Optotune liquid lenses – 5 case examples for machine vision

Liquid lens technology, with its ability to change focus within the order of milliseconds is opening up a host of new applications in both machine vision and the life sciences. It is gaining growing interest from a wide cross section of applications and easily adapts to standard machine vision lenses.

Liquid lens technology alone provides nice solutions, but when combined with advanced controls, many more applications can be solved.

To learn the fundamentals of liquid lens technology and download a comprehensive white paper read our previous blog HERE.

In this blog, we will highlight several case application areas for liquid lens technology.

Case 1: Applications requiring various focus points and extended depth of field: This does cover many applications, such as logistics, packaging and code reading in packaging. Liquid lenses provide the ability to have pre-set focus points, auto-focus or utilize distance sensors for feedback to the lens. In the example below, 2 presets can be programmed and toggled to read 2D codes at various heights essentially extending the depth of field.

Case 2: 3D imagery of transparent materials / Hyperfocal (Extended DOF Images: When using an Optotune liquid lens in conjunction with a Gardasoft TR-CL180 controller, sequence of images can be taken with the focus point stepped between each image. This technique is known as focus stacking. This will build up a 3D image of transparent environments such as cell tissue or liquid for analysis. This can also be used to find particles suspended in liquids.

A Z-stack of images can also be used to extract 3D data (depth of focus) and compute a hyper-focus or extended depth of field (EFOF) image.

The EDOF technique requires tacking a stack of individual well focused images which have preferably been synchronized with one flash per image. An example is show below with the rendered hyper focus image shown at right.

Case 3: Lens inspection: Liquid lenses can be used to inspect lenses, such as those in cell phones for dust and scratches looking through the lens stack.

For this application, a liquid lens is used in conjunction with a telescentric lens taking images through different heights of the lens stack.

Case 4: Bottle / Container inspection: Optotune Liquid lenses can be used to facilitate image bottom’s of glass bottles or containers of various heights.

In this example, the camera is consistently at the neck of the bottle, but the bottom is at different heights.

Case 5: Large surface inspections with variation in height: Items ranging from PCB’s to LCD’s are not flat, have various component heights and need to be inspected at high magnification (typically using lenses with minimal DOF). Optotune Liquid lenses are a perfect solution using preset focus points.

Machine Vision applications using Optotune Liquid lenses and controller are endless!

These applications are just the tip of the iceberg and many more exist, but this will give you a good idea of capabilities. Gardasoft TR-CL controllers are fully GigE Vision compliant, so any compatible GigE Vision client image processing software such as Cognex VisionPro, Teledyne Dalsa Sherlock or National Instruments LABVIEW can be used easily.

1st Vision’s sales engineers have over 100 years of combined experience to assist in your camera selection. With a large portfolio of lenses, cables, NIC card and industrial computers, we can provide a full vision solution!

Contact us to help in the specification and providing pricing

Ph: 978-474-0044 / info@1stvision.com / www.1stvision.com

New 1.1” FUJINON CF-ZA-1S Series machine vision lenses with 2.5um pixel resolution – Best in class

FUJINON has released its new CF-ZA-1S lens series supporting high resolution 1.1″ format images sensors down to 2.5um pixel pitches. This new series has some unique differences making it our go-to lens for this format size.

In this blog, we cover the unique differences, which are at a price point equal to or lower than competing brands, making it the best in its class.

The FUJINON CF-ZA-1S series with support of 2.5um pixels can be used essentially with any image sensor up to 1.1″ formats needing resolution for small pixels. Focal lengths from 8mm to 50mm are available.

CLICK HERE FOR FULL SPECIFICATIONS ON THE FUJINON CF-ZA-1S LENSES

Main Features of the FUJINON CF-ZA-1S machine vision lens series

High resolution and support of 2.5um pixels from center to edge
FUJINON’s “4D High Resolution” keeps uniform resolution from the image center to the peripherals regardless of lens working distance and f-stop. This is extremely beneficial in applications in which high contrast is needed from center to edge. (i.e Measurement of a part spanning the field of view)Relative illumination reaches 90% +
In general, the illumination of the peripheral areas of the image is determined by the “relative illumination” and the chief ray angle (CFA). FUJINON has designed the lens series to constrain the CRA allowing a good balance to the peripherals of the image as seen below. For machine vision applications needing even illumination, this becomes very important for repeatability.

Vibration and Impact resistant
FUJINON has done a great job within their new lens series to incorporate anti-vibration and resistance to high impacts for no extra cost! In applications such as robotic applications, autonomous vehicles and airborne applications to name a few will benefit from this feature.

