denbigh1974

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  • in reply to: Macro lens + camera for Raspberry Pi #23060
    denbigh1974
    Participant

    Thank you for your information. Is there a UK distributor for the global shutter cameras? or can I order direct from Arducam?

    Robotshop can sell the OV7251 and OV9281 (not in stock at the moment) but they do not offer OV2311.

    https://www.robotshop.com/uk/catalogsearch/result/?q=arducam+monochrome+raspberry+pi&order=relevance&dir=desc

    Thanks again!

    in reply to: Macro lens + camera for Raspberry Pi #23061
    denbigh1974
    Participant

    Hi Tiao233 – thank you for your fast reply.

    Please may I ask if OV2311 is available in the UK? Or can I order it direct from Arducam?

    Thanks again!

    in reply to: Macro lens + camera for Raspberry Pi #23032
    denbigh1974
    Participant

    Hi Tiao233 – sorry for the delay in my reply.

    My budget is around £50.

    Please may I ask if model MT9J001 is Raspberry-Pi 4  compatible? (That is, is there a library containing Raspberry Pi drivers?)

    I am now exploring the possibility of using a monochrome camera for my application instead of Bayer filter. Which monochrome camera has the best software support for use with the Raspberry Pi, please?

    in reply to: Macro lens + camera for Raspberry Pi #22683
    denbigh1974
    Participant

    Thanks very much for your reply and for checking my calculation.

    The R-Pi sensor + 16mm lens is quite expensive combined and is out of stock everywhere but, in any case, I would like to explore different options. Which would be the best Arducam model for my application, please, in your opinion?

     

    in reply to: Macro lens + camera for Raspberry Pi #22520
    denbigh1974
    Participant

    If you’ve read through the explanations above, here are some more details that I need to know:

    a. Do you need your fingerprints to cover as much of picture as a possible, or do you accept that the fingerprint only takes a center section of the image as long as it’s identifiable?

    b. Do you have strict requirements of image distortions?

    Hi Tiao233, did I give you enough information to move this forward, please?

    in reply to: Macro lens + camera for Raspberry Pi #22331
    denbigh1974
    Participant

    Thank you. What a brilliant answer! I really appreciate the time that you took to educate me on the basics.

    I read through your post carefully. To answer your questions:

    a. Only the centre section of the image needs to be identifiable.

    b. I have no strict requirements about image distortion around the periphery of the central image. The undistorted central image should be equivalent to 10x10mm of fingerprint.

    Lets suppose that the ‘pitch’ of fingerprint lines is 0.5mm. I want to pick up finer detail of imperfections if possible. The image of the fingerprint should have a minimum resolution ‘Res’, say. I would like Res to be 0.01mm although this may be asking a lot.

    On field of view, going with your numbers, the lens will have a HFoV between 19 and 28 degrees. The camera sensor will capture a 2cm wide image but only the centre 1cm will be undistorted. If the camera sensor has a resolution of 12MP (4,200 x 2,800 say) then 2800 pixels will cover 2cm. This is the same as 1 pixel = 0.007mm. Therefore, that would be the resolution of the usable part of the image. Is that correct? If so I need a 12MP sensor and lens with HFoV between 19 and 28 degrees, if I understand you correctly.

    The finger will be in a fixed position so I guess that manual focus would be fine. I understand that depth of field may be a focus issue if the finger moves slightly.

    One more mechanical limitation may be that I want to fit my light source as a ‘conical hood’ at the front of the lens. So if the lens has a threaded boss (e,g, intended for a filter) that would be perfect. However, it’s not critical, I can fabricate some mechanical support to suit the application. My light source is very light weight. The camera will be fixed when capturing the image, not hand held.

    Thanks again!

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