Dear all,
I have a jenaval microscope.
I guess my drum filter is distorted between glasses.
I can't find solutions and spare parts.
please, help me
(https://www.mikroskopie-forum.de/pictures012/314712_36038289.jpg)
dear everyone,
I separated the DIK(jeneval) filter using heat gun( BOSCH GHG20-63 with digital temp. control), which has a balsam issue.
So far, it seems to have been a successful separation.
However, there is one concern issue. It's how to attach it.
I can't get balsam fluid and I don't have equipment and technology to attach it with a high transparent urethane resin.
I'm asking you which of the two methods should I dig into to solve it.
Zitat von: Changhee in Februar 17, 2022, 16:23:20 NACHMITTAGS
dear everyone,
I separated the DIK(jeneval) filter using heat gun( BOSCH GHG20-63 with digital temp. control), which has a balsam issue.
So far, it seems to have been a successful separation.
However, there is one concern issue. It's how to attach it.
I can't get balsam fluid and I don't have equipment and technology to attach it with a high transparent urethane resin.
I'm asking you which of the two methods should I dig into to solve it.
[/img][/img]
Hi,
why not using UV bonding resin from Loctite or similar, hardenig with blue light or sun light.
Best
Michael
Dear Michael,
As a result of inquiring with a resin company, I heard that there is no Yellow mutation from UV light
when air bubbles are removed with a vacuum chamber and urethane resin is used.
I found it, but it's too expensive.
Crystal Clear 204 (0.86kg)
Best
Changhee
Dear Michael,
I have no experience using resin.
Can you recommend a more specific resin product?
Best
Changhee.
Hi Changhee,
In my opinion, the perfect way to repair your DIK-component is to use a thermoplastic resin such as Canada-Balsam (not as fluid, but in solid state) or a similar substance. These resins melt at about 100°C and are easy to apply. The great advantage is that you can separate the parts easily and without any risk if something went wrong. I would never ever use a UV-light hardening substance for such an issue.
If you have problems with the procedure, I can offer my help.
Best,
Olaf
Dear Olaf,
Thank you for your comment.
I agree with you.
According to your advice, I purchased Canadian balsam.
http://swscience.net/product/detail.html?product_no=9081&cate_no=129&display_group=1&cafe_mkt=naver_ks&mkt_in=Y&ghost_mall_id=naver&ref=naver_open&NaPm=ct%3Dkzs7fr6w%7Cci%3D3b1078776b04045054f8fce8e06679f52ff8d407%7Ctr%3Dslsc%7Csn%3D270836%7Chk%3D50608bd938980ec2170e72cea0751cbe3a2e0369
How long does it take for the filter to stick on?
Best,
Changhee
Hi Changhee,
Unfortunately I'm not able to read the description of this product written in Chinese. I hope this is the original hard and brittle resin and not any solution in xylene or other solvents. If it is the pure substance, it will get soft by heating and finally melts at about 100°C. It will be hard again immediately after cooling down. You need some experience with that stuff. Heating too far above the melting point will produce small bubbles which are hard to remove.
The solution of Canada balsam will not work for this application!!!
Best, Olaf
Dear Olaf,
Can you tell me what Balsam products you know?
I can purchase through Amazon or eBay.com web site.
And, I live in Korea. ^^
I found this product on eBay.
https://www.ebay.com/itm/162580633469?var=463887248728&hash=item25da8f977d:g:9pIAAOSwKOZcReBb
Best,
Changhee
Hi Changhee,
the argument with balsam make sense as it will be removable. I would use Conloc UV-665 and a LED light source with around 368nm. The argument for this is that jou can adjust the optical elements as long as you are operating with low light intensity. With vacum you can remove bubbles and if ok than apply the light, ready within a few seconds but not removable.
Best,
Michael
Hi Changhee,
As Olav mentioned you need the dry resin, it is hard to find. The product you are showing us here is fluid.I could send you a smal amount: Cana Balsam extra pure, dried to glas hardness for microscopy Riedel De Haen. I guess the issue will be shipment of obscure material to your country.
Best
Michael
Hallo Olav, Michael, verzeihen Sie mir meine Unwissenheit, aber was ist der Unterschied, wenn Sie den aufgelösten Kanadabalsam bei 100oC trocknen lassen?
Danke,
René
BTW, ich verwende UV-Kleber (Methacrylat) für Deckgläser auf Kunststoffzylindern. Wenn sie brechen, lege ich sie in 50-70%igem Ethanol mit etwas Spülmittel ein. Nach ein paar Wochen lassen sie sich dann zur Reparatur ablösen.
Der Brechungsindex von UV-Kleber könnte natürlich nicht ideal sein.
Dear Michael,
Thank you for your help.
I want to experiment with it myself, and I'm going to dry Canadian balsam using a hot plate machine with stir function.
If the experiment continues to fail, please give me advice.
Best,
Changhee
Hello Changee,
also from my side, please only use Canada Balsam "Glashart" here as Olaf Medenbach recommended! Why?
Two reasons: It is a reversible process and the Canada Balsam "Glashart" hardens fairly immediately after cooling. If Canada Balsam "Liquidum" (= Canada Balsam dissolved in xylene) as sold e.g. by ROTH for histology, is used, the hardening process can take months (in an oven at 60° 2-3 weeks). The glueing must be done between crossed polars (heat sensitive!), so You have to make your own simple vertical assembly system here, consisting of a light source, the polarizer (in JENAVAL, the vibration direction of the polarizer is not W-E as conventionally, but SW- NE) and analyzer with the then corresponding perpendicular NW- SE vibration direction. The DIK- prism is under 45° between both vibration directions of the polars. An intact prism helps here to figure out the location and starting point of the dark/ black interference stripe which can also assist as alignment tool here. Please also note, that if the polars are parallel other interference stripes (no black stripe but a blueish- brownish stripe according to the parallel polarization colours) are produced. Whatever alignment is used, an intact JENAVAL contrast prism must serve as reference. The fine- alignment of the prism halfs can be done with bamboo sticks or similar as long as the glue is not hard. Also the glue film should be a thin as possible. The two prism halfs must, when glued together, again produce the stripe system in the approx. same positions as the other intact prisms do. Otherwise the de SENARMONT contrast modulation will be off from your other prisms (you would then have to rotate the de SENARMONT plate in between to retain a similar contrast, which is a hassle).
The other reason for using Canada Balsam is, that for the correct crystallographic functionality of the DIK prism, of those freely- acessible optical matters for glueing optical components, only Canada Balsam has the fairly correct refractive index of nD= 1.5225 (the used optical quartz Quartz was absolutely strain- free (< 15 nm/ 2 cm) in the JENA 250-CF systems with n e = 1.55337 and n o = 1.54426 as usually). A wrong glue with a wrong dispersion will change the way how the upper DIK- prism half will reunify the two rays.
When mounting the refurbished prism back in its JENAVAL contrast prism housing, the edged wedge helps to mount it in the correct wedge direction (the wedge of the condenser DIK prism and that of the objective sided DIK prism must be the same in the JENAVAL- otherwise no DIK is produced). That is also, why in the normal "non- contrast version" of the JENAVAL, the objective- sided DIK prisms can be fully rotated by 360° in their intermediate ring mounts.
If You accidentially "flip" the prism up-side-down, also no DIK will be produced (luckily that cannot happen here, due to the alignment edge). Also, the original tilting angle must be kept, by glueing in the prism as accurately as possible (not too much glue!- for that also Canada Balsman can serve well), otherwise the DIK will also not be produced, as the c- axis tilt will change then (if the mounted prism has a different angle against the mount as in the original alignment), resulting in a wrong prism shear.
A decent JENAVAL DIK image looks like the one I have attached below, taken with an oil immersion GF- PA 50x type (no "Photoshop result", no sharpening, no contrast enhancement, nor disruptive setting of the display curve etc. -just as it is- when visually enjoying the phantastic JENA- 250 CF optics!).
The slide is from a non- public ZEISS-talk, I made, to illustrate the specialities of our JENAVAL DIK.
Take Care
Michael
Hello Changee,
in the meantime I talked to a colleague of mine who repairs astronomical instruments. But he swears for the Canada Balsam solution (!):
He applies the Canada Balsam solution to one of the two optical surfaces. Than let it dry for approx. 24 hrs (dust free environment!). With hot air any solvent residues are removed and the Canada Balsam will liquidify again. You have to experiment with the temperature here a bit. The Canada Balsam will become fluid now and the optical surface must be horizontally. The other prism half is now heated up and both halfs are pressed together. After a few minutes everything is hardened out. Canada Balsam residues that have "gone outside" -if disturbing- can be removed with xylene after a few hours. The whole new mounted DIK- prism is now ready for remounting into the JENAVAL contrast DIK mount. Before, finger prints on the prism surfaces can be removed with window glass cleaner.
Thanks
Michael
Hello together,
I found by chance, when I was searching for Canada Balsam "Glashart", in an militaria-forum a thread about repairing broken prism of field glasses
https://www.militaria-fundforum.de/forum/index.php?thread/437819-kanadabalsam-prismen-verkitten/&postID=3110009#post3110009 .
One answer there corresponds and confirms last answer from Michael's last post.
I will cite the instruction of user "porro" here:
ZitatSo wirds gemacht:
1. Kanadabalsam einseitig dünn auftragen und ca. 10-12 Std. ablüften lassen. Danach ist er schon sehr zäh aber noch nicht hart. Es empfiehlt sich, die Teile während dieser Zeit abzudecken, damit kein Staub darauf fällt.
2. Dann mit dem Fön (max. Stufe) erhitzen. Innerhalb weniger Minuten hat er ein Konsistenz wie Wasser. Deshalb ist es wichtig, die Bruchstelle waagerecht auszurichten, sonst läuft alles runter. Bei der Gelegenheit lösen sich jetzt auch evtl. noch vorhandene Luftbläschen auf.
3. Das andere Bruchstück ebenfalls erwärmen und anschließend beide Teile zusammenpressen. Die Fläche des Bruchs muss glasklar erscheinen.
Nun zügig die beiden Teile perfekt zueinander ausrichten (mit der Lupe kontrollieren) und anschließend wieder waagerecht abstellen. Innerhalb weniger Minuten sind die Teile bereits so fest verbunden, dass keine Korrektur mehr möglich ist !
Ein evtl. Überstand kann jetzt mit Xylol entfernt werden.
4. Bereits 2 Stunden ( ! ) nach dem verkitten ist der Kanadabalsam glashart :)
In meinen früheren Versuchen -ohne Hitze- war die Fläche des Bruchs nach 5 Wochen noch nicht ausgehärtet und die Teile sind unter Belastung wieder abgeschert. Das umständliche Verspannen der Teile während des Aushärtevorgangs entfällt ebenfalls.
@Changee: I hope you can read this with the help of a translator applicaton.
Best
Günter
Hallo Günter,
ja das Rezept was Du da gefunden hast, ist bei den Fernglas- und Astroleuten wohl die übliche Kittmethode für Prismen und Okularlinsen. Der Kollege lässt nur den Kanadabalsam länger Antrocknen/ Ablüften. Man kann delaminierte Optiken auch wohl chemisch vollständig entkitten ohne die reflexmindernden Beläge anzugreifen. Wie das geht, weiß ich nur theoretisch. Falls das mal gebraucht wird, gerne als PN. Das Rezept möchte ich nicht in einem Forum veröffentlicht wissen. Wie gesagt, ich kenne das auch nur vom Hörensagen. Die benötigten Chemikalien sind auch für Privatpersonen nicht erhältlich, wie so viele Sachen heutzutage.
Übrigens: Alte ZEISS- West Germany NEOFLUARE, Kpl- Okulare und POL- Filter waren auch mit Kanadabalsam gekittet, bis in die 70er Jahre hinein. Das kann man gut erkennen, wenn man die fraglichen Optiken unter gutem Licht leicht hin- und her kippt (in der Hand). Dann sieht man am Fassungsrand den gelblichen Kanadabalsam auch. Da ja die Kittschichten selbst sehr dünn sind, stört die gelbliche Eigenfarbe des Kanadabalsams wenig.
Kanadabalsam neigt praktisch nicht zur Delamination, ein weiterer Vorteil. Nachteil ist, dass dieser Stoff für die heute in der Optikfertigung allgemein üblichen Richtkittverfahren ungeeignet ist.
LG
Michael
Dear Apochromat,
Thank you for your special information.
It was the first time I knew that I could get an image of this quality from Jenaval.
It's fantastic.
I will also try to take a more beautiful image.
Best,
Changhee
Dear Günter,
Thank you for letting me know how to proceed in detail.
Best,
Changhee
Dear all,
I tried to join the glass.
First, the medium-hardened Canada balsam was heated at 100 temp.
Second, 120 temp. was heated to allow it to flow like a liquid.
Third, it was dropped into the filter like a single drop.
Fourth, two filters were heated at 120 temp..
Fifth, the two were joined and heated continuously while applying a certain amount of pressure.
Sixth, it hardened as the temperature dropped.
However, it was confirmed that there were many scratches on the glass surface coating.
So far, the work seems successful and plan to go through a few days of drying.
Best,
Changhee
Dear all,
I think there was a problem with the repair process.
I measured it with Vernier Caliper, and it varies from 4.14mm to 4.16mm depending on the location.
As expected, it doesn't seem easy. :'(
Hello Changhee,
what kind of caliper do you use? A normal industrial grade one? You shouldn't even trust your caliper with an accuracy better than 0,05 mm even though it implies to be more accurate. If you intend to measure your plate with higher accuracy, you should use a bow micrometer with a (digital) display scale of 0,001 mm.
Best regards
Kay
Dear Hoerster,
I'm using the Mitutoyo product. but it is limited 0.01mm resolution.
In the future, After removing Canada balsam, the glass filter will be separated again.
However, I need to think more about how to succeed method.
Best,
Changhee
Zitat von: Changhee in Februar 28, 2022, 08:09:41 VORMITTAG
Dear Hoerster,
I'm using the Mitutoyo product. but it is limited 0.01mm resolution.
In the future, After removing Canada balsam, the glass filter will be separated again.
However, I need to think more about how to succeed method.
Best,
Changhee
Dear Changhee,
0,01 mm is the display resolution, but this is not the measurement accuracy which is more to 0,02 - 0,03 mm according to DIN852 and depending on the caliper's length. I would again recommend to use a bow micrometer with display resolution of 0,001 mm, please follow this link for example Bow micrometer (https://shop.mitutoyo.de/web/mitutoyo/de/mitutoyo/01.02.01.0/Digimatic%20Micrometer/$catalogue/mitutoyoData/PR/293-240-30/index.xhtml)
Best regards
Kay
Dear Hoerster,
Is the answer to make Canada-balsam very thin?
To test this, I put it on with Immersion Oil and fixed to tube filter using 3M Scotch tape.
However, DIK did not occur. :(
Best,
Changhee