D076 Gladius CF 315-7875 HS_R ist 2392 mm

26.03.2008  

Gladius 315 CF - als Schwert geeignet . . .
http://www.alpineastro.com/LAZZAROTTI/Lazzarotti_Home.htm
http://www.alpineastro.com/LAZZAROTT...ifications.htm
http://www.rfroyce.com/cassegrains.htm
http://www.alpineastro.com/LAZZAROTT...rotti_Home.htm


Ein futuristisches Design - für wahr! Ein klangvoller Name aus antiken Zeiten, der Lateiner kann mit "Gladius"
tatsächlich etwas anfangen. Nur erwartet man von einem Gladius, daß es nicht stumpf ist, und auch in diesem
Fall sollte das Dall-Kirkham-System mit ellipsoidem Hauptspiegel (conic constant ca. - 0.8) und sphärischem
Fangspiegel wenigstens auf der Achse kontrastreiche Bilder abliefern, wenn der Hauptfehler, Astigmatismus
nämlich, auszumerzen wäre. Die Frage, wie man so ein System justiert, blieben Hersteller und Händler gleicher-
maßen schuldig. Und auch hier tauchen einige Merkwürdigkeiten auf.
Das System selbst ist nicht neu. Schon vor 30 Jahren wollte ich ein ähnliches System nachbauen, das Horace E.
Dall soweit ich mich noch erinnere, in Sky & Telescope veröffentlicht hatte.

Ob er damals in sein Teleskop ähnlich viele Schwachstellen eingebaut hat, wie diese Lösung hier, kann ich leider nicht
mehr beantworten.



Das erste Stirnrunzeln kommt auf, wenn man sich die Verbindung zwischen Haupt- und Fangspiegel genauer anschaut und
die Steifigkeit mittels Meßuhr genauer untersucht. Bewegt man die Fangspiegel-Einheit Meßuhr-kontrolliert um 2 mm senk-
recht nach oben, so bewegt man damit das Verbindungsstück gerade einmal - wieder Meßuhr-kontrolliert - um ca. 0.5 mm
nach oben. An dieser Stelle knickt also die Verbindung regelrecht ab und wird so ein Problem der Justage je nach Höhen-
winkel des Teleskopes selbst. Eine sich überlappende Lösung wäre weitaus stabiler gewesen, wie diese "kunstvolle" Steck-
Verbindung.



In die Hauptspiegel-Einheit sind gleich mehrere Problem-Zonen eingebaut. Auf die oben erkennbare Metallscheibe liegt der
Glaskörper des Hauptspiegels auf - eine gleichgroße Korkscheibe sucht man vergebens. Die Hauptspiegel-Bohrung senkt
man über einen ca. 0.5 mm kleineren Stahl-Haltezylinder und schiebt von vorne die Befestigungshülse, die von hinten mit
einer Mutter gehalten wird. Das ist bereits alles. Leider drückt der vordere Konus dieser Befestigungshülse auf den Glas-
körper, was der Spiegel mit einem heftigen Astigmatismus quittierte. Über soviel Sachverstand bin ich jedesmal begeistert.
Das System kommt im Übrigen ohne Hauptspiegel-Justage aus, zum einen ein Vorteil, weil man nichts verstellen kann,
setzt aber voraus, daß die mechanischen Teile alle perfekt sein müssen: Der Hauptspiegel muß also ganz exakt auf der
optischen Achse sitzen, sodaß der Glaskörper keinen Keilfehler haben darf und die Spiegelfläche exakt auf des Fangspiegels
Mitte gerichtet sein muß.



gekühlt werden muß dieses DAll-Kirkham System nicht, da aber auch keine Taukappen anzubringen sind, wäre nach ca.
1/2 Stunden Haupt- und Fangspiegel zugetaut, erzählte mir der Sternfreund. Da es noch eine kleinere Version gibt, beide
Systeme von hinten gesehen.



Zwischen Glaskörper und Metallplatte fehlt eine dünne Korkplatte oder Dämmschicht, um keine Druckspannungen einzuführen.



Die Fangspiegel-Einheit: zwar eine sehr kleine Obstruktion, dafür vergrößert sich jeder Fehler auf dem Hauptspiegel umso
mehr.



