Short Wave Infrared (SWIR) imaging enables applications in a segment of the electromagnetic spectrum we can’t see with the human eye – or traditional CMOS sensors. See our whitepaper on SWIR camera concepts, functionality, and application fields.
Until recently, SWIR imaging tended to require bulky cameras, sometimes with cooling, which were not inexpensive. Cost-benefit analysis still justified such cameras for certain applications, but made it challenging to conceive of high-volume or embedded systems designs.
Enter Sony’s IMX992/993 SenSWIR InGaAs sensors. Now in Allied Vision Technologies’ Alvium camera families. These sensors “see” both SWIR and visible portions of the spectrum. So deploy them for SWIR alone – as capable, compact, cost-effective SWIR cameras. Or you can design applications that benefit from both visible and SWIR images.
Alvium configuration and interface options – Courtesy Allied Vision Technologies
Camera models and options first
The same two sensors, both the 5.3 MP Sony IMX992 and the 3.2 MP Sony IMX993, are available in the Allied Vision Alvium 1800 series with USB3 or MIPI CSI-2 interfaces. As well as in the Alvium G5 series with 5GigE interfaces.
And per the Alvium Flex option, besides the housed presentation available for all 3 interfaces, both the USB3 and CSI-2 versions may be ordered with bare board or open-back configuration, ideal for embedded designs.
The big brother IMX992 at 5.3 MP and sibling IMX993 at 3.2 MP share the same underlying design and features. Both have 3.45 µm square pixels. Both are sensitive across a wide spectral range from 400 nm – 1700 nm with impressive quantum efficiencies. Both provide high frame rates – to 84 fps for the 5.3 MP camera, and to 125 fps at 3.2 MP.
Distinctive features HCG and DRRS
Sony provides numerous sensor features to the camera designer, which Allied Vision in turn makes available to the user. Two new features of note include High-Conversion-Gain (HCG) and Dual-Read-Rolling-Shutter (DRRS). Consider the images below, to best understand these capabilities:
Illustrating the benefits of HCG and DRRS modes – Courtesy Sony
With the small pixel size of 3.45 µm, an asset in terms of compact sensor size, Sony innovated noise control features to enhance image quality. Consider the three images above.
The leftmost was made with Sony’s previously-released IMX990. It’s been a popular sensor and it’s still suitable for certain applications. But it doesn’t have the HCG nor DRRS features,
The center image utilized the IMX992 High-Conversion-Gain feature. HCG reduces noise by amplifying the signal immediately after light is converted to an electrical signal. This is ideal when shooting in dark conditions. In bright conditions one may use Low-Conversion-Gain (LCG), essentially “normal” mode.
The rightmost image was generated using Dual-Read-Rolling-Shutter mode in addition to HCG. DRRS mode delivers a pair of images. The first contains the imaging signal together with the embedded noise. The second contains just the noise components. The camera designer can subtract the latter from the former to deliver a synthesized image with approximately 3/4 of the noise eliminated.
Alvium’s SWaP+C characteristics ideal for OEM systems
With small Size, low Weight, low Power requirements, and low Cost, Alvium SWIR cameras fit the SWaP+C requirements. OEM system builders need or value each of those characteristics to build cost-effective embedded and machine vision systems.
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Some applications require line scan cameras, where the continuously moving “product” is passed below a sensor that is wide in one dimension and narrow in the other, and fast enough to keep up with the pace of motion. See our piece on area scan vs. line scan cameras for an overview.
Linea HS 9k BSI (NUV) / visible camera – Courtesy Teledyne DALSA
Visible spectrum as well as Near Ultraviolet (NUV)
The camera uses Teledyne DALSA’s own charge-domain CMOS TDI sensor with a 5×5 μm pixel size. In addition to the visible spectrum 400 nm – 700 nm, the sensor delivers good quantum efficiency to 300 nm, qualifying Near Ultraviolet (NUV) applications in the blue range as well.
Backside illumination enhances performance
Backside illumination (BSI) improves quantum efficiency (QE) in both the UV and visible wavelengths, boosting the signal-to-noise ratio.
Interface
The Linea HS 9k BSI camera uses the CLHS (Camera Link High Speed) data interface to provide a single-cable solution for data, power, and strobe. And Active optical cable (AOC) connectors support distances up to 100m. That avoids the need for a repeater while achieving data reliability and cost control. See an overview of the Camera Link standards. Or see all of 1stVision’s Camera Link HS cameras.
Applications
Delivering high speed high sensitivity images in low light conditions, the Linea 9k HS is used in applications such as:
PCB inspection
Wafer inspection
Digital pathology
Gene sequencing
FPD inspection
Linea 9k HS suitable for diverse applications – Courtesy Teledyne DALSA
Request a quote
The part number for the Linea HS 9k BSI camera is DALSA HL-HM-09K40H.
Teledyne DALSA’s Linea families have a variety of interfaces, resolutions, frame rates, pixel sizes, and options. So if the new model isn’t the right one for your needs, browse the link at the start of this sentence, or ask us to guide you among the many choices.
