Application of Resonance Raman Spectroscopy to the Detection of Carotenoids In Vivo - Carotenoids: Physical, Chemical, and Biological Functions and Properties - page 106

Fiber bundle VHTG

Multiline
Ar +
laser

CCD camera

S1

Fiber

L1

L3 F1

BS

M

488 nm
514.5 nm

M L6

L5 NF

M

L4 F2

L2

Fiber

S2

(a)

(b)

FIGURE 6.15 (a) Schematics of RRS instrument developed for selective in vivo measurements of lycopene
and β-carotene in human skin. The optical probe features two excitation channels for blue and green light
supplied by a two-color argon laser. (b) Computer monitor display of instrument. After each measurement, the
software interface displays the raw and processed Raman spectrum obtained with the respective excitation
wavelength. Using both spectra, it also calculates separately the concentration for lycopene and the concentra-
tion for the remaining β-carotene-like carotenoids present in the measured tissue site. (From Ermakov, I.V.
et al., SPIE Proc ., 5686, 131, 2005. With permission.)

the spectrally broad background l uorescence with the l uorescence response at a wavelength that is
slightly offset from the MP Raman response. MP Raman measurements are a measure of absolute
MP concentration levels since the method does not use a reference point in the peripheral retina.
Attenuation effects caused by the optical media are therefore fully effective, and have to be avoided