Spiegelseitig erkennt man das lange Blendrohr, das für die Justage abgeschraubt werden muß. Da der Hauptspiegel nicht
justiert werden kann, reicht ein guter Justierlaser, der von Okular-Auszug mittig auf den Fangspiegel fällt und der Reflex
muß ebenfalls mittig wieder zum Ursprung des Lasers zurück. Damit wäre die Justage bereits erledigt. Die hinter dem
Fangspiegel liegenden "Bob Knops" sind dafür allerdings viel zu unsensibel, aber es geht.



Die Prüfung begann damit, daß ich mir nach der vorherigen Simulation aus den von Lazzarotti veröffentlichten System-
daten erst einmal Gewissheit verschaffte, ob sie denn stimmen. Die Prüfung des Hauptspiegels auf Rotations-Symmetrie
bzw. Astigmatismus ergab sofort den ersten neuralgischen Punkt.



Außerhalb seiner "Fassung" reagierte der Hauptspiegel auch weit weniger astigmatisch, wie man aus dem Vergleich
der beiden Interferogramme erkennen kann.



Da aber der Hauptspiegel nicht frei von Astigmatismus ist, wird dieser Fehler folgerichtig vom Fangspiegel kräftig
vergrößert und stört das runde Sternscheibchen, das gleichermaßen am Stern wie im Labor zu erkennen ist.



Unter der conic constant von - 0.805 ergäbe sich denn auch ein sehr guter Hauptspiegel von ca. 0.95 Strehl, wenn man
den Astigmatismus herausrechnet - leider ist er aber weiterhin vorhanden.



Hier nochmals die Qualität des Hauptspiegels:



Zur sanfteren Lagerung schnitt ich sowohl vorne, wie auch hinten dünne weiche Scheiben als Zwischendruckscheiben, um den
vermeidbaren Teil des Astigmatismus zu reduzieren. Also eine dünne Korkscheibe vorne, damit der Konus nicht mehr
aufs Glas drückt und . . .



. . . eine gleichgroße Scheibe hier als Druckausgleich zwischen Metall und Glaskörper.






Über den Justierlaser erledigte sich die Justage relativ flott, was man am Poison-Punkt in der Mitte erkennen kann.
Leider wird bei hoher Vergrößerung auch der Astigmatismus in aller Schönheit erkennbar.



. . . und hier die Sternaufnahme mit einfacher Genauigkeit



Schließlich interessierte mich noch, wie das System im Doppelpaß vor einen Planspiegel aussieht. Der Astigmatismus
ist nicht mehr ganz so wild, das Ronchi-Bild sagt, daß die Korrektur stimmt, der Foucault-Test zeigt die Flächen-
qualität, nutzbar wird dieses System bis ca. 200-fach sein, fotografisch möglicherweise etwas gutmütiger reagieren.



Wertet man eines der Doppelpaß Autokollimations-Interferogramme aus, dann tritt auch hier der Hauptfehler klar zu Tage:
Ohne den störenden Astigmatismus hätte man einen sehr hohen Strehl von fast 0.98 bei einem PV-Wert von L/10.
Das vom Hersteller beigelegte Certifikat ist das Papier nicht wert, auf dem es steht. Es garantiert einen RMS-Wert von
L/25, das entspricht einem Strehl von ca. 0.94 und einem PV-Wert von ca. L/7. Nur leider werden diese Werte nicht
erreicht.



Die bereits vorher ermittelten Daten haben sich einigermaßen bestätigt: Der aktuelle Radius auf dem Hauptspiegel ist
2392.2 mm, die conic constant bei ca. - 0.805. Das nutzbare Bildfeld wäre im Bereich von 12 mm Durchmesser zu suchen.
Mit ca. 7.000.- Euro halte ich das Preis-Leistungs-Verhältnis jedoch nicht für angemessen. Der Hersteller müßte eigent-
lich noch kräftig nachbessern, wenn das System überzeugen soll: Die Verbindung zum Fangspiegel ist zu instabil, die
Hauptspiegel-Lagerung überarbeitet werden, der Astigmatismus muß verschwinden ! ! !
Erst dann wird man Mond-Aufnahmen erzielen, wie sie in der Werbung propagiert wird.


  • Standard Riferimento: Gladius 315 CF - als Schwert geeignet

    Dear mr. Rohr and dear all,

    This is Paolo Lazzarotti, the Gladius maker.
    I think a clearance by my side is absolutely due as a consequence of the test made by mr. Rohr about a telescope of mine.

