Hyperspectral imaging can capture information beyond conventional RGB cameras; thus, it has many applications, such as material identification and spectral analysis. However, like many camera systems, most of the existing hyperspectral cameras are still passive imaging systems: they require external light sources to illuminate the objects to capture the spectral intensity. As a result, the collected images highly depend on the environment lighting, and the imaging system cannot function in a dark or low-lighting environment. This work develops a prototype system for active hyperspectral imaging, which actively emits different single-wavelength lights at different frequencies when imaging. This concept has several advantages: first, using the controlled lighting, the magnitude of the individual bands is normalized to extract reflectance information; second, the system is capable of collecting information at the desired spectral range by tailoring the light sources; third, an active system is mechanically easier to make, since it does not require complex band filters as used in passive systems; last, such a system may work under low light or dark environments, which greatly facilitate underground/subsurface sensing applications such as borehole based mining exploration. This prototype is achieved by using an array of low-cost and single-wavelength LED (Light Emitting Diode) lights, a remote control module controlling the LED illuminator, and the shutter of a full spectrum camera. We demonstrate that such design is feasible and could yield informative hyperspectral images for spectral analysis and machine learning-based object identification in low light or dark environments, having great potential to benefit both the academic and industry such as in geochemistry, earth science, subsurface energy, and mining.

While capturing a hyperspectral image of an object, the system will loop over all 19 channels of LED lights and capture a panchromatic image for each of them.

The illuminator consists of totaling four concentric circle rings. Each ring consists of 19 LED lights and has the same LED light bulbs to form a cluster that emits light at the same wavelength. The four LED lights for each cluster are placed at a 90 interval to create sufficiently strong illumination, at the same time as distributed as possible to reduce the creation of shadows by direct lighting. The illuminator can illuminate lights at 19 unique wavelengths, and its actual implementation was achieved through planting these LED lights onto a circular PCB (Printed Circuit Board), powered by a 3W DC supplier and controlled through electrical switches. Each LED bulb has a dimension of 3.45mm x 3.45mm, driven by a direct current power supply.

The selection of these 19 individual LEDs aims to cover the spectrum ranges as wide as possible. To this end, these 19 monochromatic LEDs cover a spectral range of (365nm–1050nm), expendable depending on the spectral resolution of the lights and the wavelength they cover, which, for example, can be extended to the ultraviolet range (1400 nm). It should be noted that most previous works use RGB LED mixers, which essentially mix the lighting spectrums of three single and fixed dye diodes that do not cover a spectrum beyond the visible range. In contrast, we directly use a single dye Diode that responds to a single electrical current excitement, which can directly emit lights at a narrow wavelength bandwidth at a higher spectral purity and operate beyond visible bands.

These hyperspectral images may use any image viewer to open.