В части интерферометра, из которого здесь пытаются сделать психкульт.
Это просто прибор и наличие его у оптика ни о чем не говорит. В первую очередь говорит опыт опытика, отработный на его опыте техпроцесс.
Например здесь
http://www.galaxyoptics.com/primarymirrors.html дадут и интерферограмму и якобы проверят, а на деле уже неоднократно встречалась информация по его зеркалам, что часто выдают просто отстой. Например здесь
http://www.lcas-astronomy.org/articles/display.php?filename=quality_of_todays_newtonian_optics&category=general(кстати по этой же ссылке в противовес galaxyoptics, Замбуто расхваливают). Но я встречал не только здесь, но и неоднократно в других местах (в части брака galaxyoptics).
Кроме этого, вспоминая скоп с замбутовским зеркалом, локвудовским и др. (было десяток больших скопов от SDM и Obsession).
Два из Obsession были с проблемами (18 и 25 дюймов диаметром). В них явно раздувало звезды (атмосферные условия были очень хороши). Чьи были зеркала в этих Obsession я не знаю, но Крейг обычно ставит или OMI или Galaxyoptics.
К остальным скопам претензий не было, в том числе и к Obsession. Кстати я внимательно отсмотрел скоп с локвудовским зеркалом, в том числе по Марсу и Сатурну, внефокалам, зведам и т.д. На мой взгляд он так-же лучше сделан, чем мое зеркало от Санковича. Речь о 16 дюймовом f/4 (т.е. весьма близком по размеру к моему скопу).
И если есть у кого есть желание (перевести), цитата Замбуто в части наличия у него интерферометра и интерферометрии в частности. Это так-сказать его личный подход.
I'm so pleased to know you're still around. And I'm tickled to know
that I still know which button to push to hear from you.
I wish to thank you for your vote of confidence. I own an
interferometer, but I'm not an interferometrist. I find the curve will
be very steep to work at the level I'm used to working with much
simpler (designed) tools. I have watched and evaluated interferometry
as performed by others in and out of this industry, and by and large I
have to say I'm disappointed in the results. Grossly disappointed.
Now don't get me wrong. You and me are in agreement on this one, and
the truth is I feel we would be in agreement on most every optical
issue there is. I have read carefully over the years what you have
written and have evaluated your theory and practice. In my opinion
every issue which I have experience in and read you on I find to be
very sound. I recall reading when you made a story-type description of
how you searched for the Encke gap with a 6" instrument, and were not
able to spot it on a particular night. I have read where you looked at
an image of a very smooth optical surface and indicated that a
knifedge test on such a surface would be *deadly accurate*. Indeed, it
would be. From what I know at present, I consider you to be among, if
not the most advanced ATM on this planet. (And if you worked in optics
professionally, I would have to leave the ATM designation out of my
description.)
So we are in agreement on interferometry in theory as we would want it
to be practiced. The interferometer has great strengths, as you have
indicated, with the key being as you have stated, well-maintained,
with a master operator working it. My beef is, *in practice* in this
industry the results are not near as good as what a good knifedge can
and has in reality put out in real product, and does so on a regular
basis. I find variations in honest attempts in interferometry that far
exceed ideal limits of error. And the hell of it is, the problem is
typically with spherical aberration, the most simple thing to test
with a knifedge. As I said earlier, the only individual I know of for
fact that works to a level I would be comfortable with is Bill Zmek,
team leader of the HST retrofit project that was done recently. The
reason I say that is he has proven that he can measure spherical
aberration, and it has been published. (I also know that Bill uses a
1/100 wave calibration sphere when setting up his work. That's the
kind of accuracy that is needed to be able to match the potential of
the knifedge, in my professional opinion). ATMJ #13 article conducted
on Bill Herbert's mirror had spherical at 1/24 and 1/25 as compared by
the digital knifedge test conducted by Dick Suiter and Bill Zmek's
interferometry. Such agreement I have never seen anywhere else. I have
for example one private case where I measure a 1/4 wavefront hole in
the center of a mirror as reduced by Suiter's Admir program and the
interferometer says it isn't there, at least not anywhere near that
deep. I also have autocollimation and a null test that shows the same
artifact as the largest error on the optic, but the interferometer
says it isn't so. That is gross disagreement, in my opinion, and it
should not be so. So my point is, I'm very disappointed in the actual
result as applied to this industry. There is much more on that subject
that we may or may not discuss in the future, as I think there is more
than one reason for such disparities. In short, what I think needs to
be done is the interferometrists in this industry need to get a
*certified* optic and all test their systems on it and get calibrated
and in agreement. When that is done, then their marketing departments
can take a look at who they call "liars" on their webpages.
Soon I'm going to put forward the data I referred to earlier. I just
received permission from one of the parties involved. I have to keep
all names and associations out of it, but I can put all the pertinent
data before the mirror group. I'm going to demonstrate a gross
weakness of the highest level phase-shifting interferometer. Yes I
agree with you Bratislav that few folks here (on this mirror group)
are bowing down to interferometry. I'm talking about the rest of the
industry and what customers are led to believe through marketing. I'm
about to take this "god" down a couple of notches.
