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Phaos Light Lab // Research Archive

The Science of Light

An authoritative research repository investigating optical geometry, photometric science, retinal adaptation, and non-visual photobiology for lighting designers and architects.

10Research Categories
CIE / IESStandard Standards
UGR < 6Darklight Protocol
Experimental Laboratory Tool // Three.js & R3F

3D Architectural Photometry Simulator

Interactively manipulate luminaire optical beam spread (8°–65°), wall setback distance (0.2m–3.5m), and Planckian CCT values. Real-time demonstration of Spot, Flood, Wallwash, Grazing, and Accent dynamics.

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Interactive Optical Instrument // CIE 117-1995 Glare Simulator

Cutoff Angle vs. Retinal Glare Discomfort (UGR)

Calculated UGR:4.2Black-Hole Darklight
Physical Shielding / Cutoff Angle (θ_c):55°
25° (Wide Diffuse)45° (Standard)55°+ (Phaos Darklight)
Emitter Luminous Package:1200 Lumens
500 lm1,500 lm3,000 lm
Showing 4 research monographs
GLAREMonograph 01 • 10 min reading time
Phaos Optical Engineering Group • January 2026

The Physics of Source Concealment: Controlled Angular Luminance Architecture for Architectural Lighting

An engineering investigation into physical shielding geometry, angular luminance distribution L_a(θ, φ), and retinal straylight attenuation.

Glare control cannot be resolved through secondary electronic dimming alone. This technical paper articulates a 5-domain optical framework demonstrating how physical shielding geometry governs angular luminance L_a(θ, φ), suppressing high-angle ocular straylight and preserving retinal target contrast.

Mathematical Expression:
Unified Glare Rating (CIE 117-1995)
UGR = 8 \cdot \log_{10} \left( \frac{0.25}{L_b} \sum_{i} \frac{L_i^2 \cdot \omega_i}{p_i^2} \right)

Standard CIE formulation for interior discomfort glare. Demonstrates that as visible solid angle ω_i → 0 via physical shielding, the luminaire’s direct contribution to the summation approaches zero, leaving only secondary surface contributions.

Standards referenced:CIE 117:1995 / IES RP-16-17CIE 117:1995 / CIBSE SLL Code for Lighting
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OPTICSMonograph 02 • 10 min reading time
Phaos Optical Engineering Group • February 2026

Asymmetric Micro-Prismatic Extraction: Uniform Vertical Surface Illuminance Engineering

Optical refraction mechanics of free-form micro-prismatic optics for high-uniformity vertical boundary illumination.

Conventional spotlights aimed at walls generate hyperbolic scallops and intense localized luminance peaks. This technical paper analyzes the optical refraction mechanics of asymmetric micro-prismatic optics designed to project uniform illuminance across vertical architectural boundaries.

Mathematical Expression:
Point-by-Point Illuminance on Vertical Surface
E_v(y) = \frac{I(\theta, \phi) \cdot \cos(\gamma)}{d^2 + (H - y)^2}

Calculates vertical illuminance E_v at height coordinate y on a wall, factoring in three-dimensional candela distribution I(θ, φ), total optical path length, and angle of incidence γ on the vertical surface normal.

Standards referenced:EN 12464-1:2021CIE 121:1996
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COLOURMonograph 03 • 11 min reading time
Phaos Optical Engineering Group • March 2026

Beyond CRI: Evaluating Light Source Color Rendition Using ANSI/IES TM-30-24

Fidelity index (R_f), gamut index (R_g), and local chroma shifts across architectural materials.

CRI R_a relies on eight historic pastel test samples established in 1965. This technical research note examines the 99 standardized Color Evaluation Samples of ANSI/IES TM-30-24, demonstrating how two-dimensional fidelity, gamut vector analysis, and material reflectance spectra characterize architectural material appearance.

Mathematical Expression:
TM-30 Fidelity Derivation Framework
R_f = f\left(\overline{\Delta E}_{\text{CAM02-UCS}}\right), \quad \overline{\Delta E} = \frac{1}{99} \sum_{i=1}^{99} \Delta E_{\text{CAM02-UCS}, i}

ANSI/IES TM-30-24 derives the overall Fidelity Index R_f from the mean color difference of the 99 standardized Color Evaluation Samples (CES) in CAM02-UCS space using the prescribed non-linear scaling transformation and bounding algorithms.

Standards referenced:ANSI/IES TM-30-24ANSI/IES TM-30-24
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MELANOPIC LIGHTMonograph 04 • 10 min reading time
Phaos Optical Engineering Group • February 2026

Melanopic Equivalent Daylight Illuminance (m-EDI) in Architectural Lighting

Metrological foundations of non-visual ocular photoreception per CIE S 026:2018.

Human ocular photoreception comprises both visual image-forming and non-visual ipRGC neuroendocrine pathways. This technical paper details the metrological translation between photopic illuminance and melanopic equivalent daylight illuminance (m-EDI) across architectural interior environments.

Mathematical Expression:
Melanopic Equivalent Daylight Illuminance (CIE S 026:2018)
\text{m-EDI} = E_v \cdot \text{m-DER}, \quad \text{m-DER} = \frac{\int S(\lambda) \cdot s_{\text{mel}}(\lambda) \, d\lambda}{\int S(\lambda) \cdot V(\lambda) \, d\lambda} \cdot \frac{K_{m,v}}{K_{m,\text{mel},D65}}

Converts corneal photopic illuminance E_v into Melanopic Equivalent Daylight Illuminance (m-EDI) using the melanopic daylight efficacy ratio (m-DER), derived from the spectral power distribution S(λ).

Standards referenced:CIE S 026:2018CIE S 026:2018
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