In scientific research experiments, thermal imagers can achieve non-contact temperature measurement of micrometer-scale targets, relying on their core infrared detection technology and precise optical system design. Traditional contact temperature measurement methods have significant limitations at the micrometer scale. For example, thermocouples or resistance temperature detectors may interfere with the target's thermal field distribution due to their large size, or cause deformation of minute structures due to contact pressure. Thermal imagers, by receiving infrared radiation emitted by the target itself non-contactly, fundamentally avoid the interference of physical contact on the measured object, providing a feasible path for micrometer-scale temperature measurement. Its technological implementation requires collaborative breakthroughs across multiple dimensions, including hardware configuration, optical adaptation, algorithm optimization, and environmental control.
At the hardware level, high-resolution infrared detectors are fundamental to achieving micrometer-scale temperature measurement. Research-grade thermal imagers typically employ focal plane array detectors, whose pixel size can be reduced to the micrometer scale, ensuring that each pixel corresponds to a smaller target area. For example, some high-end devices integrate detectors with hundreds of thousands to millions of pixels, combined with microlens array technology, to increase the effective photosensitive area to near the physical pixel size, thereby meeting the spatial resolution requirements for micrometer-scale measurement. Furthermore, the detector's sensitivity must reach the sub-milliKelvin level to capture minute temperature changes and avoid masking the target's thermal characteristics due to signal noise.
Optical system adaptation is a crucial step in achieving micrometer-level temperature measurement. Standard thermal imager lenses are limited by the diffraction limit, making it difficult to focus directly to the micrometer scale. Therefore, research often employs customized macro lenses or microscopic optical modules to improve spatial resolution by shortening the working distance and increasing the numerical aperture. For example, some devices compress the optical system's resolution to several micrometers by adding specially designed microscope objectives, combined with a high-precision three-dimensional displacement platform to achieve precise alignment between the target and the detector. Such optical modules must strictly suppress aberrations, especially chromatic and spherical aberrations; otherwise, it will lead to blurred edges in the thermal image or distorted temperature distribution.
Algorithm optimization is essential for improving temperature measurement accuracy. The infrared radiation signal of micrometer-scale targets is often weak and easily affected by background radiation, detector noise, and environmental interference. Research-grade thermal imagers can significantly improve the signal-to-noise ratio through multi-frame accumulation, non-uniformity correction, and dynamic noise suppression algorithms. For example, combining time averaging with spatial filtering can eliminate random noise while preserving the target's thermal characteristics. By establishing a detector response model and performing nonlinear correction on each pixel, temperature measurement deviations caused by device differences can be reduced. Furthermore, some devices incorporate deep learning algorithms to train neural networks to identify target thermal patterns, further reducing measurement uncertainty in complex scenarios.
Environmental control is essential for ensuring the stability of micrometer-level temperature measurements. Temperature fluctuations, air convection, and background thermal radiation can all introduce measurement errors. In scientific experiments, thermal imagers are often placed in constant temperature and humidity environments and equipped with heat shields to reduce external thermal interference. For example, in semiconductor materials research, the equipment may be integrated into a vacuum chamber, eliminating air convection through vacuuming and using liquid nitrogen cooling to reduce the detector's own thermal noise. Additionally, placing a low-temperature shield around the target can effectively isolate background radiation and improve the thermal contrast between the target and the environment.
Multimodal fusion technology further expands the application boundaries of micrometer-level temperature measurement. Research-grade thermal imagers are often used in conjunction with Raman spectrometers, atomic force microscopes, and other equipment to achieve simultaneous measurement of thermal, mechanical, and electrical multiphysics fields through data fusion. For example, in microelectronic device research, thermal imagers can provide information on the surface temperature distribution of devices, while Raman spectrometers can simultaneously acquire local lattice vibration information. Combining these two technologies can reveal the microscopic mechanisms of thermal failure. Such multimodal systems require solving challenges such as data synchronization, spatial registration, and unit conversion, typically relying on high-precision calibration targets and customized software.
The expansion of application scenarios validates the research value of thermal imagers in micrometer-scale temperature measurement. In materials science, they are used to study the thermal conduction mechanisms of nanowires and two-dimensional materials, revealing phonon transport patterns by observing the thermal diffusion process of microstructures. In biomedicine, thermal imagers can non-contactly monitor subtle temperature changes caused by cell metabolism, providing new methods for early disease diagnosis. In microelectromechanical systems (MEMS) development, they can quantify the thermal deformation of structures such as microbeams and microgears, guiding the optimization of device thermal stability. All these applications rely on the high-precision temperature measurement capabilities of thermal imagers at the micrometer scale.
In the future, with breakthroughs in metamaterials, quantum dot detectors, and terahertz thermal imaging technologies, the micrometer-scale temperature measurement capabilities of thermal imagers will be further enhanced. For example, infrared lenses based on metasurfaces can break through the traditional optical diffraction limit and achieve sub-micron spatial resolution; quantum dot detectors, with their high sensitivity and tunable response bands, are expected to improve the efficiency of capturing thermal radiation from specific materials; and terahertz thermal imaging can penetrate certain non-polar materials to achieve temperature measurement of buried microstructures. These advances will drive thermal imagers to play a key role in a wider range of scientific research fields.
