What is the mid IR range?

Mid-Infrared (Mid-IR) Range

The mid-infrared (Mid-IR) range is a specific subsection of the infrared band of the electromagnetic spectrum, which encompasses wavelengths from about 3 to 8 micrometers (μm). This range can be further extended to cover up to 14 μm by some definitions.

Significance of Mid-IR

• Spectroscopy: Mid-IR wavelengths are particularly useful for molecular spectroscopy because many molecules have vibrational and rotational transitions that correspond to these energy levels, making Mid-IR spectroscopy a common tool in chemical analysis.
• Thermal Imaging: Objects at room temperature emit thermal radiation predominantly in the Mid-IR range, making it useful for thermal imaging applications in both military and civilian contexts.
• Environmental Monitoring: The mid-IR range is used to monitor environmental gases and pollutants since many of these compounds have characteristic absorption lines in this spectrum.

Technical Details

In the Mid-IR range, photons have lower energy than visible or near-infrared light, which allows for interactions with lower energy transitions in molecules. The Mid-IR region is further divided into two bands: the short-wavelength infrared (SWIR), from 3 to 5 μm, and the long-wavelength infrared (LWIR), from 8 to 14 μm. These bands have their own distinct absorption characteristics and are used differently in various applications.

One of the challenges of Mid-IR technology is the need for specialized materials for lenses and detectors since standard optical materials like glass do not transmit Mid-IR light effectively. Therefore, materials such as germanium, zinc selenide, and chalcogenide glasses are commonly used in Mid-IR optics.