TV Mini-SEM
The TV Mini-SEM was a low cost tabletop Scanning Electron Microscope built by Akashi and distributed by ISI around 1975. It featured a single CRT screen made by NEC. The Microscope featured an air cooled oil diffusion pump of 75W power made by TSK.
It consists of 3 main parts, the Column, the main console and display console. The 19" rack mount components are fitted in wood grain vinyl veneer finished wood cabinets stacked one on top of one another. It uses a Tungsten Hairpin cathode, and has 3 lenses, with the condenser lenses having one coil each.
This microscope model suffers from aging related deterioration of the Stigmator and Deflection Coil assembly, which is made of clear polymer resin of unknown type (likely PMMA) which develops cracks and a frosted appearance due to micro cracking of the surface inside the vacuum chamber. Since this part also seals the column, this poses problems with the ability to achieve and hold the required high vacuum to operate the instrument. A Methode to repair this has been derived and tested at the museum, and has thus far proven reliable operation to be possible since mid 2024.
Scan / Recording Options
The Microscope has 4 scan modes selected by the 4 pushbuttons on the Display Console, these are
- TV (Scanning At TV Scan rate)
- Reduced Area (Scanning in a rectangular area at higher speed)
- Slow (Slow scan, using the vertical signal of the TV Scan as Vertical, and a slow horizontal Scan)
- Photo (Same as Slow, but at double the scan time)
The TV scan modes feature a automatic video amplifier which adjusts gain and contrast automatically within a range of signal intensities. A manual brightness and gain control knob are present, but the brightness one only functions for the slow scan modes.