Interpreting Results

Intensity Color

CIE chromaticity of the emission spectrum

This guide introduces Intensity Color, which uses the emission spectrum to calculate CIE chromaticity coordinates at each output angle. Use it to view emission color and its angular change.

Requirements

Intensity Color requires all three of the following conditions to produce chromaticity results:

The Intensity detector is enabled in the Emission lane of the Optics page.
The Intensity Wavelength Mode is set to Sweep.
The wavelength sweep covers 360–780 nm at a step of ≤ 5 nm.

All three conditions must be met simultaneously. On the Emission Detectors configuration page, click the auto-fix button (Set wavelength 360–780 nm, step 1) to apply all settings at once.

Spectral convention for chromaticity integration

CIE tristimulus values are integrated from the emitted radiant-power spectrum:

X=\int P_\lambda(\lambda)\bar x(\lambda)d\lambda,\qquad Y=\int P_\lambda(\lambda)\bar y(\lambda)d\lambda,\qquad Z=\int P_\lambda(\lambda)\bar z(\lambda)d\lambda

Here, $X$ , $Y$ , and $Z$ are the CIE tristimulus values, $P_\lambda(\lambda)$ is the emitted radiant-power spectrum at the current output angle, and $\lambda$ is wavelength. $\bar x(\lambda)$ , $\bar y(\lambda)$ , and $\bar z(\lambda)$ are the color-matching functions of the selected standard observer; the integration covers the sampled visible range.

When an emitter uses Probability, its photon-number spectrum is multiplied by the photon energy $hc/\lambda$ before chromaticity integration. With Power, the input spectrum is already in the required power convention. Here, $h$ is the Planck constant and $c$ is the speed of light in vacuum. Because this conversion varies with wavelength, broad and multi-peak white spectra are generally more sensitive to Spectrum Unit than narrowband spectra.

For one emitter, Conversion Efficiency and Multiplication Factor apply a common scale to the entire spectrum and therefore do not change chromaticity coordinates. With several emitters, different efficiencies and factors change their relative spectral weights and can change the mixed color.

Reading the chromaticity

The chromaticity diagram uses the CIE 1931 standard, mapping each angle's integrated emission spectrum to an (x, y) coordinate. Each angle with visible emission appears as one point on the diagram.

Observer standard: Chromaticity calculation supports both the 2° standard observer and the 10° standard observer, selectable in the Intensity configuration panel on the Optics page. The observer is frozen at the time of calculation — changing it after a run does not update the result; a new run is required.

Angle distribution: When Intensity uses angle sweep (Angle Mode = Sweep), the diagram shows one point per emission angle, representing the color at each direction. If the emission color is uniform across angles, all points cluster at the same location.

Intensity Color CIE chromaticity diagram

When multiple chromaticity points are present, the "Connect Data Points" toggle in the right-side controls draws a line through the points, making it easy to track how color shifts across emission angles.

If any angle has no effective emission in the visible range (360–780 nm), that angle is omitted from the diagram and a skipped-angle count is shown on the page.

When color is unavailable

When any of the following conditions occur, the Intensity Color page cannot display chromaticity results and shows a corresponding message:

State	Description
No result	The Intensity detector has not been run. Run the calculation first. Message: "Run the Intensity detector to compute emission color."
Weighted Average mode	Intensity is in Weighted Average wavelength mode — the wavelength dimension is collapsed and cannot be integrated for chromaticity. Switch to Sweep mode and rerun. Message: "Wavelength is in Weighted Average mode — switch Intensity wavelength to Sweep to compute color."
Single wavelength	Only one wavelength point was sampled. Computing chromaticity requires a multi-point spectrum covering the visible range. Set wavelength to a Sweep covering 360–780 nm and rerun. Message: "Only one wavelength sampled — set Intensity wavelength to a Sweep covering 360–780 nm to compute color."
No visible emission	No visible emission was detected in the sampled range (integrated intensity in 360–780 nm is zero). Check the emitter spectrum file or EML configuration. Message: "No visible emission in the sampled range."

Controls

Control	Function
Observer (2° / 10°)	Select the CIE standard observer in the Intensity configuration on the Optics page; affects the calculation, not just the display — a new run is needed for changes to take effect
Chart / Table toggle	Switch between the CIE chromaticity diagram and the per-angle color data table
Connect Data Points	Draw a line through chromaticity points in angle-sweep mode
Export CSV	Export per-angle chromaticity coordinates and color values

To see how emitted power is distributed across optical modes (Top Outcoupling, Bottom Outcoupling, Waveguide, etc.), go to Mode.

Intensity

Angular and spectral emission intensity, global peaks, envelope FWHM, and normalized views

Overview

From results pages to sweep and optimization analysis