This video highlights these features and more. It nicely details how the design constraints the CFA for even illumination and is a nice tutorial.

Ph: 978-474-0044 / info@1stvision.com / www.1stvision.com

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What are the f-numbers on machine vision lenses? f-stop explained!

Why does 1stVision focus (no pun intended) so much on machine vision lenses. As the old saying goes, if you have garbage in, you get garbage out.

The lens is the input to the machine vision system. A low quality lens means that you have already degraded the image coming into the sensor. For instance, let’s say you chose a camera with 5um pixels, which equates to a lens being able to resolve 100 lp/mm. If your lens’ Modular Transform Function (MTF) is only 50 lp/mm, you should have chosen a camera with 10um pixel size, because the lens can’t do any better than that. As a note, don’t infer that a camera with 10um pixels is worse than a camera with 5umpixels from this example, as that is not true. Learn more on MTF here

A machine vision lens gathers light and then focuses it. When we talk about focus, we are talking about the MTF, but when we discuss light gathering properties, we need to discuss the lens f-number.

FUJI -f-stop — FUJI lens showing f-stops

f-number
The f-number is defined as the ratio of the focal length by the aperture width (diameter of the entrance pupil). So a 50mm focal length lens with a f-number of 2 has a 25mm entrance pupil. The lower the f-number, the more light will be allowed into the system, however this equates to more expensive lens as you need more glass to make a wider entrance pupil.

f-stop
Many camera lenses have an adjustable iris that opens and closes at the front of the lens to limit the amount of light coming in. When open all the way, the f-stop is the f-number. From there, each f-stop from wide open halves the amount of light, which corresponds to reducing the size of the aperture by 1/sqrt(2) or about 0.707 and in turn halving the area.

The f-stop is represented by a sequence of these numbers below, each letting in half the light.

Sequence: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128

The sequence is obtained by approximating the geometric sequence

Characteristics of the f-stop

Most lenses are designed to be optimal in the F4-F5.6 range, in which they have the best MTF.
The higher f-number (ie f/8 ) is, or the more closed the aperture is, better the depth of field if achieved
The lower the f-number (ie f/1.4) is, or the aperature being wide open is where you get the least depth of field, but not great MTF.

In a practical application, you need to trade off exposure time, depth of field, and available machine vision lighting. These three variables are always in tension. If you need fast exposure AND depth of field this means very small amounts of light gets to the sensor. If you need high contrast images in this situation, something has to change. Either get more light, accept less depth of field, or have some image blur.

For a full listing of machine vision lenses, click here and use the filter to help in your selection.

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Get a 5MP lens for the price of a 3MP one! FUJI’s new XA-5M lenses.

Fujinon introduced their first 5MP series, the 5MP SA-1s over a decade ago. Back then they were the first really high quality lenses for under $500.

Now, they have introduced their next generation 5MP series, the new XA-5M , and they have made them smaller, better, and less expensive! Now you can get a 5MP rated lens for very close to what 2 or 3MP lens cost with the new HF-XA-5M series lenses! 1stVision has preferred pricing and stock! Contact us for a quote

The Fujinon XA-5M are designed to work at 3.45um resolution (and very good at 2.5um), so they are a great choice for the 3.45um pixels found in the Sony Pregius IMX line of sensors. See image below showing a heat map of the resolution.(Darker red is higher resolution, 2.7um, orange is 3.3, yellow is 4um, light blue is 5um, and dark blue is 6um)

Further, the new CMOS sensors have more of a ‘stacked’ architecture, meaning each pixel is tall. Without having a lens that has a small chief ray angle, which keeps the light rays as close to perpendicular as possible to the sensor, each pixel possibly shades its neighbor. The new Fujinon lenses are designed to solve that problem for these sensors. So when comparing this line to their competitors, there is less shading at the edges and more even illumination!

The results can be seen when comparing the center to edges in an application. In the example below, the text in the center and edge on the FUJI “4D High Resolution” lenses is crisp vs the competition on the right.

Finally, Fujinon has dramatically reduced the size of the lens, all the lenses are 29.5mm in diameter except the 6mm, which is 39.5mm. Now you can get a 5MP rated lens for very close to what 2 or 3MP lens cost with the new HF-XA-5M series lenses! 1stVision has preferred pricing and in stock! Contact us for a quote

Watch this video for more details on how the HF-XA-5M lenses compare to the competition

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