High-speed scanless entire bandwidth mid-infrared chemical imaging

Area of Science:

• Optics and Photonics
• Spectroscopy
• Chemical Imaging

Background:

• Mid-infrared (MIR) spectroscopy is crucial for identifying chemical species and functional groups by probing molecular vibrations.
• MIR hyperspectral imaging (HSI) is a powerful optical chemical imaging method, but high-speed and full-bandwidth capabilities remain a challenge.
• Existing techniques often compromise speed or spectral range, limiting their application in dynamic or complex biological systems.

Purpose of the Study:

• To develop a high-speed, entire bandwidth mid-infrared hyperspectral chemical imaging technique.
• To overcome the limitations of current MIR HSI methods regarding speed and spectral coverage.
• To demonstrate the technique's capability for detailed chemical analysis in various samples.

Main Methods:

• Chirped pulse upconversion of sub-cycle pulses at the image plane was employed for MIR HSI.
• The technique achieved a lateral resolution of 15 µm with an adjustable field of view (800 µm × 600 µm to 12 mm × 9 mm).
• Hyperspectral images (640 × 480 pixels) were acquired in 8 s over a spectral range of 640-3015 cm⁻¹ with 1069 wavelength points and a resolution of 2.6-3.7 cm⁻¹.

Main Results:

• The developed MIR HSI technique enables high-speed imaging with a frame rate of 5 kHz for discrete frequency imaging.
• It provides detailed chemical information with high spatial and spectral resolution.
• Successful identification and mapping of components in a microfluidic device, plant cell, and mouse embryo section were demonstrated.

Conclusions:

• The novel MIR hyperspectral chemical imaging technique offers significant advancements in speed and spectral range.
• Its high capacity and performance make it suitable for diverse applications in chemical analysis, biology, and medicine.
• This technique holds great promise for label-free chemical imaging and analysis in various scientific fields.