Microsecond-scale mid-infrared energy deposition (MIRED) spectroscopic imaging

The mid-infrared photothermal microscope enables super-resolution imaging of living systems in water. However, the slow tuning of the laser limits spectroscopic imaging output to one color per second. To solve this, we developed a microsecond-scale spectroscopic detection scheme with a fast-tuning quantum cascade laser array. Each laser in the array emits at a slightly different wavelength, operating independently. A sequential emission from 32 lasers is completed within 4 microseconds. The absorption spectrum is acquired by capturing the temperature rise curve and calculating the first derivative. This improved spectroscopic imaging covers 150 cm-1 wavenumbers at 5 cm-1 resolution in one second, enabling real-time multiplexed molecular analysis.