Collection: 3.3μm Bandpass Filter

Context: A thermography camera system modified to detect the specific infrared absorption signatures of gases.

Usage of Filter: The filter is positioned in the optical path between the lens and the Focal Plane Array (FPA), often cooled to minimize self-emission.

Function: It acts as a spectral gate, transmitting only the radiation wavelengths that correspond to the C-H bond vibrational modes of alkane gases.

Result: It transforms a standard thermal imager into a gas-specific radiometer, enabling the operator to see gas leaks that would otherwise be indistinguishable from thermal noise.

Context: A Correlated Interference Polarization Spectrometer (CIPS) used for remote sensing and quantitative analysis of gas concentrations.

Usage of Filter: The filter is used as a broadband pre-filter placed before the interference polarization assembly.

Function: It isolates the broader 3.3 $\mu$m window to select the target spectral order, preventing out-of-band light from creating aliasing or noise in the fine interference pattern.

Result: It ensures high-fidelity spectral data, allowing the system to distinguish and quantify specific hydrocarbon molecules with high precision.