MicrobeHunter.com Microscopy Forum

You can also access this page with: www.microscopy-forum.com
It is currently Sat Jan 19, 2019 12:46 pm

All times are UTC




Post new topic  Reply to topic  [ 56 posts ]  Go to page Previous 1 2
Author Message
PostPosted: Tue Jan 08, 2019 11:05 am 
Offline
User avatar

Joined: Sun Oct 12, 2014 2:34 am
Posts: 5284
Location: Estepona
Quote:
I followed the instructions of the lamp house article as good as I could, but whatever I tried, I could not see the two pins of the filament shown on the pictures.
Could you check again to see if any filters remained in place? If so they should be removed during the setting up process.


Attachments:
filter-location.jpg
filter-location.jpg [ 19.26 KiB | Viewed 280 times ]

_________________
Zeiss Standard WL & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)
Top
   
PostPosted: Tue Jan 08, 2019 12:33 pm 
Offline
User avatar

Joined: Mon Dec 03, 2018 7:05 pm
Posts: 96
Location: Huizen, Netherlands
I had checked (and did now again). The only filter I have is a polarization filter and I did not use that during the aligning proces. Both parts of this filter were removed from the microscope. I am very sure no filters were placed in the lightpath. Maybe the reason I can't see the wire extensions is the lens in the lamp house, which is frosted as John B. says. It cannot be removed because using it is part of the aligning proces.


Top
   
PostPosted: Tue Jan 08, 2019 1:08 pm 
Offline
User avatar

Joined: Sun Oct 12, 2014 2:34 am
Posts: 5284
Location: Estepona
Found something that clarifies this a bit.

See link: http://www.microscopy-uk.org.uk/mag/art ... ohler.html

About half way down the page there is a reference to a frosted collector lens. Just bellow that there is an image of a frosted collector Fig. 4 and a clear collector Fig. 5

"To establish Köhler illumination, this frosted glass will be removed before focusing an image of the filament into the back focal plane of the objective (see Fig. 2 for the location of the back focal plane of the objective). After completing the process of establishing Köhler illumination, the frosted glass is reinserted. In case of a frosted collector lens, the diffuse image of the filament must be projected into the back focal plane of the objective.The proper procedure to establish Köhler illumination is illustrated in many textbooks about microscopy or photomicrography."

From reading this it would seem that you have done it right.

Even though one can't quite distinguish the filament, one can achieve a similar result by focusing the diffuse image of it as much as possible.

_________________
Zeiss Standard WL & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)


Top
   
PostPosted: Tue Jan 08, 2019 2:50 pm 
Offline
User avatar

Joined: Tue Feb 03, 2015 9:42 pm
Posts: 3157
Location: Cumbria, UK
Exactly correct 75' - the blurred filament is able to be 'focused' as is it's reflection.

Jan,
Remember to focus the reflected image using the in-out reflector - usually about 2mm out is my setting. This gives 2 bright spots - one larger than the other, which need to be vertically aligned, brought adjacent then over to the eyepiece tube. Looking at the light use the focus of the lamp-house to give an even field, not to try to focus anything, just to 'blur' the two images into one big one!

Tricky, counter-intuitive and not particularly good - the one thing I find a little irksome with the Big-O - the dratted illumination, especially as I use a x2.5 as my scanning objective which makes matters more difficult than a x4 I think in use.

Looks like you're just about there, try to get the two images adjacent not together before you go to the eyepiece-tube and lamp-house condenser stage.....

Good luck, John B. :)

_________________
John B
my website


Top
   
PostPosted: Tue Jan 08, 2019 5:14 pm 
Offline
User avatar

Joined: Mon Dec 03, 2018 7:05 pm
Posts: 96
Location: Huizen, Netherlands
OK, I found the two reflections. Even thought I saw a very faint filament in the weaker one. I brought them together until the touched iets other.Then tried to blur them with the moving lamp house lens (lens between lamp and microscope housing), but that is very difficult because this lens moves to one side a little when turning the setting knob at the outside of the lamp house, causing the reflections to move to one side.

edit: Ok, think I have it now. Started with the lamp closer to the microscope house and moved it backward instead of forward. I could cleasrly see the light spreading out and became much more uniform over the whole surface.


