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liquid lens telecentric lenses

Image Quality of a Telecentric with the Flexibility of a Liquid Lens

 

Liquid lens integrated into telecentric lens for quick autofocus

 

Eliminate parallax error while changing working distance

 

Telecentricity maintained across entire working distance range

 

Ideal for gauging, measurement, and placement applications

Liquid Lens Telecentric Lenses provide fast, accurate, and precise measurements and help speed up the throughput of inspection systems. Conventional telecentric lenses have a fixed working distance and cannot compensate for objects at different working distances. In order to inspect objects with depth using a conventional telecentric lens, the object would need to be repositioned or a new telecentric with a different working distance would need to be used. This constraint leads to delays in measurement and limits throughput. On the other hand, Liquid Lens Telecentric Lenses overcome these speed limitations by quickly refocusing to different working distances in a matter of milliseconds.

Applications in Machine Vision

A conventional imaging lens requires mechanical refocusing for objects of different sizes, causing a delay that limits throughput. The animation below (Figure 1) shows how a Liquid Lens Telecentric Lens can be utilized in the inspection of circuit boards to quickly adjust working distance and refocus on different pins.

A Liquid Lens Telecentric Lens can compensate for changing working distances quickly in a machine vision system.
Figure 1: A Liquid Lens Telecentric Lens can compensate for changing working distances quickly in a machine vision system. Figures 1a and 1b (above) show where pins at different working distances are equal in sharpness and contrast. Image 1a shows that the top pin closest to the lens is bent.

Benefits of Telecentricity & Liquid Lenses

Telecentricity

The angular field of view of conventional lenses leads to a decrease in magnification as the distance between the object and the lens increases, resulting in parallax, or perspective error. This decreases accuracy, as the magnification change will make the observed measurement of the imaging system change if the object is moved, even when staying within the depth of field of the lens. Telecentric lenses eliminate parallax error by having a constant, non-angular field of view, and therefore have no change in magnification with respect to depth. This is illustrated in Figure 2, which compares images of two different objects at different working distances using both a telecentric lens and a conventional fixed focal length lens.

The Angular Field of View of the Fixed Focal Length Lens translates to Parallax Error in the Image and causes the two Cubes to appear to be different sizes
Figure 2: The angular field of view of the fixed focal length lens makes the two cubes appear to be different sizes because of parallax error.

However, telecentric lenses are optimized for a specific working distance. Integrating a liquid lens allows a lens to compensate for changing working distances even further, while maintaining telecentricity and image quality across the whole working distance range.

Advantages of Telecentricity

To learn more about telecentricity, read our application note on the Advantages of Telecentricity.


Liquid Lenses

Liquid lenses are small cells containing optical-grade liquid. This liquid can change shape when a current or voltage is applied to the liquid lens cell, causing the focal length and working distance of the lens to shift. Liquid lenses are an ideal solution for imaging applications dependent on quick refocusing, high throughput, and accommodation for changing working distances.

Illustration of the electrically focus-tunable lens in Liquid Lens Telecentric Lenses.
Figure 3: Illustration of the electrically focus-tunable lens in Liquid Lens Telecentric Lenses.

Liquid Lens Telecentric Lenses at Edmund Optics®

The TECHSPEC® MercuryTL™ Liquid Lens Telecentric Lenses from Edmund Optics® contain an integrated liquid lens for quick autofocus while maintaining telecentricity throughout the entire working distance range. They are an ideal combination of the proven performance of our TECHSPEC® telecentric lenses with the flexibility of a liquid lens.

FAQs

FAQ  What primary magnifications are available for the TECHSPEC® MercuryTL™ Liquid Lens Telecentric Lenses from Edmund Optics®?
Edmund Optics® offers Liquid Lens Telecentric Lenses with Primary Magnifications (PMAG) of 0.15X, 0.24X, 0.37X, and 0.75X. You can find more information on the product family page.
FAQ  Can Edmund Optics® make customized Liquid Lens Telecentric Lenses?

Yes, we can make customized Liquid Lens Telecentric Lenses tailored to your specific application. For more information, please contact our application support engineers.

FAQ  Can I integrate a liquid lens into another type of lens, such as a fixed focal length lens?

Yes, we can integrate liquid lenses into other types of lenses as a custom request. We also offer the modular Cx Series Fixed Focal Length Lenses, in which you can integrate interchangeable accessories including liquid lenses, fixed apertures, and internal filter holders.

FAQ  How do I mount a TECHSPEC® MercuryTL™ Liquid Lens Telecentric Lenses?
We offer two 30mm inner diameter mounting clamps with either a 1.75” or 2.25” centerline, or distance from the bottom of the mount to the center of the lens. Both can be found on the product family page.

Resources

Application Notes

Technical information and application examples including theoretical explanations, equations, graphical illustrations, and much more.

Telecentric Design Topics
Read  

Distortion and the Telecentricity Specification
Read  

Liquid Lenses in Imaging
Read  

Videos

Informative corporate or instructional videos ranging from simple tips to application-based demonstrations of product advantages.

Understanding Liquid Lens Technology
Watch  

Related Pages

Links to technical articles appearing in industry publications authored by Edmund Optics® or featuring contributions from EO's engineering team and key management.

Large Field of View Telecentric Lenses
Read  

Technical Articles

Links to technical articles appearing in industry publications authored by Edmund Optics or featuring contributions from EO's engineering team and key management.

"Telecentricity Meets Flexibility"
Read  

 

Contact Us

What limitations do you face today in your optics applications? What are the next problems that you need to be solved? Contact us today to work with our team of engineers to discover solutions to your application questions.

 

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