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Ruggedized Imaging Lenses
November 2017 | See all Trending in Optics Topics

Overview

 

Ruggedization is Required for Imaging Lenses in Hazardous Environments

 

Not All Ruggedization Created Equal

 

Emerging Applications Require More Advanced Ruggedization

 

Ruggedization Requirement: Reducing Pixel Shift and Maintaining Pointing Stability

Imaging lenses used in harsh environments have special requirements beyond those of standard imaging lenses. Lenses used in factory automation, robotics, and industrial inspection are often exposed to vibrations, shocks, temperature changes, and contaminants. Ruggedization is the act of strengthening a lens to resist these harsh environments and is growing in importance because of the worldwide surge in emerging markets like robotics, automation, and autonomous systems. Most imaging lenses labeled as ruggedized, tough, or harsh environment utilize Industrial Ruggedization to reduce cost and prevent changes in focus from shock and vibration. This is done by simplifying the mechanics. However, Industrial Ruggedization is not sufficient for the most demanding applications where the calibration of an imaging system must be maintained. A more robust type of ruggedization, called Stabilized Ruggedization, is required to reduce pixel shift and truly protects lenses from shock and vibration.

Industrial Ruggedization – Primary Benefit = Cost Reduction

In Industrial Ruggedization, lens mechanics are simplified by replacing the adjustable iris with a fixed aperture stop and replacing the non-rotating double threaded barrel with a simple single thread and a rigid locking mechanism, such as a clamp, nut, or set screws. This reduction of moving parts decreases the cost of the lens and adds additional stability compared to standard imaging lenses, making it less likely that the focus of the lens will be affected by weak shocks and vibrations. However, excessively strong shocks and vibrations may still decenter the individual optics inside the lens and cause pixel shift - meaning that objects are mapped to the incorrect location on the image sensor (see Figure 1 and Figure 2).

Unperturbed system where object crosshair is mapped to the image crosshair
Figure 1: Unperturbed system where object crosshair is mapped to the image crosshair
Perturbed system where lenses are decentered within the barrel resulting in pixel shift in which the optical pointing stability changes. Object crosshair is mapped to a different place on the image, which is enough to disrupt system calibration.
Figure 2: Perturbed system where lenses are decentered within the barrel resulting in pixel shift in which the optical pointing stability changes. Object crosshair is mapped to a different place on the image, which is enough to disrupt system calibration.

Typical Applications:

  • Situations where a system will be set up once and not changed afterwards
  • Cost-sensitive systems

Advantages:

  • Reduced cost compared to standard imaging lenses
  • Focus is less affected by weak shock and vibration than standard lenses
  • High repeatability between multiple lenses

Disadvantages:

  • Pixel shift may still be caused by shock and vibration
  • Will not protect lens from strong shocks
  • Lack of flexibility: cannot easily adjust the aperture
  • Focus travel is not as smooth as standard lenses

Stabilized Ruggedization – True Protection from Shock and Vibration

Stabilized Ruggedization protects lenses from stronger shocks and vibrations compared to Industrial Ruggedization, and also maintains optical pointing and positioning. Stabilized Ruggedized lenses feature the same mechanical simplifications of Industrial Ruggedization, such as removing the iris and using a simpler focus, but all of the individual elements in the lens assembly are glued into place to prevent movement within the housing. This maintains the focus under strong shock and vibration, while preventing pixel shift, which is essential for calibrated imaging systems. See Figure 3 and Figure 4 to see how this elimination of pixel shift impacts imaging performance. Stabilized Ruggedization allows a calibrated device to be built in one location and shipped to another without losing its calibration. Most lenses labeled as ruggedized are Industrial Ruggedized and do not feature the added benefits of Stabilized Ruggedization.

