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We work in a flour mill, and we currently have a SICK sensor that detemines bag placement on a packaging line. We have SICK part#:1029584. It appears that flour dust is getting behind the lens and not telling the bag when to stop in the proper position. Our PM basis was orginally every 6 months we would change out the eye. We have changed the eye on 4 occasions in the last four months. The last eye we installed only lasted for approximately 4 days. Is there a different product we should be using for this environment? Is there any recall on this particular product?

Dustin: The attachment of the optics to the housing of the camera/sensor is typically the weak point for ingress protection. Check out www.apgvision.com . They can probably supply (or custom build) an enclosure for the Sick sensor that will keep the flour dust out of the sensor optics.

Answered by:
Scott Gibbs
CEO
Mercator Robotec Inc
scott [at] mercatorrobotec [dot] com
(519) 884-7880

 

Have you tried an air tight enclosure and / or a clean positive pressure air purge so that flour can't get in due to a constant flow of air out?

Answered by:
Scott Bouchard
Sales Manager
Innovative Illumination & Optics
sbstang [at] yahoo [dot] com
(866) 570-5736

 

Mr. Hogan, In your application an IP67 rated housing would be best. This will allow you to have a tight seal and not allow dust to enter in the optical path. Having a sealed housing will also allow for easier PM and cleanup. Let me know if you need help selecting a housing. Regards, William Corns

Answered by:
William Corns
CEO
Wilco Imaging, Inc.
wcorns [at] wilcoimaging [dot] com
(858) 689-9050, x3202

 

Hi Dustin - I recommend enclosing the sensor in a purged NEMA 4X type enclosure and using an air blow off to keep the optical window clean. CAll us and we can quote you an APG enclosure as we are a distributor. Good luck

Answered by:
David Wyatt
CEO
Automation Doctor Incorporated
david [dot] wyatt [at] automation-doctor [dot] com
(574) 344-7936

 

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What is the use of dilation filters?

I assume you are referring to a software filter or what is more commonly called an image morphology tool. Image morphology tools are used to pre-process or "clean up" an image before analyzing it with other tools. The dilation operation will cause the boundaries of an object in an image to grow. The purpose of doing this may be to fill in small holes or connect adjacent objects together. Dilation is often done in tandem with erosion. There is some good technical imformation at the following link: http://zone.ni.com/devzone/cda/ph/p/id/146 .

Answered by:
Scott Gibbs
CEO
Mercator Robotec Inc
scott [at] mercatorrobotec [dot] com
(519) 884-7880

 

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I need to inspect long metal tubes used in automobiles for any presence of clinging burr inside it. Also I need to measure the OD of it on both sides. The OD of tube is 50 mm, length is of 1200 mm and ID is of 45mm. I am not able to find any lens with suitable depth of field (at least 600mm) so that the burr is visible clearly.Please suggest us the suitable lens. I am in a very bad need of the solution. I tried using normal lens of 25mm focal length in which case I had to position the camera at the distance of 1.75 meters from the object. This distance is too impractical to implement. I request you to suggest a cost effective solution in the lens or combination of lens for this problem.

Try bi-telecentric lenses. They will offer very high DoF. However I have to warn you, they are not cheap.

Answered by:
Kasra Ravanbakhsh
Managing Director
Kasra Hooshmand Engineering Co., P.J.S. (KDI)
kasra [at] kdi-co [dot] com
98 21 8867 8023

 

I think if you need a clear view of both the top and bottom of the tube, you may be stuck with a very long working distance in order to get the feild of view that you need. Have you considered using mirrors to "fold up" the working distance to something more manageable? Since we are speaking of mirrors, perhaps a custom optical assembly that images the top and bottom and brings the two images into the same field of view? We recommend Light Works for this kind of thing... http://lw4u.com/

Answered by:
Steve Maves
Manager of Application Engineering
Datalogic Automation
stevem [at] pptvision [dot] com
(952) 996-9504

 

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Lens Selection. I am new to machine vision and need to select a lens for my project. I have used some of the lens selection tools on the internet but was not happy with the initial results. Here are the basics of my project: Camera 1/3" sensor, C-mount. Resolution 1024x768. Working distance 18". Object measurement 18"H x 24"W. The lens typically recommended is a 3.5mm lens. I purchased one and found a lot of fish eye distortion and inability to properly focus (lens already at infinity) when at 18" working distance. Field of view was ok, but focus and distortion where the problems. Any help or direction would be appreciated.

