Learn how liquid lenses keep continuous focus on machine vision cameras when the working distance changes.

Optotune lenses solve a machine vision industry problem!

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Machine Vision applications requiring the inspection of objects at various heights can become a challenge as normal lens have limited depth of field. Objects outside of the depth of field become out of focus, limiting the vision application. Historically, a lens with motorized focus adjustment would be implemented adding complexity, cost and long cycle times. In reality, this challenge is applicable to any imaging application requiring refocusing due to various lens working distances.

Optotune Focus tuneable lenses solves this problem eliminating motorized zoom lenses or manual intervention.

Click here NOW for full detail specifications on tunable lenses

Adding an Optotune tunable liquid lens to the optical system on a standard C-mount lens and camera, allows refocusing of the imaging system on the fly. When used in conjunction with distance sensors, its possible to inspect objects of various heights, refocusing within 15 milli-seconds.

For example, vision systems using 8mm to 50mm focal length lenses can be equipped with a tuneable lens in the front, typically mounted on the filter thread. In this configuration it is possible to focus from infinity down to about 100mm or less if spacers are added.

This solution can be applied to industrial machine vision applications, ophthalmology, laser, microscopy, postal, packaging and laser applications to name a few.

Contact 1stVision for a quote on Optotunes Tunable lenses

Technology 411

Optotune’s focus tunable lenses are shape-changing lenses based on a combination of optical fluids and a polymer membrane. The core element consists of a container, which is filled with an optical liquid and sealed off with a thin, elastic polymer membrane. A circular ring that pushes onto the center of the membrane shapes the tunable lens. The deflection of the membrane and with that the radius of the lens can be changed by pushing the ring towards the membrane or by exerting a pressure to the outer part of the membrane or by pumping liquid into or out of the container.

Watch this video to see the Optotune liquid lens in action

Advantages

A change in lens radius of several micrometers can have the same optical effect as moving the entire lens several centimeters. In turn there are several advantages

Optical systems can be designed more compact, oftentimes with less lenses and usually with less or no translational movement.
Large working distance ranges can be achieved
Eliminate expensive mechanical actuators resulting in a more robust design, which can be completely closed so that no dust can enter. Essentially no moving parts for long life cycles (> 1B cycles)
Weight and volume is reduced in the system.
Low power consumption.
Fast response time of systems, down to the order of milliseconds.
Easy installation and remote focus control
Advanced controls for very accurate and repeatable control of the lens using Gardasofts TR-CL180 controllers

Want to know more? Download Optotunes comprehensive white paper here

This white paper will review the overall principles of tunable lenses, response times, wavefront quality, drive methods, and applications.

Contact 1stVision for a quote on Optotunes lenses and discuss an overall solution with cameras, lenses and lighting if required.

UPDATE: Video showing some great demo’s from the Stuttgart Vision show in 2018

July 18, 2017March 21, 2023

Considerations in selecting a lens for a large format camera sensor

For most cameras in the automated imaging marketplace, the sensor sizes are 1” and less. (1″ sensors have 16mm image circle/diameters)

Note the size in inches and the image circle size in millimeters do NOT match! 1” does not convert to 16mm!. But that is a topic for another blog post!)

Industrial cameras with C/CS mount sensors normally range from ¼” to 4/3” ( up to 22mm image circle, which is the largest a C mount is by definition).

However, there are many cameras that have sensors larger than this, with many being a full 35mm sensor. These sensors typically require larger F or EF mounts as seen in the picture above.

Click here for F-mount lenses from Kowa

Click here for F-mount lenses from Schneider

The question becomes, how do you find a suitable lens for these cameras?

First, let address the Issues with F mount lenses

The mount most commonly used by camera vendors for sensors larger than C mount are F mounts. F mounts are most popular mount for SLR cameras, designed by Nikon about 1960. https://en.wikipedia.org/wiki/Nikon_F-mount

F mount lenses for commercial and consumer/prosumer cameras are excellent optically and priced well but there are several issues you need to consider with these lenses for automated imaging applications.

First, F mount lenses are bayonet, not screw mount. That means they are not as secure as C mount, and therefore, much more prone to vibration, or even coming lose.
F mount lenses for the consumer/prosumer market are designed to take fantastic color pictures. To do this, the lens coatings are optimized for color. This can affect mono images.
Consumers want their cameras to be light, so the F mount lenses are made with as much plastic as possible. This is not great for industrial applications
These lenses are designed for automatic focus and exposure and have controls for that in the lens itself.
Finally, the last issue is that many of these lenses are designed for the automated controls with prosumer cameras, autofocus and autoexposure.

