tube by heating then stretching the tube into a tubular acicular shape an aperture is formed either by etching the glass when it is well suited for etching or by cladding glass when it is not the inner surface of the aperture is then coated with a metal film using vapor deposition techniques fig3 is a cross sectional diagram showing another example of a probe 38 whose tip tapers less sharply than the probes mentioned in the previous paragraph and whose aperture at the tip has an inner diameter of 0 2 microns onto the tip is formed by metal vapor deposition an approximately 500 u00e5 thick film 38a into which is formed an aperture 38b of approximately 500 u00e5 diameter an approximately 100 u00e5 thick metal film can optionally be formed over the surface of the film 38a by vapor deposition an aperture made as shown in fig3 creates a more uniform electric field between the tip of the probe 38 and the surface of the sample 22 and moreover allows attaining of a higher resolution another method of forming film 38a is by applying an organic film to the opening at the tip of the probe 38 and depositing by vapor deposition an approximately 100 u00e5 thick aluminum film to the surface of the organic film the organic film is then removed by heating over the surface of the aluminum film is formed a resist film the resist film is exposed to an electron beam to etch the.