabric. After a thin film transistor and a passivation film are formed on the other substrate, ITO is deposited on the passivation film and patterned to form a pixel electrode which contains open areas with 3 to 20 micron width. An electrode portion is formed by the bent portion of the conductor which extends from the distal end of the elongate shaft. The echo path estimate is applied to the first signal to determine an equalised first signal, which is is compared with the second signal to determine an estimate of the echo component. Among the advantages: the gate structure lowers overall gate resistance and reduces the short channel effect.