There are many different analysis features included in ZEMAX, each of which can be used to evaluate the performance of a design.  In this exercise, we will use four of the more fundamental, commonly known types of analyses of system performance to evaluate the singlet prior to optimization:

Layout	A layout may be opened by selecting a Analysis > Layout > 2D Layout from the main menu, or by pressing the “Lay” button on the button bar.  The 2D Layout option plots a YZ cross section through the lens, and is only valid for rotationally symmetric, axial systems.  A layout diagram of the current system is always a useful visual representation of the current optical system.
Spot Diagram	A spot diagram may be accessed by selecting “Analysis > Spot Diagrams > Standard” from the main menu, or by pressing the “Spt” button on the button bar.  The spot diagram gives indication of the image of a point object.  In the absence of aberrations, a point object will converge to a perfect image point.  By default, ZEMAX plots the spot diagram for each field point.
OPD Fan	The Optical Path Difference (OPD) fan can be opened by selecting “Analysis > Fans > Optical Path,” or by pressing the “Opd” button on the button bar.  The OPD fan is a plot of the optical path difference as a function of pupil coordinate.  In a perfect optical system, the optical path of the wavefront will be identical to that of an aberration-free spherical wavefront in the exit pupil.
Ray Fan	The Ray Fan plot in ZEMAX may be opened by selecting “Analysis > Fans > Ray Aberration” from the main menu in ZEMAX, or by selecting the “Ray” button on the button bar.  The Ray Fan plots ray aberrations as a function of pupil coordinate.  Generally, a given ray which passes through the optical system an onto the image surface, its point of intersection falls on some small but nonzero distance away from the chief ray.  Once again, in a perfect optical system, the ray aberrations should be zero across the pupil.

Note that the Spot Diagram, OPD Fan, and Ray Fan Plot are some of the most important tools that a lens designer has available for determining the different types and magnitudes of aberrations present in an optical system.  However, the process by which a designer can determine the aberrations present in his/her deisgn from these analysis features goes beyond the scope of this exercise.  Instead, these concepts are covered in great detail in several of the references mentioned in Chapter 1 of the ZEMAX User’s Guide.

Given the arrangement of the design we have constructed so far, open each one of the above analysis features to review the current lens performance.

From evaluation of the four plots above, it is obvious that the singlet design has a significant number of aberrations, including but not limited to spherical, coma, distortion, defocus, field curvature, and astigmatism.  In addition, the geometrical and RMS radii (as is reported at the bottom of the Spot Diagram) at the maximum field are roughly 734.581 and 1774.42μm, respectively.