About you: We want to hear from you! We’ve built our brand on our know-how and like to educate the marketplace on imaging technology topics… What would you like to hear about?… Drop a line to info@1stvision.com with what topics you’d like to know more about
Metrology, when done optically, requires that an object’s representation be invariant to the distance and position in the field of view. Telecentric lenses deliver precisely that capability. Telecentric lenses only “pass” incoming light rays that are parallel to the optical axis of the lens. That’s helpful because we measure the distance between those parallel rays to measure objects without touching them.
Telecentric lens eliminates the parallax effect – Courtesy Edmund Optics
Parallax effect
Human vision and conventional lenses have angular fields of view. That can be very useful, especially for depth perception. Our ability to safely drive a car in traffic derives in no small part from not just identifying the presence of other vehicles and hazards, but also from gauging their relative nearness to our position. In that context parallax delivers perspective, and is an asset!
But with angular fields of view we can only guess at the size of objects. Sure, if we see a car and a railroad engine side by side, we might guess that the car is about 5 feet high and the railroad engine perhaps 15 or 16 feet. In metrology we want more precision than to the nearest foot! In detailed metrology such as precision manufacturing we want to differentiate to sub-millimeter accuracy. Telecentric lenses to the rescue!
Assorted telecentric lenses – Courtesy Edmund Optics
Telecentric Tutorial
Telecentric lenses only pass incoming light rays that are parallel to the optical axis of the lens. It’s not that the oblique rays don’t reach the outer edge of the telecentric lens. Rather, it’s about the optical design of the lens in terms of what it passes on through the other lens elements and onto the sensor focal plane.
Let’s get to an example. In the image immediately below, labeled “Setup”, we see a pair of cubes positioned with one forward of the other. This image was made with a conventional (entocentric) lens, whereby all three dimensions appear much the same as for human vision. It looks natural to us because that’s what we’re used to. And if we just wanted to count how many orange cubes are present, the lens used to make the setup image is probably good enough.
Courtesy Edmund Optics.
But suppose we want to measure the X and Y dimensions of the cubes, to see if they are within rigorous tolerance limits?
An object-space telecentric lens focuses the light without the perspective of distance. Below, the image on the left is the “straight on” view of the same cubes positioned as in “Setup” above, taken with a conventional lens. The forward cube appears larger, when in fact we know it to be exactly the same size.
The rightmost image below was made with a telecentric lens, which effectively collapses the Z dimension, while preserving X and Y. If measuring X and Y is your goal, without regard to Z, a telecentric lens may be what you need.
Courtesy Edmund Optics.
How to select a telecentric lens?
As with any engineering challenge, start by gathering your requirements. Let’s use an example to make it real.
Object of interest is the circled chip – Image courtesy Edmund Optics
Object size
What is your object size? What is the size of the surrounding area in which successive instances of the target object will appear? This will determine the Field of View (FOV). In the example above, the chip is 6mm long and 4mm wide, and the boards always present within 4mm. So we’ll assert 12mm FOV to add a little margin.
Pixels per feature
In theory, one might get away with just two pixels per feature. In practice it’s best to allow 4 pixels per feature. This helps to identify separate features by permitting space between features to appear in contrast.
Minimum feature size
The smallest feature we need to identify is the remaining critical variable to set up the geometry of the optical parameters and imaging array. For the current example, we want to detect features as small as 25µm. That 25µm feature might appear anywhere in our 12mm FOV.
Example production image
Before getting into the calculations, let’s take a look at an ideal production image we created after doing the math, and pairing a camera sensor with a suitable telecentric lens.
Production image of the logic chip – Courtesy Edmund Optics
The logic chip image above was obtained with an Edmund Optics SilverTL telecentric lens – in this case the 0.5X model. More on how we got to that lens choice below. The key point for now is “wow – what a sharp image!”. One can not only count the contacts, but knowing our geometry and optical design, we can also inspect them for length, width, and feature presence/absence using the contrast between the silver metallic components against the black-appearing board.
Resuming “how to choose a telecentric lens?”
So you’ve got an application in mind for which telecentric lens metrology looks promising. How to take the requirements figures we determine above, and map those to camera sensor selection and a corresponding telecentric lens?
Method 1: Ask us to figure it out for you.
It’s what we do. As North America’s largest stocking distributor, we represent multiple camera and lens manufacturers – and we know all the products. But we work for you, the customer, to get the best fit to your specific application requirements.
Give us some brief idea of your application and we will contact you to discuss camera options.
Method 2: Take out your own appendix
Let’s define a few more terms, do a little math, and describe a “fitting” process. Please take a moment to review the terms defined in the following graphic, as we’ll refer to those terms and a couple of the formulas shortly.
Telecentric lens terms and formulas – Courtesy Edmund Optics
For the chip inspection application we’re discussing, we’ve established the three required variables:
H = FOV = 12mm
p = # pixels per feature = 4
µ = minimum feature size = 25µm
Let’s crank up the formulas indicated and get to the finish line!
