Whether an aperture can be cleaned and reused depends partially on the material it is made of.
Platinum Apertures
Platinum apertures are easily cleaned by either an aperture flamer or over a bunsen burner in the open air. The platinum aperture should be handled with a pair of tweezers reserved solely for this purpose.
Platinum apertures can also be cleaned chemically, however neither method will reliably remove all contaminants. Even an aperture that appears clean may produce astigmatism when reused in the microscope. The platinum aperture therefore has a limited work life.
Molybdenum Apertures
Molybdenum apertures can be cleaned 5 to 10 times more than a platinum aperture, however they must be cleaned under high vacuum, using a vacuum evaporator.
Gold Foil Disc Apertures
Conventional mechanical cleaning involving costly down-time is no longer necessary with gold foil “self-cleaning” apertures.
Advanced techniques of thin metal film application permits the apertures to retain a clean hole edge during prolonged beam exposure. Ultra-thin, half-micron design discourages contaminant accumulation and stabilizes astigmatic conditions to provide longer life. Because the foil is ultra thin, care must be taken when handling the gold foil apertures.
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