Hyperspectral Imaging System

Hyperspectral imaging is an acquisition method that combines spectroscopy and imaging, allowing each pixel of an image to contain a complete spectrum. This technology relies on the pushbroom principle, where the scene is scanned line by line: each spatial line is associated with a series of spectral bands, creating a data hypercube (x, y, λ). In our case, this technique is applied to the study of wood cores, discs, and powders to characterize the chemical and structural composition of samples at various spatial and spectral scales. This non-destructive approach enables the identification, mapping, and quantification of numerous constituents such as lignin, cellulose, extractives, and markers of degradation or treatment.

Physicochemical characterization of wood through spectral imaging in the VNIR and SWIR ranges

The system includes two complementary hyperspectral cameras:

VNIR Camera (400–1000 nm, sCMOS sensor)

• Spatial resolution: 2,184 pixels
• Spectral resolution: 2.9 nm for 946 bands
• Signal-to-noise ratio: up to 680:1
• Ideal for detecting signatures in the visible and near-infrared, such as moisture or residual chlorophyll
   

SWIR Camera (1000–2500 nm, MCT sensor)

• 384 spatial pixels, 288 spectral bands
• Spectral resolution: 12 nm
• Signal-to-noise ratio: > 1000:1
• Enables identification of specific chemical bonds (OH, CH, NH), useful for analysing cellulose, hemicellulose, or lignin
   

Both cameras can be used simultaneously, mounted on a motorized scanner (100 × 50 cm) that moves the sample under the optical beam. A smaller version (40 × 20 cm) enables detailed observation of restricted areas with macro lenses (up to 24 µm/pixel).

Analysis conditions and data processing

Wood samples are placed on a motorized translation stage. A stabilized halogen light source ensures uniform illumination. Acquisition is fully controlled via LUMO Scanner and LUMO Recorder software, which synchronize stage movement with image capture. Data are recorded in raw format with metadata and analysed using SPECIM Insight. Calibrated reflectance measurements are possible with a white reference.

Sample formats

• Wood cores: longitudinal analysis to study radial or axial compositional variation
• Wood discs: ring mapping or detection of chemical heterogeneity
• Wood powders: overall compositional measurements on homogenized ground samples
   

Service access

The service can be:

• Partial – equipment access with technical support
• Full – from acquisition to analysis, provided samples are ready for measurement.

This system is particularly suited for studies on wood quality, biological degradation, treatment effects, and differences between species or sampling sites.

Contact:

• Equipment and unit coordinator: Julien Ruelle julien.ruelle@inrae.fr