    At the present, I'm still waiting for the Gladius' return back for my own check. I've no doubt about the genuine test made by mr Rohr, but I've no doubt as well about the genuine quality delivered by the same telescope before to be sold to the customer. As most of you may suppose, I make ANY telescope double checked before to be delivered to the market. I have a visual star test with a true star by night and an interferometrical test by Massimo Riccardi of Italy. The telescope in question passed succesfully any.

    That said, something of bad happened in the between for sure, so mr. Rohr measured for sure a telescope affected by a problem which caused those HUGE astigmatism.
    Of course, I'll sort it out once the telescope will be here.
    At the same time, I'll repeat the 2 inspections as it was a new telescope and I won't miss to share those here to prove I'm not selling fake telescopes delivering aberrations as huge as 50 (!) times the declared quality!

    Meantime, I'd like to hear from mr. Rohr why any customer of mine is happy with his own Gladius and how is possible to get hires images published in the gallery of lazzarotti-optics.com website given any horrible solution I used in the Gladius design.
    Thank you for your answers.

  • Standard AW: Gladius 315 CF - als Schwert geeignet

    Dear Mr. Paolo-Gladiator,

    it's very kind of you, to have a discussion about this actual Dall-Kirkham telescope.
    At first I studied your own websites and with great interests your fotos here: http://www.alpineastro.com/LAZZAROTT...rotti_Home.htm
    If the actual system is perfect, the customer must get fotos as good as yours.

    Testing in the main mirror holder

    The system I've got from your customer, I've tested the main mirror in the holder at first. So the radius of curvature
    (ROC), the conic constant, under- or overcorrection, zones, astigmatism and so on. In this case the main mirror has a
    significant astigmatism in it's holder.

    After a significant astigmatism in it's holder, I was looking for the reasons of this. And I tested the mirror out of the
    holder, as my foto shows: http://rohr.aiax.de/@315Gladius_10.jpg Now the astigmatism was reduced. So I was looking,
    how you assembled the main mirror: There are two problems: There is no cork disk between the glas body and the steel
    disk at first, and at the front the cone is pressing on the edge of the mirrors hole.
    http://rohr.aiax.de/@315Gladius_15A.jpg

    I'm sure both cause a part of astigmatism but the mirror itself must have an additional astigmatism, too.

    Important: You cannot align the main mirror, it is fixed, you just can align the system at the secondary. So if you use
    a laser beam to align the secondary and you controll this in doublepass/autocollimation as it shown by the starttest, all
    is OK. The middle so called Poisson dot is the prove that you cannot align it better. The foto shows the star test intra-
    extrafocal by 1000 magnification.
    Poisson-Fleck/Punkt, Link1, Link2, Link3
    See also the thin Poisson dot of this system, starting at 8° Celsius to 20° Celsius temperature: http://rohr.aiax.de/C11-Gert-21.jpg und hier in einer Zusammenfassung:
    http://www.astro-foren.de/showthread...6137#post36137



    The customers star test is similar as my one. Bevore the system was aligned by the distributer.



    It would be nice of you, to publish your own star test here, at the sky and in double pass and we can compare this.
    I guess you have your own certificate of every telescope you deliever to a customer. But instead of this certificate
    http://www.alpineastro.com/LAZZAROTT...ertificate.jpg you should give your customers your star test and your
    interferogramm in double pass. In UK there is Orion Optics, they deliever their mirrors with a ZYGO certificate as this one:
    http://rohr.aiax.de/@Reits02.jpg

    If you do so, there would be no discussion about the quality, or if you show the star test intrafocal and extrafocal as my
    upper fotos show, so it would be clear the telescopes leaves the factory in a perfect condition or state.

    Besides our discussion,

    a report about a perfect system enjoy me much more. And if I can test a perfect Gladius system, may be the
    smaller one, be sure I'll write a better report in this forum. You know, this actual system is just a bad examble,
    I know D. Parker in Florida got a better one, but there was no reason for testing this. We also can test a Dall-Kirkham
    system here with Massimo.

  • #4
    Ackermann

    Standard AW: Gladius 315 CF - als Schwert geeignet

    Dear Mr. Lazzarotti,

    my name is Joerg Ackermann and I'm the customer who has huge problems with the Gladius CF 315. We have seen this astigmatism from the beginning. We have reported dual-images to our distributor and he asks you for support.