If you want to eliminate the fish eye distortion you can try going to a larger camera sensor or increase your working distance. Lens needed for your parameters with different sensor formats; 1/3" Format = 3.5mm FL Lens 1/2" Format = 4.5mm FL Lens 2/3" Format = 6mm FL Lens Lens needed for different working distances; 1/3" Format at 18" = 3.5mm FL Lens 1/3" Format at 24" = 4.5mm FL Lens 1/3" Format at 36" = 6.0mm FL Lens Image quality will differ among the same FL lens from different manufacturers, our NMV-5M23 c-mount video lens offers a very good image with minimum barrel distortion. If you have more questions please contact us.

Answered by:
Robert Prato
Training Manager
Navitar Inc.
b_prato [at] navitar [dot] com
(585) 359-4000

 

Hi Garth: Typically very short focal length lenses have a lot of geometric distortion. Not too much you can do about this. One of the things you can do (if possible) is to increase your working distance. Let me know if this is possible and to what distance you can go out to? This would allow you to use a longer focal length lens which would have very low geometrical distortion. What is the amount of geometrical distortion does your lens have (do you have a lens spec sheet)?

Answered by:
Stuart Singer
Vice President
Schneider Optics, Inc.
ssinger [at] schneideroptics [dot] com
(631) 761-5000, x204

 

Hello Garth, If you use a C-mount lens, you will have some distortion on the edges of your images. However in some applications this distortion is acceptable and in some it is not. It depends what you are going to do with your imaging system. If you want to measure dimensions with your machine vision system, I don't recommend a C-mount lens. You may try F-mount or for much better results regarding dimension measurement applications, it is recommended to use telecentric lenses. However if you don't mind to have some distortion on the edges I recommend DF6HA-1B lens from Fujinon which will work fine with your camera but you have to increase the working distance to 30 inches, as the focal length of this lens is 6mm. However its price is low and the performance is quite good. You won't have inability to properly focus anymore with this lens but as I said before there will be some distortion on the edges with all C-mount lenses.

Answered by:
Kasra Ravanbakhsh
Managing Director
Kasra Hooshmand Engineering Co., P.J.S. (KDI)
kasra [at] kdi-co [dot] com
98 21 8867 8023

 

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How could I choose a lens according my cameras, like focal length, lens mount?

nee-how-ma Amy, First determine the field of view size that you want to image based on the size of the area to be image plus its expected movement in millimeters, call it FOV. Next determine the highest accuracy with which you want to measure, locate or identify the smallest feature to be inspected by that camera in millimeters Call it FEATURE. Next divide FEATURE by 5 pixels (3 to 10 is usual) and call it MMPERPIX. Next divide FOV by MMPERPIX to get the desired number of pixels in a single dimension on the image. Choose a CCD camera that has a sensor with that number of pixels or greater in a single dimension that will be sensitive to the wavelength of light you care about at a price you can afford. The chosen camera will have a certain mount already associated with it. Typically it will be a C or CS mount, http://en.wikipedia.org/wiki/C_mount but it could be another type. http://en.wikipedia.org/wiki/Lens_mount . Go to the lens websites to pick the lens based on linepairs.

Answered by:
David Wyatt
CEO
Automation Doctor Incorporated
david [dot] wyatt [at] automation-doctor [dot] com
(574) 344-7936

 

Amy -- First -- the lens mount is determined primarily by the size of the camera's image sensor. The JIIA has developed a guide for manufacturers and users in selecting lens mounts. You should be able to find information on the AIA Vision Standards page. Second -- determine the magnification (M) you need. This is the image sensor height (or width) divided by the field-of-view height (or width). Third -- use your preferred working distance (lens to scene distance) as a good estimate of the object distance (D). Fourth -- calculate your lens' focal length (F) using the formula F = D*M/(1+M). Fifth -- find a lens with a focal distance close to what you calculated and then see if you can adjust your working distance to make it work for your need.

