Focal plane array seeker for projectiles

• US 5,129,595 A
• Filed: 07/03/1991
• Issued: 07/14/1992
• Est. Priority Date: 07/03/1991
• Status: Expired due to Term

• Current Assignee: Alliant Techsystems Incorporated (Northrop Grumman Corporation)
• Original Assignee: Alliant Techsystems Incorporated (Northrop Grumman Corporation)
• Inventors: Thiede, Edwin C., Seashore, Charles R., Cox, J. Allen
• Primary Examiner(s): Jordan, Charles T.
• Application Number:
  US07/725,196
• Time in Patent Office: 377 Days
• Field of Search: 244/3.16
• US Class Current: 244/3.16
• CPC Class Codes: F41G 7/2213 maintaining the axis of an orientable seeking head pointed at the target, e.g. target seeking gyro
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: H04N 23/20 for generating image signals from infrared radiation only
• CPC Class Codes: H04N 25/673 by using reference sources
• CPC Class Codes: H04N 25/68 applied to defects
• CPC Class Codes: H04N 25/69 SSIS comprising testing or correcting structures for circuits other than pixel cells
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

The invention provides a relatively low cost, high resolution precision target acquisition and tracking system capable of operation on nonspinning ballistic munition projectiles, or the like. The system includes an imaging IR sensor head which is preferably gimbal mounted and utilizes an ambient temperature operating, densely packed, two dimensional focal plane array of electromagnetic radiation infrared sensitive (IR) sensors. The array is adapted to operate in a staring mode and a small amount of thermal stabilization is provided. Signal processing electronics are included with stabilizing self-calibrating non-uniformity compensation processing capabilities. This is combined with a high speed, high resolution real-time image processing system to extract target features and which operates with a discriminating, tracking and control system which identifies, targets and initiates tracking to impact on a selected target.

Claims

1. An infrared (IR) sensitive seeker system for gimballed or non-gimballed mounting on a ballistic projectile capable of withstanding relatively high g forces and operating in a staring mode, the seeker system comprising:

an imaging IR sensor system having a two-dimensional focal plane array (FPA) of ambient temperature operable IR sensors, wherein each sensor in the array has a baseline output is adapted to receive radiation and produce a temperature related analog output therefrom, the system including digitizing means for digitizing the analog output and which collectively produces an output in the form of a digital stream of data;

optical system to cause incoming IR to be focused on the FPA;

signal amplification and analog to digital conversion means to initially process the output from the sensors;

high speed, high resolution real-time imaging system to produce sequential real-time high resolution frames based on the sequential output of the two dimensional array;

high speed, high resolution real-time image processing means to extract target features; and

control and discrimination means to utilize high resolution target feature image data to control the sensor and image framing and identify targets of interest and cause the ballistic projectile to track and approach identified targets of interest.

3. The seeker system of claim 1 wherein the real-time, high resolution frames are pixel images, the pixels of which are each derived from a different sensor in the array.

4. The seeker system of claim 1 further comprising means for compensating for non-uniformity in the array baseline output.

7. The seeker system of claim 1 further comprising compensation circuitry and algorithms to adapt to an arbitrary baseline temperature.

8. The seeker system of claim 1 further comprising means for stabilizing the baseline temperature of the array to the seeker ambient temperature.

9. The seeker system of claim 1 wherein the FPA is gimbal mounted.

10. The seeker system of claim 3 wherein the FPA is gimbal mounted.

2. The seeker system of claim wherein the IR sensing system is further characterized by an array of microbridge bolometer sensors.

5. The seeker system of claim 2 wherein the real-time high resolution frames are pixel images, the pixels of which are each derived from a different one of the microbridge bolometer sensors.

6. The seeker system of claim 5 in which the array baseline output further includes means which provide a uniform output for all pixels derived from microbridge bolometer sensors looking at a uniform temperature source in a field-of-view.

11. The seeker system of claim 6 wherein the FPA is gimbal mounted.

12. The seeker system of claim 2 further characterized by a Cassegrain optics system to focus the received radiation onto the focal plane array.

13. The seeker system of claim 6 further characterized by a Cassegrain optics system to focus the received radiation onto the focal plane array.

14. The seeker system of claim 11 further characterized by a Cassegrain optics system to focus the received radiation onto the focal plane array.