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

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.

Related Blog posts

Not All Lenses are Created Equal! Lens MTF Comparisons

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

Demystifying Lens performance specifications

Information courteous of Wikipedia

November 29, 2017November 23, 2021

Best in class OEM machine vision lenses, low cost, high performance with an easy to use lens selector

1st Vision‘s factory automation OEM machine vision lenses are designed using glass from one of the top Japanese lens manufacturers. These lenses are not branded and allow our clients to have excellent performance at a better price than the ‘named’ brand manufacturers, getting the most bang for your buck!

In comparing specifications, our OEM lenses have better resolution in many cases over brand name lenses, but at ~ 30% less cost in some cases.

1st Vision lens comparison — Conventional lens (left) vs 1stVision OEM lens (right)

In resolution chart comparisons, the 1st Vision OEM lens on the right outperforms the leading lens in its class. All lenses have locking screws for focus and iris. High temperature options are available providing ranges from – 30 C to +70 C.

Details specifications and pricing can be found HERE

Its now easier than every to find a desired lens it the new 1st Vision lens selector. Sort by focal length, optical format and lens quality to name a few sort attributes. Try it now HERE!

Need help in your lens selection? Our sales engineers all have over 20 years of vision experience and can help you identify the best lens for your application.

If you like our lens selector, check out the new camera selector! Watch our short video highlighting helpful new features and selectors on our website

We also have several blog posts providing additional education on lens selection including handy focal length calculators. Click on the resources below.

Resources:
Calculating Lens Focal Length
Video: Using the 1st Vision Lens calculator
Demystifying lens performance – MTF
Calculating your resolution for machine vision applications

September 19, 2017April 26, 2019

Sony has a great new 1.1” Image Sensor, but what kind of lens can I use with this format? Computar MPY Series!

Computar MPY Series Lenses — Computar MPY lens series

If you have been around industrial camera lenses for a while, you know that there are many ½” and 2/3” lenses, not as many 1” lenses, but what do you do when you have a 1.1” sensor?! The solution? Use the Computar MPY 12 Megapixel lenses!

If you have been following Sony’s new IMX image sensor product line, their newest sensors are based on a 3.65um pixel pitch. However, when you scale this up to their new 12MP sensor (Sony Pregius IMX253, IMX304), the sensor size becomes 1.1” (17.6mm diagonal) format. A 1” lens format will not cover this image circle and in turn has vignetting in your image (Read our blog post on sensor size vs. lens size ) .

One possible solution is to use a 1” lens and vignette 5% on each side, or use a 1” lens and stop it down where the vignetting goes away. However this is not an optimal solution. A second solution is to use a F Mount lens, but if the camera is a C mount, you will need a C to F adapter, again less than ideal.

Fortunately there are some C mount lenses that are greater than a 1” image format. Kowa and Schneider both have been shipping 4/3” format lenses, although these are quite expensive. Recently, Computar has come out with a line of 1.1” format lenses SPECIFICALLY for this sensor!

Key Features of the 1.1″ format, Computar MPY 12MP C-mount lenses

Click here for full series specifications

Individual Specifications can be found via this link for the models below:

8mm – V0828-MPY
12mm – V1228-MPY
16mm – V1628-MPY
25mm – V2528-MPY
35mm – V3528-MPY
50mm – V5028-MPY

1st Vision’s sales engineers specialize in industrial imaging and can help you in the lens selection. Additionally, they can help ensure you have the best lens mated to the newer sensors to ensure the highest contrast.