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How would it work? Where would you put the two lenses? Consider: - You can't really have two lenses cemented together. That'll correct for chromatic aberration
by tmplurkr 4y ago
How would it work? Where would you put the two lenses? Consider:
- You can't really have two lenses cemented together. That'll correct for chromatic aberration but, other than that, the lenses would behave as one (except for deviations from thin lens approx.)
- You can't have glasses mounting two lenses "d" apart for two reasons. 1) Having parallel lenses would terribly uncomfortable, heavy, and awkward 2) More importantly your eye and the two lenses would never be aligned (as soon as you move your focus away from the one spot the glasses were aligned for, the optical system performance would collapse)
- The best you could do, then, is contact lenses + eyeglasses. But then you have all the bother of wearing glasses and eyeglasses. Also, it's not obvious to me it would work since the contact lenses are in contact with your cornea, the pair behaving like a single lens.
- mgdlbp 4y agoI think GP is mistaken about two physical lenses being needed (until it's the future and we're all wearing expensive smart glasses, in which case you do want an additional interchangeable lens for this purpose). When designing the system, it can be thought of as a lens that corrects for refractive error of the relaxed eye (moving the eye's far point to infinity) stacked on top of another lens that makes light coming from an object parallel (producing an image of the object at infinity for the first lens and eye to receive); to implement it, you only need one lens with the combined power of the two. Edit: GP might also be talking about eyeglasses with adjustable focus, which apparently are already available. https://en.wikipedia.org/wiki/Adjustable-focus_eyeglasses https://en.wikipedia.org/wiki/Adjustable-focus_eyeglasses