Math for a lenticular

[mtarleton]

Over time I have always wondered how a Aspheric Lenticular is figured by hand. I have used a couple of different programs with differing levels of success. Does anyone out there know how to accurately figure an Aspheric Lenticular by hand.

Thanks
Mike

[Darryl Meister]

Hi Mike,

It would ultimately depend upon the specific type of lenticular, since the "formula" will differ from manufacturer to manufacturer. Some vendors may even supply you with the appropriate formulas. If you use a particular brand, you should try contacting the manufacturer, if you haven't already.

Best regards,
Darryl

[mtarleton]

Rxpiq

Well that was my thinking at first. As some of you are aware Coburn has a program called RXPIQ and it does a really nice job on the lenticulars with no mention of manufacturer. The power, thickness and sags of the blank are entered and it provides surfacing info that is correct and in some cases superior to programs costing much more. I am very curious as to how that was accomplished.

[Darryl Meister]

If you are simply trying to arrive at surfacing specifications, you really don't need to "figure the surface" as such. If you know the true curve of the optical zone, the true curve of the carrier, and the sag lens blank at some distance outside of the zone (e.g., a 50-mm bell with a 40-mm lenticular), you should be able to calculate the required back curve and finished center or edge thickness. The exact method to use would probably depend upon how you block and generate your lenses, and would still require several calculations.

Best regards,
Darryl

[Shutterbug]

I've had good success with just using the true curve for power and using a Fictitious 40mm round frame for thickness. Sometimes the multiple sag readings are just to impress you (IMHO) :0)

shutterbug