Hitachi S-4800 manual Objective Lens Aperture unit

(4)Disconnect two BNC type connectors from the objective lens aperture unit. Remove four screws fixing the flange of the unit. Pull off the unit straightly holding the flange.

BNC Connectors

Flange fixing screws

Place the sperture unit on the aluminum foil

aperture support fixing screw

(585-4421)

Aperture support (585-4488)

C970500

Aperture holder	O-ring
(589-0548)	(L456765)
	Fig. 4-1 Objective Lens Aperture unit

(10)Remove the aperture support fixing screw with a small screwdriver (the second smallest one of the watch screwdriver set).

(11)Remove the aperture support with tweezers.

(12)Remove the objective aperture plate with tweezers.

To use the plate again, clean it by heating in the vacuum evaporator. (Refer to 4.1.3 “Baking of aperture plates”)

4-2