The Scanning Electron Microscope at Noisebridge.
- "TV Mini-SEM (R)" by ISI (International Scientific Instruments)
- lives in the room that used to house the laser cutter
- is tended by Alan Rockefeller, Jeff Miller, Chris Murphy and Jim and the rest of the SEM mailing list
- If you release the vacuum without venting the pump hose, pump oil will flood the chamber and contaminate the entire mechanism, requiring 10 hours of cleanup.
- If you vent air into the column without powering down the filament, you'll probably destroy the filament ($100). The filament has a design lifetime of about 25 hours, depending on the current put through it. Adjust the specimen stage and other controls at low current, reserve higher currents for final photos.
- Mike Kan has warned that if anyone asks him anything about the SEM, he's going to move it to another hackerspace. Jeff Miller has a MinI-SEM of his own, and knows its ins and outs pretty well.
- If the power cord is not already present, ask around or post to the list a few days prior to using the 'scope.
- See PDFs on vacuum start up and operators manual linked below.
- Determine if their is sufficient interest in the SEM and morale among the group to rationalize going forward. (2013-6-20)
- Isolate vibration from external sources; buses, people, etc. Mostly finished. (2013-6-20)
- Figure out what to do about the person(s) now "occupying" the clean room which houses the SEM. (2013-6-20)
- Design/build/find a sputter coater so the SEM can be used as a useful tool as well as a curiosity.
- Create/obtain specimen stage clamp or spring to prevent specimen vibration. (2010-12-12)
- Obtain some sputter coated specimens. (2010-12-12)
- Build a forepump line vibration isolator. (2013-6-20)
- Relocate or otherwise isolate the forepump. (2013-6-20)
- Replace most of the rubber tubing with metal tubing to reduce outgassing and pump-down times. (2013-6-20)
- Column liner needs to be replaced. Larry may be able to provide a clean liner. (2010-06-15) (update: Larry has taken column liner to his lab for cleaning)(update: column liner is now clean) (2013-6-20)
- Integrate the digital capture and control unit Jeff built for his own Mini-SEM into the unit. (2013-6-20)
- Test repair of X Stigmator circuit. Replaced 741 op amp. (completed, work began 2010-11-20, tested 2010-12-10)
- Adjust vertical overscan of CRT (completed 2010-12-12, including hack sawing access port to overscan potentiometers in the CRT module)
- Fix 2x magnification toggle switch (2010-12-12)
- Diagnose and repair barrel distortion and occlusion at low magnification (2010-12-12)
- Sew dust cover (2010-12-12). Sew/heat seam new plastic dust cover, evidently the previous dust cover was destroyed. (2013-6-20)
- Rubber grommet around edge of CRT potentiometer port needed.
- Replace forepump with a (hopefully larger) pump that has a ballast port.
- Buy/find some real vacuum valves, turn simple spool pieces to serve as adapters, and electro-pneumatically interlock the valves so that valve sequencing is fool-proof.
- Evaluate air-cooled diffusion pump as source of vibration and contamination. Consider Santovac fluid and/or water-cooled pump and/or thermoelectric cold cap.
- Consider replacing filament with LaB6 cathode for brighter, sharper images and lower long-term per hour operating costs.
Repair and Enhancement Notes
- Before repair, disable pumps and high voltage then put it into operation mode by placing a magnet on the operation relay.
- schematics framed behind SEM are to a similar, potentially slightly more modern model
- poorly designed wire harness may cause linear op amp and transistor on the J1 board of the power module to fail.
- camera mounting stage and bellows hood for slow-scan exposure. Proposed (2010-06-15), Completed by Mike, Miloh, and Chris (2010-11-06)
- CRT V. scan, V bias, H. frequency potentiometers are located on the underside of the CRT module.
- broken stigmator Y lock tab is in altoids tin in SEM kit box.
How to mitigate vibration:
- Measure and pinpoint vibration sources
- Dampen vibration from the rough pump-line by one of these methods: routing it through a concrete block and adding a hose extension, sandbag the existing line, or utilize water as a mass.
- Hang the column from the ceiling with bungee cord and platform
- Potentially relocate the microscope to the server room to diminish dust and increase distance from Mission St.
- Create spring clamping specimen slug to keep the specimen from moving.
- Made in Japan
- Delivered in September, 1975
- magnifies up to 20,000x
- outputs to a CRT
- non-digital, non-NTSC, non-PAL, analog output signal
Media: Vacuum_System_Operating_Instructions.pdf - How to start the pump
Media: ISI_Mini-TV_SEM_Manual-Troubleshooting-Reference_Guide.pdf - How to use and fix the SEM
Media: Specimen_Stage_Service_Request.pdf - Why the rotating stage is broken
Media: Cards.pdf - Historic docs
Media: Other_Docs.pdf - Repair notes
Media: Packing_Lists.pdf - Original Packing Lists, the contents of the shipping crate
Overall schematics for the TV MINI-SEM (Model: MRS-2-2 WN76-7-01). These schematics are for a model of SEM that is perhaps newer than than the SEM at Noisebridge. It is still an invaluable reference to the technician. Note: This schematic is a mosaic of 9 images stitched together with Hugin 2010.2.0. Some minor alignment issues exist in the content of the schematic. I think alignment can be guessed/interpreted accurately. Available in: LOW RES 1.5MB (4330 x 3109, posterized grayscale, JPEG) and HIGH RES 8MB (8680 x 6217, color, JPEG).
Media: Polaron_Pirani_Schematics-PE_Pir-SW_Issue_4_E5000.pdf - Polaron Pirani sputter coater schematics