This paper presents the analytical form of the intrinsic aberration
coefficients for spherical plane-symmetric optical systems expressed
as a function of first-order system parameters and the paraxial chief
and marginal ray angles and heights. The derived aberration
coefficients are in the third and fourth groups with the
multiplication of two or three vector products of pupil and field
vectors.
1. INTRODUCTION
While lens design has historically focused on optical systems that have
rotational symmetry about the optical axis, there have been increasing
efforts to study and design non-rotationally symmetric systems, including
freeform optics [1]. By using a
system off-axis in the field or aperture, the rotational symmetry can be
broken to achieve unobscured reflective systems. Offner designed a unit
magnification relay using field bias [2]. Cook used an offset field and an offset aperture to form the
unobscured three-mirror anastigmat [3]. The rotational symmetry can also be broken by tilting or
decentering optical surfaces. Small tilts and decenters often occur in the
manufacturing and assembly process chain, which was investigated
independently by both Conrady [4]
and Epstein [5]. Cook used
perturbative tilts and decenters to improve performance in the final
optimization stage [6]. Another way
of breaking symmetry is to use rotationally non-symmetric surface types.
Early research was done on anamorphic surfaces independently by both Wynne
[7] and Sands [8].
In the studies mentioned above, the symmetry was broken by deviating from a
parent rotationally symmetric system. Alternatively, Buchroeder introduced
tilted-component optical systems as a new class of rotationally
non-symmetric systems that do not evolve from any parent systems [9]. Buchroeder described these systems
using a principal ray passing through the vertex of each surface. This
description method maintains the properties of Gaussian optics and is a
natural generalization of the on-axis sequential description method. With
the recent emergence of freeform optics [1], more systems are designed without dependence on rotationally
symmetric starting points [10–12].
There has been a strong interest in formulating new aberration theories and
design methods for systems that do not depend on rotationally symmetric
parent systems. Buchroeder found that the aberration contribution from a
spherical surface is symmetric about the local axis that connects the
center of curvature and the center of the pupil [9]. Shack and Thompson expanded the wave aberration theory
of Hopkins [13] in the development
of nodal aberration theory (NAT) [14–18] to express the effect of tilt and decenter on the aberration
field. Fuerschbach et al. used NAT to
derive the formulae for the wave aberrations caused by Zernike freeform
surfaces [19]. Bauer et al. utilized these formulae in a design
method based on analyzing the potential of folding geometries to correct
aberrations [20]. Aberration
theories based on ray tracing were also proposed. Tang and Gross utilized
a mixed ray-tracing method to calculate surface aberration contribution
and differentiate intrinsic and induced (extrinsic) aberration components
in symmetry-free optical systems [21,22]. This method does
not express aberrations as functions of system parameters, and therefore
cannot provide information on how system parameters affect the
aberrations. Caron and Bäumer developed a matrix formalism based on a set
of generalized ray-tracing equations [23,24] to derive ray
aberration coefficients for reflective optical systems and gave an
illustration of ray aberration coefficients for N-mirror confocal systems
where recursive relations between N-mirror and ${\rm N} + {1}$-mirror systems were used [25]. An important question is whether the
recursive relations are valid for more general non-confocal systems, since
the derivation through matrix multiplication becomes increasingly complex
as the number of mirrors increases.
In a different approach to rotationally asymmetric systems, specifically
systems with bilateral symmetry, Sasian built on the vectorial expression
of wavefront aberrations and grouped various aberrations based on the
number of vector products in the aberration expression. He derived the
aberration coefficients in the third group for plane-symmetric
(bilateral-symmetric) systems, which are expressed in system parameters
such as the radius of curvature, the distance between surface vertices,
and the tilt angle [26]. The
expressions help analyze surface contributions and the impact of
parameters. This paper expands the aberration coefficients to the fourth
group for plane-symmetric systems. This expansion enables the ability to
analytically describe higher-order aberrations in plane-symmetric systems,
raising the accuracy of the aberration theory in predicting the image
quality of plane-symmetric systems. This expansion to the fourth group is
especially important for systems with a large field and a fast $F$-number where higher-order aberrations are
significant. Section 2
reviews and illustrates the description method for plane-symmetric
systems. Section 3 reviews
the paraxial optics used in the derivation process. In
Section 4, the fourth
group’s coefficients are defined as pupil and field dependence functions.
In Section 5, an overview of
the derivation process is provided. Section 6 lists the formulae for the aberration coefficients in
the fourth group from the derivations performed. Section 7 provides an example that compares
aberration coefficients calculated from the formulae and from ray tracing
in CODE V lens design software.
2. PLANE-SYMMETRIC SYSTEM DESCRIPTION
The analytical form of the aberration coefficients is determined by which
system parameters are used to describe the optical system. This paper
follows the system parametrization method by Sasian [26] that describes a system following an optical axis ray
(OAR) connecting the center of the object and the center of the aperture
stop of the system. This OAR lies in the plane of symmetry, as shown in
Fig. 1, intersecting each
optical surface where the vertex of the surface is defined. The system is
described sequentially with the location of each surface depending on that
of the previous surface by two parameters: the distance between the
vertices, $t$, and the incident angle of the OAR at the
vertex, $I$. The field and pupil planes are defined
with their centers along the OAR and with tilt angles, ${\theta _h}$ for field planes and ${\theta _\rho}$ for pupil planes, as shown in
Fig. 1. All parameters and
local coordinate systems can have a numerical subscript denoting the
surface they correspond to. In addition, a prime symbol indicates that the
parameter is in the image space of the surface. The refractive index, $n$, and the field and pupil plane tilt
angles defined in the image space of one surface are equal to that defined
in the object space of the next surface.
A local right-handed Cartesian coordinate system is set up for each surface
as well as each field or pupil plane with its origin at the point where
the OAR intersects the surface, the $Z$ axis of the local coordinate systems
along the surface normal, and the $YZ$ plane in the plane of symmetry. The
positive $Z$ direction of each local coordinate system
points toward the propagation direction of the OAR before the surface if
the OAR has undergone an even number of reflections preceding the surface;
otherwise, the positive $Z$ direction points in the opposite
direction. This parameterization method can be applied to both reflective
and refractive systems. An example of a reflective case is shown in
Fig. 1.
All parameters in Fig. 1
adhere to the following sign conventions: (1) distance along the
OAR between two surfaces is positive if measured toward the positive
direction of the local $Z$ axis of the first surface;
(2) counterclockwise angles are positive; (3) the radius of
curvature of a surface is measured from the vertex to the center of
curvature and is positive if measured toward the positive direction of the
local $Z$ axis; (4) the incident and
refractive angles of the OAR, $I$ and $I^\prime$, at each surface are measured from the
surface normal to the OAR; (5) the field and pupil plane tilt
angles, ${\theta _h}$ and ${\theta _\rho}$, are measured from the field and pupil
planes, respectively, to a plane perpendicular to the OAR; and
(6) the refractive index is positive when the OAR is traveling
toward the positive direction of the local $Z$ axis of the previous surface.
Consequently, in Fig. 1, as
a way of example, ${\theta _{h1}}$ and ${\theta
_{h{1^{^\prime}}}}$ are the object and image plane tilt
angles for the Surface 1 and are both positive; ${t_1}$ is the distance measured from Surface 1
to Surface 2 along the OAR and is negative; and ${I_2^\prime}$ is the refractive angle of OAR after
Surface 2 and is negative.
3. PARAXIAL OPTICS IN PLANE-SYMMETRIC SYSTEMS
In paraxial optics, ray heights and angles are approximated to be linearly
related; this linear relationship becomes exact as ray heights and angles
approach zero. Paraxial optics captures the first-order behavior of rays
in optical systems. In the process of deriving the aberration
coefficients, the paraxial ray tracing in the sagittal direction was used
to define the properties of the ideal image and to approximate the light
beam footprint on each optical surface.