Top
   
PostPosted: Tue Jan 08, 2019 5:44 pm 
Offline
User avatar

Joined: Tue Feb 03, 2015 9:42 pm
Posts: 3157
Location: Cumbria, UK
Yes!!! Well done my friend, sounds like you have it beaten! :D

That's all there is to it, as with so many things, easy once you know how!
That's another piece of your beautiful 'scope in place Jan.

Now the real work begins..... ;)

John B. :)

_________________
John B
my website


Top
   
PostPosted: Wed Jan 09, 2019 7:55 am 
Offline
User avatar

Joined: Mon Dec 03, 2018 7:05 pm
Posts: 96
Location: Huizen, Netherlands
Thank you both for all the help.
I can do it now, but I don't understand everything. What I think I understand is that the goal of the alignment is (1) getting as much light as possible on the specimen (so not in other directions, missing the specimen) and (b) a uniform illumination of the specimen.

What I do not understand is, why the two light spots - image of the filament and its reflection - should not be placed as exactly as possible UPON each other, but only touching each other. I have been looking for an article explaining where exactly the reflection of the filament originates, but I haven't found one.
The whole proces looks a bit like collimating a telescope: aligning the optical axes of the instrument. It took me some time to understand this as well. I have


Top
   
PostPosted: Wed Jan 09, 2019 9:16 am 
Offline

Joined: Mon Apr 10, 2017 8:24 am
Posts: 751
Location: NorthWest England
janvangastel wrote:
What I do not understand is, why the two light spots - image of the filament and its reflection - should not be placed as exactly as possible UPON each other, but only touching each other. I have been looking for an article explaining where exactly the reflection of the filament originates, but I haven't found one.

The two images should interleave ... so that the whole patch has reasonably even luminosity.
The reflected image comes from the concave mirror behind the bulb.
[unlike your telescope mirror, this one produces a real and inverted image at 1:1 scale in the plane of the actual filament]

MichaelG.

_________________
Too many 'projects'


Last edited by MichaelG. on Wed Jan 09, 2019 9:53 am, edited 1 time in total.

Top
   
PostPosted: Wed Jan 09, 2019 9:53 am 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1304
MichaelG. wrote:
janvangastel wrote:
What I do not understand is, why the two light spots - image of the filament and its reflection - should not be placed as exactly as possible UPON each other, but only touching each other. I have been looking for an article explaining where exactly the reflection of the filament originates, but I haven't found one.

The two images should interleave ... so that the whole patch has reasonably even luminosity.
The reflected image comes from the concave mirror behind the bulb.
[assuming that there is a mirror in that lamphouse]

MichaelG.
Geometrical Optics shows, that when the object (filament in this case) and its image are of the same size, and are symmetrically located with respect to the optical axis (object above and image below, or vice versa) they are at the same distance from the reflective mirror. Hence, I conclude that such geometry uniformly illuminates a relatively large area around (perpendicular) to the optical axis. Any change of the distance between the concave mirror and the filament will either enlarge the reflected image or decrease it - depending on the distance and the focal point. I think, that when the filament and image are not of the same size, whether they appear to be overlapping or not, the uniformity of illumination is worse.

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Wed Jan 09, 2019 10:08 am 
Offline

Joined: Mon Apr 10, 2017 8:24 am
Posts: 751
Location: NorthWest England
This, from the Ortholux II manual, might help:

Attachment:
Ortholux II Lamp Alignment.jpg
Ortholux II Lamp Alignment.jpg [ 216.01 KiB | Viewed 232 times ]


Note: Some other illuminators interleave the image; to produce a small and evenly luminous source, but this one appears to place them tip-to tip to produce a square[ish] patch.

MichaelG.
.
.

The edit of my previous post crossed with Hobbyst46 quoting it

_________________
Too many 'projects'


Top
   
PostPosted: Wed Jan 09, 2019 12:26 pm 
Offline
User avatar

Joined: Sun Oct 12, 2014 2:34 am
Posts: 5284
Location: Estepona
The reason there are two images is simply to increase the illumination by capturing as much of the light emitted by the filament as possible.

The first and slightly brighter image is formed by the forward facing part of the filament.

The second image is formed by reflecting back (using a mirror) the part of the filament that shines away from the collector lens.

While many times both images are superimposed, there are other times when they are placed next to each other particularly when the filament is too small to illuminate the back focal plane on its own.

