Optical projection system

An optical projection system is disclosed comprising: a base; Is installed on the upper surface of the base, a first optical path switching unit is an engine body embedded therein; A second engine main body formed of a different expansion coefficient and a material of the rear side first engine unit mounted to the engine body 1; And a projection unit installed at the upper side of the first and second engine body; includes. Here, the engine body 2 is formed from a material with the high coefficient of thermal expansion than the first engine body. Even if the temperature difference in the first and second engine body occurs through a such a configuration that thermal deformation amount is substantially the same projection unit provided on the upper surface of the engine body 1, 2 is not a burden caused tilted. Therefore, it does not focus the projection light is changed to be projected through the projection unit.