Melanosome absorption coefficient

Consider two approaches toward measuring the absorption coefficient of melanosomes:

The following figure summarizes the results from the above studies.

Click here to enlarge

Figure: The absorption coefficient (µa [cm-1]) of the melanosome interior. Data based on threshold for explosive vaporization of melanosomes by various pulsed lasers (from Jacques and McAuliffe 1987 and Jacques et al. 1996), except for data of Goldman and data of Sliney et al. based on optical measurements. The solid red line is based on an in vivo optical fiber spectrometer measurement scaled to match data. The dashed blackline is the approximate expression mentioned at the bottom of this page.

A key lesson:

The concentration of melanin within melanosomes is quite variable. Ten-fold variation is to be expected. However, the general shape of the melanosome absorption spectrum is approximated:

µa = 1.70x1012 nm-3.48 [cm-1] for skin

µa = 6.49x1012 nm-3.48 [cm-1] for retina

where nm refers to the wavelength expressed in nanometers.


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July 7, 1998, Steven L. Jacques