×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Odd apearence in the microscope.

Odd apearence in the microscope.

Odd apearence in the microscope.

(OP)
Hello !
This is not about materials, but hopefully some of you have seen this before when looking into microscopes.

Here where I am an intern we have an old Carl Zeiss Jena microscope that im using regularly.
Out of nowhere, yesterday, some dark shades appeared over the screen. I have tried to localize where they come from and from what makes sense its from the glass where the view is split into the ocular and the camera and to right before the magnification lenses.
I have tried to lighty dust of any possible glass/filters from the bulb to the magnification lenses but they still apear and it is like they form a "filter" over all images and magnifications.

I have attached 1 photo where you can see the dark shades, and a seconond one where i tried to focus on the shades. To me it looks like cracks.




Anyone who can come with an input about this ?

RE: Odd apearence in the microscope.

Could it be the room lightning from the ceiling ?

I had a similar issue before, and when I block the light that hits on oculars the effect was cleared.
It also looks like wave interference pattern.

RE: Odd apearence in the microscope.

Or it could be a failure of the coating, all of the optics are coated.
But do try in a dark room first, and also look into alignment of the light and mirrors.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Odd apearence in the microscope.

(OP)
@ Yirmidokuz. We havent changed anything in the room according to ceiling lights so i highly doubt it. But i will try to block the occulars and see if it has any effect.

@IRstuff. Yes i was trying to catch the best picture of the "flaw" but even when i turn up the light its still there. We have recently changed the buld to a un original bulb. It worked fine until yesterday, but it might be the bulb.

@EdStainless. Sounds logic with what im thinking looking at the microscope. It is an old lady so im leaning towards something in the lane. I will try later in dark and see what happens.

Thank for your quick respons !

RE: Odd apearence in the microscope.

Quote (Kennethhp)

We have recently changed the bulb to a un original bulb. It worked fine until yesterday, but it might be the bulb.
Ding! Ding! Ding!
We have a winner!

The location of the bulb in the housing can be very important. Usually, there is an adjustment so the bulb can be moved forward, backward, up, and down. You need to adjust the bulb so the filament is "out of focus" with respect to the focal plane of the microscope lenses.

This happened to me the first time I replaced the bulb in a metallograph. It was doing just fine, but I noticed similar shadows on the photographs. I discovered that by moving the bulb, the shadows moved. From there, it was easy to determine how I had to move the bulb to eliminate the shadows.

RE: Odd apearence in the microscope.

(OP)
@Redpicker, i would asume that too. but it has been working fine for a whole month and i had it dialed in when replaced. Thats why im questioning it is the bulb ?

@IRstuff, Im not so familiar with dark field microscopy but i dont think it is ? i just had the light turned down a bit to make the flaw stand out

RE: Odd apearence in the microscope.

Or the support wires in the bulb have sagged and the filament moved. Check alignment.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Odd apearence in the microscope.

(OP)
An update to this!.

The bulb was faulty, there was nothing to see on the bulb visually but another one made the "scratches" go away. We also found that some of the dark spot was spots on one of the deep internal lenses, we have been able to clean it a bit but some of the spots are almost burned into the glass.

But thanks to you all for your help, its useable for now.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources