Projecting apparatus having light source axis and light valve surface parallel to the same plane

A projecting apparatus, disposed within a space defined with a first imaginary plane, a second imaginary plane and a third imaginary plane which are perpendicular to one another, the projecting apparatus comprising:

• a light source for emitting a light beam propagating along a first optical path, wherein the first optical path is substantially parallel with the first imaginary plane and the second imaginary plane;
• a prism, disposed in the first optical path, for refracting the light beam to propagate along a second optical path, wherein the second optical path intersects the first optical path, the prism has a light-incident flat plane and a light-exiting inclined plane which is disposed obliquely with respect to the light-incident flat plane, and the light-incident flat plane is substantially perpendicular to the first optical path and parallel to the third imaginary plane, wherein the light-exiting inclined plane refracts the light beam to propagate along the second optical path;
• a reflecting mirror, disposed in the second optical path, for reflecting the light beam to propagate along a third optical path, wherein the third optical path intersects the second optical path, and the third optical path is not parallel to the first, second and third imaginary planes;
• and
• a reflective light valve, disposed in the third optical path and having an active plane substantially parallel with the second imaginary plane, and the active plane being arranged perpendicularly with respect to the light-incident flat plane and the light-exiting inclined plane;
• wherein the reflecting mirror is arranged obliquely with respect to the light-exiting inclined plane and the active plane.