A. Paraxial Ray Tracing in the Sagittal Plane
The sagittal direction is the common $X$ axis in all local surface coordinate
systems. Sagittal planes are defined as planes containing the $X$ axis and the OAR. Alternatively,
tangential planes are perpendicular to the sagittal planes,
intersecting along the OAR. It can be derived that the paraxial ray
tracing in the sagittal plane follows the following equations:
(1)$${x_{i + 1}} = {x_i} +
{t_i}{u^\prime _i},$$
(2)$${n^\prime _i}{u^\prime
_i} = {n_i}{u_i} - {\phi _i}{x_i},$$
(3)$${u_{i + 1}} = {u^\prime
_i},$$
where the subscripts, $i$ and $i + {1}$, denote the surface number; $x$ is the sagittal ray height on the
surface, the sign of which follows the $X$ local coordinate value; $u$ is the tangent of the angle between
the sagittal ray and the OAR, the sign of which depends on the sign of $x$ and $t$; and $\phi $ is the oblique optical power
defined as (4)$${\phi _i} =
\frac{{{{n_i^\prime}}\cos {{I_i^\prime}} - {n_i}\cos
{I_i}}}{R}.$$
An illustration of paraxial ray height and ray angles is shown in
Fig. 2. Note that due to
the asymmetry between the sagittal and tangential directions, the
paraxial ray tracing in the tangential direction is different from
that in the sagittal direction.
B. Relation between Object and Image Plane Tilt Angles
By tracing a sagittal marginal ray in paraxial condition, the relation
between object and image locations for on-axis conjugates can be
derived as the Coddington equation [27], which is shown as
(5)$$\frac{{{{n_i^\prime}}}}{{{{({{{s_0^\prime}}} )}_i}}} -
\frac{{{n_i}}}{{{{({{s_0}} )}_i}}} = {\phi _i},$$
where ${s_0}$ and ${s_0^\prime}$ are the object and image distances
from the surface $i$ along the OAR, the sign of which is
positive if the object or image is on the positive $Z$ axis side of the surface local
coordinate system. Using the Coddington equation and Snell’s law, it
can be derived that for any optical surface $i$, the object and image plane tilt
angles, ${\theta _h}$ and ${\theta
_h^\prime}$, have the relation shown as
(6)$$\Delta
{\left({\frac{1}{{\cos I}}\left({\frac{{\sin I}}{R} -
\frac{1}{{{s_0}}}\tan {\theta _h}} \right)} \right)_i} =
0,$$
where the operator, $\Delta (\;)$, calculates the change of the
quantity inside the bracket on refraction. For example, $\Delta (n) = n^\prime -
n$, where $n$ and $n^\prime$ are the refractive indices before and
after the refraction, respectively.A similar relationship can be derived for pupil plane tilt angles; a
detailed derivation process is included in
Supplement
1. Note that when $I$ equals zero as in the rotationally
symmetric case, Eq. (6) is reduced to the Scheimpflug condition [28].
4. WAVE ABERRATION FUNCTION EXPANSION FOR PLANE-SYMMETRIC SYSTEMS
In a plane-symmetric system where half of the system is the exact mirror
image of the other half, the wavefront aberration function was expanded by
Sasian [26] as
(7)$$\begin{split}W({\boldsymbol
H},{\boldsymbol \rho})& = \sum\limits_{k,m,n,p,q}^\infty {W_{2k +
n + p,2m + n + q,n,p,q}}{{({\boldsymbol H} \cdot {\boldsymbol
H})}^k}\\&\quad\times{{({\boldsymbol \rho} \cdot {\boldsymbol
\rho})}^m}{{({\boldsymbol H} \cdot {\boldsymbol
\rho})}^n}{{({\boldsymbol i} \cdot {\boldsymbol H})}^p}{{({\boldsymbol
i} \cdot {\boldsymbol \rho})}^q} ,\end{split}$$
where $W$ is the wavefront aberration that
describes the departure of the real wavefront of a light beam from the
reference wavefront; ${W_{2k + n + p,2m + n +
q,n,p,q}}$ is the aberration coefficient for its
associated aberration term; ${\boldsymbol H}$ is the normalized field vector; and ${\boldsymbol
\rho}$ is the normalized pupil vector. ${\boldsymbol H}$ and ${\boldsymbol
\rho}$ lie in the $XY$ plane of the local coordinate systems of
the image and exit pupil planes, respectively. The two vectors together
define a ray that goes through the system. When the dot products are
performed between the field and pupil vectors, the vectors are put into an
overlayed coordinate system where all local coordinate systems of
surfaces, field, and pupil planes coincide with each other, and ${\boldsymbol i}$ is the unit vector pointing toward the $Y$ direction of the overlayed coordinate
system. An illustration of the overlayed coordinate system is shown in
Fig. 1. The terms in the $W$ expansion are grouped by the sum $k + m + n + p +
q$. The first four groups are listed in
Table 1. In this paper, we
expand on Sasian’s prior work by presenting the analytical form of the
aberration coefficients in the fourth
group.Table 1. First Four Groups of Aberration Terms
5. PROCESS OF DERIVING THE COEFFICIENTS FOR THE FOURTH GROUP
The derivation of aberration coefficients follows the approach of Hopkins
[13]. The optical path difference
between a general ray and the OAR is expressed as a Taylor expansion of a
function of the field and pupil vectors. The convergence condition of the
Taylor expansion is detailed in Supplement
1. The ideal image location and
magnification are defined by the paraxial ray trace in the sagittal
direction. The case for a single surface with the stop located at the
surface and an on-axis object point is derived first as the foundation for
the general case with an off-axis object and a stop (aperture stop) away
from the surface. With the off-axis object point introduced, the field
vector parameter is introduced. For the case where the surface is away
from the stop, the ray height at the surface is modeled as a function of
the chief and marginal ray heights and the field and pupil vectors.
Finally, by grouping and simplifying the terms with the same field and
pupil dependence, the analytical formulae of the aberration coefficients
for one surface are determined. The total intrinsic aberration
coefficients of a system can then be calculated by summing the
coefficients for each surface. It should be noted that this does not
include induced (extrinsic) aberrations. The detailed derivation process
can be found in Supplement
1.