_________________
Zeiss Standard WL & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)


Top
   
PostPosted: Wed Jan 09, 2019 12:47 pm 
Offline
User avatar

Joined: Mon Dec 03, 2018 7:05 pm
Posts: 96
Location: Huizen, Netherlands
Quote:
The reason there are two images is simply to increase the illumination by capturing as much of the light emitted by the filament as possible. The first and slightly brighter image is formed by the forward facing part of the filament. The second image is formed by reflecting back (using a mirror) the part of the filament that shines away from the collector lens.


OK thanks for the clarification.

From the above (MichaelG's) and other photographs I have seen, the procedure seems very easy, but it is not in practice, at least not with my Orthoplan microscope.
In starting position (position of lens in front of lamp midrange, sideways position midrange and up/down position at its lowest position) the image of the filament (the brightest one) is about centered in the field lens and the reflection of the filament is on top (top meaning towards the microscope stand, so away from the observer sitting in front of the instrument) and a little to the left, but partly out of sight. I can bring the reflection vertically in line with the image, but when I then turn the knob for verical adjustment to bring both images together, the image moves upward and when image and reflection are close together they are almost at the top of the field lens. And when I turn the focusing knob of the lens in front of the filament, the whole light patch moves, because the lens can move sideways and a little upward when moving it in the direction away from the filament. Moreover, the left/right movement mechanism does not only move the light patch to the right or to the left but is it more like a rotational movement. So it is more 'fuzzling around' until it looks OK then 'I am absolutely sure'. At the end of the whole procedure though, when I look into the eyepiece tube (without eyepiece) everthing looks well centered and uniformly lit and, looking though the eyepieces, also the specimen looks uniformly lit to the eye, even at very low light condition. I know the eye is not the best instrument to measure uniformity of light, but I don't have an objective measuring device.


Top
   
PostPosted: Wed Jan 09, 2019 1:20 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1304
The same filament-image alignment method has been applied for high pressure mercuruy and xenon lamps for fluorescence microscopy, at least the Zeiss HBO lamps. The "detector" of illumination uniformity was not the eye, but rather a bright white surface, for example a flat piece of filter paper, or the plastered wall itself. The preliminary alignment of the HBO is done with the lamp on a bench, not installed on the microscope; the light beam is directed towards the wall, at a distance of 1-2m say, the two images are brought together, side by side, to form a square light source (not superposed images) on the wall. Then the lamp is installed onto the microscope (it is epi-illumination), a piece of paper placed below the objective (instead of a sample slide) and the appearance of a white-violet spot indicates the uniformity of illumination. Perhaps a similar approach will suit the Orthoplan.

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Wed Jan 09, 2019 2:08 pm 
Offline

Joined: Mon Apr 10, 2017 8:24 am
Posts: 751
Location: NorthWest England
It may be worth checking two things:

1. That the correct [to full specification] bulb is fitted
2. That it is correctly inserted into the holder

It is not unknown for a cheap bulb to be used as a well-intentioned replacement for a better quality original item ... and they sometimes work loose.

MichaelG.

_________________
Too many 'projects'


Top
   
PostPosted: Wed Jan 09, 2019 2:34 pm 
Offline
User avatar

Joined: Mon Dec 03, 2018 7:05 pm
Posts: 96
Location: Huizen, Netherlands
I took the lamp house from the microscope and pointed it at the back of a black leather chair. Much better visible light patches now.
First image below is the two light patches vertically aligned. Second is the two patches touching each other and the third image is the defocused image of the two. This was easy to do. But when I attached the lamp house to the microscope again, the light in the eyepieces and on a piece of paper on the field lens was not centered, but brighter at the 'top-left' part of the image. It is only possible to get it centeren when I rotate the lens in front of the filament a little bit with my finger, but I don't know if this will have bad consequences. I do not think so, because the only thing happening is a little displacement of the defocused image to the center of the field. The images are taken a little from the side, so at an angle.

Attachment:
aligned.jpg
aligned.jpg [ 173.92 KiB | Viewed 209 times ]


Attachment:
close together.jpg
close together.jpg [ 139.65 KiB | Viewed 209 times ]


Attachment:
defocused.jpg
defocused.jpg [ 125.49 KiB | Viewed 209 times ]


Last edited by janvangastel on Wed Jan 09, 2019 4:19 pm, edited 1 time in total.

Top
   
PostPosted: Wed Jan 09, 2019 2:48 pm 
Offline
User avatar

Joined: Sun Oct 12, 2014 2:34 am
Posts: 5284
Location: Estepona
Just to remind posters that janvangastel's lamp house has a frosted collecting/focusing lens, this is why it is not possible to view the filament.

