lateral drifting
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![Chen, Jianbo (NIH/NCI) [E]](/images/avatar100.png "Chen, Jianbo (NIH/NCI) [E]"){kind=avatar}
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Dear everyone I have some lateral drifting problem with a new microscope during
time lapse experiment. The drifting is usually around 10 pixel for a 512 image
during 3 hours. The microscope is set on a floating table. The company people
think it is unavoidable to have some drifting for anything that is controlled
by gear (motorized stage). Is that true or just their excuse? I would
appreciate any insight from people having experiences in time-lapse experiment.
Is it common or unavoidable to have some drifting? Thanks Jianbo Chen 301-846-1841 |
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Dear Jianbao
we needed details. What kind of stage, what sample etc. Which software controls the stage? Which kind of environmental chamber Three hours is short, there should not be any problem. I would check with fluorescent beads or scratches on the coverglass. Often its a controller problem. ________________________________________ From: Confocal Microscopy List [[hidden email]] On Behalf Of Chen, Jianbo (NIH/NCI) [E] [[hidden email]] Sent: 20 February 2010 05:02 To: [hidden email] Subject: lateral drifting Dear everyone I have some lateral drifting problem with a new microscope during time lapse experiment. The drifting is usually around 10 pixel for a 512 image during 3 hours. The microscope is set on a floating table. The company people think it is unavoidable to have some drifting for anything that is controlled by gear (motorized stage). Is that true or just their excuse? I would appreciate any insight from people having experiences in time-lapse experiment. Is it common or unavoidable to have some drifting? Thanks Jianbo Chen [hidden email] 301-846-1841 Note: This message may contain confidential information. If this Email/Fax has been sent to you by mistake, please notify the sender and delete it immediately. Thank you. |
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In reply to this post by Chen, Jianbo (NIH/NCI) [E]
Hi Jianbo,
We experienced that with our Ludl stage. It was because of the calibration of joystick at startup. We tried two things to get rid of the problem and then the drifts reduced to minimal (a pixel or so in random direction):
1) Lock the joystick in central position during and after sometime of starting the controller and software. Once we mark the positions, we put the joystick away from any source of vibration (e.g. heater).
2) Ask the software to 'go back' to the position (even though imaging only one position) before acquiring an image. Best Shalin On Sat, Feb 20, 2010 at 5:02 AM, Chen, Jianbo (NIH/NCI) [E] <[hidden email]> wrote:
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In reply to this post by Chen, Jianbo (NIH/NCI) [E]
Chen, Jianbo (NIH/NCI) [E] wrote:
> Dear everyone > I have some lateral drifting problem with a new microscope during time lapse experiment. The drifting is usually around 10 pixel for a 512 image during 3 hours. The microscope is set on a floating table. The company people think it is unavoidable to have some drifting for anything that is controlled by gear (motorized stage). Is that true or just their excuse? I would appreciate any insight from people having experiences in time-lapse experiment. Is it common or unavoidable to have some drifting? Thanks > we've had the same problem and it is unavoidable. in addition, we wore out the gear box (expensive!) by excessive movement at least once, so avoid using it for this. a piezo stage on top of the motorized stage solved the problem. an additional note there, we have noticed that the piezo also can drift a very small way in the beginning but not if you constantly apply a force to have it in the pushed down state. e.g. just leave the old sample there until you replace it. /Johan > Jianbo Chen > [hidden email] > 301-846-1841 > > > |
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Johan Henriksson wrote:
> Chen, Jianbo (NIH/NCI) [E] wrote: >> Dear everyone >> I have some lateral drifting problem with a new microscope during >> time lapse experiment. The drifting is usually around 10 pixel for a >> 512 image during 3 hours. The microscope is set on a floating table. >> The company people think it is unavoidable to have some drifting for >> anything that is controlled by gear (motorized stage). Is that true >> or just their excuse? I would appreciate any insight from people >> having experiences in time-lapse experiment. Is it common or >> unavoidable to have some drifting? Thanks >> > we've had the same problem and it is unavoidable. in addition, we wore > out the gear box (expensive!) by excessive movement at least once, so > avoid using it for this. a piezo stage on top of the motorized stage > solved the problem. > > an additional note there, we have noticed that the piezo also can > drift a very small way in the beginning but not if you constantly > apply a force to have it in the pushed down state. e.g. just leave the > old sample there until you replace it. joystick theory in the other post makes more sense, our problem was vertical drift. /Johan > > /Johan > >> Jianbo Chen >> [hidden email] >> 301-846-1841 >> >> >> |
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In reply to this post by Chen, Jianbo (NIH/NCI) [E]
Dear Jianbo,
When you talk of drift there are several effects that could occur. If you leave the stage at one position for your 3 hour experiment (no point visiting etc.) - do you see a change in the coordinates of the stage? The software should show the xyz coordinates somewhere. If coordinates change without your interaction this could mean that you have one of these rubbish joysticks. I also have one of these. It's a faulty design - you should just ask for a new one. If you notice the drift in an experiment with point visiting you should compare the drift (pixel size of image x number of drift pixels) with the specification on the stage (accuracy/repeatability). Good stages with linear encoders have an accuracy/repeatability of around 1µm. But there are also stages with 8µm and more. Hope that helps. Cheers, Ralf
Dear everyone |
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If you could translate that pixel distance to a physical
distance in micron, it would be easier to judge. But a drift of a few micron is
indeed unavoidable using a stage that works with gears, because the teeth of
the gears cannot be sized to match each other exactly. There has to be a small size
differential to leave a gap, which is filled by a thin film of lubricant. So even
if the position of the driving gear is fixed, there can be a little motion in
the stage as the pressure between the surfaces causes the oil to flow. (Usually
this problem affects the focus more than the stage.) Best Regards, Emmanuel -- Am Freitag, den 19.02.2010, 16:02 -0500 schrieb Chen, Jianbo
(NIH/NCI) [E]: Dear everyone |
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