During the derivation, certain assumptions and approximations are made:
In Eq. (8), $r$ is the location of the ray intersection
at the surface, and ${\rho _x}$ and ${\rho _y}$ are normalized pupil coordinates ranging
from ${-}{1}$ to 1. The paraxial marginal and chief ray
heights at the surface are defined by ${x_a}$ and ${x_b}$ in the sagittal direction and ${y_a}$ and ${y_b}$ in the tangential direction. ${\boldsymbol k}$ and ${\boldsymbol i}$ are the unit vectors in the $X$ and $Y$ directions, respectively. By deriving the
paraxial ray height in terms of pupil and field vectors, the marginal and
chief ray heights in the sagittal and tangential directions can be shown
to have the relationships illustrated in Eqs. (9) and (10),
(9)$${y_a} = \frac{{\cos {\theta
_\rho}}}{{\cos I}}{x_a},$$
(10)$${y_b} = \frac{{\cos {\theta
_h}}}{{\cos I}}{x_b},$$
under the assumption of same field and pupil
size in the sagittal and tangential directions, the detailed derivation of
which is shown in Supplement
1. This relationship indicates an
elliptical beam footprint within paraxial approximation, which is more
accurate than the symmetrical approximation where the tangential and
sagittal ray heights are assumed equal and is used in deriving all the
coefficients presented in Section 6.B. Besides the ellipticity, the beam footprint also experiences
higher-order deformation such as a keystone-like deformation discussed by
Rogers [29]. Note that the
second-order footprint deformation, where ray heights have second-order
dependences on pupil and field vectors, has contribution to aberration
types in the fourth group. For this paper, we limit the scope to be within
the paraxial approximation where the ellipticity of the beam footprint is
the main effect.6. ANALYTICAL FORMULAE FOR THE ABERRATION COEFFICIENTS IN THE FOURTH
GROUP
A. Defining Related Mathematical Quantities
To simplify the expressions of the aberration coefficients, we define
the following quantities. In Eqs. (11) and (12), we define the quantities $A$ and $B$ as products of the refractive index
before a surface, $n$, and the paraxial incident angle of
the sagittal marginal and chief rays, ${i_a}$ and ${i_b}$, respectively. The paraxial angles of
the sagittal marginal and chief rays before the surface are denoted by ${u_a}$ and ${u_b}$, respectively:
(11)$$A = n{i_a} =
n\left({{u_a} + \frac{{{x_a}\cos I}}{R}} \right),$$
(12)$$B = n{i_b} =
n\left({{u_b} + \frac{{{x_b}\cos I}}{R}} \right).$$
We also define the quantity $C$ below, as the product of the index of
refraction and the angle before the surface, using the sine of the
real incident angle instead of the paraxial angle:
The Lagrange invariant, $\Psi$, is defined with paraxial
quantities as
(14)$$\Psi = n({u_b}{x_a} -
{u_a}{x_b}).$$
Factors related to the intrinsic anamorphism between the sagittal and
tangential directions are defined as
(15)$${\sigma _1} = \cos (I -
{\theta _h}) - 1,$$
(16)$${\sigma _2} =
\frac{{\cos {\theta _\rho}}}{{\cos I}},$$
(17)$${\sigma _3} =
\frac{{\cos {\theta _h}}}{{\cos I}}.$$
B. Aberration Coefficients
In this section, we list the analytical formulae of the aberration
coefficients in the fourth group shown in Table 1.
The derivation also includes coefficients from the third group, listed
for reference in Eqs. (18)–(32). The coefficients from
the fourth group are listed in Eqs. (33)–(67):
(18)$${W_{02002}} = -
\frac{1}{2}{C^2}\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a}({2{\sigma _2} - 1} ),$$
(19)$$\begin{split}{W_{11011}}& = \Psi \left[{\Delta ({{\sigma
_1}} ) - C\Delta \left({\frac{{\sin {\theta _h}}}{n}} \right)}
\right]{\sigma _2} \\&\quad- {C^2}\Delta
\left({\frac{{{u_a}}}{n}} \right){x_b}\left({{\sigma _2} + {\sigma
_3} - 1} \right),\end{split}$$
(20)$$\begin{split}{W_{20020}} &= \Psi \left[{\Delta ({{\sigma
_1}} ) - C\Delta \left({\frac{{\sin {\theta _h}}}{n}} \right)}
\right]{\sigma _3} \\&\quad- \frac{1}{2}{C^2}\Delta
\left({\frac{{{u_a}}}{n}} \right)\frac{{x_b^2}}{{{x_a}}}({2{\sigma
_3} - 1} ),\end{split}$$
(21)$${W_{03001}} = -
\frac{1}{2}AC\Delta \left({\frac{{{u_a}}}{n}} \right){x_a}{\sigma
_2},$$
(22)$${W_{12101}} = -
BC\Delta \left({\frac{{{u_a}}}{n}} \right){x_a}{\sigma
_2},$$
(23)$$\begin{split}{W_{12010}} &= - \frac{1}{2}\frac{{\Psi
C}}{R}\Delta \left({\frac{{\cos {\theta _h}}}{n}} \right){x_a} -
\frac{1}{2}\Psi \Delta \left({{u_a}\sin {\theta _h}} \right)
\\&\quad- \frac{1}{2}AC\Delta \left({\frac{{{u_a}}}{n}}
\right){x_b}{\sigma _3},\end{split}$$
(24)$${W_{21001}} = -
\frac{1}{2}C\Psi \Delta \left({\frac{{{u_b}}}{n}} \right){\sigma
_2} - \frac{1}{2}BC\Delta \left({\frac{{{u_a}}}{n}}
\right){x_b}{\sigma _2},$$
(25)$$\begin{split}{W_{21110}} &= - \frac{{\Psi C}}{R}\Delta
\left({\frac{{\cos {\theta _h}}}{n}} \right){x_b} - \Psi \Delta
\left({{u_b}\sin {\theta _h}} \right) \\&\quad- BC\Delta
\left({\frac{{{u_a}}}{n}} \right){x_b}{\sigma
_3},\end{split}$$
(26)$$\begin{split}
{W_{30010}} & = - \frac{1}{2}C\Psi \Delta
\left({\frac{{{u_b}}}{n}} \right)\frac{{{x_b}}}{{{x_a}}}{\sigma
_3} - \frac{1}{2}BC\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{x_b^2}}{{{x_a}}}{\sigma _3} \\&\quad-
\frac{1}{2}{\Psi ^2}\Delta \left({\frac{{\sin {\theta _h}}}{n}}
\right)\frac{{{x_b}}}{{x_a^2}}- \frac{1}{2}\frac{{\Psi
C}}{R}\Delta \left({\frac{{\cos {\theta _h}}}{n}}
\right)\frac{{x_b^2}}{{{x_a}}} \\&\quad- \frac{1}{2}\Psi
\Delta \left({{u_b}\sin {\theta _h}}
\right)\frac{{{x_b}}}{{{x_a}}},\end{split}$$
(27)$${W_{04000}} = -
\frac{1}{8}{A^2}\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a},$$
(28)$${W_{13100}} = -
\frac{1}{2}AB\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a},$$
(29)$${W_{22200}} = -
\frac{1}{2}{B^2}\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a},$$
(30)$${W_{22000}} = -
\frac{1}{4}AB\Delta \left({\frac{{{u_a}}}{n}} \right){x_b} -
\frac{1}{4}A\Psi \Delta \left({\frac{{{u_b}}}{n}}
