cussed in the CMD
section of the reference manual.</p>

<h2>Lesson #4 - Chromatic Differences</h2>

<p>When the paraxial ray trace and 3<sup>rd</sup>, 5<sup>th</sup>, and
7<sup>th</sup> order aberrations are calculated at wavelengths other
than the control wavelength, the differences in these values
characterize the 1<sup>st</sup>, 3<sup>rd</sup>, 5<sup>th</sup>, and
7<sup>th</sup> order chromatic behavior of an optical system. The
commands in this lesson are described in the CMD section of the
reference ma