Answered by:
Perry West
President
Automated Vision Systems
perry [at] autovis [dot] com
(408) 267-1746

 

Hello Amy, Navitar has a nice brochure with good explanation to help you choose the right lens for your application. Here you can download it: http://machinevision.navitar.com/pdfs/cctv_brochure.pdf Specially take a look at pages 3, 4 and 5.

Answered by:
Kasra Ravanbakhsh
Managing Director
Kasra Hooshmand Engineering Co., P.J.S. (KDI)
kasra [at] kdi-co [dot] com
98 21 8867 8023

 

Amy, I can help you with this if you like. It really depends on what your application is. I would need to know the following information: 1) What camera you are using 2) How far away from your target is the camera? 3) How big the target is? 4) If you are using this with a capture device or displaying on a screen? If so how big is the screen? 5) How much detail or resolution are you trying to get out of the image? 6) What type of light is going to be used in this application? You can reach me at the email address below.

Answered by:
William Corns
President
Wilco Imaging, Inc.
wcorns [at] wilcoimaging [dot] com
(760) 994-1125

 

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I have found Kowa 10 megapixel "c" mount machine vision lenses. I understand there are even higher resolution lenses out there that are c mount, but I cannot for the life of me source them. Do you have information on anything higher than 10 megapixel lenses?

Hello Francis, What is the model of camera that you want to use? I believe even for 10 mega pixels you shouldn't use a C-mount lens. The level of distortion will be very high. Just as a rule of thumb, go for F-mount if the horizontal or vertical resolution of your camera is higher than 2500 pixels. There are even 60 mega pixels lenses (e.g. Hasselblad), but for very high resolution imaging, C-mount lenses are not suitable.

Answered by:
Kasra Ravanbakhsh
Managing Director
Kasra Hooshmand Engineering Co., P.J.S. (KDI)
kasra [at] kdi-co [dot] com
98 21 8867 8023

 

"10 megapixel" as a lens designator is meaningless. To spec a lens you need to state the active area of your sensor and the pixel pitch. Then we can talk about the band needed (400-700 nm?), the required focal length and f-number and a few other things. Send me the details and i can make a recommendation.

Answered by:
David Gilblom
President
Alternative Vision Corporation
dave [at] alt-vision [dot] com
(520) 615-4073

 

A Kowa 10MP lens can see 200lp/mm, your camera would have to have pixels smaller than 2.5 microns before the lens was not performing beyond the capability of your sensor. I do not know of any c-mount lenses with higher resolution at this point.

Answered by:
Robert Prato
Training Manager
Navitar Inc.
b_prato [at] navitar [dot] com
(585) 359-4000

 

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Can you tell me if LCD technology is currently used as a method to control the amount of light reaching the sensor (i.e. a shutter) ?

Very rarely. The typical transmission of an LCD shutter when open is about 33% and when closed, the extinction ratio is at best 1000:1 even with narrow-band illumination. This means that the ratio of open/closed can't be very small. If a shorter shutter time is needed than can be accomplished by a mechanical shutter, then an LCD shutter could be used in combination with a mechanical shutter to improve the overall extinction ratio and provide a shirt on-time. it is better to arrange for the object to be in the dark and use a strobe if you need to use a sensor type that does not have a global electronic shutter. Even if the stray illumination cannot be completely removed, use of a narrow-band strobe (like an LED) and a matching filter on the lens might provide a high enough illumination ratio to avoid the need for a mechanical shutter.