\right),$$
(31)$${W_{31100}} = -
\frac{{{B^2}}}{2}\Delta \left({\frac{{{u_a}}}{n}} \right){x_b} -
\frac{{B\Psi}}{2}\Delta \left({\frac{{{u_b}}}{n}}
\right),$$
(32)$$\begin{split}{W_{40000}} &= - \frac{1}{8}A({\Psi + B{x_a}}
)\Delta \left({\frac{{{u_a}}}{n}} \right)\frac{{x_b^3}}{{x_a^3}}
\\&\quad- \frac{1}{4}\Psi ({\Psi + B{x_a}} )\Delta
\left({\frac{{{u_b}}}{n}}
\right)\frac{{{x_b}}}{{x_a^2}},\end{split}$$
(33)$$\begin{split}{W_{03003}} &= \frac{1}{2}{C^3}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a}\left({3{\sigma _2} -
2} \right) \\&\quad- AC\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a}({{\sigma _2} - 1} ),\end{split}$$
(34)$$\begin{split}
{W_{12012}} & = - \frac{{C\Psi}}{R}\Delta \left({\frac{{\cos
{\theta _h}}}{n}} \right){x_a}({{\sigma _2} - 1} ) - C\Delta
\left({\frac{{{u_a}}}{n}} \right)\left[{A{x_b}\left({{\sigma _2} +
{\sigma _3} - 2} \right) + B{x_a}({{\sigma _2} - 1} )} \right]+
\frac{3}{2}{C^3}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right){x_b}\left({2{\sigma _2} + {\sigma _3} - 2} \right)
\\&\quad- C\Psi \Delta \left({\frac{{{\sigma _1}{u_a}}}{n}}
\right)({2{\sigma _2} - 1} ) - \Psi \Delta \left({{u_a}\sin
{\theta _h}} \right)({{\sigma _2} - 1} ) + \frac{3}{2}{C^2}\Psi
\Delta \left({\frac{{{u_a}\sin {\theta _h}}}{{{n^2}}}}
\right){x_a}({2{\sigma _2} - 1} ),\end{split}$$
(35)$$\begin{split}{W_{21021}}& = - \frac{{C\Psi}}{R}\Delta
\left({\frac{{\cos {\theta _h}}}{n}} \right){x_b}\left({{\sigma
_2} + {\sigma _3} - 2} \right) - C\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{{x_b}}}{{{x_a}}}\left[{A{x_b}({{\sigma _3} - 1} ) +
B{x_a}\left({{\sigma _2} + {\sigma _3} - 2} \right)}
\right]\\&\quad+ \frac{3}{2}{C^3}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}\left({{\sigma _2} + 2{\sigma _3} -
2} \right) - 2C\Psi \Delta \left({\frac{{{\sigma _1}{u_a}}}{n}}
\right)\frac{{{x_b}}}{{{x_a}}}\left({{\sigma _2} + {\sigma _3} -
1} \right) - \Psi \Delta \left({{u_a}\sin {\theta _h}}
\right)\frac{{{x_b}}}{{{x_a}}}({{\sigma _3} - 1} ) \\&\quad-
\Psi \Delta \left({{u_b}\sin {\theta _h}} \right)({{\sigma _2} -
1} ) + 3{C^2}\Psi \Delta \left({\frac{{{u_a}\sin {\theta
_h}}}{{{n^2}}}} \right)\frac{{{x_b}}}{{{x_a}}}\left({{\sigma _2} +
{\sigma _3} - 1} \right) - {\Psi ^2}\Delta \left({\frac{{{\sigma
_1}\sin {\theta _h}}}{n}} \right)\frac{1}{{{x_a}}}{\sigma _2} +
\frac{3}{2}C{\Psi ^2}\Delta \left({\frac{{{{\sin}^2}{\theta
_h}}}{{{n^2}}}} \right)\frac{1}{{{x_a}}}{\sigma
_2},\end{split}$$
(36)$$\begin{split}{W_{30030}} &= - \frac{{C\Psi}}{R}\Delta
\left({\frac{{\cos {\theta _h}}}{n}}
\right)\frac{{x_b^2}}{{{x_a}}}({{\sigma _3} - 1} ) - BC\Delta
\left({\frac{{{u_a}}}{n}} \right)\frac{{x_b^2}}{{{x_a}}}({{\sigma
_3} - 1} ) + \frac{1}{2}{C^3}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^3}}{{x_a^2}}\left({3{\sigma _3} - 2}
\right)\\&\quad- \Psi \Delta \left({{u_b}\sin {\theta _h}}
\right)\frac{{{x_b}}}{{{x_a}}}({{\sigma _3} - 1} ) - C\Psi \Delta
\left({\frac{{{\sigma _1}{u_a}}}{n}}
\right)\frac{{x_b^2}}{{x_a^2}}({2{\sigma _3} - 1} )\\&\quad+
\frac{3}{2}{C^2}\Psi \Delta \left({\frac{{{u_a}\sin {\theta
_h}}}{{{n^2}}}} \right)\frac{{x_b^2}}{{x_a^2}}({2{\sigma _3} - 1}
) - {\Psi ^2}\Delta \left({\frac{{{\sigma _1}\sin {\theta
_h}}}{n}} \right)\frac{{{x_b}}}{{x_a^2}}{\sigma _3} +
\frac{3}{2}C{\Psi ^2}\Delta \left({\frac{{{{\sin}^2}{\theta
_h}}}{{{n^2}}}} \right)\frac{{{x_b}}}{{x_a^2}}{\sigma
_3},\end{split}$$
(37)$${W_{04002}} =
\frac{3}{4}A{C^2}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right){x_a}({2{\sigma _2} - 1} ) - \frac{1}{2}{A^2}\Delta
\left({\frac{{{u_a}}}{n}} \right){x_a}({{\sigma _2} - 1}
),$$
(38)$$\begin{split}
{W_{13011}}& = - \frac{1}{2}A\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a}\left[{A{x_b}({{\sigma _3} - 1} ) + B{x_a}({{\sigma
_2} - 1} )} \right] + \frac{3}{2}A{C^2}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_b}\left({{\sigma _2} +
{\sigma _3} - 1} \right)\\&\quad- \frac{1}{2}A\Psi \Delta
\left({\frac{{{\sigma _1}{u_a}}}{n}} \right){\sigma _2} +
\frac{1}{2}\frac{{C\Psi}}{R}\Delta \left({\frac{{{u_a}\sin (I -
{\theta _h})}}{n}} \right){x_a}{\sigma _2} + \frac{3}{2}AC\Psi
\Delta \left({\frac{{{u_a}\sin {\theta _h}}}{{{n^2}}}}
\right){\sigma _2},\end{split}$$
(39)$$\begin{split}{W_{22002}} &= \frac{3}{4}B{C^2}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \!\right){x_b}({2{\sigma _2} - 1}
) + \frac{3}{4}{C^2}\Psi \Delta
\left({\frac{{{u_a}{u_b}}}{{{n^2}}}}\!
\right)\frac{{{x_b}}}{{{x_a}}}({2{\sigma _2} - 1} ) -
\frac{1}{2}AB\Delta \left({\frac{{{u_a}}}{n}}
\!\right){x_b}({{\sigma _2} - 1} )- \frac{1}{2}A\Psi \Delta
\left({\frac{{{u_b}}}{n}} \!\right){x_b}({{\sigma _2} - 1}
),\end{split}$$
(40)$$\begin{split}
{W_{22020}} & = - \frac{1}{2}AB\Delta
\left({\frac{{{u_a}}}{n}} \right){x_b}({{\sigma _3} - 1} ) -
\frac{1}{2}A\Psi \Delta \left({\frac{{{\sigma _1}{u_a}}}{n}}
\right)\frac{{{x_b}}}{{{x_a}}}{\sigma _3} +
\frac{3}{4}A{C^2}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}({2{\sigma _2} - 1} )+
\frac{3}{2}AC\Psi \Delta \left({\frac{{{u_a}\sin {\theta
_h}}}{{{n^2}}}} \right)\frac{{{x_b}}}{{{x_a}}}{\sigma _3}
\\&\quad+ \frac{1}{2}\frac{{C\Psi}}{R}\Delta
\left({\frac{{{u_a}\sin (I - {\theta _h})}}{n}}
\right){x_b}{\sigma _3} + \frac{{{\Psi
^2}}}{4}\left[{\frac{2}{R}\Delta \left({\frac{{\sin {\theta
_h}\sin (I - {\theta _h})}}{n}} \right) + 3A\Delta
\left({\frac{{{{\sin}^2}{\theta _h}}}{{{n^2}}}}
\right)\frac{1}{{{x_a}}}} \right],\end{split}$$
(41)$$\begin{split}
{W_{31011}}& = - \frac{1}{2}B\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{{x_b}}}{{{x_a}}}\left[{A{x_b}({{\sigma _3} - 1} ) +
B{x_a}({{\sigma _2} - 1} )} \right]- \frac{1}{2}\Psi \Delta
\left({\frac{{{u_b}}}{n}}
\right)\frac{1}{{{x_a}}}\left[{A{x_b}({{\sigma _3} - 1} ) +
B{x_a}({{\sigma _2} - 1} )} \right] \\&\quad+
