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Ref. p. 131]

3.1 Linear optics

109

Table 3.1.10. Di erent approximations of geometrical optics.

Problem to be treated

Algorithm for solving

Given: object point O in the paraxial range,

– Gaussian collineation and Listing’s construction:

asked : image point O in the paraxial range

see Sect. 3.1.6.1.

approximation: sin σ ≈ σ .

– Gaussian matrix formalism (ABCD-matrix): see

Sect. 3.1.6.2,

ref.: [04Ber, 99Bor].

Imaging in Seidel’s range,

Formulae for Seidels aberrations: see Sect. 3.1.6.3,

asked : imaging quality

1

ref.: [70Ber, 80Hof, 84Haf, 84Rus, 86Haf, 91Mah].

approximation: sin σ ≈ σ −

σ3 .

3!

General image formation.

(Commercial) raytracing programs with geometric

and wave optical merit functions and tolerancing,

ref.: [84Haf, 86Haf].

3.1.6.1.1 Single spherical interface

Figure 3.1.30 shows the imaging by a spherical interface in the paraxial range (small x, x , h).

Gaussian imaging equation:

n

1

1

= n

1

1

or

n

=

n

+

n − n

.

(3.1.90)

r

− s

r

− s

s

s

r

Abbe’s invariant n

1

1

is a constant on both sides of the interface.

−

r

s

Object-space focal length:

f = −

nr

.

n

−

n

Image-side focal length:

f =

n r

.

n

− n

(3.1.91)

(3.1.92)

Remark : The symbol f means outside this section, Sect. 3.1.6.1, the positive focal length for a positive (converging) lens.

Newton’s imaging equation:

z z = f f .

(3.1.93)

x

P

O

x

h

r

M

z

F

V

F ’

x ’

s

s ’

O ’

f

z

f ’

z ’

Fig. 3.1.30. Imaging by a spherical interface in the paraxial range (small x [object height], x [image height], h [zonal height]). Full line: axial imaging,

dashed line: o -axis imaging, dotted line: focusing to image side F . Sign conventions: s, s > 0 , if they

point to the right-hand side of the vertex V , r > 0 , if the center of curvature of the interface is on the right-hand side in comparison with V . Here: s < 0, s > 0, r > 0. M : center of curvature of the sphere. The left-hand-side-directed arrows symbolize negative values for the corresponding parameters here.

Landolt-B¨ornstein

New Series VIII/1A1

110

3.1.6 Geometrical optics

[Ref. p. 131

Lagrange’s invariant:

x n s = x n s

(3.1.94)

with

n : object-space refractive index, n : image-space refractive index, s : object distance,

s : image distance,

r : radius of curvature of the interface, x : height of the object point,

x : height of the image point,

z : focus-related object distance, z : focus-related image distance.

Imaging through an optical system: concatenation of the imaging of the spherical surfaces in suc-

cession via (3.1.90) by using sfollowing surface = sprior surface − d, d : the distance between the surfaces, and (3.1.94) for an object height x = 0.

3.1.6.1.2 Imaging with a thick lens

Figure 3.1.31 shows the axial imaging with a thick lens, Fig. 3.1.32 depicts Listing’s construction for thick-lens imaging of a finite-height object point O to image point O .

Thick-lens imaging equation:

1

+

1

=

1

= (n

−

1)

1

1

+ t (n − 1)2 .

(3.1.95)

− a a

f

r1

− r2

n r1 r2

Radius r1

Radius r2

Radius r1

Radius r2

1

2

O

F

H

H’

F ’

O ’

z

x

3

4

F ’

O ’

’

z

O

F

5

H

H’

x ’

s

s ’

t

6

a

f

f ’

s

H

s’

a’

a

a’

H '

n = 1

n ‘

n = 1

n = 1

n ‘

n = 1

Fig. 3.1.31. Axial imaging with a thick lens. Cardinal planes and points are: object-space principal

plane with object principal point H on axis, imagespace principal plane with image principal point H on axis, object-space focal point F , image-space focal point F . Nodal points [98Mah, 96Ped] are equal

to the principal points if O and O are embedded

in media with equal refractive index as here. Then f = −f . The sign convention used here means:

Parameters characterized by an arrow pointing to the left (right) hand side show a negative (positive) sign [80Hof, 86Haf]. The dashed line shows the use of H for simplifying the plot for a ray focusing.

