Optical device for vertically positioning a sextant
Patent 4428671 Issued on January 31, 1984. Estimated Expiration Date: 
July 15, 2001. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
July 15, 2001. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesInventorAssigneeApplicationNo. 06/283583 filed on 07/15/1981US Classes:356/144, With plural images33/282, Vertical angle356/145, Lines of sight relatively adjustable with two degrees of freedomD10/66Transit or theodoliteExaminersPrimary: Rosenberger, R. A.Assistant: Dietert, L. A. Attorney, Agent or FirmInternational ClassesG01C 1/00 (20060101)G01C 1/08 (20060101) AbstractAn optical device for vertically positioning a sextant to minimize the "tilt error" which occurs in a measured angle of altitude whenever the sextant is not held orthogonal to the horizon. The optical device can be fixed to the sextant and provides in the sextant's viewing area a secondary horizon which will align with the direct horizon only when the sextant is in a vertical orientation. The device is capable of periodic calibration and can be pivoted out of the line of sight when the sextant's user is initially locating the celestial body whose altitude is being measured. | |
