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Guest
Posted: Thu Jul 12, 2007 12:15 am
As far as I can tell, diffractive surfaces (including diffractive/lens
hybrids) are not being used in consumer cameras, not even in cell
phone cameras (where the diffractive might help reduce track
lengths). I am under the impression that diffractive surfaces can be
very powerful in reducing aberrations. Does anyone know why they have
not become commonplace in these applications?

Thanks.

jfld22
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Scrim
Posted: Thu Jul 12, 2007 7:43 am
Guest
I thought they were very wavelength dependant and so no use for 'white
light' imaging.

Scrim



<jfld22@gmail.com> wrote in message
news:1184217304.942584.21870@w3g2000hsg.googlegroups.com...
Quote:
As far as I can tell, diffractive surfaces (including diffractive/lens
hybrids) are not being used in consumer cameras, not even in cell
phone cameras (where the diffractive might help reduce track
lengths). I am under the impression that diffractive surfaces can be
very powerful in reducing aberrations. Does anyone know why they have
not become commonplace in these applications?

Thanks.

jfld22
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Fleetie
Posted: Thu Jul 12, 2007 1:10 pm
Guest
Quote:
As far as I can tell, diffractive surfaces (including diffractive/lens
hybrids) are not being used in consumer cameras, not even in cell
phone cameras (where the diffractive might help reduce track
lengths). I am under the impression that diffractive surfaces can be
very powerful in reducing aberrations. Does anyone know why they have
not become commonplace in these applications?

Yeah: The Sun isn't monochromatic or coherent.


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie
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Guest
Posted: Thu Jul 12, 2007 2:33 pm
the lab I work in is working on the needed corrections, patterning the
things via ultraviolet laser interferometric patterning isnt easy (my
job)

Steve Roberts
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Phil Hobbs
Posted: Mon Jul 16, 2007 1:34 pm
Guest
Fleetie wrote:
Quote:
As far as I can tell, diffractive surfaces (including diffractive/lens
hybrids) are not being used in consumer cameras, not even in cell
phone cameras (where the diffractive might help reduce track
lengths). I am under the impression that diffractive surfaces can be
very powerful in reducing aberrations. Does anyone know why they have
not become commonplace in these applications?

Yeah: The Sun isn't monochromatic or coherent.


Martin

A few waves of diffractive correction is good for achromatizing single
element lenses.

Cheers,

Phil Hobbs
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Willem-Jan Markerink
Posted: Tue Jan 01, 2008 11:23 pm
Guest
[posted and mailed]

jfld22@gmail.com wrote in news:1184217304.942584.21870
@w3g2000hsg.googlegroups.com:

Quote:
As far as I can tell, diffractive surfaces (including diffractive/lens
hybrids) are not being used in consumer cameras, not even in cell
phone cameras (where the diffractive might help reduce track
lengths). I am under the impression that diffractive surfaces can be
very powerful in reducing aberrations. Does anyone know why they have
not become commonplace in these applications?

Thanks.

jfld22


The Canon 400mm/f4.0 IS-DO has Diffractive Optics.
But the fact that this one was launched several years ago, and still has not
seen any brothers & sisters, partly proves your point....
(optically it is considered not as perfect as the other white/high-end
tele's, but in terms of weight/size decrease, it does serve a purpose, at
least for some photo markets, where quality is less important)

Perhaps not a real consumer lens, but it surely fits any consumer-grade EOS
camera....Wink)

--
Bye,

Willem-Jan Markerink

The desire to understand
is sometimes far less intelligent than
the inability to understand

<w.j.markerink@a1.nl>
[note: 'a-one' & 'en-el'!]
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Helpful person
Posted: Wed Jan 02, 2008 3:11 am
Joined: 22 Jun 2004 Posts: 692
On Jan 1, 10:23 pm, "Willem-Jan Markerink" <w.j.marker...@a1.nl>
wrote:
Quote:
[posted and mailed]

jfl...@gmail.com wrote in news:1184217304.942584.21870
@w3g2000hsg.googlegroups.com:

As far as I can tell, diffractive surfaces (including diffractive/lens
hybrids) are not being used in consumer cameras, not even in cell
phone cameras (where the diffractive might help reduce track
lengths).  I am under the impression that diffractive surfaces can be
very powerful in reducing aberrations.  Does anyone know why they have
not become commonplace in these applications?

Thanks.

jfld22

The Canon 400mm/f4.0 IS-DO has Diffractive Optics.
But the fact that this one was launched several years ago, and still has not
seen any brothers & sisters, partly proves your point....
(optically it is considered not as perfect as the other white/high-end
tele's, but in terms of weight/size decrease, it does serve a purpose, at
least for some photo markets, where quality is less important)

Perhaps not a real consumer lens, but it surely fits any consumer-grade EOS
camera....Wink)

--
Bye,

Willem-Jan Markerink

      The desire to understand
is sometimes far less intelligent than
     the inability to understand

w.j.marker...@a1.nl
[note: 'a-one' & 'en-el'!]

Diffractive optics for white light lenses have several intersting
properties. Their advantage is that their high chromatic aberration
can give excellent color correction for a lens system. In addition
they can also be simulate an aspheric surface giving much better
monochromatic aberrtion correction.

Their problem is diffraction efficiency. They are generally
transmission holograms (surface relief) and as such they cannot
maintain high diffraction eficiency over the full visible waveband.
If I remember correctly their diffraction efficiency falls to below
95% (please someone confirm this number) when one tries to cover the
visible waveband. Most of the lost energy ends up in the zero order.

One solution that can solve the diffraction eficiency problem is to
use reflection holograms instead of transmission ones. In this case a
single element consists of two reflection holograms (DCG), one
directly after the other. The double reflection results in a
transmissiion element. This arrangement is more difficult to design
and manufacture but can result in a high diffraction efficiency
element with any "lost" light diffracted away from the image plane.

I believe (but am not certain) that the Canon lens uses two reflection
holograms.

www.richardfisher.com
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