Piezo stage/control recommendations
drolive...@gmail.com
I figure unless there's a piezo stage insert that will fit within, or interfaces with, the recess for the nikon circular stage plate, we have a couple of options -
1) Replace the whole microscope stage with either a) a full custom piezo stage mounted to the microscope or optical table, or b) a manual stage with rectangular stage insert suitable for a more traditional square/rectangular z-stage (we could relatively easily modify the cut-out in the faraday cage to integrate the piezo stage design surface if needed)
2) Purchase a Nikon piezo nosepiece and jump on this.
3) Use a small intermediate objective spacer with piezo displacement - hopefully there will be sufficient downward travel in the nosepiece focus movement to compensate for the increased mounting height of the objective and prevent change in absolute position of back focal plane of objective relative to the TIRF lens.
4) Use a stepper motor to adjust the manual fine-focus control knob of the microscope, either a commercial system or home built equivalent.
5) any other suggestions?
Does anyone have any experience of any of these solutions? Any advice on the pros and cons, especially with regard to operability with pgFocus, speed of response, sensitivity of focus adjustment, cost and practicality, would be really helpful.
Many thanks in advance
Oliver
Karl Bellve
Really interested in implementing pgFocus on our custom built TIRF system, based on a Nikon Ti U inverted microscope.I thought I'd ask the community for advice or recommendations as to the relative merits of different focus control options. We carry out imaging on non-standard samples, often within a faraday cage/box (~25cm^2 footprint) which would likely limit some of our piezo stage options as we need large, flat, stage footprint and relatively large area for access from under the sample.
I figure unless there's a piezo stage insert that will fit within, or interfaces with, the recess for the nikon circular stage plate, we have a couple of options -
1) Replace the whole microscope stage with either a) a full custom piezo stage mounted to the microscope or optical table, or b) a manual stage with rectangular stage insert suitable for a more traditional square/rectangular z-stage (we could relatively easily modify the cut-out in the faraday cage to integrate the piezo stage design surface if needed)
2) Purchase a Nikon piezo nosepiece and jump on this.
Or, do you plan on integrating the complete Perfect Focus, or just use the nose piece from the Nikon with pgFocus? If the latter, that would be very cool to see done...
But, my guess is the entire Perfect Focus control system is in that nosepiece, optics+electronics...rather than just a dichroic to get the infrared beam in/out.
3) Use a small intermediate objective spacer with piezo displacement - hopefully there will be sufficient downward travel in the nosepiece focus movement to compensate for the increased mounting height of the objective and prevent change in absolute position of back focal plane of objective relative to the TIRF lens.
4) Use a stepper motor to adjust the manual fine-focus control knob of the microscope, either a commercial system or home built equivalent.
But, this would also increase the error on focus control due to slow z-stepper and gear lash. However, most commercial systems rely on the a stepper drive to control focus and it works well enough for them. Depends whether you need ±3nm control with 30Hz control loop or you don't. Hmm..you did write TIRF..so my guess you do need very fine focus control. We use pgFocus on our TIRF microscopes.
5) any other suggestions?
Does anyone have any experience of any of these solutions? Any advice on the pros and cons, especially with regard to operability with pgFocus, speed of response, sensitivity of focus adjustment, cost and practicality, would be really helpful.
drolive...@gmail.com
On Friday, March 17, 2017 at 2:50:29 PM UTC, Karl Bellve wrote:
On Thu, Mar 16, 2017 at 7:08 PM <drolive...@gmail.com> wrote:
Really interested in implementing pgFocus on our custom built TIRF system, based on a Nikon Ti U inverted microscope.I thought I'd ask the community for advice or recommendations as to the relative merits of different focus control options. We carry out imaging on non-standard samples, often within a faraday cage/box (~25cm^2 footprint) which would likely limit some of our piezo stage options as we need large, flat, stage footprint and relatively large area for access from under the sample.
I figure unless there's a piezo stage insert that will fit within, or interfaces with, the recess for the nikon circular stage plate, we have a couple of options -
1) Replace the whole microscope stage with either a) a full custom piezo stage mounted to the microscope or optical table, or b) a manual stage with rectangular stage insert suitable for a more traditional square/rectangular z-stage (we could relatively easily modify the cut-out in the faraday cage to integrate the piezo stage design surface if needed)
2) Purchase a Nikon piezo nosepiece and jump on this.
Can you actually buy this as a separate part????? It would be really cool if you could! I wonder what the cost would be. Usually, commercial focus control systems are as much as $20,000US.
Or, do you plan on integrating the complete Perfect Focus, or just use the nose piece from the Nikon with pgFocus? If the latter, that would be very cool to see done...
But, my guess is the entire Perfect Focus control system is in that nosepiece, optics+electronics...rather than just a dichroic to get the infrared beam in/out.
3) Use a small intermediate objective spacer with piezo displacement - hopefully there will be sufficient downward travel in the nosepiece focus movement to compensate for the increased mounting height of the objective and prevent change in absolute position of back focal plane of objective relative to the TIRF lens.
You should be able to put spacers underneath the nikon stage to compensate for the height added by the piezo and our piezo adds 15mm to the height of the objective. If you can move your stage down >15mm, you should be fine without spacers. If this works, this seems to be the simplest option.
4) Use a stepper motor to adjust the manual fine-focus control knob of the microscope, either a commercial system or home built equivalent.
This would just slow down pgFocus and I haven't written the software to manipulate a Z-stepper motor yet. Software isn't hard to do though. I am not sure slowing down pgFocus due to control loop to adjust a Z-stepper motor is a big issue. The biggest issue on TIRF systems is slow temperature drift, I wouldn't think it would be an issue...
But, this would also increase the error on focus control due to slow z-stepper and gear lash. However, most commercial systems rely on the a stepper drive to control focus and it works well enough for them. Depends whether you need ±3nm control with 30Hz control loop or you don't. Hmm..you did write TIRF..so my guess you do need very fine focus control. We use pgFocus on our TIRF microscopes.
Karl Bellve
- Out of interest, which piezo objective mount do you use?
We just use a PI P-721.LLQ coupled to a PI E-662 controller.
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