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Spatial resolution is an essential machine vision concept

image sensor

Spatial resolution is determined by the number of pixels in a CMOS or CCD sensor array.  While generally speaking “more is better”, what really matters is slightly more complex than that.  One needs to know enough about the dimensions and characteristics of the real-world scene at which a camera is directed; and one must know about the smallest feature(s) to be detected.

Choosing the right sensor requires understanding spatial resolution

The sensor-coverage fit of a lens is also relevant.  As is the optical quality of the lens.  Lighting also impacts the quality of the image. Yada yada.

But independent of lens and lighting, a key guideline is that each minimal real-world feature to be detected should appear in a 3×3 pixel grid in the image.  So if the real-world scene is X by Y meters, and the smallest feature to be detected is A by B centimeters, assuming the lens is matched to the sensor and the scene, it’s just a math problem to determine the number of pixels required on the sensor.

There is a comprehensive treatment how to calculate resolution in this short article, including a link there to a resolution calculator. Understanding these concepts will help you to design an imaging system that has enough capacity to solve your application, while not over-engineering a solution – enough is enough.

Finally, the above guideline is for monochrome imaging, which to the surprise of newcomers to the field of machine vision, is often more better than color, for effective and cost-efficient outcomes.  Certainly some applications are dependent upon color.  The guideline for color imaging is that the minimal feature should occupy a 6×6 pixel grid.

If you’d like someone to double-check your calculations, or to prepare the calculations for you, and to recommend sensor, camera and optics, and/or software, the sales engineers at 1stVision have the expertise to support you. Give us some brief idea of your application and we will contact you to discuss camera options.

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1st Vision’s sales engineers have an average of 20 years experience to assist in your camera selection.  Representing the largest portfolio of industry leading brands in imaging components, we can help you design the optimal vision solution for your application.

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1st Vision is the most experienced distributor in the U.S. of machine vision cameras, lenses, frame grabbers, cables, lighting, and software in the industry.

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What can multifield linescan imaging do for me?

Multifield imaging is a new imaging technology that enables capturing multiple images simultaneously at various lighting conditions e.g. brightfield, darkfield, and backlight in a single scan. It’s a variation on the concept of sequence modes. Teledyne Dalsa Linea HS is the industry’s first TDI camera capable of capturing up to three images using light sources at different wavelengths.

OK, cool.  How does that help me?  How does it differ from other imaging methods?  What applications can it solve that couldn’t be tackled before?

Backlight, Darkfield, and Brightfield images of same target

Perhaps a quick review of area scan imaging and conventional linescan imaging will help set the stage:

Area scan cameras are most intuitive, creating in one exposure a rectangular array of pixels corresponding to an entire scene or field of view.T hat’s ideal for many types of machine vision imaging, if the target fits wholly in the field of view, and if the lighting, lens, and image processing can best achieve the desired outcome at an optimal price point.

But linescan imaging is sometimes a better choice, especially for continuous-flow applications, where there is no discrete start and end point, in one dimension.  Linescan systems can capture an image “slice” that is enough pixels wide to make effective imaging computations, and, where required, to archive those images, using fewer active pixels and reducing sensor costs compared to area scan.  Other benefits include high sensitivity and the ability to image fast moving materials without the need for expensive strobe lighting.

Understanding line scan applications: concepts still relevant!

… so much for the review session.  So, what can multifield linescan imaging do for me?  Multifield capable linescan cameras bring all the benefits of conventional linescan imaging, but additionally deliver the perspectives of monochrome, HDR, color/multispectral (NIR), and polarization views.   This can enable machine vision solutions not previously possible, or solutions at more attractive price points, for a diverse range of applications.

Multifield imaging is a new imaging technology that enables capturing multiple images simultaneously at various lighting conditions e.g. brightfield, darkfield, and backlight in a single scan.

Consider OLED display inspection, for example. Traditionally an automated inspection system would have required multiple passes, one each with backlight, darkfield, and brightfield lighting conditions. With a multifield solution, all three image types may be acquired in a single pass, greatly improving throughput and productivity.

Flat panel glass is inspected at every stage of manufacturing

So how is multifield imaging achieved? In this blog we’re more focused on applications. For those new to Time Delay and Integration (TDI), it is the  concept of accumulating multiple exposures of the same (moving) object, effectively increasing the integration time available to collect incident light. The key technology for a multifield linescan camera is the sensor uses advanced wafer-level coated dichroic filters with minimum spectral crosstalk to spectrally isolate three images captured by separate TDI arrays, i.e. wavelength division multifield imaging.

Multifield images on one sensor using filters to isolate wavelengths

This new technology significantly boosts system throughput as it eliminates the need of multiple scans. It also improves detectability as multiple images at different lighting conditions are captured simultaneously with minimum impact from mechanical vibration.

