materialSpectra: compute standard material spectra

Description

Compute hypothetical neutral gray material reflectance/transmittance, and absorbance of the human lens, as a function of age.

Usage

neutralMaterial( gray=1, wavelength=380:780 )
lensAbsorbance( age=32, wavelength=400:700 )

Arguments

gray

a vector of gray levels, in the interval [0,1]. gray=1 represents the perfect reflecting diffuser.

age

a vector of ages in years; all ages must be >= 20.

wavelength

a vector of wavelengths for the returned object

Value

neutralMaterial returns a colorSpec object with quantity equal to 'reflectance'. The reflectance of each spectrum is constant. The number of spectra in the object is the number of gray levels = length(gray). lensAbsorbance returns a colorSpec object with quantity equal to 'absorbance'. The absorbance model for the human lens is taken from Pokorny. The number of spectra in the object is the number of ages = length(age).

References

Pokorny, Joel, Vivianne C. Smith, and Margaret Lutze. Aging of the Human Lens. Applied Optics. Vol. 26, No. 8. 15 April 1987. Table I. Page 1439.

Examples

Run this code

#   make a perfect reflecting diffuser (PRD)
prd = neutralMaterial( 1 )

#   make a perfect transmitting filter (PTF)
ptf = prd
quantity(ptf) = 'transmittance'

#   compare transmittance at 3 ages: 20, 32, and 80 years
plot( linearize(lensAbsorbance( c(20,32,80) )), col='black', lty=1:3 )