Dual field of view catadioptric optical system

• US 4,877,317 A
• Filed: 02/27/1987
• Issued: 10/31/1989
• Est. Priority Date: 10/03/1983
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Cottle, Wilbur W., Gibbons, Robert C.
• Primary Examiner(s): ARNOLD, BRUCE
• Application Number:
  US07/002,061
• Time in Patent Office: 977 Days
• Field of Search: 350/559
• US Class Current: 359/421
• CPC Class Codes: G02B 17/0808 on-axis systems with at least one of the mirrors having a central aperture
• CPC Class Codes: G02B 17/0852 having a field corrector only
• CPC Class Codes: G02B 17/0896 with variable magnification or multiple imaging planes, including multispectral systems systems with only refractive elements G02B15/14

Abstract

A dual field of view catadioptric optical system is disclosed which includes a narrow field of view (FOV) and a wide FOV. The narrow field of view includes an apertured stationary primary reflector and a secondary reflector which may be pivoted into a common optical path for blocking radiant energy for the wide field of view during operation in the narrow field of view and pivoted out of the common optical path for operation in the wide field of view. In another embodiment, the secondary reflector is replaced by a transparent/reflector which is always located in the common optical path. The element is transparent to radiant energy until heated at which time it becomes reflective. Thus, when transparent, the system operates in the wide field of view mode and when reflective, the system operates in the narrow field of view mode.

Claims

1. A dual field of view optical system including a narrow field of view optical subsystem, a wide field of view optical subsystem and a relay subsystem common to said narrow field of view and wide field of view optical subsystems, comprising:

(a) said narrow field of view optical subsystem including a reflective objective system for forming a first focal plane, the reflective objective system including a primary reflector for reflecting radiant energy incoming thereto and a fixed optical element responsive to an external source of electrical power for reflecting radiant energy from said primary reflector towards the relay subsystem to form a first focal plane, said fixed optical element mounted in the optical path between said wide field of view subsystem and said optically refractive relay subsystem;

(b) said wide field of view optical subsystem including a refractive objective lens system for forming a first focal plane and including said fixed optical element which transmits the wide field of view light to said relay subsystem when said fixed optical element provides radiant energy transmission in response to an absence of supplied electrical power;

(c) said optically refractive relay subsystem common to the narrow field of view reflective objective system optical path and wide field of view refractive objective lens system optical path for forming an exit pupil, said exit pupil being a second focal plane at an accessible location, said optically refrative relay subsystem including an apertured means serving as a field stop for substantially eliminating the passage of any extraneous energy; and

(d) control means in the optical path between the narrow field of view optical subsystem and the wide field of view optical subsystem for controlling selectively the fixed optical element coupling of the narrow field of view optical subsystem or the wide field of view optical subsystem to the optically refractive relay subsystem;

(e) the control means for controlling selectively the optical coupling of the narrow field of view optical subsystem and the wide field of view optical subsystem to the optically refractive relay subsystem comprises an electrical means for converting the fixed optical element into one of a secondary reflector for blocking the wide field of view subsystem from the optically refractive relay subsystem and optically connecting the narrow field of view subsystem to the optically refractive relay subsystem;

wherein

(f) the transparent reflector optical element changes from being a transparent to a reflector element with temperature and the electrical means includes an electrical heater mounted in close proximity to the transparent reflector optical element and a circuit means for selectively providing power to the heater means whereby temperature is selectively changeable with the selectively providing of power to the heater means and thus the optical coupling of the narrow field of view optical subsystem and the wide field of view optical subsystem to the optically refractive relay subsystem is controllable.

2. The dual field of view optical system according to claim 1 wherein the static optic element comprises:

a vanadium dioxide element.

3. The dual field of view optical system according to claim 1 wherein the wide field of view optical subsystem is a lens doublet.

4. A dual field of view optical system including a narrow field of view optical subsystem, a wide field of view optical subsystem, a fixed optical element and a relay subsystem common to said narrow field of view and wide field of view optical subsystems, comprising:

(a) said narrow field of view optical subsystem including a reflective objective system for forming a first focal plane, the reflective objective system including a primary reflector for reflecting radiant energy incoming thereto and said fixed optical element responsive to a source of electrical power for providing light reflection for receiving reflected radiant energy from said primary reflector and reflecting said received radiant energy towards said relay subsystem to form a first focal plane, said fixed optical element mounted in the optical path between said wide field of view subsystem and said optically refractive relay subsystem;

(b) said wide field of view optical subsystem including a refractive objective lens system and said fixed optical element responsive to the absence of electrical power supplied thereto to transmit therethrough radiant energy from said refractive objective lens system for forming a first focal plane;

(c) said optically refractive relay subsystem common to the narrow field of view reflective objective system optical path and wide field of view refractive objective lens system optical path for forming an exit pupil, said exit pupil being a second focal plane at an accessible location; and

(d) control means for selectively providing electrical power signals to said fixed optical element coupling of the narrow field of view optical subsystem and the wide field of view optical subsystem to the optically refractive relay subsystem to control the condition of said fixed optical element.

5. A dual field of view optical system as set forth in claim 4 wherein said optically refractive relay subsystem includes an apertured means in said primary reflector providing a field stop for substantially eliminating the passage of any extraneous energy to said second focal plane.