Gallium arsenic (GaAs) photocathode demonstrates an excellent quantum efficiency superior to multialkali photocathode. Because of an ion barrier film existed on the input face of microchannel plate (MCP), gen.3 image intensifiers tubes (IIT), even the thin film gen.3 IIT, have not shown evident advantage on the main parameters of singal-to-noise ratio and resolution under standard test condition over super gen.2 IIT which updated simultaneously. The effective availability of photocathode quantum efficiency of IIT are evaluated by introducing a conception of MCP noise figure. Necessity of the realization of unfilmed gen.3 IIT is emphasized. The problem remains in the currently unfilmed MCP gen.3 IIT are indicated. The methods to improve MCP endurance capability of electron scrubbing resistance degassing treatment and further reduction of the number of poison species which contain in MCP substrate are researched, while the feasibility and technology approach for high reliability and high performance unfilmed MCP gen.3 IIT are pointed out.