1. Field of the Invention
The present invention relates to a projection lens for obtaining a magnified projection image of an object to be inspected, and more particularly to such a lens with an elevated, i.e., high magnification.
2. Description of the Prior Art
A projection lens of elevated magnification generally has a very short focal length and therefore has a short working distance that is inadequate for manipulation. Particularly where the object to be inspected has deep surface irregularities, such lens not only inhibits the free displacement of the object but also does not allow observation of the recessed portion.
USPTO Backgrounds
USPTO Backgrounds