Optical measuring device and a device which includes an optical system

Light intensity of the scattered light from the sample and can measure the spatial distribution, to provide a device with excellent optical measuring device and an optical system sensitivity. In the apparatus, light emitted from the first object, while reaching the second object, two or more even number of times, by a structure that is reflected by the ellipsoidal mirror, suppress image distortion. Two ellipsoidal mirror, a common focal point one focal point of each other, the arrangement in which the remaining two focal line up at opposite sides with respect to said common focal point, and a common focus on the blank, the first object the one focus, and by arranging the second object to the other focal point, suppresses the distortion of the image.