Machine vision

Focus within milliseconds
Large working distance ranges
Easier installation and remote focus control
Long life time (>1B cycles)

You would like to inspect your product at different working distances? Or read 2D codes quickly no matter how far away they are?

Focus tunable lenses provide a versatile and compact solution with focusing times of only a few milliseconds. As no translational mechanics are involved such systems are robust and achieve billions of cycles. Optotune’s lenses can be combined with off-theshelf imaging lenses by mounting them either in front or at the back. A few example configurations follow, many more can be found in our application notes.

Applications:

Quality control (e.g. liquids, electronics, bottles, LCDs, PCBs, ICs, CCMs)
Packet sorting, box filling, palletizing
Bar code reading
Robot vision
3D image stacking

Front-lens configuration provides large WD changes

Vision systems of 8mm to 50mm focal length can be equipped with a tunable lens in the front, typically mounted on the filter thread. In this configuration it is possible to focus from infinity (tunable lens at 0 diopters) down to about 100mm (tunable lens at 10 diopters) or less if spacers are added. Especially compact systems can be realized in combination with M12 board lenses, whereas the tunable lens can be mounted directly on the C-mount camera as shown on the left.

Machine vision example with off the shelf M12 lens 2

Back lens configuration is ideal for large image sensors

By placing the focus tunable lens at the back of an endocentric imaging lens it is possible to achieve image circles of up to 30mm. Placing the lens between camera and C-mount lens acts like adding a spacer. This makes sense for lenses with focal lengths of 35mm or more and offers very nice macro possibilities. With M42 mount cameras there is usually enough space to place the tunable lens at the back, such that working distances up to infinity are possible as well. While this configuration usually provides less optical leverage (smaller WD ranges) than the front lens configuration it can offer better resolution and reproducibility of the focus plane.

The following examples show an Optotune EL-16-40-TC-VIS-5D-M42 placed behind a Zeiss Distagon 25mm M42-mount lens providing a 30mm image circle and an EL-10-30-Ci-VIS-LD-MV placed between a 50mm lens and C-mount camera.

EL 16 40 TC VIS 5D M42 on Zeiss Distagon 25mm lens

Optotune EL 10 30 Ci between camera and 50mm lens website

Telecentric lenses

SILL 2x telecentric lens with EL 16 40 TC on M42 mount camera Great results are also achieved in combination with telecentric lenses. However, not many off-the-shelf configurations are available as the tunable lens is preferrably placed right after the aperture stop. If that is the case examples for achievable z-ranges are 20mm at 1x and 10mm at 2x magnification. Detailed reports can be found below.

The configuration shown on the right includes a SILL Correctal 2.0 telecentric lens, which was optimized to integrate Optotune's EL-16-40-TC-VIS-5D-M30, providing an image circle of 30mm. Read the full test report.

High magnification

To achieve magnifications of 1x up to 100x, the tunable lens is best placed between objective lens and tube lens. For industrial inspection, systems including optical zoom are available such as the Dynamic Focus VZM lens by Edmund Optics or the Optem FUSION sytem by Qioptiq.