Advantages of Telecentric lenses in machine vision applications

Telecentric lenses are essential in eliminating distortion errors caused by standard lenses in machine vision applications.  


Telecentric lenses are defined by lenses only accepting incoming light ray bundles whose principal rays are parallel to the optical axis of the lens as seen in the diagram below

 




















Key advantages to a Telecentric lens are constant magnification, no perspective error and very low distortion

 









 



How do the advantages of telecentric lenses help in machine vision applications?  

Constant Magnification

Telecentric lenses can provide constant magnification, and not influenced by varying lens to object distances.  



Example: The image to the right shows 2 screws in which the 2nd screw is 10mm further away from screw 1 when viewed from the Telecentric lens in the setup.












Using a standard lens, screw #1 which is closer will appear to be larger














Using a Telecentric lens, the screws look the same size and not influenced by the lens to object distance.  

This is very helpful in applications to ensure accurate measurements negating any deviations from part placement.

Perspective Error

Standard lenses show significant perspective errors, whereas telecentric lenses are able to eliminate any perspective effects.  In cases where measurements are critical, using a telecentric lens is a must!




Low Distortion

Regular lenses have 1-2% distortion, whereas telecentric lenses have 0.1%





Regular lens will either have “Barrel” (left image) or “Pin cusion” distortion (right image) 






    Barrel Distortion                   Pin Cushion Distortion

In barrel distortion, image magnification decreases with distance from the optical axis. This is common in fish-eye lenses.  

In pincushion distortion, image magnification increases with the distance from the optical axis.  

Using telecentric lenses in machine vision applications will eliminate barrel and pin cusion distortion.  Low distortion is imperative where accuracy is required.  

How can it get any better!  – Use Collimated light!


Telecentric lenses provide a high level of accuracy, but when coupled with a collimated light source, edge definition is increased.

Diffused backlights can generate unwanted border effects and create a “fake” image of the edge of a part.  Collimated backlights allow only parallel rays to pass by objects.  This setup would be setup like the diagram below.  

   
The result is very crisp edge definition as seen in the images below.  The left image is using a standard backlight in which light “wraps” around the cap.  The right images use a collimated back light providing excellent edge definition.










 

Images courteously of Opto Engineering!1st Vision has extensive knowledge in industrial imaging and can help answer any questions.  We have over 100 years of combined knowledge and look forward to discussing your application.  Please do not hesitate to Contact us!  1st Vision can provide a complete solution including cameras, lenses, lighting and cables.  

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Grade 1 image sensors provide a performance gain over Grade 2 image sensors! Learn how this effects your cameras quality.

 

When image fidelity is of high importance, seeking out cameras with a better “Grade” image sensor is required.

BUT.. What does this mean?  
What defines the “Grade” of an image sensor?

ON-Semiconductors (Formerly Kodak) is one of the few sensor manufacturers that provide options in sensor grades.  Camera manufacturers can typically select a Grade 1 or Grade 2 sensor for their camera designs.  All image sensors have some amount of defective pixels.  The number of defects determines the quality grade and the value of the image sensors.  Most camera manufacturers select Grade 2 due to lower cost sacrificing image performance except a select few.  



Defective pixels can either be dark, as they don’t collect any light, OR be bright (hot pixel), as they are always outputting a signal.  


An example of a “Hot Pixel” is shown to the right


Defective pixels, in turn can result in incorrect processing of an image!

In most all cases, cameras are corrected at the factory prior to shipment and found in the “defect map” that is stored in the camera.    

Under challenging conditions or high temperature environments, additional defective pixels may appear.  These can be corrected using a custom defect map. 

Defect pixel correction suppresses pixels or clusters and reconstructs the expected value by interpolating the neighboring pixels.  Standard algorithms use the pixel to the left or to the right of the defect pixel for the interpolation, however more advanced algorithms can be used.  

Image Sensors from ON-SEMI are graded per the number of defects within the sensor.  This encompasses bright and dark pixel defects along with cluster defects.  

Below is an example from the ON-Semiconductor 29MP KAI-29050 sensor defect description.   

** Chart is courtesy of ON-Semiconductor KAI-29050 specification 


Need additional help in making decisions on selecting a high resolution camera?  Visit our High Resolution camera page

1st Vision has extensive knowledge in industrial imaging and can help answer any questions.  We have over 100 years of combined knowledge and look forward to discussing your application.  

Please do not hesitate to Contact us!  1st Vision can provide a complete solution including cameras, lenses, lighting and cables.  

Ph:  978-474-0044
info@1stvision.com
www.1stvision.com  

Follow us on Social Media!

     https://www.facebook.com/pages/1st-Vision/944658058935262?fref=ts             

Low cost Dalsa Nano’s with TurboDrive (Fast GigE) camera family expanded + NIR sensors

Teledyne Dalsa, whose highly successful, low cost Nano cameras have added NIR enhanced ON-SEMI sensors to their product line in addition to 2MP and 5MP sensors.


The Nano cameras offer Turbo Drive capabilities providing frame rates exceeding GigE capacity using GigE Vision standards.