Answered by:
David Gilblom
President
Alternative Vision Corporation
dave [at] alt-vision [dot] com
(520) 615-4073

 

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Hello! Is there a fast focusing technique for C-mount lenses (< 20 ms). The range of the focus distance is about 200 mm. I've found a product with piezo actuators - but it seems that this only works in microscopy. Another possibility would be lenses with a very high depth of focus. Since I have to cover an area of about 300x200 mm and have short (<50µs) exposure times I can not close the iris to much to enhance the depth of focus because there would not be enough light. Perhaps you can provide me with other ideas or you know companies that concentrate there work on these topics. Thanks and best regards Martin Wollendorfer

Martin, Telecentric lenses are designed to have a large range of focus with no magnification charge throughout that range of focus. Possible downside for you could be overall size and high F# might effect exposure times. Telecentric lenses look at the object being viewed with parallel light rays, therefore the diameter of the lens needs to be equal to or larger than the object you are looking at. We have C-Mount telecentric lenses with magnification factors of 0.04X but they will only produce a 240mm x 180mm FOV at a 500mm working distance. They will give you a field depth of 380mm (+/- 190mm from the 500mm WD) that the object will stay in focus and not change magnification. You can also use a 12.5mm video lens at 500mm WD to get your required FOV and by setting f/stop at 2.8 you can get 200mm depth of focus, magnification will change as WD changes. If you have more questions please let me know. Regards, Bob

Answered by:
Robert Prato
Training Manager
Navitar Inc.
b_prato [at] navitar [dot] com
(585) 359-4000

 

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Do you know what filters will work with a Navitar 59 LGM 601 lens? I am looking to cut down on the amount of light with ND filters or Polarizing filters.

Here is the link to the drawing - http://machinevision.navitar.com/pdfs/59LGM601_OL.pdf Unfortunately, it does not show the front thread. It looks like a 25mm diameter filter is big enough because the object circle is only 11 mm. but you might have to make a special mount to hold it on the lens. Keep the filter very clean or dirt will show up in your images.

Answered by:
David Gilblom
President
Alternative Vision Corporation
dave [at] alt-vision [dot] com
(520) 615-4073

 

Jessica, I recommend you call the team at Midwest Optics (847) 359-3550. Scott Hanneman and/or Jason Dougherty can answer all of your questions and help you make the right decision with filtering. We work them all the time.

Answered by:
Nicholas Tebeau
Manager Machine Perception
LEONI Vision Solutions
nicholas [dot] tebeau [at] leoni [dot] com
(586) 979-9900

 

Jessica -- Do you know the filter thread for the lens? It should be on the data sheet or available from tech support at Navitar. I would expect it is a standard size. You can order the neutral density filters in threaded mounts from Midwest Optical Systems. I've used their products on a number of applications and been pleased with the quality and service.

Answered by:
Perry West
President
Automated Vision Systems
perry [at] autovis [dot] com
(408) 267-1746

 

There is no Optical reason you can not put a ND Filter or Polarizing filter onto the 59 LGM 601 Telecentric lens. If there are female threads you may be able to find a filter that will just screw in, if not there are filters that slip over outer diameter and lock down with a few thumb screws. If you have other questions please contact me. Regards, Bob Prato Navitar, Inc.

Answered by:
Robert Prato
Navitar Inc.
b_prato [at] navitar [dot] com
(585) 359-4000

 

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Dear Sir/Madam, we are using EKE light bulb (21V 150W) to do some experiments. We want to know the relative light intensity at different wavelength from 400 to 500 nm. This information is very important to our experiments. Please help me. Thanks.

Is your light source a product you purchased from Navitar? If it is please contact Chris Garnish at c_garnish@navitar.com and he can attempt to gather that information for you.

Answered by:
Robert Prato
Regional Account Manager
Navitar Inc.
b_prato [at] navitar [dot] com
(585) 359-4000 x3245

 

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Good Day, What lense i have to use to inspect small pieces like corn grains (FOV: 1 cm X 1cm ) at a work distance about 70 cm. Thanks.

Navitar has a line of products we refer to as Video Microscopes that are designed to work with c-mount cameras. These VM systems have both zoom capability and fixed magnification configurations. The Precise Eye fixed mag system can achieve a 9.4mm x 7.2mm FOV at 113mm working distance using a 1/2" format CCD camera.

Answered by:
Robert Prato
Regional Account Manager
Navitar Inc.
b_prato [at] navitar [dot] com
(585) 359-4000 x3245

 

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