230nm Bandpass Filter

Context: Systems and processes for early detection of biological ammonia oxidation in water (drinking water utilities).

Usage of Filter: Optical Excitation Filter.

Function: The filter is placed in the optical path of a fluorometer to isolate and transmit only the specific 230 nm wavelength from the light source (e.g., Xenon flash or LED) onto the water sample.

Result: It successfully excites the biological byproducts of nitrification, causing them to fluoresce at ~345 nm. This allows the system to detect water quality degradation (nitrification events) days or weeks earlier than traditional chemical testing.

Context: Measurement of nitrate-nitrogen concentration in soil based on optical attenuation (Precision Agriculture).

Usage of Filter: Spectral Selection / Isolation Filter.

Function: The filter restricts the measurement light to the deep UV region (specifically including the 200–230 nm range). This is the specific spectral fingerprint where Nitrate (NO3) strongly absorbs light.

Result: By measuring the absorbance (attenuation) of this 230 nm light through the soil extract, the device calculates the precise nitrate concentration, enabling real-time, on-site soil fertility mapping without complex lab reagents.

Context: Antimicrobial device using ultraviolet light (Far-UVC) for disinfection in occupied spaces.

Usage of Filter: Safety Cut-off / Emission Shaping Filter.

Function: While the device generates UV light (via electron beam or excimer source) in the 200–230 nm range, a bandpass filter is typically used as the "exit window" or secondary optic to block any harmful wavelengths above 230 nm (such as the 254 nm peak) which are dangerous to humans.

Result: The device effectively kills pathogens (bacteria/viruses) using the 200-230 nm energy, but remains safe for human skin and eyes, allowing for continuous disinfection while people are present.