Telecentric lenses with tunable working distance

10. May 2017

In case measuring objects at different heights in industrial testing applications, telecentric lenses are indispensable. Unfortunately, users quickly hit the limitations of the exploitable depth of field.

To benefit from a significantly larger variation of the working distance and still maintaining the necessary resolution, a variable focusing is needed. In corporation with Optotune Switzerland, Sill Optics has designed telecentric lenses with tunable working distance. They are able to achieve an adequate focusing without any mechanical movement and thereby preserving performance in the given tuning range.

These new products allow telecentric measurements with temporally adjustable working distance up to image capture speeds of 40 fps. The working distance is thereby linearly proportional to the dioptic power (reciprocal of the effective focal length) of the focus tunable lens element. Due to the retroactive effect of the focal length, the magnification of the lens is not constant. With calibration of the setup, this small difference can be corrected for consistent accuracy, because of the linear behavior. Variation of working distance is also offering additional possibilities via z-scan through a measurement object and therefore another approach in 3D measurement technology.

The first prototypes have been successfully launched at the Vision 2016. From May 2017, Sill optics is offering a broad series of telecentric lenses with variable working distance. This range covers lenses with magnifications from 0.13x to 0.66x for sensors up to 16mm diagonal length and magnifications from 1x to 3x for sensor diagonals of 35 mm.

We are offering a consolidation of this topic in the course of a presentation at the “Control Vision Talks” as well as on our booth at the Control and the Laser – World of Photonics. As Sill Optics is known as a supplier for customized optics, we are also open to any special projects in this product range. 

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