Automating microscope focus

Have questions about the equipment used for macro- or micro- photography? Post those questions in this forum.

Moderators: rjlittlefield, ChrisR, Chris S., Pau

WalterD
Posts: 616
Joined: Mon Jul 06, 2015 12:01 pm
Location: Rotterdam, the Netherlands
Contact:

Post by WalterD »

Hi Pau,

Inspiring thread. Thinking about it, would be nice indeed to see this automated; manually turning the focussing knob while making stacks does not have much added value.
I also would not want to have a solution that is too complicated or not "fool proof". Understood that one of your major concerns is that the focussing block is in its end position while the stepper motor continues attempting to turn the fine focussing knob, resulting in permanent damage of the delicate focussing block. The solution that popped up for me was based on a thread from Rik 8 years ago where he utilized a plastic tube to connect a stepper motor to the instrument.
http://www.photomacrography.net/forum/v ... hp?t=11008
A completely different application is a vinyl record cleaner I created 3 years ago from a ultrasonic bath combined with a disco-ball stepper motor. For this application I connected the motor with the spindle for the vinyl records to be cleaned by a plastic tube of the right diameter. But hey that's another forum :)
The idea is to choose a plastic tube that is slightly flexible and with a minimal clearance to shove it over the fine focussing knob. The other end of the pipe can permanently be connected with the Micromate outgoing spindle. (that 2nd half of the pipe could be made solid by filling it up with a piece of material of appropriate diameter. All and all it is about the torque the microscope knob needs to be turned, the maximum torque the stepper motor can deliver and the minimum torque necessary to make the tube slip over the focussing knob. So the block reaches its end position while the stepper motor will continue turning, the plastic tube slipping over the knob.
This may sound to be flimsy or unrelaible but I think clearance and material specs will be translated into that range of torques. One could play with the clearance between the knob and the inner tube by (minimal) increasing the knob diameter with a / some layer(s) of adhesive tape (e.g pvc or paper).
Anyhow for my record cleaning machine I already noticed that slipping effect!



I mentioned the Micromate from wemacro, previously mentioned by Michael, and would be interested to work with that stacking tool as well; seems to be the only comercially avaialble rig designed for microscopes so far. I am interested in the way the sofware interacts with EOS Utility and whether it is much different from the configuration for non-microscope setup. If forum members have got experience with this, I'll be interested.

Will provide an update when I got it working.

Best regards,

Walter

Image

Pau
Site Admin
Posts: 6053
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

Hi Walter,
Thanks for your comments, the Rik's pipe approach is always an alternate option for my goals. I still think that the magnetic approach potentially can be superior if I end with an adequate solution: easier to mount in different stands, lower elasticity (higher precision?) and more precise and repeatable torque limit.
I very likely will get the Micromate and once tested I could be able to post my impressions.
Pau

mawyatt
Posts: 2497
Joined: Thu Aug 22, 2013 6:54 pm
Location: Clearwater, Florida

Post by mawyatt »

Hi Walter,

I don't use a microscope for stacking, so take my notes lightly :roll:

Stepper motor stepping torque is somewhat proportional to winding current so it seems that limiting the motor current might be an effective way to implement an electrical clutch.

The Stackshot controller allows many parameters including motor current to be specified, which might prove useful for limiting motor torque for electrical clutch use.

The WeMacro controller does not have a torque limiting capability, but I surmise one could easily be implemented by locating the motor driver chip. The supply voltage to this chip should be the nominal 12 volts. Locate the chip connection pin (or pins) that supplies the motor driver current and add a power resistor in series with this pin(s). Some experimenting with the resistor value is necessary to establish the desired motor torque limit. Of course this will void the WeMacro warranty and should only be attempted by those familiar with electronics.

Other options with the WeMacro controller would be to place equal value power resistors in series with the motor windings (in series with the motor wires). Also reducing the power supply voltage to the controller might work as well, and maybe a power resistor in series with the power supply to drop the supply voltage (be aware these options may introduce unwanted controller behavior by voltage starving other circuits like the logic or Bluetooth RF module).

Anyway just my 2c on electrical clutch possibilities.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

WalterD
Posts: 616
Joined: Mon Jul 06, 2015 12:01 pm
Location: Rotterdam, the Netherlands
Contact:

Post by WalterD »

Hi both,

Interesting to hear about approaching this from different angles. The Micromate attracts me because it is plug & play, affordable and it does have software that can communicate with the camera as well as the stepper motor.
@Pau: looking forward to learn about your findings and first test results! will keep you updated about mine.
@ Mike: that's another way to deal with it. My microscopes fine focussing knobs have different torque requirements (the Ortholux II may need additional "greasing") Got the impression that the WeMacro stepper motors are rather powerfull.

Next challenge will be to automate the X-Y stage for stitching :twisted:

Update:
All and all I doubt the usability for my setups, so for now I think I'll leave it.

Pau
Site Admin
Posts: 6053
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

I bought the MicroMate and it works well. Now I've tested my approach with a magnetic coupling and it works perfectly, better if I put a disc of silicone rubber between the magnet and the iron washer glued to the fine focus knob.
Will post it in next days once tested in different focus blocks

Thanks all for your ideas.
Pau

Pau
Site Admin
Posts: 6053
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

Thanks all for your ideas!

I've followed my own one, very close to Jörgen's and the system works like a charm:
http://www.photomacrography.net/forum/v ... 122#232122
Pau

Post Reply Previous topicNext topic