Hyperspectral imaging is a potential optical modality employed in several applications. The adaptability of the systems is essential for expanding hyperspectral imaging capabilities, which incorporates profilometry, Raman spectroscopy, and fluorescence imaging.
A recent study published in Sensors proposes a unique laboratory hyperspectral imaging system designed for biomedical optics. The design, characterization, calibration, and verification processes required to set up such systems are all described in this study keeping the overall standardization objective in mind. As an added novelty, the suggested hyperspectral imaging system employs reflectance imaging, which is crucial for biomedical optics applications due to the removal of sample heating, using a specially constructed broadband LED-based light source.
Applications of Hyperspectral Imaging
Hyperspectral imaging is widely used in remote sensing applications due to the quick advancement of acquisition methods. Examples include identifying the type of vegetation and water sources, regulating the use of wood and wood products, monitoring food safety and quality, restoring the authenticity of works of art, and biomedical optics.
Hyperspectral imaging, with its non-ionizing radiation and ability to record biochemical data sensitive to clinically significant changes (such as hyper-metabolism and angiogenesis), has distinctive advantages in biomedical optics.
Limitations of Standard Hyperspectral Imaging Systems
Commercial systems for standard hyperspectral imaging are easily accessible and very helpful for imaging reflectance and transmittance. However, the versatility needed for broad hyperspectral imaging applications, which would involve profilometry, fluorescence imaging, and Raman spectroscopy, is often absent from these systems.
Requirements of Hyperspectral Imaging Systems for Biomedical Optics Applications
The conditions required for hyperspectral imaging systems to be utilized in biomedical optics applications involve a human hand-sized sample to be imaged by the system with a field of view (FOV) of 20 to 30 cm and a spatial resolution of roughly 100 µm. To suit certain applications, it should also be possible to alter both the FOV and spatial resolution.
To analyze the intricate spectrum details of chromophores, the system should have a spectral range between 400 nm and 1000 nm (determined by tissue native chromophores, i.e., tissue components absorbing light).
Development of a Custom-Made Laboratory Hyperspectral Imaging System
Stergar et al. has developed a unique laboratory hyperspectral imaging system for biomedical optics applications. It features a specially constructed reflectance source that eliminates sample heating and has flexible spatial resolution and spectral precision of a few nm.
The primary goal of the developed system was to improve and characterize a modular multi-modal hyperspectral imaging system using an LED light source to enable imaging in a broad visible and near-infrared spectral band spanning from 400 nm to 1000 nm.
The secondary goal was to validate the specially designed laboratory hyperspectral imaging system with the hope of pilot standardizing the calibration protocols, which would allow studies to be conducted using various instruments.
The researchers developed a hyperspectral imaging system for biomedical optics applications with a cutting-edge LED light source that solves sample heating issues. The researchers also provided a generic framework for calibrating, testing, and characterization of any hyperspectral imaging system in addition to the system construction.
For the 50 mm objective lens, a reduction in resolving power by increasing wavelength was observed during the resolving power testing. Although the drop must be taken into account, it does not present challenges for biological imaging applications, as details in the imaged tissues often blur due to how light interacts with tissue.
The versatility built into the purposed hyperspectral imaging system's design is a key benefit. The proposed system can withstand changing geometries, a crucial component of any hyperspectral imaging application in biomedical optics. The field of vision and system resolution can be adjusted using different objective lenses.
The system's versatility with light sources makes it simple to expand its applications, such as in Raman spectroscopy and fluorescence imaging. The modular system architecture makes it possible to integrate additional imaging modalities such as thermal imaging and 3D laser profilometry, which in turn makes it easier to acquire multi-modal images that provide a level of insight not seen in systems that simply use spectrum imaging.
The modularity and adaptability of the suggested system can aid in creating imaging applications and protocols for those particular samples that current commercial systems cannot sufficiently accommodate.
Stergar, J., Hren, R., & Milanič, M. (2022). Design and Validation of a Custom-Made Laboratory Hyperspectral Imaging System for Biomedical Applications Using a Broadband LED Light Source. Sensors, 22(16), 6274. https://www.mdpi.com/1424-8220/22/16/6274/htm