Objective Long-wave infrared has the advantages of good atmospheric transmittance, high temperature sensitivity, and high spatial resolution, making it suitable for various complex environments. Infrared multispectral imaging technology combines the advantages of infrared imaging and multispectral technology, greatly improving the accuracy of target detection. Using an infrared multispectral camera, spatial characteristics, temperature radiation, and spectral characteristics of the target can be obtained. Filter wheel-based multispectral cameras have the advantages of compact structure, small size, high spatial resolution, large field of view, and good flexibility. Domestic and foreign scholars have conducted a lot of research on this. However, these studies have shortcomings such as slow band switching, low frame rate, and low synchronous imaging accuracy, which are not suitable for high-speed imaging applications. This study designs a filter wheel-based infrared multispectral synchronous imaging system for high-speed imaging. To address the synchronization challenges, a phase-locked loop synchronous control method is proposed, and the theoretical accuracy is analyzed and calculated to achieve high-precision synchronous imaging, providing reference for the design of similar instruments.

Methods The synchronous control circuit is the core of the system, and research is conducted on the synchronous control method and imaging accuracy calculation method. Firstly, to address the challenges of synchronization, a cascaded dual closed-loop synchronization control method is proposed to link the pulse signal of the position sensor with the external trigger signal of the detector, ensuring closed-loop frequency synchronization between spectral segment switching and detector imaging. Subsequently, a method for evaluating synchronization imaging accuracy is proposed, along with error analysis and accuracy calculation. Finally, the complete system is developed, and the synchronous imaging accuracy of the encoder and Hall sensor is experimentally tested, followed by infrared imaging experiments.

Results and Discussions Experimental results show that six groups of through-hole images with different phases can be collected (Fig.12-Fig.13), and the imaging center position remains consistent, verifying that the system can achieve band switching synchronized with the detector imaging. After registering the collected images at the pixel level, error analysis results show that the experimental errors of the encoder and Hall synchronous control are both less than 3.255°, meeting the design requirements of the system. The accuracy of the encoder synchronous control is 0.107°, and the imaging error is only one pixel, which is 10 times higher in accuracy compared to the Hall method (Tab.1). The cascaded dual closed-loop synchronization control method can achieve high-precision synchronized imaging for the filter wheel infrared multispectral camera.

Conclusions An analysis of the shortcomings of the existing filter wheel multispectral camera system design is provided, and a filter wheel-type infrared multispectral synchronized imaging design suitable for high-speed imaging is proposed. The electronic architecture of the system is introduced, with a focus on high-precision synchronized imaging technology. To address the synchronization issue, a phase-locked loop synchronous control method is proposed, which utilizes the closed-loop correlation between the pulse signal of the position sensor and the external trigger signal of the detector to ensure precise triggering of imaging under each spectral segment. The synchronization imaging accuracy is quantified for the first time, and an error analysis method for synchronization imaging is proposed to evaluate and calculate the theoretical accuracy. A series of experiments demonstrate the significant effectiveness of the proposed method. The accuracy of the synchronous control based on the encoder is 0.107°, with an imaging error of only 1 pixel, fully meeting the design requirement of 3.255° for the system. High-precision synchronous imaging has been achieved. The system is suitable for high-speed infrared multispectral imaging applications and provides a reference for the design of similar imaging instruments.