BH-S18 Multi-Range Filter

The BH-S18, also designated B64, offers a shortpass profile with its 50 % cut-off measured at 519.2 nm. The passband is exceptionally bright, peaking at 95.1 % near 481 nm and averaging above 92 % from 380 to 502 nm. Unlike some shortpass filters, the BH-S18 features a gradual transition slope rather than a razor-sharp edge, with residual transmission of approximately 9 % in the yellow and 8 % in the red band, and a secondary rise to about 23 % in the NIR. This softer roll-off is characteristic of the B64-class coatings, designed for applications that prioritize passband flatness and spectral smoothness over absolute edge steepness.

Key Advantages

• 519 nm cut-off with 95.1 % peak – Bright passband covering 380-502 nm at > 92 % average, delivering efficient blue-cyan throughput.
• Smooth transition slope – Gradual roll-off from 500 to 550 nm reduces spectral ringing and coating stress, improving wavefront quality.
• B64-class coating design – Optimized for passband flatness and coating robustness rather than maximum edge steepness.
• Hard-oxide durability – Ion-assisted sputtered coating survives thermal cycling, humidity, solvents, and repeated cleaning.
• Custom formats – Round, square, or free-form blanks from 5 mm to 450 mm, thickness 0.21-3.8 mm, on Borofloat, soda-lime, Schott D263 T, or Corning Eagle XG glass.

Typical Applications

• Broadband blue-cyan filtering – Provides a wide, spectrally smooth blue-cyan window for imaging systems that require clean passband shape over absolute blocking depth.
• Visual photometry – Approximates a CIE photopic short-wavelength weighting function for luminance measurements.
• Machine vision with soft color separation – Separates blue-cyan from green in systems where a gradual transition reduces edge artifacts.
• Projection optics – Smoothly splits cool and warm tones in projection light engines without introducing spectral discontinuities.
• LED color management – Shapes blue-cyan LED output for color mixing systems where smooth spectral profiles improve uniformity.

Need the BH-S18 in a specific size or substrate? KUPO Optics provides rapid prototyping and volume production - contact us.