Fig. 3.1.32. Listing’s construction for thick-lens imaging of a finite-height object point O to image point O . Scheme of construction: Ray 1 (parallel with axis) is sharply bent at plane H towards F . Ray 3 towards H is continued at H with the angle σ = σ . Ray 5 through F is bent sharply parallel with axis at H-plane. The magnification x /x =

a /a can be calculated by elimination of a from (3.1.95) x .

Landolt-B¨ornstein

New Series VIII/1A1

Ref. p. 131]

3.1 Linear optics

111

Position of the principal point H:

s

=

n − 1

f t .

(3.1.96)

H

− n r2

Position of the principal point H :

s

=

n − 1

f t .

(3.1.97)

H

− n r1

Distance between the principal planes:

= t

1

f

n − 1

1

1

.

(3.1.98)

H H

−

n

r1

− r2

Thin lens: t 0 : (3.1.95) “Lens maker’s formula”.

3.1.6.2Gaussian matrix (ABCD-matrix, ray-transfer matrix) formalism for paraxial optics

Three tasks can be treated with the help of the ray-transfer matrix:

1.full description of paraxial optics (this section, Sect. 3.1.6.2),

2.Gaussian beam propagation (coherent radiation) by combination with a special beam calculation algorithm (see Sect. 3.1.7 on beam propagation),

3.propagation of the second-order moments of the radiation field (inclusion of partial coherent radiation) (see Chap. 2.2 on beam characterization).

The optical system can be the separating distance in an optical medium, a single spherical optical surface or a true, more complicated optical system.

There are di erent definitions for the ABCD-matrices:

Here: The slope components of the input and output rays are the real angles without any relation to the refractive indices at input and output spaces of Fig. 3.1.33 [66Kog1, 66Kog2, 84Hau, 91Sal, 95Bas, 96Ped, 96Yar, 98Hec, 98Sve, 01I , 05Gro1, 05Hod]. Then, the determinant of the matrix M : M = n /n with n the index of the medium of the input plane and n the index of the medium of the output plane.

Other authors [75Ger, 86Sie, 88Kle, 04Ber] use:

slope parameter = (angle) × (related refractive index). Then the equation M = 1 applies.

In Fig. 3.1.34 the concatenation of di erent ray-transfer matrices for di erent types of subsystems is shown.

Input plane

Output plane

x

x

dx

dx

1 dz 1

2

dz

2

x

1

x2

z

z

Input

Optical system

Output

x1

x2

A B

x1

x2

1

=

2

2

C D

1

x2

=

M

x1

2

1

Fig. 3.1.33. Transfer of the input height x1 and slope α1 into the output height x2 and slope α2 with the raytransfer matrix M. The sign of slope α1 is positive in this

figure. The German standard DIN 1335 uses a di erent sign with change of some signs in the ABCD matrices

[96Ped].

Landolt-B¨ornstein

New Series VIII/1A1

112

3.1.6 Geometrical optics

[Ref. p. 131

Element 1

Element 2

Element 3

Following

Lens

Air distance

System

elements

1

x1

2

x2

x

3

x4

4

x

n

M 1

3

n

M2

M3

Output plane

Input plane

Output plane

of element 1

= input plane

M = Mn 1... M3 M2 M1

of element 2

Fig. 3.1.34. Concatenation of di erent ray-transfer matrices for di erent types of sub-systems. Matrices known for systems before can be used to construct the matrix for a larger system containing the known systems. The sequence of the matrices is shown at the bottom of the figure.

