Patent ID: 8446583

Claim:
A light focusing unit, comprising: a light source section configured to emit light; a light guiding section configured to guide the light emitted from the light source section along multiple parallel light incidence paths; and a light focusing section configured to direct the light from the guiding section to be incident on a test position of a sample at different incidence angles, the light focusing section including: a focusing section body having a shape of a rod, the rod having a predetermined width along a first direction and a predetermined length along a second direction perpendicular to the first direction, the predetermined length of the rod being larger than the predetermined width of the rod, a first incidence plane part with a substantially flat surface on the focusing section body, and a first emergence plane part with a convex surface on the focusing section body opposite the first incidence plane part, a distance between the first incidence plane part and the first emergence plane part being defined along a third direction substantially perpendicular to each of the first and second directions, and the first emergence plane part having a plurality of sub-parts having different curvature radii and being detachably stacked.