1. Technical Field
The present invention relates to all-reflective optical systems and, more particularly, to a boresight transfer system which enables the line of sight of an active laser transmitter system to be transferred and used as a reference to determine the line of sight of or align other optical systems.
2. Discussion
Current state of the art sensor packages which employ active and passive sensors of various wavelengths, such as visible TV, laser rangers or designators, MWIR, and LWIR FLIRS or the like, are utilized to direct a beam onto an object, to illuminate the object, and receive information therefrom. For maximum utility, the direction which each of the above sensors is pointing must be known and oftentimes must be corrected to a common line of sight.
It is desirable to enable testing of the sensors to analyze the boresight alignment, as well as correcting the alignment of the other above sensors, to ensure that the transmitted and received beams are accurately aligned. Relevant art equipment for carrying out boresight alignment testing is relatively bulky, heavy and expensive. A relevant art boresight testers is U.S. Pat. No. 4,260,254 entitled "Compact Boresight Tester for Laser Designators", assigned to the same assignee as the present invention. This art teaches a multiple pass optical system which employs a refractive lens in the entrance and exit paths. Energy efficiency of this type of boresight tester is very low due to the overlap of the beam on the various optical surfaces during multiple passes. Also, applications that involve the conversion of the laser energy to MWIR and LWIR, through heating of the surface located at the input laser focus, is limited because of the difference in refractive index of the lens material between the laser wavelength and the MWIR or LWIR, thus producing boresight error.