User:Pranav Rathi/Notebook/OT/2012/09/21/Fiber light for Olympus microscope

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Contents

Introduction

I have invented a fiber-light system for Olympus microscope IX71. This system is compatible to Olympus power supply TH4-100. The system has 4 parts: Olympus power supply, Dolan Jenner fiber bundle, fiber-feeder and illuminator & fiber plugin adapter. Fiber plugin adapter can be directly mounted on the illuminator and the whole system can be controlled through Olympus power supply. I designed it such that it requires least amount of machining with regular tools and components available in any optics lab.

Motivation

Why fiber-light when Olympus illuminator works fine? Following reasons why fiber-light becomes important:

  • DNA experiments are really sensitive to temperature (thermal energy) even few degrees make a big difference.
  • Microscope (optical trap) is enclosed inside an enclosure (to avoid airborne noise and currents), so within few hours temperature of the microscope wall rises almost twice due to the halogen lamp used for illumination, this heats up the entire enclosure with the sample.
  • Temperature hike may make two similar data sets which are taken some time apart different.
  • Fiber light solves the problem of temperature hike by providing clean light and removing heat production through the lamp and conduction through the microscope skin.
  • With fiber light temperature inside the enclosure goes from 23.7 to 25.5 total 1.8 degree Celsius hike in comparison to halogen lamp where temperature goes from 23.7 to 49 total 25.3 degree hike over a period of 10 hours (see slide 3).

There are many good fiber-light feeder available in market by Dolan Jenner . The reason I made my own is the following:

  • Olympus power supply is better designed to feed the illuminator and I wanted something which I can control through Olympus hardware. The feeder I designed can be directly controlled through Olympus power supply or microscope.
  • I used Dolan Jenner fiber-feeder (fiber-lite model 3100) but it was not good enough for two reasons: For intensity I could only choose 3 settings in comparison to Olympus where I can choose any intensity, Flickers; fiber-lite probably uses half rectifier because I was seeing flickers in the camera in comparison to Olympus where the intensity was smooth and constant.
  • Design and construction: I designed the system such that I would have to do least amount of machining with all the components available in normal size optics lab just as mine, take less time to make (it took me around 10 hours to make it work including troubleshooting all the bugs) and costs be around $400 including my time.
  • Optical trap is very sensitive to mechanical vibrations; I wanted to have something which does not have fan inside. Fan vibration can travel through the fiber bundle to the microscope and to the sample. In this design I mount an external fan mounted above the optical table so no physical contact to the fiber-feeder.

Design & Construction

For more information please see the slide-show and web-album.

Fiber-light system has four parts (sees slide 5):

  1. Olympus power supply model TH4-100
  2. Dolan Jenner optical fiber bundle
  3. Fiber-light feeder
  4. Illuminator & fiber plugin adapter

Components

Please see the slides; all the components are labeled with their part number and company. Power supply is from Olympus and fiber bundle is from Dolan Jenner.

Illuminator & fiber plugin adapter

  • Illuminator & fiber plugin adapter has 2 parts. Illuminator is from Olympus and it comes with all the microscopes in some form or other based on the design.
Fiber pluging adapter
  • 2 X ER2-thorlabs 2 inches cage assembly rod
  • 2 X S1TM08-thorlabs lens cell adapter
  • 2 X CP02-thorlabs cage plate
  • 1 X AD11F-thorlabs adapter
  • 1 X SM1L03-thorlabs lens tube
  • 1 X (2.5 X .5 inches) aluminium metal plate
  • some 4/40 screws.