If you can find an all metal manual F mount lens from 20 to 30 years ago, it would be great for an industrial application! If not, we suggest you turn to one of the companies that make F mount lenses specifically for this market. The major vendors are Schneider, Edmund Optics, and Kowa. All have a series of F mount lenses that are much more rugged than a prosumer F mount lens, and also don’t have the extra controls for automatic focus/iris. They have lock screws as well to hold their settings. The major limitation to these lenses are that they cost more than prosumer lenses, and are in just a small range of focal lengths.

Contact us for further specifications and pricing

EF Lenses

Since many of the new large format lenses can be controlled electronically via the camera, the automated imaging industry has created several products to use these lenses. The solutions from Birger Engineering, www.birger.com are straightforward to use. They make a mount that attaches to the camera and allows for the use of EF mount lenses. Attached to their mount are connections to drive the lenses, via serial commands with their SW. Several camera manufacturers have built cameras with EF mounts as part of the camera. This is an especially nice solution since there are no wires hanging out for control, and the lens is controlled directly from the camera’s SDK.

This provides a high level overview of the considerations in selecting a lens and size for large format camera sensors. 1st Vision has extensive knowledge with lenses and cameras and will help you in the selection process.

Please contact us and discuss your application with our sales engineer!

Related Blog posts:

Canon EF mount integrated into Allied Visions GT1930L

Imaging Basics – Calculating lens focal lengths

Not all lenses are created equal!

July 18, 2017October 4, 2021

10 key things you need to know when selecting a machine vision lens

Improper selection of the correct quality and type of machine vision lens can make your camera selection useless!

In many cases, we see customers attempting to choose a low quality lens for a camera that really needs quality optics to resolve the pixel sizes. Conversely, we also see customers trying to over specify a lens, where you simply need a lens that’s “good enough”

1st Vision has a white paper to help in the lens selection and provide valuable knowledge on various topics to make the best decisions.

Learn the 10 key things you need to know in selecting a lens for machine vision cameras. Download the white paper now!

In this comprehensive white paper, you’ll learn the following

Background basics on lenses and what they really do!
The science in some basic formulas to calculate MAG, focal length and angular FOV
What are extension rings used for?
How are lenses rated? MTF explained
The myth behind “Megapixel” lens ratings
How many pixels do I really need?
What is the ” f# ” of a lens
What does the “lens format” mean?
Comparison of lens types from security to Factory Automation (FA)
How to get some practical advice!

Download the White Paper

1st Vision has many other resources in our educational blogs. Please find related links to lenses below.

We are happy to discuss your imaging application in details – Just contact us!

Links:

Advantages of Telescentric lenses in machine vision

Macro lenses vs Extension tubes – What provides the best results?

Image Basics – Calculating lens focal length

Demystifying lens performance specifications

February 24, 2017November 23, 2021

What are the attributes to consider when selecting a camera and its performance?

We first need to start with some of the basic attributes of the camera such resolution, frame rate, color vs monochrome and interface. From there, depending on the application, we may look at more advanced attributes such as dynamic range, sensitivity, dark noise and signal to noise ratios.

The basic attributes are easy to understand, but the advanced attributes can be confusing and the data is not easily accessible. The more advanced information can be found on EMVA 1288 reports from the camera manufacturers when available. This is a standard which helps provide an apples to apples comparison on key camera sensor attributes.

Allied Vision has done a great job to help understand the attributes by defining the terms and putting them in a graphical format as seen below.

The following is a graphic to help understand the

terminology along with the definitions (Courtesy of Allied Vision!)

Definitions are as follows:

Absolute Sensitivity Threshold: The smallest detectable amount of light. Expressed in number of electrons. The point where signal equals temporal dark noise. This is important to understanding low light performance!
Photon Shot Noise: Signal noise equal to the square root of the incoming photons. Due to the randomly distributed particle nature of light.
Temporal Dark Noise: Noise when no light is hitting the sensor, also known as read noise. Due to electric dark current, quantization noise, and other noise sources depending on the specific construction of the sensor and the camera electronics.
Saturation Capacity: The maximum number of electrons each pixel can hold before reaching non-linear response.
Dynamic Range: Ratio of maximum signal (saturation capacity) to the minimum signal (temporal dark noise)
Signal to Noise at Saturation: Ratio of the maximum signal (saturation capacity) to noise (photon shot noise). At saturation, temporal dark noise is insignificant compared to photon shot noise and can be ignored.

The EMVA 1288 information is available for most cameras upon request. Contact us to discuss and obtain this information.

Need help on some of the basics in your camera selection? We have many helpful blog ports ranging from Calculating camera resolutions to understanding interfaces.