MWIR thermal imaging spectrometer based on the acousto-optic tunable filter

Area of Science:

• Optics and Photonics
• Infrared Spectroscopy
• Remote Sensing Technology

Background:

• Mid-wavelength infrared (MWIR) thermal imaging spectrometers are crucial for remote sensing, industrial detection, and military applications.
• Acousto-optic tunable filter (AOTF)-based spectrometers offer advantages like fast tuning and no moving parts for MWIR applications.
• Traditional optical design methods using refractive gratings or parallel glass models to simulate AOTFs limit imaging performance.

Purpose of the Study:

• To develop an accurate simulating model for an actual MWIR AOTF using a user-defined surface function in ZEMAX.
• To design and test an AOTF-based MWIR thermal imaging spectrometer utilizing this new model.
• To evaluate the performance and effectiveness of the developed imaging spectrometer.

Main Methods:

• Implementation of a user-defined surface function in ZEMAX optical design software to accurately model a MWIR AOTF.
• Design of a MWIR thermal imaging spectrometer based on a tellurium dioxide (TeO2) AOTF.
• Integration of a three-mirror off-axis afocal telescope with a 2.4°×2.0° field of view.
• Computer control for spectrometer operation and image acquisition.
• Laboratory testing and experimental validation of the imaging spectrometer.

Main Results:

• Successful design and testing of an AOTF-based MWIR thermal imaging spectrometer.
• The spectrometer operates in the 3.0 to 5.0 μm spectral range with a resolution of 30.8 nm at 3.392 μm.
• Experimental results confirm the efficiency of the proposed AOTF model.
• The imaging spectrometer demonstrated effective discrimination between real hot targets and interfering targets.

Conclusions:

• The developed user-defined surface function model in ZEMAX provides an accurate simulation for MWIR AOTFs.
• The AOTF-based MWIR thermal imaging spectrometer is a viable and high-performing system for target detection and identification.
• This technology enhances the capabilities of thermal imaging in various critical applications.