3.1.6.2.1 Simple interfaces and optical elements with rotational symmetry

In Table 3.1.11 ABCD-matrices for simple interfaces and optical elements with rotational symmetry are listed.

3.1.6.2.2 Non-symmetrical optical systems

Rotational symmetry lacks and the axis is tilted due to the non-symmetrical optical system. In such a system, the central ray of imaging is called the basic ray. The optics in a narrow region around the basic ray is called parabasal optics [95Bas, Vol. 1, p. 1.47] as analogon to paraxial optics. For treatment of astigmatic pencils see [72Sta].

A special case of the non-symmetrical optical system is a system without torsion: Two orthogonal cases do not mix during propagation. Examples are di erent setups of spectroscopy and laser physics (ring resonators).

In Table 3.1.12 ABCD-matrices for non-symmetrical optical elements without torsion are listed.

3.1.6.2.3 Properties of a system

Properties of a system included in its ABCD-matrix are discussed in [75Ger, 96Ped, 05Hod, 05Gro1]. In Table 3.1.13 distances between cardinal elements of an optical system are listed, in Table 3.1.14 the meaning of the vanishing of di erent elements of the ABCD-matrix is depicted.

3.1.6.2.4 General parabolic systems without rotational symmetry

The generalization of the two-dimensional ray transfer after Fig. 3.1.33 to three dimensions [69Arn] is shown in Fig. 3.1.35. The ray in the input plane is characterized by two coordinates x1 and y1 of the piercing point P and two small (paraxial range) angles α1 and β1 .

The matrix S relates these parameters to the corresponding parameters in the output plane like in Fig. 3.1.33:

Landolt-B¨ornstein

New Series VIII/1A1

H, H : principal planes.
Unfolding of the mirror;
sign(r) > 0 , if the incident light sees a concave mirror surface.

Ref. p. 131]

3.1 Linear optics

113

Table 3.1.11. ABCD-matrices for simple interfaces and optical elements with rotational symmetry.

E ect

Figure

ABCD-matrix

Remark

Propagation

1 d

The rays propagate from I to O

d

0 1

within the same medium.

l

O

Spherical

1

0

Sign: r > 0 for convex surface seen

surface

r

n1 − n2

n1

by the propagating light.

n

n

1

2

n2 r

n2

I O

Plane

1

0

0

n1

n1

n2

n2

I

O

Corresponds to a spherical surface with r ∞ .

Planar plate

0

n1

Contains two refractions.

d

1

1

n2 d

n1

n2

n1

IO

Thin lens

r1

r2

I

O

n1

n2

n1

Thick lens

in air

r1>0

r2<0

t

n

sH

s’H ’

IH H’ O

Spherical

r

mirror

substituted

by

I =O

I O

Gradient-

n

index lens

n1

n1

or

thermal

t

lens

I

O

1

0

1

=

n2 − n1

1

1

,

1

1

f

n1

r1

− r2

−

f

air: n1 = 1 .

1

sH

d

1

= (n

1)

1

1

+

(n − 1)2 t

,

nsH

−

1f

f

−

r1 − r2

n r1 r2

−

1 +

(n

1) f t

f

f

sH =

−

−

, see (3.1.96) ,

n r2

s

H

=

−

(n − 1) f t

, see (3.1.97) ,

n r1

1 0 − 2r 1

C D

1

2γ t / n0 2γ ;

A B

A = cos

√2γ t ;

√

2

−

1

0

B = n

sin

√

−

D =

2γ t ;

√2γ t

C =

√2γ n /n

sin

;

n = n0 (1 γ x ) ;

cos

√

γ > 0 : higher

development

of

the

trigonometric

index on axis

functions for

√

t 1 simpli-

2γ

fications

Gradient optics:

see [02Gom, 05Gro1].

(continued)

Landolt-B¨ornstein

New Series VIII/1A1

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