So far we've been labeling and defining attributes of the blood. The
point of this excercise is to understand how a pulse oximeter measures
them. People have known for a while that different hemoglobin
-complexes (HbO₂, HHb, MHb, HbCO, …) have differnt absorbtion
-spectra (Fig.~\ref{fig:absorbtion}), and they have been using this
-difference since the 1930's to make pulse-oximeters based on two-color
-transmittance measurements (see [Tremper 1989][T89]).
+complexes (HbO₂, HHb, MHb, HbCO, …) have differnt absorbtion spectra,
+and they have been using this difference since the 1930's to make
+pulse-oximeters based on two-color transmittance measurements (see
+[Tremper 1989][T89]).
[[!img absorbtion.png
size="600x418"
wavelength $\lambda$</dd>
<dt id="L">$L$</dt><dd>Length of tissue through which light must pass</dd>
<dt id="LDC">$L_\text{DC}$</dt><dd>Diastolic finger width</dd>
- <dt id="R">$R$</dt><dd>Optical density ratio}</dd>
+ <dt id="R">$R$</dt><dd>Optical density ratio</dd>
<dt id="LED">LED</dt><dd>Light emitting diode</dd>
</dl>