OPT's liquid lenses enable extremely fast focusing for Automatic Optical Inspection (AOI)

OPT's self-developed liquid lens has been newly launched to meet customers′ needs for improving quality and efficiency. Under combined applications with smart code readers and industrial cameras, it exhibits outstanding performance, achieving instantaneous focusing and offering more flexibility in working distance. They are thus ideally suited for the 3C industry (computers, communications, and consumer electronics), logistics, and many other industries.

Liquid lens technology: an example of Bionics

The model for liquid lenses is biological eyes, such as those of humans. In a fluid-filled chamber, an elastic lens is deformed by muscle force (ciliary muscle) to achieve focusing.

OPT's liquid lenses use the principle of two-phase liquid lens technology. A chamber contains two immiscible liquids (an aqueous salt solution and a non-conductive oil) with different refractive indices. If an electrical voltage is applied, the shape and curvature of a liquid are influenced, as well as the focal length of the entire liquid lens.

The most significant advantage of liquid lenses is the fast focusing without mechanical wear. Working distances or focal lengths can be reliably changed within a few milliseconds. The control is electrical.

Conventional autofocus lenses are considerably slower and the wear on the mechanics is considerable. For this reason, they are reluctantly used in machine vision.

Another advantage of liquid lenses is that they can be particularly compact. This means that code readers and intelligent cameras can be made even smaller.

If the distance of the object to the liquid lens changes, the liquid lens technology allows the object to be tracked in space by permanent and instantaneous focusing. The object is thus in focus at any working distance.

Fast and precise focusing, flexible working distance

Most applications for liquid lenses are found where codes need to be read quickly, but the codes may be present at different working distances. This can be the case in logistics and especially in applications on conveyor belts.

There, the barcode reader is usually permanently installed and the objects to be measured move quickly under the reader. An example of this is packages, which can have different sizes. To be able to read the barcodes on the packages, the images of the codes must be focused very quickly. Only sharp images can be evaluated reliably during production.

Not only barcode readers and intelligent cameras can be equipped with liquid lenses, but also conventional industrial cameras.

In applications where several images are taken in quick succession as test shots with different settings, the use of liquid lenses can lead to faster results. In addition, the number of images captured can be significantly reduced.

Overall, with the use of liquid lenses, one achieves more freedom due to the variability of the working distance and the possibility of very fast and precise focus adjustment.

OPT's newly developed liquid lens features a precision design with no moving parts, is small and compact, and can be used in miniaturized or space-constrained automation equipment.

It can be easily and flexibly installed and commissioned, thus best meeting the requirements of complex machine vision applications.