N241-026 TITLE: Automatic Boresight Alignment of Optical Sensors

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a capability for automated in-situ boresight alignment of multi-spectral imaging sensors and lasers.

DESCRIPTION: The Navy is fielding a suite of imaging sensors (cameras) with unprecedented capability. These sensors will provide both wide field of view (WFOV) and narrow field of view (NFOV) video imaging across a full 360° in both visible and infrared (IR) bands. Imagery from these cameras has a variety of uses from navigation to target detection, identification, and tracking. WFOV cameras will cue potential targets of interest to NFOV cameras which will then center on the target location for higher resolution inspection of the target. Therefore, knowing the axis along which each camera is looking, relative to a common reference (the position of the camera on the vessel) is critical in sensor coordination and cueing.

The optical axis of an imaging sensor normal to the center point of its focal plane, or a NFOV reticle at or near the center, is its boresight. The optical axis of laser devices, such as a NFOV rangefinder, must also be boresight aligned with the imaging sensor reticle in order to receive reflected energy from the intended target. The mechanical mount and positioning structure of the sensor serves to point the optical axis in the desired location. However, mechanical tolerances naturally cause a difference between the mechanical axis of the sensor’s mount and the true optical axis. For deployed sensors, ship vibration and harsh environmental conditions can cause alignment to degrade over time. Calibration to correct or compensate for misalignment of the optical and mechanical axes is known as boresight alignment. Therefore, boresight alignment applies across multiple elements to include the imaging sensors, laser(s), and line-of-sight (LOS) pointing by the director mount. Boresight alignment is an important step in preparing the sensor for deployment and it is particularly critical for NFOV, high magnification cameras.

Mechanical and optical alignment of the Navy’s optical sensor modules, known as line replaceable units (LRUs), is typically done in the factory or some centralized Government facility, both when the sensor is newly manufactured and after depot overhaul of the system. When the system is installed on a ship as an assembly, or following organizational level maintenance of the LRUs of a LOS director, the combination of factory alignment and mechanical tolerances is insufficient to ensure alignment across imaging sensor, laser, and LOS director elements. This results in manual, labor intensive processes that require skilled technicians to execute differing procedures across multiple systems. The current process also requires the ship to be in port with distant objects within view and is not practicable while the ship is underway. Therefore, if alignment could be performed in-place utilizing automated processes and a minimum of additional equipment, the current difficulties of calibration could be eliminated, thereby resulting in a reduced mean time to repair and significant cost savings. In addition, performance of the imaging system could be maintained while underway as environmentally induced misalignment could be periodically corrected or compensated for.

The Navy needs a technique (realized in software and hardware) for in-situ boresight alignment of optical imaging sensors (cameras) and rangefinders. There is no current capability commercially available. Techniques that generate an offset table for registration of the imagery to the baseline frame of reference are acceptable. The technique must also be useful for cameras operating in the IR spectra as well as the visible spectrum. The solution must be applicable to imaging sensors where multiple focal plane arrays use the same aperture as well as systems that have co-located but separate apertures. Most Navy systems of interest incorporate lasers that operate in the short-wave infrared (SWIR) for range finding so the solution should include the facility to calibrate in conjunction with the laser (which also may be subject to misalignment). The visible, near infrared (NIR), SWIR, and mid-wave infrared (MWIR) bands are of most interest however, a technique that could be extended to the long-wave infrared (LWIR) is attractive.

The technique should provide boresight alignment to an accuracy of 100 micro-radians or better. Solutions that require a minimum amount of added hardware (hardware added either permanently to the sensor baseline or installed temporarily for the calibration process) are desired. Likewise, the solution should be largely automatic, requiring no more skill or human intervention for calibration than typically required of the operator during normal system operation. A technology that requires no added hardware and is fully automated, if feasible and sufficiently precise, represents a full solution to the problem. Solutions that require the cooperation of other vessels or aircraft, solutions that are only feasible in certain locations of the ocean (e.g., along known coastlines), and solutions that can only be deployed to specific ship classes or require extensive modification of the vessel are not of interest. Solutions that make use of two or more imaging sensors (either co-located or not) working together are potentially acceptable, although it should be noted that the feasibility decreases rapidly as the number of cooperating sensors required for calibration goes up. For this effort, NFOV cameras are of primary interest. However, the fundamentals of the technique should be extensible to any format and magnification imaging system.

Note that the Navy does not intend to furnish tactical or otherwise representative imaging system hardware for this effort. The proposed solution should therefore include the means for test and demonstration on surrogate hardware, provided as part of the solution. A prototype (hardware and software) of the technology will be delivered to NSWC Crane Division at the conclusion of Phase II.

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by 32 U.S.C. § 2004.20 et seq., National Industrial Security Program Executive Agent and Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA) formerly Defense Security Service (DSS). The selected contractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances. This will allow contractor personnel to perform on advanced phases of this project as set forth by DCSA and NAVSEA in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material during the advanced phases of this contract IAW the National Industrial Security Program Operating Manual (NISPOM), which can be found at Title 32, Part 2004.20 of the Code of Federal Regulations. Reference: National Industrial Security Program Executive Agent and Operating Manual (NISP), 32 U.S.C. § 2004.20 et seq. (1993). https://www.ecfr.gov/current/title-32/subtitle-B/chapter-XX/part-2004

PHASE I: Develop a concept for an automated boresight alignment technique that meets the objectives stated in the Description. Demonstrate the feasibility of the concept in meeting the Navy’s need by any combination of analysis, modelling, and simulation. Analyze the accuracy of the proposed technique in compensating for axial misalignments in NFOV multi-spectral imaging systems. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.

PHASE II: Develop and deliver a prototype automated boresight alignment technique for imaging sensors based on the concept, analysis, preliminary design, and specifications resulting from Phase I. Demonstration of the automated boresight alignment technique shall be accomplished through test of a prototype in a laboratory or controlled outdoor environment utilizing surrogate cameras, lasers, and mounts. At the conclusion of Phase II, prototype hardware and software shall be delivered to NSWC Crane along with complete test data, installation and operation instructions, and any auxiliary software and special hardware necessary to operate the prototype.

It is probable that the work under this effort will be classified under Phase II (see Description section for details).

PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology for Government use. Develop specific hardware, software, and operating instructions for specific Navy optical sensor systems. Establish hardware and software configuration baselines, produce support documentation, production processes, and assist the Government in the integration of the boresight alignment technology into existing and future imaging sensor systems.

The technology resulting from this effort is anticipated to have broad military application. In addition, there are scientific, security and commercial navigation applications. This would include commercial aircraft maintenance and assembly, power generation plants, machining, and automotive maintenance.

REFERENCES:

1. Merchant, D. C., et al, "USGS/OSU progress with Digital Camera In Situ Calibration Methods." The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, November 2003. https://www.researchgate.net/publication/228848245_USGSOSU_progress_with_digital_camera_in-situ_calibration_methods
2. Yastikli, N., et al, "In-Situ Camera and Boresight Calibration with Lidar data." May 2012. https://www.researchgate.net/publication/242207954_IN-SITU_CAMERA_AND_BORESIGHT_CALIBRATION_WITH_LIDAR_DATA

KEYWORDS: Rangefinder; Imaging Sensor; Boresight Alignment; Video Imaging; Narrow Field of View; Optical Axis.

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