Timeline for Are there any secrets in lens design?
Current License: CC BY-SA 3.0
12 events
| when toggle format | what | by | license | comment | |
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| Jul 4, 2015 at 20:34 | comment | added | supercat | @mattdm: Patents must include information that a typical person skilled in the art would find both novel and useful. It is not necessary that a patent include all such information known to the inventor. If the patent includes a design which would work better than any other design that didn't rely upon proprietary information, such a design would qualify as "novel and useful information" even if such improvements were nowhere near as great as others known to the inventor. | |
| Jul 4, 2015 at 3:26 | comment | added | Brandon Dube | @mattdm I think you will find the same elsewhere. Patents for optical constructions aren't possible for each and every possible layout - they cover essentially a small cluster of solutions at the end of optimization but more importantly the criteria that led to that construction. The front asphere is one of the items of the patent - specially its location, strong conic nature, and resulting distortion. There are also bounds for focusing, the spacing of the wide angle adapter from the master lens and more. These are patent worthy, a 24mm f/1.4 is not; any f/1.4 lens can be scaled to 24mm. | |
| Jul 4, 2015 at 3:17 | comment | added | mattdm | I don't doubt you at all, but that obfuscation seems to be a terrible violation of the spirit of the patent system, which is essentially an agreement to reveal secrets in exchange for commercial protection. If the revealed secrets are actually half-truths, that protection shouldn't be given — the patent should be invalidated. | |
| Jul 3, 2015 at 20:28 | vote | accept | feetwet | ||
| Jul 3, 2015 at 20:28 | comment | added | Brandon Dube | An enormous number of them have no good reverse-engineering tool. The glasses are particularly difficult - even if you know the index at one wavelength and the V number you do not know for certain what material it is. Additionally, any asphere will be remarkably difficult to replicate without the original equation. Measuring the airspaces and the radii of curvature is also very difficult. | |
| Jul 3, 2015 at 20:19 | comment | added | feetwet | Fascinating: So there are single lenses for which there exists no good reverse-engineering tool? | |
| Jul 3, 2015 at 19:42 | comment | added | Brandon Dube | @feetwet a lensometer does not measure the required specifications - they are for eyeglass lenses. Nikon certainly obfuscated the aspheric coefficients to protect their intellectual patent. A 3D profilometer is needed to re-generate the aspheric coefficients, and this provides a limited degree of precision. When you reach the stage of doing curve fitting to that profile there may also be multiple solutions with that profile. An interferometer could also be used, but the first asphere in that lens has a very large departure - too great for an interferometer to see. | |
| S Jul 3, 2015 at 19:15 | history | edited | Hugo | CC BY-SA 3.0 |
Typos and grammar
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| S Jul 3, 2015 at 19:15 | history | suggested | feetwet | CC BY-SA 3.0 |
Typos and grammar
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| Jul 3, 2015 at 19:13 | comment | added | feetwet | To clarify the Nikon patent example: Did they intentionally obfuscate the exact specification of the front aspheric in the patent? And even so, isn't it a matter of taking a production sample's lens and putting it in front of a lensometer to get those coefficients, should someone wish to reproduce it once it's off patent? Or is it not so easy to measure aspherics? | |
| Jul 3, 2015 at 19:10 | review | Suggested edits | |||
| S Jul 3, 2015 at 19:15 | |||||
| Jul 3, 2015 at 18:57 | history | answered | Brandon Dube | CC BY-SA 3.0 |