Telecentric illumination system
Patent 4386828 Issued on June 7, 1983. Estimated Expiration Date: 
May 13, 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.
May 13, 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 References 3399014 3549230 InventorAssigneeApplicationNo. 06/263174 filed on 05/13/1981US Classes:359/687, + - + + Arrangement359/380, Variable magnification359/663Telecentric systemExaminersPrimary: Corbin, John K.Assistant: Gass, Rebecca D. Attorney, Agent or FirmInternational ClassesG02B 21/06 (20060101)G02B 19/00 (20060101) Foreign Application Priority Data1980-05-26 JPAbstractAn illumination system for telecentric illumination throughout a wide variation range of magnification while keeping a large distance to an object to be illuminated is disclosed. The telecentric illumination system comprises a first lens group which is convergent and remains fixed when the magnification is varied; a second lens group which is divergent and movable along the the optical axis; a third lens group which is convergent and movable along the optical axis; a fourth lens group which is convergent and remains fixed when the magnification is varied; and a light source located at the focal point of the fourth lens group. The second and third lens groups are moved along the optical axis in a determined relation so as to make an imge of the light source formed between the first and third lens groups thereby changing the state of illumination between that for high magnification and that for low magnification. | |
