US 11,698,579 B2
Wavelength conversion element, light source device, projector, and method of manufacturing wavelength conversion element
Koya Shiratori, Matsumoto (JP); Wataru Yasumatsu, Azumino (JP); Takashi Gokuden, Azumino (JP); and Kunihiko Yano, Shiojiri (JP)
Assigned to SEIKO EPSON CORPORATION, Tokyo (JP)
Filed by SEIKO EPSON CORPORATION, Tokyo (JP)
Filed on Mar. 11, 2021, as Appl. No. 17/198,364.
Claims priority of application No. JP2020-043298 (JP), filed on Mar. 12, 2020.
Prior Publication US 2021/0286253 A1, Sep. 16, 2021
Int. Cl. G03B 33/12 (2006.01); G03B 21/20 (2006.01)
CPC G03B 33/12 (2013.01) [G03B 21/204 (2013.01); G03B 21/2066 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A wavelength conversion element comprising:
a substrate;
a dichroic layer provided to a first surface of the substrate;
an intermediate layer disposed so as to be opposed to the substrate via the dichroic layer; and
a wavelength conversion layer disposed so as to be opposed to the dichroic layer via the intermediate layer, and configured to convert light in a first wavelength band into light in a second wavelength band different from the first wavelength band, wherein
the dichroic layer has two or more types of refractive index layers having respective refractive indexes different from each other, and
when denoting a refractive index of the wavelength conversion layer by nm, a refractive index of the intermediate layer by nLm, a refractive index of a refractive index layer having a first refractive index out of the two or more types of refractive index layers by nL, and a refractive index of a refractive index layer having a second refractive index out of the two or more types of refractive layers by nH, and nH is higher than nL,
θB≥θC is fulfilled with respect to θB obtained by a formula (1) described below and θC obtained by a formula (2) described below:

OG Complex Work Unit Math
wherein the θB corresponds to an angle that satisfies Brewster's condition at an interface between the wavelength conversion layer and the dichroic layer, and
the θC is an total reflection angle at an interface between the wavelength conversion layer and the intermediate layer.