CRI-4 is a colour-rendering improvement (CRI) filter that warms and smooths spiky LED/HMI spectra by trimming deep blue and broad yellow-green while preserving a clean cyan window and strong long-red. Transmission sits high in near-blue (~82–90% from ~390–440 nm), dips to ~40–42% at a narrow notch near ~455–465 nm, rebounds to ~92–94% across ~490–520 nm, then forms a broad trough of ~33–36% centered ~565–575 nm. It rises to ~92–95% from ~630–705 nm, easing to ~86–90% around ~730–760 nm and finishing near ~90% by ~780 nm.
Key advantages
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Raise CRI/TLCI and R9 — moderates the ~460 nm spike and the ~540–600 nm band while keeping long-red energy for natural skin, wood, food, and fabrics.
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Targeted blue control — a measured notch at ~455–465 nm reduces harsh LED blue without crushing cyan detail.
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Cyan window preserved — high throughput (~92–94% T) across ~490–520 nm keeps whites crisp and skies clean.
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Broad green/yellow shaping — smooth trough (~33–36% T) around ~565–575 nm delivers predictable, non-banded correction.
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High long-red throughput — ~92–95% T from ~630–705 nm with gentle roll-off beyond ~720 nm for rich reds and flattering faces.
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Built for production — durable dielectric stack for sets, stages, and architectural fixtures; optional rear-surface AR and slight wedge to suppress ghosts.
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Custom formats — Borofloat®, Eagle XG, or D263 T (0.21–3.8 mm) for high-temp duty to ~450 °C; soda-lime for ≤150 °C. Sizes 5–450 mm.
Typical applications
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Cinema/TV lighting — lift TLCI/CRI and skin-tone accuracy with less in-camera correction.
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Photography & events — warmer, more flattering faces and textiles under LED or HMI.
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Retail, museum & hospitality — reduce green cast and reveal natural reds in merchandise and art.
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Architectural & display — refine off-the-shelf luminaires for premium colour.
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Machine vision — stabilize channels where red features matter and blue/green glare is problematic.
Need test chips tomorrow or thousands next quarter? CRI-4 filters are coated and cut-to-size (including dicing) to your exact spec—fast.