\frac{3}{2}B{C^2}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}\left({{\sigma _2} + {\sigma _3} -
1} \right)+ \frac{3}{2}{C^2}\Psi \Delta
\left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}}\left({{\sigma _2} + {\sigma _3} -
1} \right) - \frac{1}{2}B\Psi \Delta \left({\frac{{{\sigma
_1}{u_a}}}{n}} \right)\frac{{{x_b}}}{{{x_a}}}{\sigma _2}
\\&\quad- \frac{1}{2}{\Psi ^2}\Delta \left({\frac{{{\sigma
_1}{u_b}}}{n}} \right)\frac{1}{{{x_a}}}{\sigma _2}+
\frac{1}{2}\frac{{C\Psi}}{R}\Delta \left({\frac{{{u_a}\sin (I -
{\theta _h})}}{n}} \right)\frac{{x_b^2}}{{{x_a}}}{\sigma _2} +
\frac{3}{2}BC\Psi \Delta \left({\frac{{{u_a}\sin {\theta
_h}}}{{{n^2}}}} \right)\frac{{{x_b}}}{{{x_a}}}{\sigma
_2}\\&\quad+ \frac{3}{2}C{\Psi ^2}\Delta
\left({\frac{{{u_b}\sin {\theta _h}}}{{{n^2}}}}
\right)\frac{1}{{{x_a}}}{\sigma _2},\end{split}$$
(42)$$\begin{split}
{W_{40020}} & = - \frac{1}{2}{B^2}\Delta
\left({\frac{{{u_a}}}{n}} \right)\frac{{x_b^2}}{{{x_a}}}({{\sigma
_3} - 1} ) - \frac{1}{2}B\Psi \Delta \left({\frac{{{u_b}}}{n}}
\right)\frac{{{x_b}}}{{{x_a}}}({{\sigma _3} - 1} ) +
\frac{3}{4}B{C^2}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^3}}{{x_a^2}}({2{\sigma _3} - 1} )-
\frac{1}{2}B\Psi \Delta \left({\frac{{{\sigma _1}{u_a}}}{n}}
\right)\frac{{x_b^2}}{{x_a^2}}{\sigma _3} \\[-2pt]&\quad-
\frac{1}{2}{\Psi ^2}\Delta \left({\frac{{{\sigma _1}{u_b}}}{n}}
\right)\frac{{{x_b}}}{{x_a^2}}{\sigma _3} + \frac{3}{4}{C^2}\Psi
\Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{x_a^2}}({2{\sigma _3} - 1} )+
\frac{1}{2}\frac{{C\Psi}}{{\rm R}}\Delta \left({\frac{{{u_a}\sin
(I - {\theta _h})}}{n}} \right)\frac{{x_b^3}}{{x_a^2}}{\sigma _3}
+ \frac{3}{2}BC\Psi \Delta \left({\frac{{{u_a}\sin {\theta
_h}}}{{{n^2}}}} \right)\frac{{x_b^2}}{{x_a^2}}{\sigma
_3}\\[-2pt]&\quad+ \frac{3}{2}C{\Psi ^2}\Delta
\left({\frac{{{u_b}\sin {\theta _h}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{x_a^2}}{\sigma _3} +
\frac{1}{2}\frac{{{\Psi ^2}}}{R}\Delta \left({\frac{{\sin {\theta
_h}\sin (I - {\theta _h})}}{n}} \right)\frac{{x_b^2}}{{x_a^2}}+
\frac{3}{4}{\Psi ^2}({\Psi + B{x_a}} )\Delta
\left({\frac{{{{\sin}^2}{\theta _h}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{x_a^3}},\end{split}$$
(43)$${W_{13102}} = -
AB\Delta \left({\frac{{{u_a}}}{n}} \right){x_a}({{\sigma _2} - 1}
) + \frac{3}{2}B{C^2}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right){x_a}({2{\sigma _2} - 1} ),$$
(44)$$\begin{split}
{W_{22111}}& = - B\Delta \left({\frac{{{u_a}}}{n}}
\right)\left[{A{x_b}({{\sigma _3} - 1} ) + B{x_a}({{\sigma _2} -
1} )} \right] - B\Psi \Delta \left({\frac{{{\sigma _1}{u_a}}}{n}}
\right){\sigma _2}+ \frac{{C\Psi}}{{\rm R}}\Delta
\left({\frac{{{u_a}\sin (I - {\theta _h})}}{n}}
\right){x_b}{\sigma _2} \\[-2pt]&\quad+ 3B{C^2}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_b}\left({{\sigma _2} +
{\sigma _3} - 1} \right) + 3BC\Psi \Delta \left({\frac{{{u_a}\sin
{\theta _h}}}{{{n^2}}}} \right){\sigma
_2},\end{split}$$
(45)$$\begin{split}{W_{31120}} & = - {B^2}\Delta
\left({\frac{{{u_a}}}{n}} \right){x_b}({{\sigma _3} - 1} ) +
\frac{3}{2}B{C^2}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}({2{\sigma _3} - 1} ) - B\Psi \Delta
\left({\frac{{{\sigma _1}{u_a}}}{n}}
\right)\frac{{x_b^2}}{{x_a^2}}{\sigma _3}+ 3BC\Psi \Delta
\left({\frac{{{u_a}\sin {\theta _h}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}}{\sigma _3} \\[-2pt]&\quad+
\frac{{C\Psi}}{{\rm R}}\Delta \left({\frac{{{u_a}\sin (I - {\theta
_h})}}{n}} \right)\frac{{x_b^2}}{{{x_a}}}{\sigma _3}+ \frac{{{\Psi
^2}}}{{\rm R}}\Delta \left({\frac{{\sin {\theta _h}\sin (I -
{\theta _h})}}{n}} \right)\frac{{{x_b}}}{{{x_a}}} +
\frac{3}{2}B{\Psi ^2}\Delta \left({\frac{{{{\sin}^2}{\theta
_h}}}{{{n^2}}}} \right)\frac{1}{{{x_a}}},\end{split}$$
(46)$${W_{05001}} = -
\frac{1}{8}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)x_a^3{\sigma _2} + \frac{3}{8}{A^2}C\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a}{\sigma
_2},$$
(47)$$\begin{split}
{W_{14010}} & = - \frac{1}{8}\frac{{C\Psi}}{{{R^3}}}\Delta
\left({\frac{{\cos {\theta _h}}}{n}} \right)x_a^3 -
\frac{1}{8}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)x_a^2{x_b}{\sigma _3} - \frac{1}{8}\frac{{A\Psi}}{R}\Delta
\left({\frac{{{u_a}\sin (I - {\theta _h})}}{n}}
\right){x_a}\\[-2pt]&\quad+ \frac{3}{8}{A^2}C\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_b}{\sigma _3} +
\frac{3}{8}{A^2}\Psi \Delta \left({\frac{{{u_a}\sin {\theta
_h}}}{{{n^2}}}} \right) - \frac{1}{8}\frac{\Psi}{{{R^2}}}\Delta
\left({{u_a}\sin {\theta _h}}
\right)x_a^2,\end{split}$$
(48)$${W_{14101}} = -
\frac{1}{2}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)x_a^2{x_b}{\sigma _2} + \frac{3}{2}ABC\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a}{\sigma
_2},$$
(49)$${W_{23001}} = -
\frac{1}{4}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a}x_b^2{\sigma _2} + \frac{3}{4}AC\Psi \Delta
\left({\frac{{{u_a}{u_b}}}{{{n^2}}}} \right){\sigma _2} +
\frac{3}{4}ABC\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right){x_b}{\sigma _2},$$
(50)$$\begin{split}
{W_{23110}}& = - \frac{1}{2}\frac{{C\Psi}}{{{R^3}}}\Delta
\left({\frac{{\cos {\theta _h}}}{n}} \right)x_a^2{x_b} -
\frac{1}{2}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a}x_b^2{\sigma _3}+
\frac{1}{2}\frac{\Psi}{R}\left({A{x_b} + B{x_a}} \right)\Delta
\left({\frac{{{u_a}\sin (I - {\theta _h})}}{n}}
\right)\\[-2pt]&\quad + \frac{1}{2}ABC\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_b}{\sigma _3} -
\frac{1}{2}\frac{\Psi}{{{R^2}}}\Delta \left({{u_a}\sin {\theta
_h}} \right){x_a}{x_b}+ \frac{3}{2}AB\Psi \Delta
\left({\frac{{{u_a}\sin {\theta _h}}}{{{n^2}}}}
\right),\end{split}$$
(51)$${W_{23201}} = -
\frac{1}{2}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a}x_b^2{\sigma _2} + \frac{3}{2}{B^2}C\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a}{\sigma
_2},$$
(52)$$\begin{split}
