Canon’s new 600mm and 800mm lenses

Started 3 months ago | Discussions thread
AiryDiscus Senior Member • Posts: 2,138
Re: DOE vs Phase Fresnel

Jack Hogan wrote:

bclaff wrote:

AiryDiscus wrote:


No, it doesn't simplify the lens design. My guess is that they use the front element as a stop, much as a telescope, so there is no stop at all (could be wrong). ...



(Example 3 is the 780mm lens)

Unfortunately I still haven't taught the Optical Bench to do diffractive elements

Are DOE elements the same as Nikon's Phase Fresnel, Bill? If so the bench would need a lot more detail on that front element.


DOE = Diffractive Optical Element.  It's a generic term like asphere.  There are multiple equations that can define one.  The equation for the equivalent sag depends on the type of DOE it is.  Nikon Phase Fresnel is a type of kinoform, which is commonly fabricated via stereolithography.

I assume that Nikon, as a manufacture of litho steppers and inspection equipment, makes theirs this way since it is cost effective.  Canon's DOE is a different type, as it is formed along a curved profile instead of flat.  I don't know if it aligns to a common type.

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