The low cost series is now available in color, mono and NIR with resolutions from VGA to 5MP.  The new ON-SEMI sensors coupled with TurboDrive, provide frame rates up to 862 fps in full frame mode.  

NIR cameras starting @ $450!


See the full portfolio of Genie Nano’s featuring Turbo Drive

The quantum efficiency (QE) of the NIR image sensors offers increased sensitivity from 700nm to 1000nm providing a better response in NIR wavelengths as seen in the graph to the right.  
This additional response directly correlates to brighter images when used within the NIR spectrum as seen in the application examples below.

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What are the benefits and results of a Near Infrared enhanced camera?


NIR enhanced cameras when combined with NIR light sources, provide solutions normal cameras and lighting can not solve.

The longer wavelengths can be used to penetrate through various mediums allowing subsurface features to be seen and enhancing contrast.  

The following are a couple application examples where NIR cameras with the correct lighting can solve machine vision applications.  

We can provide full details on the camera, light and lens combination on these applications.  Simply send us an email with the subject “Send me the NIR image details” with your contact information and we’ll send you a brief write-up.

Bottle Inspection:  Various machine vision inspections are needed in bottle manufacturing, but can be challenging due to dark glass and short exposure times. As the bottles are rapidly moving, a short exposure time is required to stop bottle motion, which limits the light collecting on the sensor. To overcome this challenge, a NIR enhanced camera combined with a NIR illuminator allows light to pass through the dark glass.  As the sensor is enhanced in the NIR, a higher grey scale value can be achieved which can allow for shorter exposures and increased throughput.



The image on the left was taken with a standard Genie Nano camera and the new Nano NIR enhanced camera image is on the right.  

Using the identical exposure settings, lighting and lensing, the NIR enhanced camera provided a significantly higher grey scale (130 vs 75) image and better contrast.






PCB conductors:  In electronics manufacturing, various inspections are performed including verification of traces not visible to the naked eye.  In order to overcome this, NIR light is used to help pass through the PCB material.  A NIR enhanced camera is used to provide the best response allowing for shorter exposure times and increasing the system scan time.

The comparison images below used a standard Genie Nano camera (left) and Nano NIR enhanced camera (right).  Using identical settings, the NIR enhanced camera provided a better response and brighter image for light passing through the PCB.  

 






























Do not forget – Send us an email with the subject “Send me the NIR image details” if you want more details

There are many more applications that can be solved with the right combination of vision hardware.  1st Vision has extensive knowledge in industrial imaging and can help select the best camera, lens and lighting combinations for your application.  

We have over 100 years of combined knowledge and look forward to discussing your application!

Please do not hesitate to Contact us!  

Ph:  978-474-0044
info@1stvision.com
www.1stvision.com  

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Image Sensor Chaos – Sony Pregius vs ON-Semi Python – What is best for my camera application?

Which image sensor and camera is best for my application?

This is total Chaos with so many new sensors!

The image sensor market has rapidly changed in the past year, and has become very chaotic in determining the best image sensor and camera for an application.  

Sony and ON-Semiconductor have both launched a family of image sensors which provide global shutter using advanced CMOS designs resulting in high speed, crisp images.  

These CMOS sensors are now a viable alternative to CCD’s and older CMOS technology, providing higher performance and lower costs.  

BUT.. Which one is most suited for my application?  

Its best to start with understanding what is most important application.  Do we need speed?  Low noise?  Dynamic Range? or maybe a combination of attributes.  

1st Vision has helped make sense of the chaos in providing some considerations and comparisons between the Sony Pregius and ON-Semi Python Series sensors in the following chart.    

 


From the data, you can use these general guidelines

  • If you need the highest speed,  ON-Semi is your choice.   
  • If you need the highest dynamic range, Sony Pregius is your choice.
  • As a great general all around sensor, the Pregius IMX249 sells for ~ $500 in both GigE and USB3  This camera is 2.3MP @ 40fps and can be used in VGA, XGA SXGA modes by setting a ROI.   Read about various resolutions with setting a ROI

Most applications however are not that simple to just choose an image sensor based on speed or dynamic range. In many cases it requires a combination of many factors such as signal to noise, quantum efficiency and saturation capacity.    

1st Vision has more specific data we can discuss with you from various tests we have run and applications solved.  

PLEASE CONTACT US TO DISCUSS YOUR APPLICATION and receive more detailed information.  

Cameras with the Sony Pregius and ON-Semi image sensors continue to expand!  The following links provide a listing of the associated cameras

Visit the Sony Pregius camera web page

Visit the ON-Semi camera web page

1st Vision has extensive knowledge in industrial imaging and can help answer any questions.  We have over 100 years of combined knowledge and look forward to discussing your application.  

1st Vision can provide a complete solution including cameras, lenses, lighting and cables.  

Ph:  978-474-0044
info@1stvision.com
www.1stvision.com  

Follow us on Social Media!

     https://www.facebook.com/pages/1st-Vision/944658058935262?fref=ts