Three New Research Papers Feature the heliCam’s Lock-in Imaging
The heliCam from heliotis is used by research groups worldwide to visualize extremely small signal changes, even under demanding conditions. Three recent publications demonstrate how lock-in imaging enables new pathways in biometrics, quantum sensing, and field/signal imaging.
Robust hyperspectral measurement despite ambient light: Remote biometrics (PPG, SpO₂, BP/ECG reconstruction)
A team from the University of Wisconsin–Madison presents a lock-in camera-based hyperspectral framework that modulates wavelength-specific illumination and synchronizes detection. This significantly suppresses ambient light fluctuations – a key weakness of traditional hyperspectral systems. In the validation for photoplethysmography (rPPG), heart rates are estimated with 3 bpm error; additionally, SpO₂ dynamics are extracted with 3% maximum error using dual-wavelength illumination (660/940 nm). From these high-quality signals, the authors even reconstruct blood pressure and ECG features via ML.
Diamond sensing: Detuning-insensitive wide-field imaging of vector microwave fields
Researchers at the Institute of Physics, Chinese Academy of Sciences present a method for rapid imaging of microwave fields using NV centers in diamond that is robust against detuning (e.g., due to temperature/magnetic field fluctuations). Instead of Rabi oscillations, they utilize power broadening (line broadening) in ODMR and detect differential changes via the lock-in principle (amplitude modulation + demodulation). Wide-field imaging of a micro-antenna array is demonstrated with ~800 nm resolution, including vector reconstruction across multiple NV axes and good linearity over a large dynamic range.
Quantum SiC Microscope: Imaging electrical signals current-induced magnetic fields
A team at the Helmholtz-Zentrum Dresden-Rossendorf and the Technische Universität Dresden demonstrates for the first time a Quantum Silicon Carbide Microscope (QSiCM) based on silicon vacancies in 4H-SiC. The platform utilizes lock-in detection to spatially resolve magnetic fields from electrical currents. Reported features include 50 ms time resolution, ~30 µm spatial resolution, and a sensitivity of ~2 µT Hz⁻¹ per pixel. Additionally, the authors show a dual-frequency measurement strategy for improved robustness against temperature/strain influences, as well as a simplified microwave-free imaging mode via spin-level anticrossing.
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These three publications exemplify how lock-in imaging with the heliCam makes diverse signal sources in research (biomedical optics, quantum/diamond and SiC sensing, field and signal imaging) accessible in a robust, wide-field manner with high ambient light suppression — thus enabling new measurement concepts in innovative sensor technology.
Click the link for more publications related to the heliCam: heliCam papers
Click the link for more about research applications with lock-in imaging: Research C4
About heliotis
heliotis develops, manufactures, and distributes optical 3D measurement technology for industrial quality control. Their core competence is in the development of CMOS image sensors, FPGA-based cameras, and optical measurement technology. Thanks to sustainable investments in research and development, these 3D sensors are among the most accurate and fastest non-contact sensors in the world.
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