Linescan camera acquisition lower than expected

[achille]

Hi,
I have a Hamamatsu linescan camera. The camera scans at a frequency of 1.5 KHz.
In the NI Max I have used the values of 1280 pixels for the width of the image and 20 lines for the height of the image.
So it's time I have an image of 1280x20. Taking into account the camera scanning frequency I suppose that I expect 75 images of 1280x20 per second (1500/20=75).
WHen I use the grab button in the NI Max in the right low corner there is a message of 21frames/second.
My question is what about the other frames?
Also with 1.5KHz scanning speed in order to acquire 20 lines I normally need 13msec. But in NI Max it need a timeout setting of about 47msec in order to acquire the 20 lines.
Is there something I can do about that?
Thank in advance for your help.

Achille

[muks]

What is the conveyor speed/Rotation speed?

[achille]

The conveyor speed is about 0.6m/sec (36m/min). According to hamamatsu the scanning speed of the camera for this speed must be set to 1.5KHz.

[seVEMes]

Are you in free run mode? If not what is your triggering setup? When you say "I normally need 13msec" do you mean that you have acquired at that rate with some other setup or framegrabber or is it a simple calculation?

What NI framegrabber are you using? What are the Aquisition Parameters in MAX? (like bit depth) What camera are you using? Could you post a link to the datasheet?

[achille]

Dear Vince,
Thank you for your message. I will try to answer your questions.
1. It is in free run mode. No triggering.
2. The 13msec comes from a calculation. 1.5KHz frequency, so 1/1500=time for a single line, so (1/1500)*20lines=13msec time for acquiring 20 lines.
3. The frame grabber I use is PXI 1422
4. Acquisition paramters in MAX: Maximun acquired window= 1280(pixels)x 64 lines, acquired window= 1280x20, bitdepth=12, timeout=50msec.
5. The camera I am using is a hamamatsu line scan camera 9750-05FC

Hope this details help you to understand my problem. If you need more details please tell me.
Please can you help me overcoming this problem? It is very important for me.

Thank you.

Best regards,
Achille

[seVEMes]

Achille,

I looked over the data sheet and have not found anything yet. I was curious to know where you got the 1.5KHz? On the data sheet for the Hamamatsu line scan camera 9750-05FC it says that the speed is 4m/min to 40m/min. Is this something that can be adjusted? Did you set it to be 1.5KHz?
Also, for that camera I see 640 pixels not 1280; at the slowest speed with 1280 pixels I calculate 23 frames per second which is close to what you are getting. Do you actually have the 10FC or 10TC camera? Perhaps if you reduce the number of pixels from 1280 to 640, that may double your acquisition time.

Let me know if any of these suggestions help.


Message Edited by seVEMes on 07-23-2008 08:52 AM

[achille]

Dear Vince,
Thank you for your reply. You are rigth. The camera is C9750-10FC. It is a camera with 512mm length and 0.4mm resolution so 512/0.4=1280 pixels.
In this camera there is a parameter for the conveyor speed. The camera works for speeds from 4m/min to 40 m/min.
The 4m/min coresponds to frequency 0.166KHz while the 40m/min corresponds to 1.667KHz.
So when i set to the camera the parameter for the conveyor speed to 36m/min (my application speed) it automatically adjust the frequency. So for my application it automatically set the frequency to 1.5KHz. This is something that i have checked sending a serial command to camera and answering me that the frequency equals to 1.5KHz.
I cannot reduce the width of the camera from 1280 to 640 pixels because I am using the whole width of the camera.

Can you please send to me the NI MAX icd file you created for this camera? If it is possible to be for the 9750-10FC model it would be great.
I could not found an icd file for this model in NI database so I created my own but I am not sure about some things. So if I have also yours for the 9750-10FC I can cross-check some things. It will really help me.
Thank you.

Best regards,

Achille

[seVEMes]

Achille,

We do not have a camera file for that particular camera. One of the best things you can do is to find the icd file that is closest to that camera and modify it using the NI Camera File Generator.

To find an icd file that is close: right click on your camera and select Open Camera... This will bring you to a list of icd files. Use this to find the location of the icd files. Find the file closest to your camera then you can modify it accordingly. I found over five Hamamatsu cameras.