Dye Editor

Note: Dye Editor is only available for fluorescent material.

Note: You can create, open or save a pigment. In this case you can save your pigment as a .dye file.

In diffusing and fluorescent material, light can interact with a particle. The probability of a photon to propagate without interaction follows the extinction laws:

Transmission = exp (- extinction coefficient * thickness)

Light interacting with dyes can be absorbed, scattered or fluoresced. The extinction coefficient is composed of the spectral absorption, scattering and fluorescence (quantum efficiency) coefficient. These coefficients are evaluated with absorption, efficiency and excitance spectrum. Excitance spectrum is absorption times efficiency. Then user has to define only spectrum of the list.

When propagating a photon, a random distance is computed according to extinction coefficient.

Then the photon has a probability equal to the quantum efficiency (efficiency spectrum) to be re-emitted with a new wavelength.

This new wavelength is chosen randomly using the dye's emission spectrum.

Finally, a new random direction for the photon is computed.

Note: For the computation, the photon's direction generated by florescence does not depend on the photon's direction which has been absorbed. It is emitted again in an isotropic way, with all directions equiprobable.

Then the photon is propagated to the next interaction.

Spectrum

You must select two spectra.

Absorption Spectrum

Each dye has an absorption spectrum.

Absorption is proportional to the concentration. Absorption spectrum has to be defined in mm-1.

You can click Spectrum to edit a spectrum or browse an existing spectrum. For more details, you can view Spectrum Editor.

Efficiency Spectrum

The efficiency value is spectral. The related spectrum has to be written in percentage.

You can click Spectrum to edit a spectrum or browse an existing spectrum. For more details, you can view Spectrum Editor.

Excitance Spectrum

Excitance spectrum is expressed in mm-1 and is obtained by multiplying the absorption spectrum by the efficiency spectrum.

You can click Spectrum to edit a spectrum or browse an existing spectrum. For more details, you can view Spectrum Editor.

Emission Spectrum

You can click Spectrum to edit a spectrum or browse an existing spectrum. For more details, you can view Spectrum Editor.

Scattering Properties

Define in this table the properties of photon scattered by the dyes particles.

For more details, you can view Scattering properties.

Particle: Refractive Index and Size

Particle: refractive index and size is available when Give particles specifications: Optical properties of the medium will be evaluated using MIE theory from Scattering properties tab has been selected.

With Particle: refractive index and size tab, you can select a .material file containing the pigment refraction index. In this case the material absorption, diffusion and fluorescence parameters are not taking into account.

Emission Distribution Type

Emission distribution tab define properties of photon fluoresced by the dyes particles.

Emission distribution type tab is available when Unscattering material from Scattering properties tab has not been selected.