Telecentric Lenses
A telecentric lens is a special optical system where the main light beam is parallel to the lens optical axis and the angle of view is 0°. Unlike a regular lens, the magnification does not change even if the workpiece moves and the focus becomes misaligned, and image distortion due to parallax error does not occur. Therefore, the image size does not change and the measurement error does not occur. Moreover, although the illumination light beam is not perpendicular to the workpiece, the telecentric illumination is built-in, which makes it easy to output illumination light parallel to the optical axis. These products are suitable for the precision inspection and measurement of workpieces that have depth and individual differences in size. They are used for applications such as high-speed image processing, a surface inspection of silicone wafers, dirt inspection of glass substrates and 2D coordinate reading. Types are available that differ according to the application. For example, an object-side telecentric lens that has a telecentric structure on the object side only; an image-side telecentric lens; and an object-side telecentric lens that has a telecentric structure on both the object side and image side.