Abstract: A novel human operator safety device is disclosed for use with motorized machines that have a danger zone that includes sharp cutting implements that can potentially cause operator harm. The operator safety device includes an optical or thermal sensor for either processing optically derived information to determine whether an extremity of an operator is within a predetermined proximity of the danger zone of the machine and processing thermal information to determine whether an extremity of an operator is within a predetermined proximity of the danger zone of the machine. If a presence is detected, at least a portion of the machine what may cause operator harm is stopped. For example, a thermal camera, an optical camera, laser or thermal sensor is used for determining whether an extremity of an operator is within a predetermined proximity of the danger zone.