Edmund Double-Gauss Lenses Produce Sharp Focus

Edmund Double-Gauss Lenses Produce Sharp Focus

I have been working on a 3D vision application using the SICK Ranger camera. My application involves precision measurement, so I want to get the best results possible from the equipment.

The Ranger came with a Fujinon 35mm lens which focused sharply in the center of the field of view. However there was significant blur near the edges. (The CMOS sensor on the Ranger is 15.4mm diagonal. That exceeds the specification of most common machine vision lenses.)

I tried a Tamron 35mm lens, and achieved better results, but there was still blur on the edges.

A Tamron 50mm lens worked better than the 35, but I moved my camera position back almost 3 inches to get the same field of view. My application is very space constrained and this is undesirable.

I remembered a presentation at a PPT vision seminar by Patrick McKenna, a Machine Vision Solutions Engineer from Edmund Optics. He talked about Edmund's Double Gauss lenses. So I gave Patrick a call, and ordered the 35mm focusable Double Gauss lens. (Despite ordering after 5 pm, I still got it the next day, one of the things I love about Edmund.)

The Double Gauss lens did exactly what Patrick said it would. The image focused sharper than ever in the middle, and was just as sharp at the edges.

Here's my data for a 1 inch Field of View. (The Sick Ranger has a 9.5 micron pixel size.) lp/mm is Line Pairs per Millimeter.

Fujinon 35mm: Center of field: 8.0 lp/mm, edge: 5.04 lp/mm

Tamron 35mm: Center of field: 8.98 lp/mm, edge: 8.0 lp/mm

Tamron 50mm: Center of field: 14.3 lp/mm, edge: 11.3 lp/mm

Edmund Double Gauss: Center of field: 16 lp/mm, edge: 16 lp/mm


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