| 摘要 |
PROBLEM TO BE SOLVED: To provide a wavelength conversion element that can inhibit a high-temperature state of a wavelength conversion layer.SOLUTION: The wavelength conversion element of the present invention includes a circular plate, a wavelength conversion layer provided on a first surface of the circular plate, and a reflection layer provided between the circular plate and the wavelength conversion layer, and satisfies expression (1) -d&rgr;w(r0)/dr<d&rgr;s(r0)/dr. In the expression, when circular coordinates with the rotation center of the plate as an origin are set on a plane parallel to the first surface of the circular plate, r represents a moving radius; r0 represents a radius of the circular plate; &rgr;s(r) represents a thermal resistance of a thermal path between a point of the moving radius r on the first surface of the circular plate and the entire surface of the circular plate routing through the interior and surfaces of the circular plate; and &rgr;w(r) represents a thermal resistance in a thickness direction of the wavelength conversion layer at the moving radius r of the wavelength conversion layer. |
