User:Pranav Rathi/Notebook/OT/2012/01/12/Extend your Opto-mechanical controls with Lego for out of box control
Introduction
Due to some airborne noise in our lab we had to put our optical tweezers in a plastic enclosed box. This means that either I had to make huge doors or openings in the box to reach the optomechanical controls or control them from outside. And I chose the second one. There are two ways to control them from outside; first by manual- mechanical control and second is by electro-mechanical control. I choose the first one because it was easier and a step stone to electro-control/servo control. Now to mechanical control the optics from outside was not easy because there was no system built on the device itself to tweak the control knob ( I call it knob A) from outside as we can see from slide 2. All I had was two knobs (A knobs). So to control the device from outside I had to build the system around this knob A in a way to extend and transform this knob to the outside of the box. Once this system is in place I can control the knob A with knob B (the one I put). I call the system (structure) Gear Box, because that is what it is. Once the gear box is in place knob A can be controlled with knob B (manual-mechanical) OR servo control (electro-mechanical).
Design and construction
Hardware
- ST1XY-S - XY Translator with Micrometer Drives (thorlabs) or any other optomechanical device
- Lego (2x) 40-Tooth Gears
- Lego (4X) 24-Tooth Gears
- Lego (5x) 8-Tooth Spur Gears
- Lego (2X) Worm Gear
- Lego Universal Joint
- Lego Axles
- Lego Bushings and stoppers
- 8-32,#8,4-40 and #4 screws and nuts
- Gorilla Epoxy
- 1/16” thick aluminum plate
- Round Dowel of 1/2” and 3/16”
- Knobs
- and tools like metal cutter, screwdriver, power drill with bits and dremel set.
Design
I am planning to control 2 devices; QPD and steering lens with this. Both the devices are attached to two different Thorlab’s ST1XY-S - XY Translator with Micrometer Drives. This drive is not designed to handle Lego or any kind of attachments like shown in slide 2, 3 and 4. So to attach gears I had to first create my own attachments. So this is what I did: I first create attachments like shown in slide 2,3 and 4 by Epoxy gluing 8-32 nuts directly on the face of the driver in slide 2. But on other side (X-axis) I did not glue the 4-40 nuts on the face but glue on the platform of the knob A, slide 4, because on X-axis the Knob A moves in the vertical Y-direction. So the gearbox has to move with the knob which is not the case on Y-axis. Once I glued the nuts I waited for 24hrs for the glue to set. Now I can bolt the gearboxes directly on the nuts. Next step is to prepare the gear box. I prepared the gearbox such that it can provide me following: Enough precision and speed, constant directionality (both the knobs are in the same direction), some degree of freedom in alignment with aperture-openings on the box, which is provide my Lego universal joints (with these joints the knob does not have to align the opening on the box slide 16) and possibility to servo control. So that’s why I choose Lego because it has all the gears and axels but not the chassis, so I had to design my own chassis. Third part is knobs B. I bought the round dowel from Home Depot and maneuver them to fit with Lego universal joint on one side and knob on other.
Construction
Demonstration
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