Physics / mechanism
Spectral sensing measures the interaction of electromagnetic radiation with matter across defined wavelength bands — absorption, reflection, transmission, or emission — to identify materials, concentrations, or physical states. Core physics: Beer-Lambert law governs absorption; quantum transitions define fingerprint wavelengths. Key sub-domains: NIR (700–2500 nm) for organics and moisture; SWIR (1–2.5 µm) for silicon wafer inspection and gas detection; MWIR/LWIR (3–14 µm) for thermal and molecular fingerprinting; hyperspectral imaging stacks spatial + spectral data simultaneously. Performance benchmarks: spectral resolution 1–10 nm for grating/FP-based systems; SNR >60 dB for INIR detectors; frame rates 10–100 fps for pushbroom hyperspectral. Detector materials: InGaAs (SWIR), HgCdTe (MWIR/LWIR), emerging colloidal quantum dots and Ge-on-Si for CMOS-compatible integration.
Competitive landscape
Traditional lab spectroscopy (FTIR, Raman, mass spec) competes on accuracy but not form factor or cost. Miniaturised alternatives converge on similar markets:
| Approach | Strengths | Weaknesses |
|---|---|---|
| MEMS Fabry-Pérot | CMOS-integratable, low cost | Narrow FSR, moderate resolution |
| Colloidal QD arrays | Tunable absorption, cheap fab | Stability, uniformity at wafer scale |
| Photonic integrated circuits | High resolution, compact | Narrow band, III-V cost |
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.