Blue colored glass is a type of optical filter material that exhibits high transmittance in the blue-green region of the visible spectrum while demonstrating strong absorption in the red and near-infrared bands — this is its most fundamental optical behavior. It achieves selective spectral absorption through the doping of specific metal ions (such as Cu²⁺, Co²⁺, etc.) into the glass matrix, making it an essential fundamental component for spectral regulation in optical systems.
Excellent spectral selectivity, capable of blocking unwanted wavelengths without the need for coatings
Good temperature stability and high processing flexibility
The cut-off edge is not steep enough
Peak transmittance has a practical upper limit
| Color Category | Typical Spectral Characteristics | Peak Transmission Band | Cut-off / Attenuation Band | Typical Applications |
| Blue | Blue-green bandpass, red/NIR cutoff | 400–520 nm | ≥ 550 nm (cut-off) | Underwater photography filters, fluorescence excitation, color temperature correction, laser safety windows |
| Gold | Yellow-orange bandpass, blue/UV cutoff | 530–620 nm | ≤ 480 nm (cut-off) | Sodium line filtering, night vision protection, low-light imaging, fluorescence observation |
| Green | Green bandpass, dual cutoff (red & blue) | 500–560 nm | ≤ 480 nm & ≥ 610 nm | Traffic signal filters, machine vision contrast enhancement, reticle aiming |
| Purple | Violet-blue bandpass, mid-IR & visible cutoff | 350–450 nm | ≥ 480 nm (cut-off) | UV fluorescence excitation, black light filters, currency authentication, biochemical analysis |
| Red | Red bandpass, green/blue cutoff | 620–750 nm | ≤ 590 nm (cut-off) | Laser sight filters, traffic signals, IR temperature measurement windows, darkroom lighting |
| Neutral | Uniform attenuation across full visible spectrum, no wavelength selectivity | 400–700 nm (uniform transmission) | No cut-off peak; constant transmission | Light intensity adjustment/attenuation, laser power attenuation, exposure control, optical balancing |
