Light source device and optical engine

A light source device, comprising:

• a first laser module, a second laser module, and a third laser module, each including
• at least one first laser diode configured to emit a first laser beam having a wavelength λ1 and being linearly-polarized along a first direction, and
• at least one second laser diode configured to emit a second laser beam having a wavelength λ2 which is longer than the wavelength λ1 and being linearly-polarized along the first direction or along a second direction which is orthogonal to the first direction;
• said light source device further comprising
• a beam combiner disposed between the third laser module and the second laser module and configured to combine the first laser beam and the second laser beam emitted from each of the first laser module, the second laser module, and the third laser module, the beam combiner including
• a first optical film including a first dichroic film configured to transmit light of the wavelength λ1 and to reflect light of the wavelength λ2,
• a second optical film including a λ/2 phase plate for the wavelength λ2 configured to rotate a polarization direction of light of the wavelength λ2 by 90 degrees, and a second dichroic film configured to transmit light of the wavelength λ2, transmit light of the wavelength λ1 being polarized along the first direction, and to reflect light of the wavelength λ1 being polarized along the second direction, the second optical film and the first optical film being provided side by side along a first plane,
• a third optical film including a third dichroic film configured to transmit light of the wavelength λ2 and to reflect light of the wavelength λ1, and
• a fourth optical film including a λ/2 phase plate for the wavelength λ1 configured to rotate a polarization direction of light of the wavelength λ1 by 90 degrees, and a fourth dichroic film configured to transmit light of the wavelength λ1, transmit light of the wavelength λ2 not passing through the λ/2 phase plate for the wavelength λ2, and to reflect light of the wavelength λ2 having passed through the λ/2 phase plate for the wavelength λ2, the fourth optical film and the third optical film being provided side by side along a second plane, wherein,
• the first plane and the second plane intersects at a line of intersection between the first optical film and the second optical film and between the third optical film and the fourth optical film;
• the first laser module is disposed at a position for obliquely irradiating rear sides of the first optical film, the second optical film, the third optical film, and the fourth optical film with the first laser beam and the second laser beam going out from the first laser module;
• the second laser module is disposed at a position for obliquely irradiating front sides of the second optical film and the first optical film with the first laser beam and the second laser beam going out from the second laser module;
• and wherein
• the third laser module is disposed at a position for obliquely irradiating front sides of the third optical film and the fourth optical film with the first laser beam and the second laser beam going out from the third laser module.