Is It Normal to See This Spectrum in Certain Bands After Calibration and Focusing?

[polanco06]

Hi everyone,

I am currently using a hyperspectral imaging system with a Cubert Ultris S5 camera, and I’ve been capturing RAW data of a scene (specifically, human hands placed approximately 2 meters away from the sensor). I have already applied all the recommended calibration steps and adjusted the focus based on the specified distance.

However, when visualizing individual spectral bands from the RAW cube, I noticed that in some wavelengths, the target (hands) appears very faint or even almost invisible, while in others, the spectral content seems exaggerated or quite noisy.

You can see an example in the attached image:

Each subplot represents a different band (wavelength).

The focus distance was set correctly.

This visualization is based purely on the RAW data .

The illumination source used was an Effilux Effiflex White LED.

My question is: Is this spectral variation normal behavior for this type of sensor, even in RAW mode?
Or could it be a sign of:

Improper calibration?

Spectral sensitivity limitations at certain bands?

Focus or exposure misconfiguration?

Any insights or suggestions would be really appreciated.

Thanks in advance!

Best regards,

[domthom21]

Hi polanco06,

you didn't wrote which camera you use, I expect you use the X20.

If you want to work with the raw data without white calibration,
I suggest to make yourself familiar with the applied sensor, CMV20000.
In its manual you'll find information about the quantum efficency and spectral response (Mono) of the sensor.

In addition, you apply an LED instead of a recommended halogen with a more homogenous excitation spectrum.
This way. you only illuminate your sample in the red, green and blue color bands.

The measured wavelength dependend signal will be a convolution of your illumination, sample reflectane and sensor sensitivity.

I'm not from cubert, so this is no official response.

Best,
Dominik

[polanco06]

Thank you very much for the comment. The camera is an S5.

[birkholz-cubert]

Hey,

this seems to be an issue regarding your specific camera. I would recommend you open an issue on our service desk http://support.cubert-hyperspectral.com/ so that you can receive more specific help.