Determine required array size = image sensor
Array size formula for the chip inspection example – Courtesy Edmund Optics
So we need about 1900 pixels horizontally, plus or minus – with lens selection, unless one designs a custom lens, choosing an off-the-shelf lens that’s close enough is usually a reasonable thing to do.
Reviewing a catalog of candidate area scan cameras with horizontal pixel counts around 1900, we find Allied Vision Technology’s (AVT) Manta G-131B, where G indicates a GigEVision interface and B means black-and-white as in monochrome (vs. the C model that would be color). This camera uses a sensor with 2064 pixels in the horizontal dimension, so that’s a pretty close fit to our 1920 calculation.
Determine horizontal size of the sensor
H’ is the horizontal dimension of the sensor – Courtesy Edmund Optics
Per Manta G-319 specs, each pixel is 3.45µm wide, so 20643.(45) = 7.1mm sensor width.
Determine magnification requirements
The last formula tells us the magnification factor to fit the values for the other variables:
Magnification = sensor width / FOV Courtesy Edmund Optics
Choose a best-fit telecentric lens
Back to the catalog. Consider the Edmund Optics SilverTL Series. These C-mount lenses work with sensor sizes 1/2″, 2/3″, and 1/1.8″ sensors, and pixels as small as 2.8µm, so that’s a promising fit for the 1/1.8″ sensor at 3.45µm pixel size found in the Manta G-131B. Scrolling down the SilverTL Series specs, we land on the 0.50X Silver TL entry:
Some members of the SilverTL telecentric lens series – Courtesy Edmund Optics
The 0.5x magnification is not a perfect fit to the 0.59x calculated value. Likewise the 14.4mm FOV is slightly larger than the 12mm calculated FOV. But for high-performance ready-made lenses, this is a very close fit – and should perform well for this application.
Optics fitting is part science and part experience – and of course one can “send in samples” or “test drive” a lens to validate the fit. Take advantage of our experience in helping customers match application requirements to lens and camera selection, as well as lighting, cabling, software, and other components.
About you: We want to hear from you! We’ve built our brand on our know-how and like to educate the marketplace on imaging technology topics… What would you like to hear about?… Drop a line to info@1stvision.com with what topics you’d like to know more about
As anticipated when Teledyne DALDA’s AxCIS Line Scan Series was introduced a few months ago, color models have now been released. The “CIS” in the product name stands for Contact Image Sensor. In fact a CIS doesn’t actually contact the object being imaged – but it’s so close to touching that the term has become vision industry jargon to help us orient to the category.
Courtesy Teledyne DALSA
What can CIS do for me?
Think “specialized line scan”. Line scan in that it’s a linear array of sensors (vs. and area scan camera), requiring motion to create each successive next slice. And “specialized” in that CIS is positioned very close to the target, Plus low power requirements. And excellent price-performance characteristics.
Why is the new color offering interesting?
Just as with area scan imaging, if the application can be solved with monochrome sensors, that’s often preferred – since monochrome sensors, lensing, and lighting are simpler. If one just needs edge detection and contrast achievable with monochrome – stay monochrome! BUT sometimes color is the sole differentiator for an application, so the addition of color members to the AxCIS family can be a game changer.
Why Teledyne DALSA AxCIS in particular?
A longtime leader in line scan imaging, Teledyne DALSA introduces the AxCIS series in 2023 and continues to release new models and features. Vision Systems Design named the AxCIS family of high-speed high-resolution integrated imaging modules with their 2024 Gold Honoree Award.
Compact modules integrating sensors, lenses and lights
Option to customize the integrated lighting for specific CRI to aid in color measurement.
Current width choices 400mm (16 inches) or 800mm (32 inches)
Customizable lengths coming, in addition to the 400mm and 800mm models
CIS covers entire FOV – without missing any pixels and without using interpolation, allowing for accurate measurements. The competition has gaps between sensors causing areas which are not imaged and inability to measure properly
Selectable pixel sizes up to 900dpi
Gradient index lenses are used so there is no parallax and essentially telecentric. (Great for gauging applications)
Binning support, summed to provide brighter images
HDR Imaging – High Dynamic Range – Courtesy Teledyne DALSA
By using two adjacent rows of sensors, one row may be used for a short exposure to capture the rapidly saturated portions of an image. A second row of sensors can take a longer exposure, creating nuanced pixel values of areas that would otherwise have been undersaturated. Then the values are combined to a composite image with a wider dynamic range with more useful information to be interpreted by the processing algorithms.
Applications
While not limited to the following, popular applications include:
Popular AxCIS applications – Courtesy Teledyne DALSA
Want to see other Teledyne DALSA imaging products?
Teledyne DALSA is long-recognized as a leader and innovator across the diverse range of imaging products – click here to see all Teledyne DALSA products.
About you: We want to hear from you! We’ve built our brand on our know-how and like to educate the marketplace on imaging technology topics… What would you like to hear about?… Drop a line to info@1stvision.com with what topics you’d like to know more about.
