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Spectral Imaging

The ISAAC Research Centre has developed a series of versatile and modular spectral imaging systems that enable automated high spatial resolution imaging from remote distances of tens of metres (80 micron resolution at distance of 10m) to close range imaging in the microscopic mode (a few micron resolution), from hyperspectral to broad band imaging.

Reflectance spectra can be collected alongside the imaging function, creating the opportunity to compare and identify the materials present- in a heritage context, this is most often used for pigment identification.

Reflectance Spectral Imaging:

  • enables automated high spatial resolution imaging from close range to remote distances of tens of metres (80-micron resolution at distance of 10 m),

  • efficiently collects millions of reflectance spectra in one image cube (2D spatial and wavelength in the 3rd dimension),

  • uses automated scanning to collect images and data from a large area.

 

​The automated scanning functionality of the technique is particularly suited to the analysis of large decorated surfaces such as murals and decorated architectural sites such as churches- these applications are discussed on our Remote Sensing page

The spatial and spectral parameters of the ISAAC Lab's spectral imaging systems are shown below.

Spectral imaging.png

Short wave infrared (SWIR) spectral imaging of the decoration on the Macedonian tomb at Aghios Athanasios, Greece, during our 2023 Molab analysis visit

In situ spectral imaging of the Canterbury Roll in New Zealand, 2018.

applications of spectral imaging
  • Revealing underdrawings on paintings and drawings using the imaging functionality

  • Pigment identification by collection of reflectance spectra during the analysis

isaac instrumentation

Micro-level Spectral Imaging

System

VIS-NIR hyperspectral imaging

Developer

ISAAC Lab

Spectral Range

400-1000 nm

Spectral Resolution

2.8 nm

Maximum Spatial Resolution

3 µm

Working

Distance

30 mm

Service

MOLAB/

FIXLAB

Close Range Spectral Imaging

System

Close Range

VIS-NIR Hyperspectral Imaging

VIS-NIR

miniature Hyperspectral imaging

(SPECIM-IQ)

Close-Range SWIR Hyperspectral Imaging

Close-Range VIS-NIR Spectral Imaging (PRISMS)

Mid-Infrared (MIR) Imaging

Developer

ISAAC Lab

SPECIM

NEO

ISAAC Lab

FLIR

Spectral Range

400- 1000 nm

400- 1000 nm

930- 2500 nm 

400- 850 nm

1500- 5000 nm

Spectral Resolution

2.8 nm

7 nm

5.5 nm 

50 nm

600- 2000 nm 

Working

Distance

20 cm

15- 50 cm

10 cm

1.5- 20 m

1- 3 m

Service

MOLAB/

FIXLAB

​​​

MOLAB/

FIXLAB

MOLAB/

FIXLAB

MOLAB/ 

FIXLAB

MOLAB/

FIXLAB

Ground- based Remote Imaging

System

Remote VIS-NIR Spectral Imaging

 

Remote VIS-NIR Hyperspectral Imaging

Remote SWIR Hyperspectral Imaging

Developer

ISAAC Lab

ISAAC Lab

ISAAC Lab/

Neo

Spectral Range

400 nm – 850 nm

400 – 1000 nm

930 – 2500 nm

Spectral Resolution

50 nm

2.8 nm

5.5 nm

Maximum Spatial Resolution

60 µrad

30 µrad

​45 µrad​

 

Working

Distance

> 1.5 m

> 3.5 m

> 3.5 m

Service

MOLAB/

FIXLAB

MOLAB/

FIXLAB

MOLAB/

FIXLAB

Airborne Remote Spectral Imaging

System

UAV-based VIS/NIR Hyperspectral Imaging + LIDAR system ​
(UAV LIDAR-HSI)

Developer

Headwall

Spectral Range

400 nm – 1000 nm

Spectral Resolution

2.2 nm

Working

Distance

> 10 m

Service

MOLAB

Hybrid OCT and Spectral Imaging System

ISAAC Hybrid OCT System:

Developer

 OCT Depth Resolution (air/polymer) 

OCT Transverse Resolution

Working Distance

Spectral Imaging Spectral Range

Spectral Imaging Spectral Resolution

Spectral Imaging Transverse Resolution

Hybrid OCT @ 1350 nm​ &

VIS/NIR Microscopic Spectral Imaging

ISAAC Lab

5 µm / 3.3 µm

10 µm

40 mm

415 nm – 845 nm

10 nm

5 µm

selected publications

​This is a selection of our Spectral Imaging publications. Our full publication list can be found here

Liggins, F., Vichi, A., Liu, W., Hogg, A., Kogou, S., Chen, J. & Liang, H., 2022.​ Hyperspectral Imaging Solutions for the Non-Invasive Detection and Automated Mapping of Copper Trihydroxychlorides in Ancient Bronze. Heritage Science 10, 142. https://doi.org/10.1186/s40494-022-00765-8

Kogou, S., Li, Y., Cheung, S., Han, N., Liggins, F., Shahtahmassebi, G., Thickett, D. and Liang, H. 2025 Ground-Based Remote Sensing and Machine Learning for in Situ and Noninvasive Monitoring and Identification of Salts and Moisture in Historic Buildings. Analytical Chemistry 2025 https://doi.org/10.1021/acs.analchem.4c05581

Kogou, S., Shahtahmassebi, G., Lucian, A., Liang. H, Shui, B., Zhang, W., Su, B. and van Schaik, S. 2020. From remote sensing and machine learning to the history of the Silk Road: large scale material identification on wall paintings. Sci Rep 10, 19312 (2020). https://doi.org/10.1038/s41598-020-76457-9

Read, M., Cheung, C.S., Ling, D., Korenberg, C., Meek, A., Kogou, S. and Liang, H., 2019. A Non-Invasive Investigation of Limoges Enamels using both Optical Coherence Tomography (OCT) and Spectral Imaging: A Pilot Study. In: H. Liang and R. Groves, eds., Optics for Arts, Architecture, and Archaeology Vii. SPIE Optical Metrology, Munich, Germany, 24-27 June 2019. SPIE Proceedings 11058, 1105803 https://doi.org/10.1117/12.2527092

Wijsman, S., Neate, S., Kogou, S., Liang, H., 2018. Uncovering the Oppenheimer Siddur: using Scientific Analysis to Reveal the Production Process of a Medieval Illuminated Hebrew Manuscript. Heritage Science 6, 15.  https://doi.org/10.1186/s40494-018-0179-0

Kogou, S., Neate, S., Coveney, C., Miles, A., Boocock, D., Burgio, L., Cheung, C.S. and Liang, H., 2016. The Origins of The Selden Map of China: Scientific Analysis of the Painting Materials and Techniques Using a Holistic Approach. Heritage Science, 4, 18. https://doi.org/10.1186/s40494-016-0098-x

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