Telecentric Optics for Machine Vision - Opto Engineering

Opto Engineering Telecentric Lenses

Telecentric lenses are useful in machine vision and precision-gauging applications with the benefits of low optical distortion, high degree of telecentricity and accurate image reproduction. Opto Engineering telecentric lenses offering high quality telecentricity, high resolution levels and minimal distortion. Opto Engineering offers bi-telecentric lenses for matrix and linear detectors.

Telecentricity Defined
Machine Vision applications often require a high level of accuracy and telecentric lenses differ from conventional lenses through their unique ability to view an object as the same size despite its distance from the lens. This is called telecentricity. The key capability of a telecentric lens is to accept only parallel light rays and to block those rays which are not parallel to the optical axis. Another way to put this is to describe it as removing parallax.

Figure: Opto Engineering telecentric lenses (bottom right) view the object field from the same or nearly the same angle across the whole field of view, and providing true diameter or width measurements.

Near-zero Distortion
Common machine vision lenses exhibit more than 1-2% of distortion that severely limit dimensional measurement applications but Opto Engineering telecentric lenses are certified with near-zero distortion at under 0.1%. This applies to resolving both radial and trapezoidal distortion. Telecentric lenses accomplish this accuracy by accepting ray cones where the "principal ray" is parallel to its mechanical axis because the entrance pupil is placed at infinity.

Opto Engineering telecentric lenses accomplish all this but add 3 differentiating advantages to its competitors:

1. The principal ray is chosen as being the ray striking the camera detector in the centre of radiometric distribution.
2. The principal ray is also the axis of the acceptance cone, assuring a symmetric grey level distribution at the edges.
3. The telecentric lenses are bi-telecentric meaning that they are also telecentric in the image space i.e. on the sensor side.

This is important for machine vision applications because significant errors can occur in applications such as measuring bottles on a conveyor that "walk" side-to-side changing their distances from the camera or an automated circuit-board assembly that requires measurements of a few thousandth of an inch. 3D objects when viewed by a conventional lens also suffer perspective errors and image position errors. Therefore telecentric lenses can prove extremely useful in the inspection of 3D objects or scenes where image size and shape accuracy are crucial.

Opto Engineering telecentric lenses offer quality imaging with their low optical distortion, high degree of telecentricity and accurate image reproduction for almost any kind of machine vision application.

Adept Electronic Solution (AES) is a specialist Australian and New Zealand distributor of machine vision systems and image analysis software. With a broad range of world class machine vision hardware such as Opto Engineering's telecentric lenses, AES provides a complete machine vision systems solution.

For more information or to purchase please contact us by consulting our expert vision engineers today at Tel Sydney (02) 99792599 / Perth (08) 92425411 / Melbourne (03) 95555621