Editing SEM

===There is no longer a Scanning Electron Microscope at Noisebridge. We used to have one. The rest of this is historical. -JH 2016-03-07===

= 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 [https://www.noisebridge.net/mailman/listinfo/sem SEM mailing list]

=== Warnings ===
# 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.

=== Startup procedures ===
# If the power cord is not already present, get it from whoever has it. A post to the list a day or two before you plan to use the 'scope
  should do it.
# See PDFs on vacuum start up and operators manual linked below.

=== Todo list ===
Short Term:
# 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)

Medium Term:
# 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) 

Long Term:
# 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.

=== 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 [http://hugin.sourceforge.net/ 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: 
[[Media: TV_MINI-SEM_Schematics-Overall_MRS-2-2_WN76-7-01_Mosaic_v._1.0_Low-Res.jpg | LOW RES 1.5MB (4330 x 3109, posterized grayscale, JPEG)]] and 
[[Media: TV_MINI-SEM_Schematics-Overall_MRS-2-2_WN76-7-01_Mosaic_v._1.0.jpg | 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 ===

<gallery widths=200px heights=166px>
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_0652.jpg|Mechanical pencil graphite smudge on aluminum slug. 1000x magnification. This is post repair of X Stigmator. Imaged by the Noisebridge SEM. Mike Kan, Chris Murphy.

Image:IMG_0655.jpg| Tip of mechanical pencil graphite  on aluminum slug. 500x magnification. This is post repair of X Stigmator. Imaged by the Noisebridge SEM. Mike Kan, Chris Murphy.

Image:IMG_0654.jpg| Tip of mechanical pencil graphite on aluminum slug. 1000x magnification. This is post repair of X Stigmator. Imaged by the Noisebridge SEM. Mike Kan, Chris Murphy.

Image:IMG_0656.jpg| Tip of mechanical pencil graphite on aluminum slug. 5000x magnification. This is post repair of X Stigmator. Imaged by the Noisebridge SEM. Mike Kan, Chris Murphy.

Image:IMG_0657.jpg| Tip of mechanical pencil graphite on aluminum slug. 10,000x magnification. This is post repair of X Stigmator. Specimen was moving on the slug due to mechanical vibration. Imaged by the Noisebridge SEM. Mike Kan, Chris Murphy.

Image:IMG_0624.jpg|Semiconductor ball grid array at 20x magnification prior to repairing the X Stigmator. Mike Kan, Chris Murphy

Image:IMG_0649.jpg|Snapped metal region of a box cutter razor blade. Imaged on the Noisebridge SEM. About 5000x magnification. This is post repair of X Stigmator. Mike Kan, Chris Murphy

Image:IMG_0007.jpg|Head of a small 2mm allen type machine screw. Less than 1000x magnification. This is post repair of X Stigmator. Mike Kan, Chris Murphy

Image:Allen_close_up.jpg|Head of a small 2mm allen type machine screw. About 1000x magnification. This is post repair of X Stigmator. Mike Kan, Chris Murphy

Image:IMG_0026.jpg|Diatom imaged in fast scan mode (lower resolution than slow scan photo mode). Magnification unrecorded. Mike Kan, Chris Murphy. 12/12/10

</gallery>

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