the backside revisited

[Hayde]

Thank you for the feedback.

If I'm understanding (and surmising) correctly, the equations used for 'compensated' Rx generation have only advanced so far into the complexity of optics calculations. (I'm assuming it's not really a lack of computing power in digital surfacing data processing.) By removing the base curve calculations from the 'optimization', the backside equation is simply simpler and there's fewer opportunities for clumbsy functions to get tangled into unpredictable abberations?

We're not really talking about better, more nuanced optimization equations waiting in the wings because base curve math was hogging the RAM, are we?

Either way, sounds like a subject I'm woefully under-read on. I'm not really qualified to discount the assertion...I just innately distrust 'marketing-speak.' ; )

[ThatOneGuy]

I think you all are making it more complicated than it really is.

Freeform lenses are not being calculated point by point, as some marketing departments would have you believe (nanoptix, anyone?). The lens design is a 3d plot of the lens surface with an ideal target form. Spline mathematics are used to then manipulate the design for a given Rx. Spline mathematics allow the Rx curves to be implemented without catastrophic consequences to the intended target design. That is it. The 3d model now has the required xyza coordinate data to transmit to the generator that then cranks out the product in ~90 seconds.

A lens, therefore, is still only as good as its design, and that design can be adjusted to account for back vs front surface curves.

[CCGREEN]

So which higher learning institution is going to start handing out doctorate's for this &#$@?
We should start a TV sitcom. Instead of The Big Bang Theory we will call it The Big Bang Optical Theory.
The usefulness of realistic optical formulas are quickly becoming over thought.
The only one of any real value IMHO is wrap compensation. Please someone convince me of the worthiness of all this newer jargon.
I may have just become the stick that stirs the pot.

[HarryChiling]

Thank you for the feedback.

If I'm understanding (and surmising) correctly, the equations used for 'compensated' Rx generation have only advanced so far into the complexity of optics calculations. (I'm assuming it's not really a lack of computing power in digital surfacing data processing.) By removing the base curve calculations from the 'optimization', the backside equation is simply simpler and there's fewer opportunities for clumbsy functions to get tangled into unpredictable abberations?

We're not really talking about better, more nuanced optimization equations waiting in the wings because base curve math was hogging the RAM, are we?

Either way, sounds like a subject I'm woefully under-read on. I'm not really qualified to discount the assertion...I just innately distrust 'marketing-speak.' ; )

You can improve anything to the point where it has cup holders on it. The design can be phenominal (ex. Enigma Lenses) but without a means of production the design is useless. PALs were invented around the turn of the 20th century, it took another 40+ years until Maintenez invented the equipment to create the Varilux PAL. I still hear people say the Varilux was the first PAL.

Mold manufacturing is much more sophisticated, offputting the best curve design calcs to mold generation simplifies the back side operations so that the design can become more complex without running into manufacturing issues.

The first generation FF lenses were constrained due to manufacturing processes.

Prism causes an increase in stock removal at the base.

Higher curves had more stock removal at the periphery.

Decentered blanks had more stock removal at the opposite edge.

With improvements in processes the lens designs were able to start decentering, incorporating prism, and offering expanded ranges. This too can be a way of expanding bounds by simplifying back side calcs so that they can be made more sophisticated towards other more important goals.

You know they're done when we get cup holders.

[Robert Martellaro]

I think you all are making it more complicated than it really is.

Freeform lenses are not being calculated point by point, as some marketing departments would have you believe (nanoptix, anyone?). The lens design is a 3d plot of the lens surface with an ideal target form. Spline mathematics are used to then manipulate the design for a given Rx. Spline mathematics allow the Rx curves to be implemented without catastrophic consequences to the intended target design. That is it. The 3d model now has the required xyza coordinate data to transmit to the generator that then cranks out the product in ~90 seconds.

A lens, therefore, is still only as good as its design, and that design can be adjusted to account for back vs front surface curves.

Yup. The basic progressive lens design, first and foremost. Then, the ability to stay true to that design through variations in position of wear and Rx, through the use of advanced optical engineering, mathematics and computer programing, and free-form manufacturing. Easy peasy.

[HarryChiling]

Yup. The basic progressive lens design, first and foremost. Then, the ability to stay true to that design through variations in position of wear and Rx, through the use of advanced optical engineering, mathematics and computer programing, and free-form manufacturing. Easy peasy.

I feel like if anyone breaths in this thread it might over complicate things more than that summation.

[drk]

/gigo