Since the Ag-O-Cs (S-l) thin film photoelectric cathodes was discovered in 1930

the polycrys-talline thin films as surface emission electron source were developed in different light sensitive materials

which successfully applied in night vision image tube

photoelectric tube

photo multiplier tube and low level light camera tube

and facilitated the developments of photoelectric and special purpose photoelectric imaging devices.The Sb-Cs and Na-K-Cs-Sb thin films in S series of photoelectric cathodes are limited in application because they have no solar blind characteristics

though they have higher quantum efficiency in the range of near UV (200-380nm).In recent

surface emitters with the stable

homogeneous and no change in photoemission when exposed to air are needed in some conditions.So

the studies on gold (Au)

aluminum (Al) photosensitive films are noticeable in recent years.This paper gave an introduction of preparation of Au and Al thin film and made a study on the characteristics of their UV photoelectric emission.Preparation of metallic photosensitive film is simple.The quartz glass of YS series that has good thermal and chemistry stability was selected as the window in the range of 200-380nm

which has a transmittance to be larger than 85%.Evaporation coating method was used to prepare the metallic film.The film thickness was monitored by the system of testing transmittance or by the measuring apparatus for film thickness based on the theory of quartz vibration.The relationship between the transmittance of white light and the one of UV

and between the transmittance of UV and the photoelectric current density were proposed to be use as a criterion of optimum film thickness.The stability of Au film photoemission is good when exposed to air for many times.Because of it has high chemistry stability.The photoemission of Al film is stable in vacuum

but reduces fast when it was exposed to air and reaches to a definite value for 36 hours as the result of forming a natural oxidation layer.The relationship between thickness and photoemission of Au and Al were given in this paper

In a word

the theory of metal photoemission is relatively in maturity

where Fowler theory can be used as a tool for analyzing and discussing.Practically photoemission mainly depends on the film structure and preparation technology.The surface photoelectron source obtained from Au and Al film will find applications in characteristics test of microchannel plates

dynamic analogue of imaging tube and some special UV imaging devices.