Definition (40–60 words):
Optical black refers to a material or surface engineered to minimize unwanted light return to an observer or detector. This can be achieved by reducing reflectance, increasing absorbance, or controlling surface gloss. Each metric matters differently depending on whether the goal is imaging accuracy, glare suppression, or visual uniformity.
| Metric | What It Measures | Why It Matters | Typical Use Cases |
|---|---|---|---|
| Total Reflectance | All light reflected from a surface (specular + diffuse) | Directly determines stray light and contrast loss | Optical housings, camera interiors, sensors |
| Specular Reflectance | Mirror-like reflection at equal incident angles | Primary cause of glare and ghosting | Lenses, laser systems, display bezels |
| Absorbance | Fraction of light converted to heat or internal energy | Controls how much light is removed from the system | Beam dumps, optical traps, laser marking |
| Gloss | Perceived shininess related to surface smoothness | Affects visual appearance more than optical performance | Consumer optics, housings, aesthetic parts |
| Haze | Angular spread of reflected or transmitted light | Determines light scattering behavior | Diffusers, matte black coatings |
Imaging systems: Total and specular reflectance dominate performance.
Laser environments: Absorbance and thermal stability are critical.
Visual black surfaces: Gloss and haze shape perceived blackness.
Optical black materials: Must balance all three metrics, not just color.
Many “black” pigments appear dark to the eye but still reflect significant near-infrared or angled light. Conversely, a matte surface with low gloss may still have high total reflectance. Optical black is therefore a system-level property, not a single material parameter.
For application-specific guidance and material selection, see:
Optical Black Material Application Guide
No. Ultra-black typically refers to extremely low reflectance materials (e.g., <1%), while optical black focuses on functional light control within a system.
Rarely. Gloss increases specular reflection, which undermines optical black performance.
Not necessarily. Surface texture and microstructure strongly affect reflectance behavior.
Reflectance measured via integrating sphere (ISO 9050, ASTM E903)
Gloss measured at 60° or 85° (ASTM D523)
Haze evaluated per ASTM D1003
ISO 9050: Glass and optical material reflectance
ASTM D523 – Standard Test Method for Specular Gloss
Optical Engineering Handbook, McGraw-Hill