SEM

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=== Specimen Images ===
 
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Image:IMG_0004.jpg|Image of mechanical pencil graphite smudge on an aluminum slug at approximately 20x magnification. The specimen is about 1 mm across. This is prior to repairing the X Stigmator. Magnification was limited. Imaged by Chris Murphy and Mike Kan.
 
Image:IMG_0004.jpg|Image of mechanical pencil graphite smudge on an aluminum slug at approximately 20x magnification. The specimen is about 1 mm across. This is prior to repairing the X Stigmator. Magnification was limited. Imaged by Chris Murphy and Mike Kan.
  

Revision as of 02:01, 12 June 2011

Contents

The Scanning Electron Microscope at Noisebridge.

  • "TV Mini-SEM (R)" by ISI (International Scientific Instruments)
  • lives in the "science ghetto" on the west end of the south wall at 2169.
  • is tended by Mike Kan and the rest of the SEM mailing list

Warnings

  1. 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.
  2. If you vent air into the column without powering down the filament, you'll probably destroy the filament ($100).

Startup procedures

  1. Get the power cord from Mike.
  2. See PDFs on vacuum start up and operators manual linked below.

Todo list

Short Term:

  1. Isolate vibration from external sources; buses, people, etc. See Repair and Enhancement notes below. (2010-12-12)
  2. Create/obtain specimen stage clamp or spring to prevent specimen vibration. (2010-12-12)
  3. Obtain some sputter coated specimens. (2010-12-12)

Long Term:

  1. 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)
  2. Build digital capture stage to replace CRT mechanism (2010-06-15)
  3. Replace 8.4" slow scan CRT with slow scan XGA LCD? (see above)
  4. Build sputter coater for specimen preparation (2010-06-15)
  5. Test repair of X Stigmator circuit. Replaced 741 op amp. (completed, work began 2010-11-20, tested 2010-12-10)
  6. Adjust vertical overscan of CRT (completed 2010-12-12, including hack sawing access port to overscan potentiometers in the CRT module)
  7. Fix 2x magnification toggle switch (2010-12-12)
  8. Diagnose and repair barrel distortion and occlusion at low magnification (2010-12-12)
  9. Sew dust cover (2010-12-12)
  10. Rubber grommet around edge of CRT potentiometer port needed

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:

  1. Measure and pinpoint vibration sources
  2. 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.
  3. Hang the column from the ceiling with bungee cord and platform
  4. Potentially relocate the microscope to the server room to diminish dust and increase distance from Mission St.
  5. Create spring clamping specimen slug to keep the specimen from moving.

Specifications

  • 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

Documentation

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

Schematics

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: Schematic_of_Photomultiplier.pdf‎

Media: Polaron_Pirani_Schematics-PE_Pir-SW_Issue_4_E5000.pdf - Polaron Pirani sputter coater schematics

Media: Polaron_Pirani_Gauge_Head_for_Sputter_Coater.pdf

Specimen Images

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