{W_{32010}}& = - \frac{1}{4}\frac{{C\Psi}}{{{R^3}}}\Delta
\left({\frac{{\cos {\theta _h}}}{n}} \right){x_a}x_b^2 -
\frac{1}{4}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)x_b^3{\sigma _3} + \frac{3}{4}ABC\Delta
\left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}{\sigma _3}+ \frac{3}{4}AC\Psi
\Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}} \right){\sigma _3}
\\[-2pt]&\quad+ \frac{1}{2}\frac{{B\Psi}}{R}\Delta
\left({\frac{{\sin (I - {\theta _h})}}{n}} \right){x_b} +
\frac{1}{4}\frac{{{\Psi ^3}}}{R}\Delta \left({\frac{{\sin (I -
{\theta _h})}}{{{n^2}}}} \right)\frac{1}{{{x_a}}}-
\frac{1}{4}\frac{\Psi}{{{R^2}}}\Delta \left({{u_a}\sin {\theta
_h}} \right)x_b^2 + \frac{3}{4}AB\Psi \Delta
\left({\frac{{{u_a}\sin {\theta _h}}}{{{n^2}}}} \right)
\\[-2pt]&\quad+ \frac{3}{4}A{\Psi ^2}\Delta
\left({\frac{{{u_b}\sin {\theta _h}}}{{{n^2}}}}
\right)\frac{1}{{{x_a}}},\end{split}$$
(53)$${W_{32101}} = -
\frac{1}{2}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)x_b^3{\sigma _2} + \frac{3}{2}{B^2}C\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_b}{\sigma _2} +
\frac{3}{2}BC\Psi \Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right){\sigma _2},$$
(54)$$\begin{split}{W_{32210}} & = -
\frac{1}{2}\frac{{C\Psi}}{{{R^3}}}\Delta \left({\frac{{\cos
{\theta _h}}}{n}} \right){x_a}x_b^2 -
\frac{1}{2}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)x_b^2{\sigma _3} + \frac{3}{2}{B^2}C\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_b}{\sigma
_3}\\[-2pt]&\quad+ \frac{{B\Psi}}{R}\Delta
\left({\frac{{{u_a}\sin (I - {\theta _h})}}{n}} \right){x_b} -
\frac{1}{2}\frac{\Psi}{{{R^2}}}\Delta \left({{u_a}\sin {\theta
_h}} \right)x_b^2 + \frac{3}{2}B\Psi \Delta
\left({\frac{{{u_a}\sin {\theta _h}}}{{{n^2}}}}
\right),\end{split}$$
(55)$$\begin{split}{W_{41110}}& = -
\frac{1}{2}\frac{{C\Psi}}{{{R^3}}}\Delta \left({\frac{{\cos
{\theta _h}}}{n}} \right)x_b^3 -
\frac{1}{2}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{x_b^4}}{{{x_a}}}{\sigma _3} +
\frac{3}{2}{B^2}C\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}{\sigma _3}\\&\quad+
\frac{3}{2}BC\Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}}{\sigma _3} +
\frac{{B\Psi}}{R}\Delta \left({\frac{{{u_a}\sin (I - {\theta
_h})}}{n}} \right)\frac{{x_b^2}}{{{x_a}}} +
\frac{1}{2}\frac{{{\Psi ^2}}}{R}\Delta \left({\frac{{{u_b}\sin (I
- {\theta _h})}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}}\\&\quad-
\frac{1}{2}\frac{\Psi}{{{R^2}}}\Delta \left({{u_a}\sin {\theta
_h}} \right)\frac{{x_b^3}}{{{x_a}}} + \frac{3}{2}{B^2}\Psi \Delta
\left({\frac{{{u_a}\sin {\theta _h}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}} + \frac{3}{2}B{\Psi ^2}\Delta
\left({\frac{{{u_b}\sin {\theta _h}}}{{{n^2}}}}
\right)\frac{1}{{{x_a}}},\end{split}$$
(56)$${W_{41001}}= -
\frac{1}{8}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{x_b^4}}{{{x_a}}}{\sigma _2} +
\frac{3}{8}{B^2}C\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}{\sigma _2} + \frac{3}{4}BC\Psi
\Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}}{\sigma _2}+ \frac{3}{8}C{\Psi
^2}\Delta \left({\frac{{u_b^2}}{{{n^2}}}}
\right)\frac{1}{{{x_a}}}{\sigma _2},$$
(57)$$\begin{split}{W_{50010}} & = -
\frac{1}{8}\frac{{C\Psi}}{{{R^3}}}\Delta \left({\frac{{\cos
{\theta _h}}}{n}} \right)\frac{{x_b^4}}{{{x_a}}} -
\frac{1}{8}\frac{{AC}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{x_b^5}}{{x_a^2}}{\sigma _3} +
\frac{3}{8}{B^2}C\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^3}}{{x_a^2}}{\sigma _3}+ \frac{3}{4}BC\Psi
\Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{x_a^2}}{\sigma _3} \\&\quad+
\frac{3}{8}C{\Psi ^2}\Delta \left({\frac{{u_b^2}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{x_a^2}}{\sigma _3} +
\frac{1}{4}\frac{{B\Psi}}{R}\Delta \left({\frac{{{u_a}\sin (I -
{\theta _h})}}{n}} \right)\frac{{x_b^3}}{{x_a^2}}+
\frac{1}{4}\frac{{{\Psi ^2}}}{R}\Delta \left({\frac{{{u_b}\sin (I
- {\theta _h})}}{{{n^2}}}} \right)\frac{{x_b^2}}{{x_a^2}}
\\&\quad- \frac{1}{8}\frac{\Psi}{{{R^2}}}\Delta
\left({{u_a}\sin {\theta _h}} \right)\frac{{x_b^4}}{{x_a^2}}+
\frac{3}{8}A\Psi ({\Psi + B{x_a}} )\Delta \left({\frac{{{u_a}\sin
{\theta _h}}}{{{n^2}}}} \right)\frac{{x_b^3}}{{x_a^4}} +
\frac{3}{4}{\Psi ^2}({\Psi + B{x_a}} )\Delta
\left({\frac{{{u_b}\sin {\theta _h}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{x_a^3}},\end{split}$$
(58)$${W_{06000}} = -
\frac{1}{{16}}\frac{{{A^2}}}{{{R^2}}}\Delta
\left({\frac{{{u_a}}}{n}} \right)x_a^3 + \frac{1}{{16}}{A^3}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a},$$
(59)$${W_{15100}} = -
\frac{1}{8}\frac{A}{{{R^2}}}\left({2A{x_b} + B{x_a}} \right)\Delta
\left({\frac{{{u_a}}}{n}} \right)x_a^2 + \frac{3}{8}{A^2}B\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a},$$
(60)$${W_{24000}}= -
\frac{1}{{16}}\frac{A}{{{R^2}}}\left({2A{x_b} + B{x_a}}
\right)\Delta \left({\frac{{{u_a}}}{n}} \right){x_a}{x_b} -
\frac{1}{{16}}\frac{{A\Psi}}{{{R^2}}}\Delta
\left({\frac{{{u_a}}}{n}} \right)x_a^2 +
\frac{3}{{16}}{A^2}B\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right){x_b}+ \frac{3}{{16}}{A^2}\Psi \Delta
\left({\frac{{{u_a}{u_b}}}{{{n^2}}}} \right),$$
(61)$${W_{24200}} = -
\frac{1}{4}\frac{A}{{{R^2}}}\left({A{x_b} + 2B{x_a}} \right)\Delta
\left({\frac{{{u_a}}}{n}} \right){x_a}{x_b} + \frac{3}{4}AB\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a},$$
(62)$${W_{33300}} = -
\frac{1}{2}\frac{{AB}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right){x_a}x_b^2 + \frac{1}{2}{B^2}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_a},$$
(63)$${W_{33100}}= -
\frac{1}{4}\frac{A}{{{R^2}}}\left({A{x_b} + 2B{x_a}} \right)\Delta
\left({\frac{{{u_a}}}{n}} \right)x_b^2 -
\frac{1}{4}\frac{{A\Psi}}{{{R^2}}}\Delta \left({\frac{{{u_b}}}{n}}
\right){x_a}{x_b} + \frac{3}{4}AB\Psi \Delta
\left({\frac{{{u_a}{u_b}}}{{{n^2}}}} \right)+
\frac{3}{4}A{B^2}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right){x_b},$$
