The object-space telecentric Lenses means, in some optical system, we place the aperture stop on the image-space focal plane. When the aperture stop inset image-space focal plane, the object-space changes with the change of image-space, but the consequence of measurement does not change, therefore the size of the measured objects will not be changed. As a result of distortion minimized,object-space telecentric lenses are used in industrial precision measurement. Even some high performance systems can eliminate the influence of distortion.