A light guide assembly comprising: - a first transparent monolithic optical part having a refractive index; - a second transparent monolithic optical part having the same refractive index as the first transparent monolithic optical part; wherein - the first transparent monolithic optical part has a first surface having two successive sets composed of one flat surface (301, 303, 502, 504) followed by one prism array (302, 304, 503, 505), the flat surface of each set has a partially-reflective coating thereon, and the first transparent monolithic optical part further has an opposite second surface that is flat, - each prism array of the first surface of the first transparent monolithic optical part has at least two prisms, each prism being composed of a first surface and a second surface which are oblique with respect to each other and with respect to said opposite second surface of the first transparent monolithic optical part, the first surfaces of the prism arrays have a partially-reflective coating thereon and the second surfaces of the prism arrays have no reflective coating thereon, - the second transparent monolithic optical part has a first surface having a geometrically complementary shape with respect to the shape of the first surface of the first transparent monolithic optical part, and the second transparent monolithic optical part of the light guide assembly further has an opposite second surface that is flat, - the first and second transparent monolithic optical parts are assembled together using an optically transparent adhesive material, such that the second surfaces of the first and second transparent monolithic optical parts of the light guide assembly are parallel to each other, the optically transparent adhesive material having the same refractive index as the first and second transparent monolithic optical parts. - a first transparent monolithic optical part having a refractive index; - a second transparent monolithic optical part having the same refractive index as the first transparent monolithic optical part; - the first transparent monolithic optical part has a first surface having two successive sets composed of one flat surface (301, 303, 502, 504) followed by one prism array (302, 304, 503, 505), the flat surface of each set has a partially-reflective coating thereon, and the first transparent monolithic optical part further has an opposite second surface that is flat, - each prism array of the first surface of the first transparent monolithic optical part has at least two prisms, each prism being composed of a first surface and a second surface which are oblique with respect to each other and with respect to said opposite second surface of the first transparent monolithic optical part, the first surfaces of the prism arrays have a partially-reflective coating thereon and the second surfaces of the prism arrays have no reflective coating thereon, - the second transparent monolithic optical part has a first surface having a geometrically complementary shape with respect to the shape of the first surface of the first transparent monolithic optical part, and the second transparent monolithic optical part of the light guide assembly further has an opposite second surface that is flat, - the first and second transparent monolithic optical parts are assembled together using an optically transparent adhesive material, such that the second surfaces of the first and second transparent monolithic optical parts of the light guide assembly are parallel to each other, the optically transparent adhesive material having the same refractive index as the first and second transparent monolithic optical parts.