The present invention is characterized in that a light emitting part of LED 1 has a planar and point-symmetrical shape, a light emission angle distribution is a Lambert distribution and a light emission face is a scattering face; a hemispheric mirror 3 forms a reflection face 3a on the interior face, and has an aperture 3b at the center, while the reflection face 3a is disposed so as to oppose to LED 1; a normal line of LED 1 and an optical axis of the hemispheric mirror 3 are coincident with each other; an interval between LED 1 and the hemispheric mirror 3 is equal to or smaller than a curvature radius of the hemispheric mirror 3; a dimension of the aperture 3b of the hemispheric mirror 3 is substantially equal to a radiation dimension; and sin (tan−1 d LED/2t)≈NA object is established.