US3695750A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compact four element objective lens
Assignee: Polaroid Corp
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Filing: 1971-07-28
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Granted: 1972-10-03
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Expires: 1991-07-28
Abstract
Abstract A compact air-spaced four element photographic objective lens is shown with an overall length less than one-tenth its focal length. Chromatic and spherical aberrations, coma, astigmatism, field curvature, and distortion are corrected. Focusing is accomplished by a movable first element. The corrections are optimum when the objective focuses a subject approximately nine focal lengths distant. The ratio of the minimum Abbe Nu value of the first and fourth elements to the maximum Abbe Nu value of the second and third elements (i.e., Baker''s Ratio) is 0.91. The Petzval sum is 0.199.
Inventors
- 👤 James G Baker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:34
CPC Classifications
G; G02; G02B; G02B9/00; G02B9/34; G02B9/36; G02B9/44; G02B13/00
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
137 words
A compact, four element, photographic objective lens having the design parameters for a unit focal length, F, presented in the following table: F 1.000 L.O.A. 0.0945F f/8.0 Lens nd Nu d Radii Thicknesses I 1.678 55.2 R1 +0.2182 l F t1 0.0188F R2 plano 0.0057 < OR = s1 < OR = 00597F II 1,511 60.4 R3 0.5772F t2 0.0079F R4 +0.3267-F s2 0.0105F III 1.626 35.7 R5 -0.5302F t3 0.0079F III 1.626 35.7 R6 +0.3385F s3 0.0270F IV 1.651 55.9 R7 1217F T4 0.0167F wherein Roman numerals identify lens elements in order from front to rear; nd is the refractive index at 587.6 nanometers; Nu d is Abbe''s ratio; R1, R2, . . . represent radii of successive refractive surfaces from front to rear; t and s represent thicknesses of lens elements and air spaces, respectively.
Claim 2
Dependent Claim
137 words
A compact, four element, photographic objective lens having the design parameters for a unit focal length, F, presented in the following table: F 1.000 L.O.A. 0.0945F f/8.0 Lens nd Nu d Radii Thicknesses I 1.678 55.2 R1 +0.2182 l F t1 0.0188F R2 plano 0.0057 < OR = s1 < OR = 00597F II 1,511 60.4 R3 0.5772F t2 0.0079F R4 +0.3267-F s2 0.0105F III 1.626 35.7 R5 -0.5302F t3 0.0079F III 1.626 35.7 R6 +0.3385F s3 0.0270F IV 1.651 55.9 R7 1217F T4 0.0167F wherein Roman numerals identify lens elements in order from front to rear; nd is the refractive index at 587.6 nanometers; Nu d is Abbe''s ratio; R1, R2, . . . represent radii of successive refractive surfaces from front to rear; t and s represent thicknesses of lens elements and air spaces, respectively.
Claim 3
Dependent Claim
27 words
The compact, four element, photographic objective lens described in claim 1 wherein focusing is accomplished by moving the first element, Lens I, with respect to the others.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-03 | 1976-04-03 | 1976-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-03 | 1980-04-03 | 1980-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-03 | 1984-04-03 | 1984-10-03 | $7700.00 | Window Closed / Lapsed |