Fiber-feeder

  • Fiber-feeder has 4 parts:Box, Lamp mount, lens assembly and fiber outlet adapter.
  • I used 6X3X2.5 inces aluminum box, 4 rubber legs and 2 banana connectors and 2 leads. Any size box can be used with any mind of connectors.
Lamp Mount
  • Halogen lamp came out of Olympus illuminator
  • PCB plates (ceramic is better for this purpose, but i couldn't find any)
  • Aluminium plates (have to be machined to fit the lamp)
  • Some 3/8 nuts and bolts
Fiber outlet adapter
  • 2 X CP02T-thorlabs cage plate. Use 2 cage plates back to back, do not use wood.
  • 2 X SM1T2-Thorlabs coupler
  • 2 X SM1A1-Thorlabs adapter
Lens assembly
  • 2 X CP02T-thorlabs cage plates
  • 2 X ER2-thorlsba 3’’ cage assembly rod
  • 1 X LA1951-A thorlabs f25mm lens
  • 1 X TR2-thorlabs post
  • 1 X RA90-thorlabs post clamp
  • 1 X TR075-thorlabs pos
  • Some 1/4 and 3/8 screws

Some parts i might have missed to list so go to the slides for more information. I have not included the tools considering no special tools are used besides normally available tools in the lab.

Design

Illuminator & fiber plugin adapter

The plugin adapter is designed such that it can fit inside the illuminator, so the illuminator optics can be used without putting any external optics for the fiber. The plugin is designed such that the fiber can be inserted or removed by the screws and the whole adapter can be installed or removed without making any changes to the original form of the illuminator, for an example If i do not want to use the fiber-light I can remove it through the holding screws, install the lamp and housing back and restore the original illuminator in seconds. The two cage plates provide the z-adjustment to put the fiber outlet in the focus to the lens.

Fiber-feeder

The are many good ways to design the fiber-feeder. I designed it such because i did not want to buy any hardware, i want to use the hardware available in my lab. A better design might be using a parabolic mirror/retro reflector setting over lens setting where most of the light is not collected. In current setting i loose most of the light but what ever light i collect (with high NA lens) i can focus it very tightly and still have more than enough light. I have to blow the lamp hardly over 50% to get enough brightness in the sample plane. In current settings the lens assembly works like 3-D stage and let me focus the spot over the fiber opening with great accuracy. There are no fans so in any optical setup where vibration are killer this setup is ideal, even though i would still recommend a fan installed externally like I did with no physical contact.

Fiber-feeder is connected to the power supply with banana connectors and uses the same lamp as the illuminator. Fiber outlet adapter is on a xy translation cage plate for the last little adjustments. The fiber can be inserted through the opening.

Construction

I apologize not to discuss every little detail considering the fact that those detail are not necessary because of design specificity. Any good designer only needs an idea not the very gory details.

Power Supply

I start with Olympus power supply slide 5. Identify and label the ground and +12ve pins with multimeter and turnoff and unplug the power supply wait few minutes. Prepare 1 to 2 meter long banana connector wire depending on the requirement. Insert the open ends into the pins identified and tape it (keep the power supply off and unplugged all times).

Illuminator & fiber plugin adapter

Prepare fiber plugin adapter first.

Fiber plugin adapter

Get all the components and arrange them as shown in the slides 9 & 10.

Illuminator

Remove the illuminator from the microscope very carefully and remove the housing and lamp; slide 8. For directions go to user manual of you microscope section (how to replace the lamp?). Do not touch the optics at any time.

Measure the length between the cage plate rods; see the slide 9 (the white arrow). Now go to slide 11 the long white 2-sided arrow shows that the center hole on the little stage is in the center of the lens. Measure the half of the length of the cage plate rods on each side of this hole (little stage) over wall and make a notch to fit 4/40 screw completely like showed in slide 11 (you can use hack saw). Now cover the lens with a cloth and drill a 4/40 size hole on the wall roughly 3/4 cms from the top-edge and from the notch; see slide 12. Next prepare a thin aluminum restoring-plate as shown in the slide 13. The hole and the big notch should align the holes on the wall and the little stage; see slide 14. Now mount the plugin adapter as shown in the slide 15, 16, and 17. Insert the fiber through the opening; a rubber cushion can be used for the extra space and between the screw and the fiber bundle skin slide 18.

