SCHOTT BG40 IR-Cut Glass — 1.6 mm, BBAR / AR — One Surface

SCHOTT BG40 IR-cut glass

SCHOTT BG40 absorbing near-IR filter glass. 1.6 mm requested finished thickness; BBAR / AR — One Surface. Review the 380–1100 nm spectrum, red-light transmission and IR rejection together. Cut size and fabrication confirmed by quotation.

Red edge and near-IR rejection

Absorptive glass provides a gradual spectral roll-off rather than a fixed, abrupt cutoff. More thickness improves infrared rejection but also reduces useful visible and red transmission. Specify the edge definition and maximum allowed transmission across the entire blocked band; a single cutoff wavelength does not define blocking performance. Absorbed power becomes heat. No standalone NVIS compliance is implied.

Calculated internal transmission at 1.6 mm

Calculated from published 1 mm reference data using T_i(d) = T_i(d_ref)^d/d_ref. Values reported below the source limit are upper-bound estimates.

Read the spectral overlays

The graph covers 380–1100 nm, with the published 1 mm reference dashed and calculated 0.7, 1.1, 1.6, 2 and 3 mm curves. Source: SCHOTT BG40 datasheet, 04.01.2023, 10 nm reference samples. Calculations assume homogeneous glass and normal incidence. Internal transmission excludes surface reflection and coating effects; the graph does not establish total transmission of a finished coated filter.

Finished thickness and coating

1.6 mm is a requested custom finished thickness. Confirm blank size, polishing, thickness tolerance, clear aperture and edges. One surface specified for BBAR / AR treatment; define the coated face and useful band. AR is not itself an IR-blocking coating.

Lot tracked. Availability, dimensions and optical requirements are confirmed by quotation. Plotted thicknesses do not establish stock or fabrication feasibility.

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