See Fig. 4


Attachments:
frosted and clear focusing lens.png
frosted and clear focusing lens.png [ 358.13 KiB | Viewed 206 times ]

_________________
Zeiss Standard WL & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)
Top
   
PostPosted: Wed Jan 09, 2019 6:20 pm 
Offline

Joined: Sat Dec 15, 2018 4:31 pm
Posts: 10
Believe it or not, this is the exact same process I struggled with on my Orthoplan. I have the same lamp house and frosted lens. I tried tracing paper to no avail too because of the frosted lens.

First I projected the image on the wall using a slide, but then I realised that when I introduced the swing out lens just behind the field diaphragm into the light path, a virtual image was formed on the back of it and a bright one on the front. The back one is the one you want I think... Even though this virtual image was hard to view though the base port (because it's at an angle) it still showed the two fuzzy filament images, enabling me to align them with respect to each other and to separate them enough so that they weren't blocking each other (even though they emit light they are of course opaque!). It seems to be OK or at least I'm getting an even field with the 2.5x lens. I will try checking the back of the objective next...


Top
   
PostPosted: Wed Jan 09, 2019 6:44 pm 
Offline

Joined: Mon Apr 10, 2017 8:24 am
Posts: 751
Location: NorthWest England
Just a thought : If you wet the frosted surface of the lens with water or oil, it should turn almost transparent.

Appropriate clean-up will, of course, be required.

Electrical safety should be no problem [low voltage], but there is a risk of thermal shock breaking the bulb ... so take care not to splash cold liquid on it.

MichaelG.

_________________
Too many 'projects'


Top
   
PostPosted: Wed Jan 09, 2019 7:22 pm 
Offline
User avatar

Joined: Mon Dec 03, 2018 7:05 pm
Posts: 96
Location: Huizen, Netherlands
Quote:
Even though this virtual image was hard to view though the base port (because it's at an angle) it still showed the two fuzzy filament images, enabling me to align them with respect to each other and to separate them enough so that they weren't blocking each other (even though they emit light they are of course opaque!).


I had also seen those images and just had a closer look at them. On the back of the lens is a brighter one and a fainter one and the look like a filament as you say. They are perfectly aligned vertically, like I aligned them on the back of a chair with the lamphouse away from the microscope and the barely touch each other. Only thing I don't understand is why I cannot get them centered in the field lens without rotating the frosted lens a little. Maybe the lens should not be rotatable at all but should only be able to move back and force while being rock steady in other directions. I don't know.

Quote:
If you wet the frosted surface of the lens with water or oil, it should turn almost transparent.

That could work, but I do'nt think I can do it without making a mess. It's not easy to get between the lens and the housing to clean up.


Top
   
PostPosted: Thu Jan 10, 2019 10:10 pm 
Offline

Joined: Sat Dec 15, 2018 4:31 pm
Posts: 10
janvangastel wrote:
I had also seen those images and just had a closer look at them. On the back of the lens is a brighter one and a fainter one and the look like a filament as you say. They are perfectly aligned vertically, like I aligned them on the back of a chair with the lamphouse away from the microscope and the barely touch each other. Only thing I don't understand is why I cannot get them centered in the field lens without rotating the frosted lens a little. Maybe the lens should not be rotatable at all but should only be able to move back and force while being rock steady in other directions. I don't know.


If the light point source moves when rotate the frosted lens in the condenser then I guess one explanation is that the frosted lens may be misaligned within it's housing.

I decided to try and check for other forms of misalignment on mine and notices that the swing out field lens is out of alignment. It lands slightly tilted so it's not orthogonal to the light source.

To see what's up, I've turned the microscope on it's back, and there is a gap in the bottom casting where you can see what's going on. The lens doesn't land straight when it's tilted into position.

There is a wedge which acts as a stop - you can see it move then you tilt the lens back and forth with the scope on it's back.

This wedge has a black flat headed screw to the side, which controls where the lens lands when in position. I think this might be the adjustment screw for the lens position. Unfortunately mine is screwed all the way in, so there is no more adjustment to be had. The wedge has what looks like a rolled steel pin through it which is connected to the lens tilt mechanism. I suppose it must be spring loaded somewhere in there. I will try upload an image from my phone but it takes big images so I need to reduce them somehow...