    You have got the following diffraction pattern from the distributor:



    We requested serious support and that was your answer (excerpt):

    "The image says nothing to me - it's too much defocused! Frankly speaking, I don't know how*to state the telescope has problem with the mirror alignment by this image.*You should get an unsaturated image less defocused coming out from an averaged portion of, say, 50 frames or so. A single frame like this one could be heavily affected by seeing effects. I'm afraid the customer*could have misaligned the secondary mirror (the Gladius I delivered to you was aligned, the primary mirror cannot be misaligned!) by rotating randomly the 3 knobs. Please, suggest*to take a look on daytime at the bright sky or at a illuminated wall throughout the focuser without eyepiece.*You should notice something like the image attached. No external portion of the sky/wall should be noticed when moving the eye toward the left-right-up-down edge of the field. But if this happens, that means the secondary mirror requires a rough alignment until the external portion is no longer seen. Once done that, a star is required to get a fine alignement."

    It is correct that the first image you have got was selected by hand (one of the best undisturbed images) and we adapted the levels and gradation in Adobe Photoshop to improve the patterns and some parts of it where saturated. One day later you have got (as requested) the image above. The image is the average of about 50 frames and it was taken with the original collimation. We have got never an answer from you. It is very interesting that you are now able to interpret the diffraction patterns.

    We marked with an overhead marker the original positions of the alignment knobs of the secondary mirror. Now we tried to turn the knobs, never exceeding a half of a round. So it was possible to turn the knobs back to the original position at every time. But the diffraction patterns changes not in the expected way. We have always seen an oval pattern moving through the field of view. Please have a look at our in-focus diffraction pattern. You can see the Poisson dot as well. It means it is aligned.

    So we decided to bring the telescope back to the distributor to check what's wrong. The Gladius was there from mid of December 2007 to beginning of February 2008 (7 weeks!!). You were informed about it (from beginning!), but you never take the chance to come to Germany and see what's not in place. We have got it back nearly in the same state. Two markings match exactly and the third one was only a line width aside. But the oval diffraction patterns remains.

    After some additional tests we decided to measure the optical quality of the Gladius. The result you can find in the report from Mr. Rohr.

    An other problem of the Gladius is the condensation on the secondary mirror. Under normal conditions it takes about half an hour and the secondary mirror is completely moistened. Without an additional dew shield the telescope is not usable from autumn to spring in Central Europe latitudes. At the same time it is no problem with a normal dew shield on a Maksutov-Cassegrain to use the telescope for several hours.

    The next problem is the mask ring to reduce the aperture to 8 inch. The metal ring fits exactly on the main mirror, but only at room temperature. If the ambient temperature goes down to 0°C or lower it cannot be removed anymore. The plastic plate coming with this mask needs to be fixed in the mask too. Otherwise it is possible that it hits the main mirror when the cover is removed for normal observing.

    One last word to the Gladius you delivered to Mr. Parker (Florida). It is easy to see the difference in the thickness of the main mirror. Maybe the holder is different too.



    We received the return receipt from our distributor on Thursday (3.4.2008) and we will send it back on Monday morning.

    Best Regards

    Joerg Ackermann



    Bilder werden nicht überall angezeigt, daher von mir eingefügt. WRohr
    Geändert von Rohr (05.04.2008 um 09:27 Uhr)

  • #5

    Standard Riferimento: Gladius 315 CF - als Schwert geeignet

    Dear mr. Rohr and Ackermann,

    It's out of any doubt you had a problem with this telescope.
    But I won't say a word about this problem until the telescope will get here.
    I'll be happy to share here my own diagnosis as soon as possible.
    Remember it's my highest priority to tell anybody this telescope had a problem succesfully fixed.
    For sure, the problem is not coming out from the primary holder desing because otherwise I'd have had a 100% defective telescopes production!
    That's quite obvious.

    Just to clear my position, the reseller informed me about a problem occurred on last December and I gave him detailed directions how to fix it. And he was successful according to what he reported to me on Jan. 29th.
    From that period on, I heard no longer from him, so I supposed anything went fine. That's all. You can stay sure I would have come to Germany or asked for a return back here of that telescope if this was considered as required by the reseller to fix a problem he couldn't fix!! That's quite obvious, isn't it?
    This test by mr. Rohr was a very cold shower indeed, both to myself and to the reseller.
    Again, I won't add anything else until the telescope will get here.
    I'll get my own conclusions only after my inspection around the telescope.

