WHAT SHOULD YOU CONSIDER WHEN SETTING UP A HYPERSPECTRAL CAMERA SOLUTION?

Where can hyperspectral cameras be used, and what information can they provide? What does it mean to integrate hyperspectral imaging in the industrial production process, and what parameters need to be considered?

Hyperspectral cameras are sensitive to specific wavelengths, and the spectral range selected should be based on the measured material and its characteristics. There is plenty of scientific research done with hyperspectral cameras if you have no prior knowledge of how spectral features (signatures) are related to the material characteristics.

On our product page, you find a good overview of applications that can be solved with each product and wavelength range they cover.

See also our short video to learn how to select the correct spectral camera for the application.

When selecting the illumination for a spectral imaging system, three major points must be considered.

Illumination Strength

Spectral imaging requires much more light than traditional RGB or grey scale black-and-white imaging. The required total illumination power depends on

• The geometry of the illuminating beam and the distance from the sample,
• Width of the illuminated target (like conveyer belt)
• The integration time per the image

Need for illumination power increases with

• Longer distance to the target
• Less illuminating light collimated to the target
• Shorter integration time.

The wavelength range of the illumination source

Illumination for hyperspectral imaging must always have a continuous spectrum that covers the full wavelength range of the hyperspectral camera. If the illumination does not have a signal in some of the wavelengths, the measured data on those wavelengths is not valid.
The illumination types compatible with hyperspectral imaging sensors are

• For visible range, most typical is halogen illumination (spots or linear), LED is also used. Supercontinuum lasers show good potential.
• For NIR range: halogen is most typical. LEDs and supercontinuum lasers show good potential.
• For SWIR range: halogen illumination
• For MWIR and LWIR range: thermal illumination

Illumination uniformity

It is important to ensure that the illumination covers the full measurement area with uniform intensity and spectral range, minimum shadows, or specular reflections. To learn more about the illumination for spectral cameras, watch our tutorial video on how to estimate required illumination power for a hyperspectral camera (applies to halogen spot based illumination).

Most industrial sorting and quality inspection applications require a high image rate to accurately monitor small objects traveling at fast-line speeds. A higher image rate limits the integration time (the time that the camera has to collect light reflected from the material stream). Specim FX cameras provide both the highest image rates and light collection efficiency in the market to keep up with the industrial speed requirements.

How to select the correct frame rate for your application:

In addition to the spectral camera and illumination, specific data processing is required for a complete application solution. Knowledge of how the object spectrum is affected by the object characteristics (e.g., by its chemical composition) is needed to build classification and sorting models, which are then applied in real-time to the data acquired by a spectral camera.

The hyperspectral data is an enormous source of information and requires adequate processing power from the system. The data contain repetitive information where the actual chemical information of the material is often carried by a limited spectral range or number of feature wavelength regions. Traditional so-called chemometrics methods and rapidly developing machine learning techniques are very powerful to extract the relevant information from this type of data. They apply mathematical and statistical methods and are often used to obtain classification or quantifications results from the data measured by a hyperspectral camera.

SpecimONE is a complete spectral imaging platform that makes browsing and exploring spectral data and applying that to industrial sorting solutions fast and easy without in-depth knowledge of hyperspectral imaging.

The SpecimONE platform includes the industry-proven Specim hyperspectral camera, SpecimCUBE processing hardware, and SpecimINSIGHT, an easy-to-use software tool to analyze spectra and create and validate classification models.

The SpecimONE platform allows new application discovery, prototype building, and continued development to enable faster go-to-market timeframes.

Several third-party software solutions also provide the tools to build classification and prediction models for hyperspectral data. The suppliers that support Specim cameras are CAMO, PerClass Mira, and LuxFlux.

All these software give output in standard machine vision formats; thus, integration to existing machine vision software (e.g., Halcon, Cognex, Labview, or Sherlock) is straightforward. The results can then be used to control the air nozzles or picking robots.

Specim FX series cameras provide the speed and flexibility required by industrial processes. Camera speed can be adjusted based on the application requirements. The tolerance for delays of the entire inspection chain, i.e., from acquiring the spectral image to taking action by system control, is typically very strict. Specim FX series cameras are designed to meet these requirements. An industrial PC or another high-performance platform is usually required to run the classification in real-time.