If I can't adjust it the proper way, then, seeing I don't want to disturb the field diaphragm housing and all, I would prefer to add a shim to the wedge to try get it closer to alignment. I have some old feeler gauges I can cut worst case.

The whole block which houses the swing out lens and diaphragm and I guess a diagonal mirror, does look like it can be removed. I'm not sure if it can be put repeatedly back though and assembly was probably done with a jig or something.

I suspect that, unless you get the field lens aligned with the condenser, and all the rest behind it from the lamphouse, I guess you aren't going to get perfect Kohler illumination. What effects on resolution this may have I don't know but is the condenser is achromatic I imagine that would also affect things.

Does anyone have a service manual for the Orthoplan? That would help. I don't want to disturb too much on this scope...


Top
   
PostPosted: Thu Jan 10, 2019 11:07 pm 
Offline

Joined: Mon Apr 10, 2017 8:24 am
Posts: 751
Location: NorthWest England
Nicksmith wrote:
I will try upload an image from my phone but it takes big images so I need to reduce them somehow...

If it's an iOS device, I suggest you have a look at the 'CropSize' App.
http://www.cropsize.com

MichaelG.

_________________
Too many 'projects'


Top
   
PostPosted: Fri Jan 11, 2019 9:27 am 
Offline

Joined: Sat Dec 15, 2018 4:31 pm
Posts: 10
On Android used image shrink app. Here goes.

Wedge B controls where swing out lens C lands. Screw A seems to act as a "stop" to park the lens in position D. Lens holder C is tilted. (F is the underside of the field iris).

As you can see in position E the screw is already screwed in as far in as possible and no further inwards adjustment is possible.

The main block upon which all this is mounted has a central hex screw G and several others which possibly mount the block to the chassis. The two screws close together might be an adjustment area, not sure. There might be a prism or mirror to reflect light upwards into the condenser.

Does anyone know what lies beneath this? It would be good to know before I take it apart... Hence request for service manual. Cheers!


Attachments:
File comment: Orthoplan viewed from underside showing swing out lens adjustment and housing.
20190111_090857.jpg
20190111_090857.jpg [ 48.21 KiB | Viewed 132 times ]
20190111_090535.jpg
20190111_090535.jpg [ 44.97 KiB | Viewed 132 times ]
Top
   
PostPosted: Fri Jan 11, 2019 11:15 am 
Offline
User avatar

Joined: Mon Dec 03, 2018 7:05 pm
Posts: 96
Location: Huizen, Netherlands
A way of checking the position of the swing out lens would be to remove the frosted lens in front of the lamp and the lamp itself. Then make something holding a laser to mount in the hole of the lens at the back of the lamp house and point the laser at the field iris. Then (I think) the swing out lens and the mirror or prism can be aligned to get the beam at the right place in the field lens or condensor. Not an easy job. There's no good way now to check the position of every single optical element, at least I don't see it. For telescopes all kinds of of mechanical and optical aligment tools (collimation tools) are sold, but I haven't found these for microscopes. Assume the swing out lens is a little out of place. It might be possible to correct for that by changing the position of the frosted lens and/or the position of the prism behind the swing out lens little. Result will be that the light beam ends at the right spot but does not follow a straight path. I don't know it that will influence the quality of the image in the eyepiece.


Top
   
PostPosted: Fri Jan 11, 2019 3:01 pm 
Offline

Joined: Sat Dec 15, 2018 4:31 pm
Posts: 10
I have something called a Glatter Laser Collimator with a target diffraction grating so I may try that. I think in this case it's just a matter of adding a shim and checking a full frame image with stretched histogram to see if the field is being made uneven by this lens.


Top
   
PostPosted: Fri Jan 11, 2019 3:47 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1304
I believe you folks are aware that pointing a laser or even a laser pointer through the microscope or its accessories should be done with great care, to avoid accidental reflections and refractions hitting the eyes.

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Fri Jan 11, 2019 8:32 pm 
Offline

Joined: Sat Dec 15, 2018 4:31 pm
Posts: 10
Hobbyst46 wrote:
I believe you folks are aware that pointing a laser or even a laser pointer through the microscope or its accessories should be done with great care, to avoid accidental reflections and refractions hitting the eyes.


I certainly value my eyesight more than my microscope :)


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 56 posts ]  Go to page Previous 1 2

All times are UTC


Who is online

Users browsing this forum: No registered users and 4 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited