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Images measuring light intensity

Hello,

 

I am an undergraduate researcher doing work on laser beams, and I need help creating a labview program that will show the light intensity of images. I would like for the image to look like the image that is attached to this post.

 

Does anyone have any idea how to achieve this?

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Message 1 of 11
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What have you tried so far?

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Message 2 of 11
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Hi Romanus58,

 

In order to help you, we need a bit more of information so can you explain the hardware you are using to acquire data. What have you done so far in LabVIEW?

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Hello,

 

I have this question as well. Actually I am using Edmund Optics Camera (EO-2013c) and save the images of laser beam focused on camera detector. The pixel depth of camera is 8-bit and I am saving the images as PNG format using "write PNG file.vi".

The thing that I am in quest of is Intensity and by intensity I mean the common definition which is "the energy recieved per unit time per unit area". If I take out the color planes(Red,Green,Blue,Hue,Saturation,Luminance,Intensity) of image in each of color modes available in labview (RGB,HSV,HSL), I can get numbers in 0-255 (8-bit) range but I think non of these are giving me the intensity which I am looking for because the numbers are different from plane to plane as it is supposed to be.
I have this question :
Is there any way that I can extract a unique number indicating the intensity which I am looking for? I don't think so if Light meter VI or grayscale could help me because they all give me the same information as I could get from color planes.
What about Power Spectral Density?

I am sorry that I don't upload my VI because it is not an integrated VI and also I am using some built-in camera software to save images. I also can not get intensity information from camera directly but the color planes!

 

Cheers,
Iman

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Message 4 of 11
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Hi Iman,

 

Is there any way that I can extract a unique number indicating the intensity which I am looking for?

All you need is a math formula describing your desired calculation result!

Which kind of "intensity" calculation do you want to implement? Can you provide such a formula?

 

I guess the resulting number will always be "unique" for each image… 😄

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
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I did not understant what you mean at all. 
Let me say an example :
Forget the unique number. I am sending a laser light to a camera detector. By changing the intensity of laser , I can see that the brightness of image is changing which means the enery arrived by the detector is changing (the thing that could exactly hapen to your eye). The camera can give me a 0-255 pixel values for each principle color planes (R,G,B,H,S,V,L,I). What are these numbers? Are they representing the arriving energy? If not, what are they then?

 

Best Regards,
Iman

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Message 6 of 11
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Hi Iman,

 

The camera can give me a 0-255 pixel values for each principle color planes (R,G,B,H,S,V,L,I). What are these numbers? Are they representing the arriving energy?

This is no LabVIEW question, but a question you have to ask the manufacturer of your camera!

In general the pixel value is related to the light intensity - but the camera might apply its own algorithms…

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
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RGB and HSV represent the same and are probably redundant. Of course light intensity varies over many orders of magnitude and 8 bits (256 values) typically represent a scaled and quantized value depending on many camera parameters (aperture, gain, exposure, etc.). To get absolute light intensities, you need these calibration factors.

 

So your image seems to be a 2D array of 64bits/element, each byte representing one of these eight items in your list. "Index array" will get  you the values of a single pixels where you then can extract the desired bytes for further processing, e.g. by typecasting.

 

 

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I work with lasers professionally.

 

The camera you're using is not appropriate for laser imaging.  Laser light is emitted in an extremely narrow wavelength (determined by the type of laser you're using, i.e. HeNe or whatever).  As such, you want to use a monochromatic camera to measure laser beams.  Color cameras have pixel grids where they alternate having red, green, and blue filters over them in order to produce a color image, and this gives inaccurate measurements.

 

Without knowing more about your application I can't begin to recommend a proper measurement tool, but you probably want to get a camera already paired with beam measurement software, and then you use LabVIEW to interface with that software.  Here's 3 vendors I've used:

 

https://www.coherent.com/measurement-control/main/laser-beam-diagnostics

https://www.ophiropt.com/laser--measurement/beam-profilers/products/Beam-Profiling/Camera-Profiling-...

https://www.dataray.com/beam-profiling-cameras.html

 

Of the 3 I prefer the Ophir BeamGage software when interfacing with LabVIEW (best combination of ease of use plus reliability) but sometimes the other vendors have cameras at better prices or more appropriate specs for an application.

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Message 9 of 11
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Thank you very much Altenbach. I have a good control on exposure, gain,etc and I know the color depth of camera is 8-bit. my question was about the fact that what happens exactly to light intensity while processing in camera circuit which means I have to know about camera sensor response if it is linear or logarthmic? But Thank you very uch. I now, more or less have an idea of whats going on.

Cheers

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