To learn what kinds of applications are well-suited for a Contact Image Sensor
To see the unique features only found in the Teledyne DALSA AxCIS series
You already know (or can catch up quickly):
Contact Image Sensors don’t actually contact the things they are imaging. But they get to within 15 mm = 0.59 inches! So they are ideal for space-constrained applications.
And they aren’t interchangeable with line scan cameras, they are a variant on line scan concepts. They share the requirement that “something is moving” and that the sensor array is a single row of pixels.
Applications for Contact Image Sensing
Courtesy Teledyne DALSA
Why Teledyne DALSA AxCIS in particular?
You may want to review the whole Teledyne DALSA AxCIS series, and the datasheet details. Go for it! Geek out. Full transparency as always.
Or maybe you’d like a little help on what we think is special about the Teledyne DALSA AxCIS series?
T2IR – Trigger to Image Reliability
This is a Teledyne DALSA proprietary innovation that helps to de-mystify what’s happening inside a complex vision system. It uses hardware and software to improve reliability. In high level terms, T2IR monitors from trigger through image capture, and on to host memory transfer, aiming to protect against data loss. And to provide insights for system tuning if needed. T2IR is compatible with many Teledyne DALSA cameras and frame grabbers – including the AxCIS series.
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
Unless one calculates and sets the line rate correctly, there’s a risk of blur and sub-optimal performance. And/or purchasing a line scan camera that’s not up to the task; or that’s overkill and costs you more than would have been needed.
Perhaps you know about area scan imaging, where a 2D image is generated with a global shutter, exposing all pixels on a 2D sensor concurrently. And you’d like to understand line scan imaging by way of comparing it to area scan. See our blog What is the difference between an Area Scan and a Line Scan Camera?
30 minute informative overview of Line Scan imaging – Courtesy Teledyne DALSA
Maybe you prefer seeing a specific high-end product overview and application suggestions, such as the Teledyne DALSA 16k TDI line scan camera with 1MHz line rate. Or a view to tens of different line scan models, varying not only by manufacturer, but by sensor size and resolution, interface, and whether monochrome or color.
Either you recall how to determine resolution requirements in terms of pixel size relative to defect size, or you’ve chased the link in this sentence for a tutorial. So we’ll keep this blog as simple as possible, dealing with line rate calculation only.
Line scan cameras – Courtesy Teledyne DALSA
Calculate the line rate
Getting the line rate right is the application of the Goldilocks principle to line scanning.
Line rate too slow…
Line rate too fast…
Blurred image if due to too long exposure, and/or missed segments due to skipped “slices”
Oversampling can create confusion by identifying the same feature as two distinct features
Why we need to get the line rate rate right
A rotary encoder is typically used to synchronize the motion of the conveyor or web with the line scan camera (and lighting if pulsed). Naturally the system cannot be operated faster than the maximum line speed, but it may sometimes operator more slowly. This may happen during ramp up or slow down phases – when one may still need to obtain imaging – or by operator choice to conserve energy or avoid stressing mechanical systems.
Naming the variables … with example values
Resolution A = object space correlation to sensor; FOV / pixel array; e.g. if 550mm FOV and 2k sensor = 550/2000 = 0.275 pixels per mm
Transport speed T = mm per sec; e.g. 4k / 1mm yields rate of motion
Sampling frequency F = T / A; for example values above F = 4000 / 0.275 = 14545.4545 = 14.5kHz; spelled out: Frequency = Transport_speed / Pixel_spatial_resolution (what 1 pixel equals in target space)
For the example figures used above, a line scan camera with 2k resolution and a line scan frequency of about 14.5 kHz will be sufficient.
Justclick here, or on the image below, to download the spreadsheet calculator. It includes clearly labeled fields, and examples, as the companion piece for this blog:
Not included here… but happy to show you how
We’ve kept this blog intentionally lean, to avoid information overload. Additional values may also be calculated, of course, such as:
Data rate in MB / sec: Useful to confirm camera interface can sustain the data rate
Frame time: The amount of time to process each scanned image. Important to be sure the PC and image processing software are up to the task – based on empirical experience or by conferring with software provider.
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
Product innovation continues to serve machine vision customers well. Clever designs are built for evolving customer demands and new markets, supported by electronics miniaturization and speed. Long a market leader in line scan imaging, Teledyne DALSA now offers the Linea HS2 TDI line scan camera family.
Linea HS2 16k TDI line scan camera with 1 MHz line rate – courtesy Teledyne DALSA
Video overview
The video below is just over one minute in duration, and provides a nice overview:
Backside illumination enhances quantum efficiency
Early sensors were all used frontside illumination, and everybody lived with that until about 10 years ago when backside illumination was innovated and refined. The key insight was to let the photons hit the light-sensitive surface first, with the sensor’s wiring layer on the other side. This greatly improves quantum efficiency, as seen in the graph below:
QE substantially enhanced using backside illumination (BSI – Courtesy Teledyne DALSA
Applications
This camera series is designed for high-speed imaging in light staved conditions. Applications include but are not limited to inspecting flat panel displays, semiconductor wafers, high density interconnects, and diverse life science uses.
Courtesy Teledyne DALSA
Line scan cameras
You may already be a user of line scan cameras. If you are new to that branch of machine vision, compare and contrast line scan vs. area scan imaging. If you want the concept in a phrase or two, think “slice” or line of pixels obtained as the continuous wide target is passed beneath the camera. Repeat indefinitely. Can be used to monitor quality, detect defects, and/or tune controls.
Time Delay Integration (TDI)
Perhaps you even use Time Delay Integration (TDI) technology already. TDI builds on top of “simple” line scan by tracking how a pixel appears across several successive time slices, turning motion blur into an asset through hardware or software averaging and analysis.
Maybe you already have one or more of Teledyne DALSA’s prior-generation Linea HS line scan cameras. They feature the same pixel size, optics, and cables as the new Linea HS2 series. With a 2.5x speed increase the Linea HS2 provides a seamless upgrade. The Linea HS2 offers an optional cooling accessory to enhance thermal stability.
Frame grabber
The Linea HS2 utilizes Camera Link High Speed (CLHS) to match the camera’s data output rate with an interface that can keep up. Teledyne DALSA manufactures not just the camera, but also the Xtium2-CL MX4 Camera Link Frame Grabber.
Xtium2-CL MX4 Camera Link Frame Grabber – Courtesy Teledyne DALSA
The Xtium2-CL MX4 is built on next generation CLHS technology and features:
16 Gigapixels per second
dual CLHS CX4 connectors
drives active optical cables
supports parallel data processing in up to 12 PCs
allows cable lengths over 100 meters with complete EMI immunity
Which camera to choose?
As this blog is released, the Linea HS2, with 16k/5μm resolution provides an industry leading maximum line rate of 1 MHz, or 16 Gigapixels per second data throughput. Do you need the speed and sensitivity of this camera? Or is one of the “kid brother” models enough – they are already highly performant before the new kid came along. We can help you sort out the specifications according to your application requirements.
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.
