What is Light Field Imaging?
A photographic camera captures the radiant intensity of light in a plane. A light field camera (also known as a plenoptic camera) captures the entire light field in a plane by recording not just the intensity, but also the direction of incoming light rays. This technology, popularized by companies like Lytro, relies on arrays of microlenses placed in front of the image sensor, allowing each pixel (or image point) to store angular information. Thus, if you know the radiant intensity and direction of the light in one plane, you can also calculate the intensity and direction of this light in other planes.
On the right: The working principle of an ordinary light field camera is shown. A camera array captures a scene from different angles, and thus the intensity, position, and direction of the light are recorded.
Why Light Field HSI is Such a Great Idea
A typical light field camera utilizes a microlens array in front of a conventional image sensor. This array generates a multitude of similar images onto the sensor — a principle reminiscent of an insect’s compound eye. Each small image point represents a slightly different viewing angle. From these angular variations, the direction of the light rays can be calculated, allowing for rich light field data reconstruction. However, because each sub-image carries partially redundant information, this process inherently reduces the overall resolution of the camera system.
In hyperspectral light field imaging, we use this principle not as a limitation, but as an opportunity to add a new dimension of measurement to the system: the wavelength. Each sub-image effectively becomes a narrowband spectral slice, capturing unique distance settings and light behavior. In our advanced camera platforms, every single micro-image records a slightly different wavelength of the scene while conserving all other strengths of the light field technology — including angular information, depth-of-field control, and flexible refocusing. This makes our solution particularly suitable for applications in computer graphics, scientific imaging, and high-precision image capture where spectral variation matters.
Each sensor readout holds the following multidimensional dataset:
The complete dataset is captured within milliseconds and can be read out with video frame rates.
Instead of losing sensor pixels (as with light field cameras), we transform this sensor data into the wavelength dimension. Thus, the cameras do not lose the resolution of the underlying sensor. The resolution of each band can be chosen by the simple formulation:
Spatial resolution = chip resolution / # of bands.
This setup is highly adaptable, and in addition to our off-the-shelf products, we offer solutions with customizable specifications to match your requirements.
On the left: Hyperspectral light field cameras are highly adaptable, and the resolution of each band can be chosen by dividing the sensor resolution by the number of desired bands.
Why Light Field HSI Offers Superior Quality
The core working principle of every spectrometer is its wavelength specificity. The quality and characteristics of the whole system are determined to a significant degree by this element. For good spectral separation, this element should be of the highest possible quality.
However, for some snapshot spectral imaging technologies, this element must be limited so other goals can be achieved. Filter-on-chip technologies, for example, can only use simple spectral filters to achieve the goal of maximum miniaturization.
The light field approach, on the other hand, enables the use of filters with the highest quality in terms of transmission, blockage, and crosstalk reduction. This is mainly due to the fact that, in comparison with filter-on-chip approaches, we can use highly reliable optical thin film filters, which achieve these superior specifications due to the application of 50-150 coating layers.
On the right: Filter specifications of the ULTRIS X20. The filters have a transmission >90% and feature a blocking of OD4*. The resulting spectra are equidistant and equally broad for every wavelength. *(OD4 equals 0.01% transmission in unwanted wavelengths.)
Why Light Field HSI Offers Superior Reproducibility
The reproducibility of hyperspectral measurements plays an important role in the reliability of data analysis, especially when an application has to work on multiple systems at once.
The reproducibility of a system is mainly governed by its mechanical and thermal stability and the intrasystem reproducibility of a given filter set. For hyperspectral systems employing electrically tunable filters, electrical stability plays another important role.
Light field spectral imaging cameras possess some major advantages over their predecessors due to their construction. The devices are monolithic, with no moving parts, and thus offer extremely high mechanical stability. Due to the small building height and the physical properties of the filter set, the thermal stability is excellent.
The intrasystem stability was measured for a test set of 100 systems. The typical wavelength error is in the range of +/- 0.8 nm. For special applications, the filter sets can be preselected to achieve even higher accuracy.
On the right: Wavelength accuracy of a test set of 100 systems. The central wavelength error ranges between -0.8 to +0.8 nm.
Light Field HSI in Summary
In summary, light field hyperspectral imaging features some striking advantages. These advanced camera systems offer a hyperspectral snapshot data cube with high spatial resolution and exceptional spectral fidelity. The light throughput is very high, supported by precision-engineered microlens arrays and high-performance filters. Thanks to the physical and mechanical stability of the components, the devices provide excellent reproducibility, making them reliable tools for long-term data acquisition and repeatable imaging processes. With further analysis of the recorded light field data, even 3D reconstruction becomes possible — enabling flexible adjustment of focal planes, virtual refocusing, and application-specific distance settings, all based on a single spectral snapshot.
Light field hyperspectral imaging advantages:
About the Author
Dr. René Heine is the Co-Founder and CEO of Cubert GmbH, a leader in real-time spectral imaging. Since founding the company in 2012, René has been instrumental in shaping Cubert’s technological direction and growth. He holds a Doctor of Physics degree from the University of Ulm, where he graduated magna cum laude, and completed his diploma thesis at Harvard Medical School. René’s deep expertise in physics and his vision for cutting-edge imaging technologies drive Cubert’s innovations and advancements in hyperspectral solutions.
