380nm UV Bandpass Filter OD4

380nm UV Bandpass Filter OD4At the UVA edge (315–400 nm), a 380 nm/10 nm FWHM band pass filter isolates near-UV spectral features while achieving OD4 out-of-band blocking to suppress glare and fluorescence. To ensure high UV transmission and minimal autofluorescence, UV-grade fused silica (transmitting from approximately 185 nm to 2.1 µm) or calcium fluoride (CaF₂; approximately 180 nm to 8 µm) substrates are recommended. Deuterium lamps are ideal for calibration and illumination due to their continuous emission across the 200–400 nm range. Interference filters exhibit a blue shift in wavelength with increasing angle of incidence (AOI); therefore, it is advised to maintain near-normal incidence (close to 0°) and apply anti-reflection (AR) coatings to reduce surface losses. Optical density (OD) is defined as OD = −log10 T. It should be noted that most measurement systems have a practical detection limit of approximately OD 5; therefore, transmission curves beyond this range are typical…