Desktop Instrument for Measuring Boresight Error as a Function of Incident Angle

The infrared (IR) tracking system of an interceptor vehicle works by determining the position of an object via the line of sight (LOS) between the vehicle and the object of interest and then feeding that information into the guidance system. In all cases there is a protective window or dome in front of the IR tracking system. If a temperature gradient is formed between the front side and the back side of this protective window, such as might occur in supersonic and hypersonic flight, the measured LOS between the vehicle and the object of interest will be different than the actual LOS, resulting in a missed interception. The degree of this difference is referred to as the boresight error, or BSE. To complicate matters further, as the vehicle’s angle changes, the BSE also changes, by an amount characterized by a quantity referred to as boresight error slope or BSES.1 Negative BSES tends to prevent the guidance system from accurately compensating for the BSE. To overcome this challenge, the DOW is exploring solutions in a variety of disciplines, including novel ceramic materials to replace the protective window and thereby minimize the BSE and BSES. Current testing facilities to assess the BSE and BSES of such IR window materials include wind tunnel and flight tests. These are effective but very costly and have limited time availability. Therefore, to reduce risk when such high-speed air flow tests are performed there is a need for measurements without high-speed air flow in a benchtop laboratory environment. This solicitation seeks to develop and deliver a desktop testing apparatus that would allow for iterative testing of the BSE and BSES of unmounted and mounted window materials as a function of temperature, incidence angle, and temperature gradient without high-speed air flow for DOW applications in supersonic and hypersonic environments.