    MIRROR GETTING WET
    There are 2 mods I'll introduce over this month with the new CF315 release: a new 20cm long CF shield around the primary mirror and a particular solution increasing the thermal inertia of the secondary mirror. As you can easily notice, there's no way I can get a wider secondary shield for obvious reasons of obstruction increasing. Mirrors get wet as faster as the thermal inertia is lower and the secondary mirror has a very little inertia indeed. An heater should fix the problem entirely, but I don't like the idea of having a cable coming out of a telescope.

    PRIMARY MIRROR DIFFERENCE
    The Gladius you could see in D. Parker's hands is my own unit which was made 2,5 years ago as the Gladius # 0 with a traditional flat mirror, now discontinued because considered as "risky" over the long term. I think such a design could get its original shape as lost in several years with any negative consequence you can imagine. Any primary mirror held by its central hole (typically SCTs and MCTs) owns a shape close to the actual Gladius primary mirror. Hence the difference you noticed.

    PRIMARY CAP W/MASK
    This solution was made at no extra cost for the very first time with this telescope, so it wasn't tested yet in any condition.
    Of course, now I know from you about this problem under low temps, I'll fix it for sure. I do appreciate any feedback.

    CERTIFICATE ENCLOSED
    My policy is NOT to enclose any interferometrical test with Gladius telescopes. The certificate you can find there is signed by myself and states the quality I assure. I 100% agree and share the same reason which lead companies as respectable and valued as Astrophysics and TEC to do so.
    Any way, I'm evaluating to publish there an additional star test.

    Hope now situation is a bit clearer than before...
    Can't wait to get the telescope here for my own diagnosis. Believe me!
    Also, I like to discuss about my solutions and hear ideas from any of you. The perfect telescope simply doesn't exist, but we can get as close to the perfection as more feedbacks and suggestions are coming.


  • #6

    Standard AW: Gladius 315 CF - als Schwert geeignet

    OK, dear Paolo,

    let's wait for your test results, when the telescope is back to you. But meanwhile you could publish here your controll star test or the other test results of this individual telescope, you have. Use your host surver for the images here, it's better.

    My interest is, how do you fix the main mirror in the testing setup at first, and then I'm interested in a RoC-interferogramm or an interferogramm by compensation in a setup as you can find here: http://www.astro-foren.de/showthread...3294#post33294
    I'm sure, Massimo was calculating a compensating setup for your main mirror as a Null test as we do with parabolas: http://rohr.aiax.de/Kompens503lens.jpg

    Remove my cork disks. Have a look, how the small cone presses on the edge of the glas body in front of the mirror . The white teflon distance ring is to thin. You can see the scratches at the metall cone itself. Think about a better assembling the main mirror and how to hold in position the screw nut behind the holder. This component is rotating itself by rotation the eyepiece holder. There are more than one problems.

    This is my RoC interferogramm of the main mirror and the AtmosFringe file:
    http://rohr.aiax.de/P1010034A.jpg
    http://rohr.aiax.de/P1010034Alin.frg
    Herzlichen Gruß! Wolfgang Rohr
    ICQ-Nr.200281996 SkypeName: codiac_75
    Neu: Zygo-Vermessung
    http://rohr.aiax.de
    email: Diese E-Mail-Adresse ist vor Spambots geschützt! Zur Anzeige muss JavaScript eingeschaltet sein!
    Tel: 09521 5136


     


  • #7

    Standard Re: Gladius 315 CF - als Schwert geeignet

    If a mirror mount introduces astigmatism, how long does it take the mirror to recover once the problem is corrected?

    I ask because we once looked at a 6" f/8 Newtonian that had horrible astigmatism. We found someone had driven wedges between the mirror and the edge of the cell, holding it so tightly it was warped. We removed the wedges. After four hours the astigmatism was still there. While obviously better, it was still fairly severe. Unfortunately, we never saw the telescope again, so I don't know if it finally recovered completely, and how long it took.

    Thanks, and clear skies, Alan
     


  • Standard AW: Gladius 315 CF - als Schwert geeignet

    Dear Alan,

    this could be a bigger problem:

    At first, if you remove the pressure on a glas disk, the glas will instantly fall in it's normal position or shape.

    You can introduce astigmatism by the main mirror itself (the worst case), by the mirror cell and any pressure to the glas body and at last
    you can introduce astigmatism by the flat secondary, if it is not a flat, or if it has an astigmatic surface, or there is a mistake with the secondary cell.