(64)$${W_{42200}} = -
\frac{3}{4}\frac{{AB}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)x_b^3 - \frac{1}{4}\frac{{A\Psi}}{{{R^2}}}\Delta
\left({\frac{{{u_b}}}{n}} \right)x_b^2 + \frac{3}{4}{B^3}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}} \right){x_b} +
\frac{3}{4}{B^2}\Psi \Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right),$$
(65)$$\begin{split}{W_{42000}}& = -
\frac{1}{{16}}\frac{A}{{{R^2}}}\left({A{x_b} + 2B{x_a}}
\right)\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{x_b^3}}{{{x_a}}} -
\frac{1}{8}\frac{{A\Psi}}{{{R^2}}}\Delta \left({\frac{{{u_b}}}{n}}
\right)x_b^2 + \frac{3}{{16}}A{B^2}\Delta
\left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}}\\&\quad+ \frac{3}{8}AB\Psi
\Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}} + \frac{3}{{16}}A{\Psi ^2}\Delta
\left({\frac{{u_b^2}}{{{n^2}}}}
\right)\frac{1}{{{x_a}}},\end{split}$$
(66)$$\begin{split}{W_{51100}}& = -
\frac{3}{8}\frac{{AB}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{x_b^4}}{{{x_a}}} -
\frac{1}{4}\frac{{A\Psi}}{{{R^2}}}\Delta \left({\frac{{{u_b}}}{n}}
\right)\frac{{x_b^3}}{{{x_a}}}\\&\quad +
\frac{3}{8}{B^3}\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^2}}{{{x_a}}} + \frac{3}{4}{B^2}\Psi \Delta
\left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{{x_a}}}\\&\quad+ \frac{3}{8}B{\Psi
^2}\Delta \left({\frac{{u_b^2}}{{{n^2}}}}
\right)\frac{1}{{{x_a}}},\end{split}$$
(67)$$\begin{split}{W_{60000}}& = -
\frac{1}{{16}}\frac{{AB}}{{{R^2}}}\Delta \left({\frac{{{u_a}}}{n}}
\right)\frac{{x_b^5}}{{x_a^2}} -
\frac{1}{{16}}\frac{{A\Psi}}{{{R^2}}}\Delta
\left({\frac{{{u_b}}}{n}}
\right)\frac{{x_b^4}}{{x_a^2}}\\&\quad + \frac{1}{{16}}({\Psi
^3} + {B^3}x_a^3)\Delta \left({\frac{{u_a^2}}{{{n^2}}}}
\right)\frac{{x_b^3}}{{x_a^5}}\\&\quad+ \frac{3}{{16}}A\Psi
(\Psi + B{x_a})\Delta \left({\frac{{{u_a}{u_b}}}{{{n^2}}}}
\right)\frac{{x_b^3}}{{x_a^4}} \\&\quad+ \frac{3}{{16}}{\Psi
^2}(\Psi + B{x_a})\Delta \left({\frac{{u_b^2}}{{{n^2}}}}
\right)\frac{{{x_b}}}{{x_a^3}}.\end{split}$$
7. EXAMPLE
A one-surface system is used as an example to compare the aberration
coefficients derived from the theory and computed from ray tracing with
CODE V. As shown in Fig. 3,
a collimated beam with a 50-mm diameter is incident on a tilted concave
mirror and is focused on the paraxial image plane. The mirror serves as
the stop and has a tilted angle $I = - {20}^\circ$ and a radius of curvature $R = - {100}\;{\rm
mm}$. The distance of the paraxial image plane
can be calculated using Eqs. (1)–(4) to be $d = - {53.2}\;{\rm
mm}$. Therefore, the system is approximately
F/1.
To compute the wavefront error, optical paths of real rays are calculated
from a starting plane perpendicular to the incident beam to a reference
sphere located at the exit pupil which is at the same location as the
mirror as shown in blue in Fig. 3. The reference sphere is centered at the paraxial image point.
The location of the starting plane can be chosen arbitrarily in object
space. The wavefront error of a ray is calculated by subtracting the
optical path of the ray from that of the chief ray, producing a map of
wavefront error of rays in different pupil locations. Note that some rays
need to be traced backwards after the reflection to reach the reference
sphere. The optical path of the backwards tracing is signed negative. In
other cases, the optical path is always positive regardless of the sign of
the refractive index.
To find the aberration coefficients computationally, a Fringe Zernike
polynomial [30] is fitted to the
wavefront error map, leveraging the orthogonality of the polynomial for
more accurate fitting. In this case, the map is sampled at 201 points over
the pupil diameter, and a 37-term Fringe Zernike polynomial is fitted to
the data. From the definition of the Fringe Zernike terms, wavefront
aberration coefficients can be approximated as
(68)$$\begin{split}{W_{02000}}
&\approx 2{Z_4} + {Z_5} - 6{Z_9} - 3{Z_{12}} + 12{Z_{16}}
\\&\quad+ 6{Z_{21}} - 20{Z_{25}} - 10{Z_{32}} + 30{Z_{36}} -
42{Z_{37}},\end{split}$$
(69)$${W_{02002}} \approx -
2{Z_5} + 6{Z_{12}} - 12{Z_{21}} + 20{Z_{32}},$$
(70)$$\begin{split}{W_{03001}}
&\approx 3{Z_8} + 3{Z_{11}} - 12{Z_{15}} - 12{Z_{20}} +
30{Z_{24}}\\&\quad + 30{Z_{31}} -
60{Z_{35}},\end{split}$$
(71)$$\begin{split}{W_{04000}}
&\approx - 6{Z_9} + 4{Z_{12}} - 30{Z_{16}} - {Z_{17}} - 20{Z_{21}}
\\&\quad+ 90{Z_{25}} - 5{Z_{28}} + 60{Z_{32}} - 210{Z_{36}} +
420{Z_{37}},\end{split}$$
(72)$${W_{03003}} \approx -
4{Z_{11}} + 16{Z_{20}} - 20{Z_{27}} - 40{Z_{31}},$$
(73)$${W_{04002}} \approx -
8{Z_{12}} - 8{Z_{17}} + 40{Z_{21}} + 40{Z_{28}} -
120{Z_{32}},$$
(74)$${W_{05001}} \approx
10{Z_{15}} + 15{Z_{20}} - 60{Z_{24}} + 5{Z_{27}} - 90{Z_{31}} +
210{Z_{35}},$$
(75)$$\begin{split}{W_{06000}}
&\approx 20{Z_{16}} + 15{Z_{21}} - 140{Z_{25}} + 6{Z_{28}}
\\&\quad- 105{Z_{32}} + 560{Z_{36}} -
1680{Z_{36}}.\end{split}$$
Table 2 lists the
coefficients calculated from the theoretical formulae and from ray tracing
and fitting. In this example, only the coefficients with no field
dependence are calculated. Note that the theoretical value of ${W_{02000}}$ is zero due to the nature of the paraxial
image plane. The results from both methods are in general agreement. The
differences between the results can come from several possible sources
including the approximation used during the derivation of the analytical
formulae, omitted contributions from higher-order Fringe Zernike terms,
and numerical error resulting from sampling and fitting. The results also
show that besides the main aberration contributions from the constant
astigmatism, ${W_{02002}}$, and constant coma, ${W_{03001}}$, the aberration types from the fourth
group, ${W_{03003}}$, ${W_{04002}}$, and ${W_{05001}}$, also have non-negligible
contributions.
