2026/07/17Research Background and Challenges
A recent study led by researchers at the University of Science and Technology of China (USTC) demonstrates high-resolution upconversion imaging of incoherent thermal radiation in the 10 μm spectral range, addressing key challenges in LWIR detection and system design.
The long-wave infrared (LWIR, 8–14 μm) range is widely used in thermal imaging, molecular analysis, and remote sensing. It aligns well with room-temperature thermal radiation and contains strong molecular signatures, making it highly valuable across scientific and industrial applications.
However, traditional infrared detectors such as MCT and T2SL still face practical limitations. These include high noise, limited sensitivity, complex manufacturing, and high cost. Performance also drops as wavelength increases, which makes high-quality LWIR imaging more difficult.
Upconversion detection provides an alternative approach. It converts infrared signals into visible light, so they can be captured by mature silicon-based detectors. This method has been successfully used in mid-infrared imaging. But for LWIR, especially when dealing with incoherent thermal sources, progress has been limited.
The main challenges come from three areas: achieving high spatial resolution, understanding how optical factors affect image quality, and controlling system parameters such as numerical aperture and pump beam profile.
Note: Schematic diagram of the experimental setup.
Key Scientific Findings on LWIR Upconversion Imaging
This work demonstrates high-resolution upconversion imaging of incoherent thermal targets at 10 μm for the first time.
- Spatial resolution reached close to the theoretical limit under incoherent illumination.
- Key factors affecting resolution were clearly identified and experimentally verified, including numerical aperture, depth of field, and astigmatism.
- Analytical models for depth of field and astigmatism were established and matched well with experimental results.
- The shape of the pump beam was found to directly influence resolution in different directions.
- A critical system parameter was quantified, which helps guide pump beam and system design.
These results provide practical guidance for optimizing LWIR upconversion systems and support future development of high-performance imaging solutions.
Note: High-resolution imaging of incoherent thermal radiation at 10 μm was demonstrated for the first time, achieving a minimum resolvable line width of 198.4 μm.
Why Choose Dhyana 95 for LWIR Upconversion Imaging
Long-wave infrared (LWIR) upconversion imaging at 10 μm presents several technical challenges. The upconverted signal is inherently weak, conversion efficiency is limited, and matching incoherent light sources adds further complexity. At the same time, achieving high-resolution imaging requires large numerical aperture optics, which can introduce aberrations such as astigmatism and shallow depth of field—placing stringent demands on the detector’s overall performance. After careful evaluation, the research team selected the Dhyana 95 V2 as the core imaging device for the system.
Broad spectral sensitivity for weak signal detection
The Dhyana 95 V2 features a back-illuminated sCMOS architecture with high quantum efficiency across a wide 200–1100 nm range. It delivers strong sensitivity near 970 nm, making it highly effective for capturing faint near-infrared upconverted signals.
Ultra-low noise and high dynamic range for quantitative accuracy
With just 1.6 e⁻ read noise, combined with 11 μm large pixels and a 100 ke⁻ full well capacity, the camera significantly improves signal-to-noise ratio in low-light conditions. This ensures precise quantitative analysis of key parameters such as intensity distribution and fringe contrast.
Large sensor format for wide field imaging
The 31.9 mm large-format sensor supports wide field-of-view requirements in standard 4f optical systems, enabling accurate experimental validation and quantitative analysis of critical imaging characteristics, including resolution, depth of field, and astigmatism.
References
Han, Z.-Q.-Z., Wang, X.-H., Li, J.-P., Liu, B.-W., Zhou, Z.-H., Zhang, H., Li, Y.-H., Zhou, Z.-Y., Shi, B.-S. High-resolution up-conversion imaging in the 10-μm band under incoherent illumination. arXiv:2505.24367 [physics.optics], 2025. https://doi.org/10.48550/arXiv.2505.24367
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