    We mostly test a parabola in vertical position as this foto shows:
    http://www.astro-foren.de/showthread...5325#post35325


    If you test large mirrors, this can introduce a significant astigmatism as my wavefront diagram shows: But if you look to
    the Zernical coeffitients here http://www.astro-foren.de/showthread.php?t=6659, this must be a low order astigmatism,
    as the diagram shows. coeffitients Z04 Astigm X or Z05 Astigm Y.

    Herzlichen Gruß! Wolfgang Rohr
    ICQ-Nr.200281996 SkypeName: codiac_75
    Neu: Zygo-Vermessung
    http://rohr.aiax.de
    email: Diese E-Mail-Adresse ist vor Spambots geschützt! Zur Anzeige muss JavaScript eingeschaltet sein!
    Tel: 09521 5136


  •  

    Standard Riferimento: Gladius 315 CF - als Schwert geeignet

    Dear mr. Rohr,

    Find here the two original interferometrical test reports made by Massimo Riccardi on Oct. 20th, 2007 with the Gladius CF315 just out from factory and a while before to be delivered to the reseller.

    Full aperture:
    http://www.lazzarotti-optics.com/ima...315_071001.jpg

    D=235mm sub-aperture w/the mask on:
    http://www.lazzarotti-optics.com/ima...001_d235mm.jpg

    As you can see, it exceeds the 0.04 RMS frontwave correction I ensure with any telescope I make, so I had no doubt both with the mirror set and the mechanical assembly. This happens routinely here...
    The diafragmed mirror (D=235mm) shows an even better correction as expected.

    This definitively proves the Gladius part. n. 071001 left factory with no problems.

    The problem happened elsewhere, I'll investigate in depth where, what and why this happened. Stay sure.
    I'll fix the problem as well and I'll pristine that scope at the original quality level. Hope the mirror surface had no irreversible deformation.

    The primary mirror support works OK and flawlessly with any Gladius I produced so far in any condition.
    The "scratched ring" you could notice there in the conical section of the internal tube running inside the primary itself proves that tube has been rotated. Any Gladius has that "scratched ring", the aluminum is softer than Pyrex glass, so this is easy to happen and it's good to happen to avoid localized severe pressure concentrations!

    The tube's conical section meeting the mirror internal edge has a 5.8° inclination, so the preloaded force I use to steadily keep the primary in place is greatly transmitted to the mirror in a radial way through its innermost edge. Not to bore you with math, simply try to imagine a lamberjack using a wood wedge to fall a tree. The wedge make the tree falling because "pushing out" the tree top.
    The radial force cannot cause any surface aberration because of the very huge reaction given by the 315/2mm glass wall, 55mm thick at the center!!

    Axial forces only can cause a surface deformation if applied in front of the mirror. The original white nylon washer should be thus almost unloaded. Thus, the additional cork washer you added is not fixing that astigmatism problem. I'll remove it for sure.
    Also, remember it's hard indeed to get a surface deformation in a 55mm thick glass!! If any, these should be very localized all way around the central hole which is "obscured" any way by the 66mm wide secondary support.

    That's all for now.
    I'll write up a new message here once I'll have analized the scope in question.
    Thank you for your attention.
     

  • #10
    Dear Paolo,

    now look: There are some similarity between our fringes map, if you rotate the wave front diagram. Look at 08:00 and
    03:00 o'clock at these image and



    at 10:00 and 04:00 o'clock of Massimo's image. This shows the same shape of surface, this must be reality.



    Now look my report of the main mirror out of the holder: Without the astigmatism it would be a Strehl as high as yours, if
    you subtract the astigmatism. There is anything, what introduce astigmatism and this must be a matter of the main
    mirror. This is my fringes map and the *.frg file:
    http://rohr.aiax.de/P1010034A.jpg
    http://rohr.aiax.de/P1010034Alin.frg



    Your fringes map looks OK, it's made in autokollimation/flat with the complete system, so we need the scale 0.5
    But now there is an astigmatism and it's definitely the main mirror. I guess, you will test at first the main mirror
    for this, without any other compensation optic.

    The astigmatism what we measured by three independent persons must have any cause. Soon, you will get this
    individuel system back, and I'm interested for your results. What kind of glas material do you use?

    My result on the holder:
    http://rohr.aiax.de/@315Gladius_09.jpg

    out of holder: these are the upper Newton rings.
    http://rohr.aiax.de/@315Gladius_11.jpg

    I guess, Massimo is using the Bath Interferometer, is'n it?

    Did you consider about the influence of the transport?
    Herzlichen Gruß! Wolfgang Rohr