Apparatus and a method for separating a light beam using a hybrid dichroic mirror and a method for manufacturing the apparatus

A method of light separation using a flat plate formed of a material comprising the steps:

• allowing an incident light beam which is admitted at the first angle to penetrate into the material without reflection;
• allowing only a light beam with a first wavelength from the incident light beam to penetrate outside the material at the first angle and first-reflecting light beams with other wavelengths within the material at the second angle;
• second-reflecting the first-reflected light beam within the material at the second angle;
• allowing only a light beam with a second wavelength to penetrate outside the material at the first angle and third-reflecting a light beam with a third wavelength at the second angle from the second-reflected light;
• fourth-reflecting the third-reflected light beam within the material at the second angle;
• and
• allowing the light beam with the third wavelength to penetrate outside the material at the first angle without reflection.

A method for manufacturing a light separation apparatus using a flat plate formed of a material comprising the steps of:

• applying a wide band anti-reflection coating film to a part of a first side of the flat plate, the flat plate having a thickness t, a refractive index n, and sufficient flatness of the first side and a second side opposite to the first side to allow penetration of an incident light beam generated by a light source into the material at a first angle without reflection;
• applying a first dichroic mirror to a part of the second side of the flat plate to allow only a light beam with a first wavelength to penetrate at the first angle and to reflect light beams with other wavelengths at a second angle from the light beam penetrated through the wide band anti-reflection coating film;
• applying a wide band high-reflection coating film to a remaining area of the first side of the flat plate to reflect the light beam reflected by the first dichroic mirror at the second angle;
• applying a second dichroic mirror on the second side of the flat plate adjacent to the first dichroic mirror to allow a light beam with a second wavelength to penetrate at the first angle and to reflect a light beam with a third wavelength at the second angle;
• and
• applying an anti-reflection coating film on the second side of the flat plate adjacent to the second dichroic mirror to allow the light beam with the third wavelength to penetrate at the first angle without reflection.