1stVision is pleased to offer our customers a multifield linescan camera from Teledyne Dalsa, the HL-HF-16K13T: https://www.1stvision.com/cameras/models/Teledyne-DALSA/HL-HF-16K13T

Contact 1stVision for support and / or pricing.

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Give us some brief idea of your application and we will contact you to discuss camera options.

1st Vision’s sales engineers have an average of 20 years experience to assist in your camera selection.  Representing the largest portfolio of industry leading brands in imaging components, we can help you design the optimal vision solution for your application.

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Computar ViSWIR Visible + SWIR lenses

1stVision is pleased to make available two new lens series from Computar: both the ViSWIR HYPER / APO Lens Series, and the VISWIR Lite Series. Traditionally, applications landed in either the visible or the SWIR range, so components tended to be optimized for one or the other. The new lens series are designed to perform well with for both visible and SWIR, enabling cost-effective and performant imaging systems for a range of applications.

ViSWIR Hyper / Multi-Spectral Lens Series were created for the latest Vis-SWIR imaging sensors, the IMX990/IMX991 SenSWIR, currently found in the new Allied Vision Goldeye G-130. The series was recognized as a Gold Honoree by Vision Systems Design in 2021:

With fully corrected focus shift in visible and SWIR range (400nm-1,700nm), spectral imaging is achievable with a single sensor camera by simply syncing the lighting. Per Sony, “the IMX990/IMX991 top indium-phosphorus (InP*2) layer inevitably absorbs some visible light, but applying Sony SWIR sensor technology makes this layer thinner, so that more light reaches the underlying InGaAs layer. The sensors have high quantum efficiency even in visible wavelengths. This enables broad imaging of wavelengths from 0.4 μm to 1.7 μm. A single camera equipped with the sensor can now cover both visible light and the SWIR spectrum, which previously required separate cameras. This results in lower system costs. Image processing is also less intensive, which accelerates inspection.”

With ViSWIR HYPER-APO, it is unnecessary to adjust focus for different wavelengths or to keep the high resolution from short to long working distances. The focus shift is reduced at any wavelength and any working distance, making the series ideal for multiple applications, including machine vision, UAV, and remote sensing.

Computar ViSWIR HYPER-APO lens series

Since diverse substances respond to differing wavelengths, one can use such characteristics as the basis for machine vision applications for materials identification, sorting, packing, quality control, etc. To understand the value of these lenses, see below for an example of conventional lenses that cannot retain focus across different wavelengths:

Conventional lenses only focus in specific wavelengths

Now see images across a wide range of wavelengths, with the award winning Computar lens, that retain focus:

Diverse materials under diverse lighting – in focus at each wavelength.
The same lens may be used effectively in diverse applications.

Also new from Computar is the VisSWIR Lite series, providing:

— High transmission from Visible to SWIR (400-1700nm) range
— Reasonable cost performance for narrow band imaging
— Compact design
Key features of Computar VisSWIR Lite seriesComputer

Computer ViSWIR Lite lens series

Which to select? APO or Lite series?

Contact 1stVision for support and / or pricing.

Contact us to talk to an expert!Give us some brief idea of your application and we will contact you to discuss.

1st Vision’s sales engineers have an average of 20 years experience to assist in your camera selection.  Representing the largest portfolio of industry leading brands in imaging components, we can help you design the optimal vision solution for your application.

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Allied Vision G-130 TEC1 SWIR Camera

1stVision is pleased to announce that we can obtain Allied Vision’s new G-130 TEC1 SWIR camera for our customers. Utilizing Sony’s innovative IMX990 sensor, based on their SenSWIR technology, the camera is responsive in both the visible as well as the short-wave infrared range, spanning from 400 – 1700nm.

AVT G-130 TEC1 SWIR camera

While there are a number of cameras that cover short-wave infrared (SWIR) alone, from 900 – 1700nm, this sensor’s responsivity down to 400nm in the visible range opens up applications possibilities not previously possible with a single sensor camera.

Besides the wide spectral range, the sensor uses small 5µm pixels, with high quantum efficiency, offering precise detection of details.

The Goldeye 130 with IMX990 1.3MP SXGA sensor can deliver 110fps with Camera Link interface, or 94fps with GigEVision interface. The camera is fan-less, using thermoelectric sensor cooling (TEC1), yielding a robust and compact design.

Contact 1stVision for support and / or pricing.

Click to contact
Give us some brief idea of your application and we will contact you to discuss camera options.

1st Vision’s sales engineers have an average of 20 years experience to assist in your camera selection.  Representing the largest portfolio of industry leading brands in imaging components, we can help you design the optimal vision solution for your application.