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Optics / Lenses / Filters Questions

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Hello, A question about Telecentric Lens: Can i measure a hole that varies the height from 90 mm to 130 mm and have a diameter of 8 mm with a Telecentric Lens of 16 mm FOV, however, the Object Depth of 2 mm? Because to increase the object depth it is necessary to increase the FOV, however, If the FOV increases, the resolution have to also increase.

1 Answers

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Brian Durand - President
I4 Solutions, LLC
bdurand [at] i4solutions [dot] us
(612) 888-6000

Hi Daniel, To confirm I understand your question correctly... Your working distance (measured from front of lens to the object) varies from 90 to 130 mm. The hole in the object is 2 mm deep. The necessary FOV is 16 mm. We really need to know the camera sensor size to determine the necessary magnification. Then, given the pixel size and lens F#, we could calculate the depth of field that is needed to accommodate the changing working distance. As an example, consider a camera having the Python 5000 sensor. The sensor has 2592 x 2048 pixels, each 4.80 µm in size. The ideal magnification would be 0.614 for a 20.2 x 16.0 mm FOV. One popular lens manufacturer offers a 1" lens with 0.767 magnification. Combined with the image sensor, you get a 16.2 x 12.8 mm FOV. With a fixed working F# of 16, the lens has a DOF of just 2 mm. Bottom line (assuming I understood your requirements) is that no conventional lens can delivery the huge DOF you need. Consider moving the lens as needed.

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