Table 2. Aberration Coefficients Calculated from the Theoretical Formulae
and from Ray Tracing and Fitting for the System Shown in
Fig. 3
8. CONCLUSION
The fourth-group’s aberration coefficients for plane-symmetric optical
systems are derived as functions of the first-order system parameters and
the paraxial chief and marginal ray angles and heights. The aberration
coefficients are useful for providing valuable information on the amount,
types, and surface balancing of imaging aberration in an optical system,
as well as how the aberration is affected by first-order system parameters
and the paraxial sagittal chief and marginal ray angles and heights. The
coefficients expand the aberration theory for plane-symmetric systems and
enable the analytical calculation of their higher-order aberrations.
Access to these computations is timely because systems that demand more
and more stringent specifications, such as faster $F$-numbers and larger fields of view, are
undoubtedly emerging.
Funding
National Science Foundation
I/UCRC Center for Freeform Optics (IIP-1338877,
IIP-1338898, IIP-1822026,
IIP-1822049); National
Aeronautics and Space Administration (NASA)
(80NSSC21K1838).
Acknowledgment
We thank Aaron Bauer for simulating discussion for this work.
Disclosures
The authors declare no conflicts of interests.
Data availability
Data underlying the results presented in this paper are not publicly
available at this time but may be obtained from the authors upon
reasonable request.
Supplemental document
See Supplement
1 for supporting content.
REFERENCES AND NOTES
1. J. P. Rolland, M. A. Davies, T. J. Suleski, C. Evans, A. Bauer, J. C. Lambropoulos, and K. Falaggis, “Freeform optics for
imaging,” Optica 8,
161–176 (2021). [CrossRef]
2. A. Offner, “Unit power imaging catoptric
anastigmat,” U.S. patent 3,748,015 (July 24,
1973).
3. L. Cook, “Three mirror anastigmatic
optical system,” U.S. patent 4,265,510 (May 5,
1981).
4. A. E. Conrady, “Decentred
lens-systems,” Mon. Not. R. Astron.
Soc. 79,
384–390 (1919). [CrossRef]
5. L. I. Epstein, “The aberrations of slightly
decentered optical systems,” J. Opt. Soc.
Am. 39,
847–853 (1949). [CrossRef]
6. L. Cook, “Three-mirror anastigmat used
off-axis in aperture and field,” Proc.
SPIE 0183,
207–211 (1979). [CrossRef]
7. C. Wynne, “The primary aberrations of
anamorphotic lens systems,” Proc. Phys. Soc.
B 67, 529
(1954). [CrossRef]
8. P. Sands, “Aberration coefficients of
double-plane-symmetric systems,” J. Opt. Soc.
Am. 63,
425–430 (1973). [CrossRef]
9. R. A. Buchroeder, “Tilted component optical
systems,” Ph.D. dissertation (The University
of Arizona, 1976).
10. A. Bauer and J. P. Rolland, “Design of a freeform
electronic viewfinder coupled to aberration fields of freeform
optics,” Opt. Express 23, 28141–28153
(2015). [CrossRef]
11. A. Bauer, M. Pesch, J. Muschaweck, F. Leupelt, and J. P. Rolland, “All-reflective electronic
viewfinder enabled by freeform optics,” Opt.
Express 27,
30597–30605 (2019). [CrossRef]
12. A. Bauer and J. P. Rolland, “Roadmap for the unobscured
three-mirror freeform design space,” Opt.
Express 29,
26736–26744 (2021). [CrossRef]
13. H. H. Hopkins, Wave Theory of Aberrations
(Clarendon,
1950).
14. R. Shack and K. Thompson, “Influence of alignment errors
of a telescope system on its aberration field,”
Proc. SPIE 251,
146–153 (1980). [CrossRef]
15. K. Thompson, “Description of the third-order
optical aberrations of near-circular pupil optical systems without
symmetry,” J. Opt. Soc. Am. A 22, 1389–1401
(2005). [CrossRef]
16. K. P. Thompson, “Multinodal fifth-order optical
aberrations of optical systems without rotational symmetry: spherical
aberration,” J. Opt. Soc. Am. A 26, 1090–1100
(2009). [CrossRef]
17. K. P. Thompson, “Multinodal fifth-order optical
aberrations of optical systems without rotational symmetry: the
comatic aberrations,” J. Opt. Soc. Am.
A 27,
1490–1504 (2010). [CrossRef]
18. K. P. Thompson, “Multinodal fifth-order optical
aberrations of optical systems without rotational symmetry: the
astigmatic aberrations,” J. Opt. Soc. Am.
A 28, 821–836
(2011). [CrossRef]
19. K. Fuerschbach, J. P. Rolland, and K. P. Thompson, “Theory of aberration fields
for general optical systems with freeform surfaces,”
Opt. Express 22,
26585–26606 (2014). [CrossRef]
20. A. Bauer, E. M. Schiesser, and J. P. Rolland, “Starting geometry creation and
design method for freeform optics,” Nat.
Commun. 9, 1756
(2018). [CrossRef]
21. Z. Tang and H. Gross, “Extended aberration analysis
in symmetry-free optical systems - part I: method of
calculation,” Opt. Express 29, 39967–39982
(2021). [CrossRef]
22. Z. Tang and H. Gross, “Extended aberration analysis
in symmetry-free optical systems - part II: evaluation and
application,” Opt. Express 29, 42020–42036
(2021). [CrossRef]
23. J. Caron and S. Bäumer, “Aberrations of
plane-symmetrical mirror systems with freeform surfaces. Part I:
generalized ray-tracing equations,” J. Opt.
Soc. Am. A 38,
80–89 (2021). [CrossRef]
24. J. Caron and S. Bäumer, “Aberrations of
plane-symmetrical mirror systems with freeform surfaces. Part II:
closed-form aberration formulas,” J. Opt. Soc.
Am. A 38,
90–98 (2021). [CrossRef]
25. J. Caron, T. Ceccotti, and S. Bäumer, “Progress in aberration theory
for freeform off-axis mirror systems,” Proc.
SPIE 12078, 120780G
(2021). [CrossRef]
26. J. M. Sasian, “How to approach the design of
a bilateral symmetric optical system,” Opt.
Eng. 33,
2045–2061 (1994). [CrossRef]
27. H. Coddington, A Treatise on the Reflexion and
Refraction of Light being Part 1 of A System of Optics
(Cambridge University,
1829).
28. T. Scheimpflug, “Improved method and apparatus
for the systematic alteration or distortion of plane pictures and
images by means of lenses and mirrors for photography and for other
purposes,” British patent No.
1196 (May 12,
1904).
29. J. Rogers, “A comparison of anamorphic,
keystone, and Zernike surface types for aberration
correction,” Proc. SPIE 7652, 129–136
(2010). [CrossRef]
30. The Fringe Zernike polynomial was developed by John Loomis at the
University of Arizona, Optical Sciences Center in the 1970s, and
is described on page 712 of the CODE V® Version 11.5 Lens System
Setup Reference Manual (Synopsys, Inc., 2021).