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. Optotune 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 camera 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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Learn about the new 5GigE camera interface

Machine vision interfaces have continued to evolve over the years increasing data throughput and cable lengths. Commonly used interfaces are GigE and USB3. However, 5GigE is an interface now gaining attention in the industrial imaging / machine vision market with some nice advantages.

We will outline the benefits of 5GigE, but first, lets give a brief overview of the commonly used camera interfaces, with their pluses and minuses:

GigE / GigE Vision

110 MB/s of sustainable throughput. In real world terms, a HD, 2MP camera can get 50-55 fps in 8 bit mono or 8 bit color mode. Note, this isn’t real HD, since you need 60 FPS.
Data cable lengths up to 100m using regular CAT 5e/6 cable.
Easy to put multiple cameras on a system.

USB 3 / USB3 Vision

420 MB/s of data throughput. A HD 2MP camera can run 60 fps in 8 bit mono or color and can also run RGB at 60 FPS no problem. With the higher throughput, a 5MP camera can achieve 85 fps in 8 bit mode.
Data cables up to 5 meters and up to 20 meters with active cables. However, active cables can be quite costly, adding up to $200 in cost.
Not as easy as GigE to put multiple cameras on a system, and gets harder with each additional camera, especially if you have limited USB3 controllers.

As a note, there is no cost difference when using cameras with the same sensor from the same manufacturer with USB or GigE! They will cost about the same with no premium for one interface over the other.

What are the limitations of GigE and USB3 now solved by 5GigE?

USB3 is limited in cable length, so going faster than GigE is great, but you can not have long cable lengths.
GigE has cable lengths up to 100 meters, but is limited to ~ 110MB/s of data, so you do not have the high frame rates as in a USB3 camera.
USB3 in 4+ camera systems is not as stable as GigE AND you’re still limited on cable lengths.

Wait! – What about 10GigE?

Up until now, 10G was the next interface. However, the jump to 10G has quite a few limitations as outlined below.

Heat generation is significant, so cameras are large and not in the smaller 29 x 29mm cube form factor.
Not a lot of demand for very high speed 10G, so not a lot of sensors being offered
Minimal number of manufacturers for 10G, higher cost.
Special cabling, either optical or high quality cat 7.

What we have found is that there are several types of applications for 10G cameras and are as follows

Applications where you need 10G of speed of course (high resolution + fast frame rates)
Require greater than 110MB/s of data and need long cable lengths.
Where there is the required combination of 110MB/s for high frame rates, multiple cameras and long cable lengths, 10G is a perfect solution.

We have seen that the need for higher bandwidth + long cable lengths is more prominent vs. the real need for 10GigE!

Introducing 5GigE that provides increased bandwidth, long cable lengths at reasonable prices! or N Base T.

5GigE (also known as N Base T) has become a new standard for industrial, machine vision cameras.

In the general compute world, a much much larger market than vision, there has also been a need to go faster than GigE. However, the issue of replacing the existing cabling is the major issue preventing this. If you think of a big box store, say a Home Depot for instance, the amount of cabling is huge. Ripping that out and rewiring far exceeds the cost of the equipment to use it!

5G was made to go faster, but use existing cabling. Regular cat6e cable can be used, and 5G is a subset of 10G, so all switches etc. can be kept in service.

5G gives users in the vision market USB3 speeds, but with ALL of the regular GigE features, at a very small premium!