Evaluating NDIR Optical Cavity Signal Degradation under Field Humidity Exposure
Field humidity degrades NDIR cavities through liquid condensation scattering and mirror oxidation, requiring hydrophobic vents and controlled wall heating.
Diamond like Carbon Coating
Surface Protection
Amorphous carbon films provide high hardness and low friction coefficients for mechanical and optical components. Applying a diamond like carbon coating increases the durability of infrared optics exposed to abrasive environments. The film acts as a barrier against windborne sand and salt spray.
Friction Reduction
Interfacial energy is minimized by the unique atomic structure of the deposit. A diamond like carbon coating reduces the wear rate on moving parts by preventing direct metal to metal contact. Lubrication requirements are frequently lowered in systems using these treatments.
Refractive Index
Spectral properties of the film must be matched to the underlying germanium or silicon substrate to maintain transmission. Since the diamond like carbon coating has a high refractive index, it often functions as an antireflection layer for the eight to twelve micrometre band. Layer thickness is tuned to the specific target wavelength.
Adhesion Quality
Metrological testing of the bond strength involves nano indentation and scratch tests to ensure the film does not delaminate under stress. Standard specifications for diamond like carbon coating include hardness values exceeding 20 gigapascals. Environmental cycling verifies that the coating survives rapid temperature changes without cracking.
Stress in the film is managed by controlling the ion energy during the deposition process.