The invention discloses a method for preparing a compound type light-weighted reflecting mirror blank and the compound type light-weighted reflecting mirror blank. The preparation method comprises the steps: (1) acid
pickling and activation, specifically, placing a
titanium substrate into a
pickling solution to be subjected to acid
pickling and activation to obtain an activated substrate; (2) electrochemical oxidation, specifically, forming a
titanium oxidation layer on a junction surface of the activated substrate through electrochemical oxidation, and obtaining an oxidized substrate; and (3)
diffusion bonding, specifically, enabling the junction surface of glass to be closely attached to the oxidation layer of the oxidized substrate, and obtaining the compound type light-weighted reflecting mirror blank through hot-pressing
diffusion bonding or field-assisted
diffusion bonding. According to the preparation method, the compact and uniform
titanium oxidation layer (a low-valence
titanium oxide film) is formed on the surface of the substrate through electrochemical oxidation; the junction surface of the glass and the titanium oxidation layer of the substrate are closely attached to each other to be subjected to
diffusion bonding; the process is stable, and the rate of finished products is high; the
bonding strength of the titanium substrate and the glass in the reflecting mirror blank is high, and the compound type light-weighted reflecting mirror blank can be widely applied to optical
fast scanning and tracking systems of numerous types of photoelectric detection equipment such as aircraft photoelectric reconnaissance radars and tank
fire control stabilized sighting systems.