OPTICAL SEMICONDUCTOR DEVICE FOR AF AUXILIARY OPTICAL SOURCE

PROBLEM TO BE SOLVED: To provide an optical semiconductor device for an AF auxiliary optical source which can obtain highly precise focusing with high convergence and little luminance unevenness. SOLUTION: The optical semiconductor device is provided with a light emitting element, a seating for fixing the light emitting element, a resin part which covers the light emitting element on the seating to transmit and converge an irradiated light from the light emitting element, a reed which connects an external circuit with the light emitting element, and a holder which is contact with the end of the resin part and is formed cylindrically in the light radiation direction. The resin part is equipped with a light radiating side of curvature radius r. When the distance between the light radiating side and a light emitting side of the light emitting element is d, the refractive index of the resin part is n, and the emission size of the light emitting element is g, convergence coefficient Σ expressed with Σ=r/((1-n)d+nr) and the function of (1/r)gΣ4satisfy 2