Cognex Blogs

Liquid lens technology for variable focus applications


In-Sight 视觉系统


Machine Vision

Manufacturers can speed production, minimize defects and reduce costs with machine vision technologies

John Keating, 09-27-2011

Variable focus is required in applications such as reading barcodes on different sized boxes or parts moving along a conveyor causing varying focal distances from the Fixed-Mount Barcode Readers. With the liquid lens, it does not matter if the code appears near or far because you won’t have to manually adjust the focus on the line. Even when the focal ranges are unknown, you can refocus the reader automatically by a software command over Ethernet or serial. For high speed lines, the liquid lens allows the scanner to change focus from box to box or part to part, quickly enough to scan for all barcodes present in the field of view.



In Handheld Barcode Scanners applications, variable focus technology provides one ID reader the ability to read small direct part marks (DPM) close up and then read large 1-D barcodes far away with the same scanner (see image). Typically, this type of application would require two readers: one to read the smallest 2-D matrix codes and one to read wide 1-D barcodes. With variable focus technology, one ID reader’s liquid lens can toggle between two or more focal distances without manual adjustment between reads.