STANDARD IMAGING LENS
Ruggedized Lenses Line Art
Figure 3: As the imaging system shakes due to shock and vibration, the image produced on the camera sensor also shakes, causing the image to shift onto different pixels each time. Pixel shift is caused by the lens elements decentering inside the lens barrel as the imaging system shakes. In the image above, you can see the blue lens elements move inside the lens barrel and how the image moves on the sensor.
STABILIZED RUGGEDIZED Cr SERIES LENS
Ruggedized Lenses Line Art
Figure 4: Pixel shift is minimized in Stabilized Ruggedized lenses compared to standard imaging lenses. As the imaging system shakes from shock and vibration, the lens elements inside remain stationary inside the lens barrel and the image remains stationary. In the image above, view how the blue lens elements remain stationary inside the lens barrel and how the image does not move on the sensor.

Typical Applications:

  • Calibrated Imaging Systems
  • Measurement and Gauging
  • 3D Stereo Vision
  • Robotics and Sensing
  • Autonomous Systems
  • Object Tracking
Typical Applictions

Advantages:

  • No pixel shift with shock and vibration
  • Protected against stronger shocks than Industrial Ruggedized lenses
  • High repeatability between multiple lenses

Disadvantages:

  • Lack of flexibility: cannot easily adjust the aperture
  • Focus travel is not as smooth as standard lenses

Webinar: Different Types of Ruggedization for Imaging Lenses

Learn more about the different types of ruggedization for imaging lenses in our webinar presented by Greg Hollows, Director of the Imaging Business Unit at Edmund Optics®.

Stabilized Ruggedized Lenses from Edmund Optics®

Edmund Optics® is a premier provider of Stabilized Ruggedized imaging lenses and customizes lenses for ruggedization upon request. These lenses are ideal for harsh environments involving shock and vibration, along with calibrated imaging applications including autonomous vehicles, vision-guided robotics, measurement and gauging, and object tracking.

TECHSPEC® Compact Ruggedized (Cr) Series Lenses

 

Stabilized Ruggedized to minimize pixel shift after shock and vibration

 

Individual lens elements glued in place to maintain optical pointing stability

 

Simplified focus mechanism with wide range of fixed aperture options

 

Stainless steel locking C-Mount clamps
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FAQ's

FAQ  Where can I find more information on the various types of Ruggedization?
You can find more information on Stability and Industrial Ruggedization in our Ruggedization of Imaging Lenses application note and whitepaper in the Resources section at the bottom of this page.
FAQ  My application requires different specifications than those listed for your standard ruggedized lenses. Are custom options available?

Yes, Edmund Optics® has a staff of experienced optical and mechanical designers, along with world class manufacturing, to support prototypes and deliver the lens you require for your application. For more information, please contact our Technical Support Engineers.

FAQ  I’m currently using a different Edmund Optics® imaging lens. Can you ruggedize my lens?

Yes, we can ruggedize the lens and also do a number of other modifications such housing modification, working distance adjustment, filter or liquid lens integration, aperture replacement, and more. For more information, please contact our Technical Support Engineers.

FAQ  Are Zemax prescription files available for your standard ruggedized lenses?
Yes, please submit a prescription request and one of our Technical Support Engineers will contact you.
FAQ  Can ruggedization make lenses waterproof?
Ingress Protection Ruggedization is another type of ruggedization in which lenses are sealed using O-rings or RTV silicone to make them waterproof, dustproof, and fog proof. Edmund Optics offers an off-the-shelf line of Ingress Protection Ruggedized lenses, TECHSPEC® HEO Series M12 μ-Video™ Imaging Lenses. For more information on Ingress Protection Ruggedization, please visit our Ruggedization of Imaging Lenses application note.

Resources

Application Notes

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

Ruggedization of Imaging Lenses
Read  

Videos

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

Ruggedized Imaging Lenses Webinar
Watch  

White Papers

Downloadable detailed technical paper.

Ruggedization of Imaging Lenses
Download  

Published Articles

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

"Lens sees clearly even through shock and vibration" by Jessica Gehlhar and Cory Boone - Design World
Read  

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