In a magnetic disk apparatus, mounting of plural heating elements to a magnetic head slider is permitted. Therefore, the imaging apparatus and the imaging method can directly start an AF operation at current image focusing locations of two imaging optical systems, without setting the image focusing locations to fixed initial locations in a focusing operation of the imaging optical systems. A random number and a random seed are received from the authentication agent. A latch actuator is mounted on the mullion at a selected position vertically spaced apart from the latch arm, and includes a slide which shifts between latched and unlatched positions.