Fiber-feeder

Box

Any size box can be used I used 6X3X2.5 inches aluminum box. Legs are optional; any kind of legs can be used remembering that box gets enough hot to melt plastic, rubber or wood if in direct contact. On one side make holes for banana connectors horizontally and make 3/8’’ holes for screws vertically; slide 20 of lamp side. On other side make 1’’ hole for fiber outlet at the center; see slide 20 fiber outlet side. In the bottom make 3/8’’ hole at the center of the small side of the box roughly .25’’ away; slide 20 bottom sides. Do not make any other holes yet.

Lamp Mount

This is the trickiest and most important part. This part depends on what materials you use, if you ceramic besides PCB then the procedure would be little different. I used PCB because the ceramic was not available in my lab. Get a plane PCB plates cut them in size of 1.5X2 inches get 6 of them and stack them together; slide 21 and 22. Make 3/8’’ through holes in all the plates on long side to align the holes made on the box on lamp side vertically. Prepare two peace of 1/4 thick metal (choose you own dimensions) as shown in the slide 22. Make 2 3/8 holes on each side of each plate. Drill one through hole on each plate to fit the lamp connector pins (this is important to be very careful). Take 3 PCB plates and make 4 4/40’’ through holes to align the 4 holes on the 2 metal plates. Take 2 PCB plates and make 4 4/40 screw’s head size holes to fit the 4/40 screw heads. Leave the left over PCB plate alone. Now stack them in this order: put 4/40 screws in 3 (4/40’’ size hole) PCB plates in front, 2 (4/40’’ screw‘s head size) plate after that and the leftover PCB plate in the end. Now put the metal plates on the 4 screws and tight the nuts. Since the holes on the metal plates are bigger than screws you can use washer now. Mount the PCB plates on the vertical holes on the box. Mount the lamp on the metal plates to fit the lamp connectors you can now slide the plates in and out because the plate holes are lot bigger than the screws, once find the right setting (lamp should not be loose) tight the nuts and solder the banana connectors to the plates. Check the lamp if it works.

Fiber outlet adapter

See the slides 23 and 24; arrange the components as shown, do not use wood use 2 extra cage plates, couplers and adapter and arrange them back to back. I used wood because I did not have enough hardware available in my lab. If you use wood make sure you cover the wood with aluminum plate not in contact with wood, otherwise it will burn. Mount the adapter through the 3/8’’ hole at the bottom slide 25.

Lens assembly

Assemble the lens assembly as in slide 26. Mount it on the box as shown. The location of the hole on which it is mounted depends on the focal length of the lens roughly. The hole might be 2f (f=focal length of the lens) length away from the lamp mount side. In this case I have 1/4 inch hole 50mm from the lamp side and .5’’ inches away from the side wall; slide 27. Once this is mounted the focal spot can be aligned by adjusting the lens assembly; slide 28, 29 and 30. Since there is no fan inside, I made some jumbo size holes in the cover; slide 31. The feeder can be mounted with fan as shown in the slide32. The fiber can be inserted through the fiber outlet side.

Once the system is ready the illuminator can be installed back on the microscope slide 34.

Alignment

Do not touch the box when the lamp is on for a while it can be very hot. To optimize the light through the fiber do following:

  • Like in slide 27 put the fiber through the fiber outlet, turn on the lamp and keep it low (avoid looking direct into the lamp).
  • Adjust the cage plates for focus and adjust the 90 deg clamp for xy adjustment of the focal spot over fiber opening; slide 28. Once the spot is on the fiber like in slide 29 you can further adjust the fiber outlet cage plate.
  • To bring the fiber in focus on illuminator adjust the cage plate setting on the fiber plugin adapter like in slide 18 and 30 ( DO NOT look into the illuminator if it is too bright). Keep adjusting until you see the fiber crispy and big.

Demonstration

I an using fiber-light for months now. Below is the video I recorded: DNA-ethering in D2O sample.

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