| 摘要 |
PURPOSE:To obtain an invariably sharp display image even when the distance to a subject and working temperature vary greatly by providing a means which controls the movement of an optical image formation system. CONSTITUTION:Projection luminous flux 22 from a scanning mirror 5 is made incident to a four-quadrant detector 23 through lenses 9a and 9b of optical image formation system and orthogonally arranged cylindrical lenses 24a and 24b, and if defocusing occurs, the shape of the incident luminous flux 32 becomes elliptic. Four quadrant detection signals 18a-18d and inputted to a signal processing circuit 23 and a target position signal 25 is applied from a scanning control circuit 16 to output a focusing control signal 21 corresponding to the defocusing of the subject. The focusing control signal 22 controls said lenses 9a and 9b along an optical axis 10 of image formation through a servomotor 20 and a holder 19 to obtain the best image wherein the subject is invariably in focus, and the two- dimensional infrared image of the subject 1 is displayed on a display device 7 with a display image signal 15. |
