edu.nrao.sss.astronomy
Enum StokesParameter

java.lang.Object
  java.lang.Enum<StokesParameter>
      edu.nrao.sss.astronomy.StokesParameter

All Implemented Interfaces:

Serializable, Comparable<StokesParameter>

public enum StokesParameter
extends Enum<StokesParameter>

A set of values that describe the polarization state of electromagnetic radiation¹.

This enumeration has the same name, and elements that have the same names and are in the same order, as the corresponding ALMA enumeration, which in turn is based on a CASA enumeration.

References

• World of Physics
• ATNF
• Wikipedia
• University of Arizona (there's a great 3D motion display here)

¹Stokes parameters. (2007, September 2). In Wikipedia, The Free Encyclopedia. Retrieved 15:13, September 24, 2007, from http://en.wikipedia.org/w/index.php?title=Stokes_parameters&oldid=155199986.

Version Info:

$Revision: 1763 $

$Date: 2008-11-24 16:22:07 -0700 (Mon, 24 Nov 2008) $

$Author: dharland $ (last person to modify)

Since:

2007-09-24

Author:

David M. Harland

Enum Constant Summary

I
Total intensity.

LCIRCULAR

LINEAR
Single dish polarization type (ALMA definition).

LL
Circular polarization measurement equal to I - V.

LR
Circular polarization measurement equal to Q - iU, where i = (-1)^1/2.

LX

LY

PANGLE
Linear polarization angle, equal to 0.5 * arctan(U/Q), in radians (ALMA definition).

PFLINEAR
Linear polarization fraction, equal to PLINEAR / I (ALMA definition).

PFTOTAL
Polarization fraction, equal to PTOTAL / I (ALMA definition).

PLINEAR
Linearly polarized intensity, equal to (Q²+U²)^1/2 (ALMA definition).

PP

PQ

PTOTAL
Polarized intensity, equal to (Q²+U²+V²)^1/2 (ALMA definition).

Q
The Q, or S₁, Stokes parameter.

QP

QQ

RCIRCULAR

RL
Circular polarization measurement equal to Q + iU, where i = (-1)^1/2.

RR
Circular polarization measurement equal to I + V.

RX

RY

U
The U, or S₂, Stokes parameter.

V
The V, or S₃, Stokes parameter.

XL

XR

XX
Linear polarization measurement equal to I + Q.

XY
Linear polarization measurement equal to U + iV, where i = (-1)^1/2.

YL

YR

YX
Linear polarization measurement equal to U - iV, where i = (-1)^1/2.

YY
Linear polarization measurement equal to I - Q.

Method Summary

static StokesParameter	fromString(String text) Returns the stokes parameter represented by text.
static StokesParameter	getDefault() Returns a default stokes parameter.
static SortedSet<StokesParameter>	getStokesFor(PolarizationType p1, PolarizationType p2) Returns a set of stokes parameters than can be created from the given polarizations.
static StokesParameter	valueOf(String name) Returns the enum constant of this type with the specified name.
static StokesParameter[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

I

public static final StokesParameter I

Total intensity. For the Stokes Parameters, I² = Q² + U² + V².

Q

public static final StokesParameter Q

The Q, or S₁, Stokes parameter. Q, along with U, represents linear polarization.

U

public static final StokesParameter U

The U, or S₂, Stokes parameter. U, along with Q, represents linear polarization.

V

public static final StokesParameter V

The V, or S₃, Stokes parameter. V represents circular polarization.

RR

public static final StokesParameter RR

Circular polarization measurement equal to I + V.

RL

public static final StokesParameter RL

Circular polarization measurement equal to Q + iU, where i = (-1)^1/2.

LR

public static final StokesParameter LR

Circular polarization measurement equal to Q - iU, where i = (-1)^1/2.

LL

public static final StokesParameter LL

Circular polarization measurement equal to I - V.

XX

public static final StokesParameter XX

Linear polarization measurement equal to I + Q.

XY

public static final StokesParameter XY

Linear polarization measurement equal to U + iV, where i = (-1)^1/2.

YX

public static final StokesParameter YX

Linear polarization measurement equal to U - iV, where i = (-1)^1/2.

YY

public static final StokesParameter YY

Linear polarization measurement equal to I - Q.

RX

public static final StokesParameter RX

RY

public static final StokesParameter RY

LX

public static final StokesParameter LX

LY

public static final StokesParameter LY

XR

public static final StokesParameter XR

XL

public static final StokesParameter XL

YR

public static final StokesParameter YR

YL

public static final StokesParameter YL

PP

public static final StokesParameter PP

PQ

public static final StokesParameter PQ

QP

public static final StokesParameter QP

QQ

public static final StokesParameter QQ

RCIRCULAR

public static final StokesParameter RCIRCULAR

LCIRCULAR

public static final StokesParameter LCIRCULAR

LINEAR

public static final StokesParameter LINEAR

Single dish polarization type (ALMA definition).

PTOTAL

public static final StokesParameter PTOTAL

Polarized intensity, equal to (Q²+U²+V²)^1/2 (ALMA definition).

PLINEAR

public static final StokesParameter PLINEAR

Linearly polarized intensity, equal to (Q²+U²)^1/2 (ALMA definition).

PFTOTAL

public static final StokesParameter PFTOTAL

Polarization fraction, equal to PTOTAL / I (ALMA definition).

PFLINEAR

public static final StokesParameter PFLINEAR

Linear polarization fraction, equal to PLINEAR / I (ALMA definition).

PANGLE

public static final StokesParameter PANGLE

Linear polarization angle, equal to 0.5 * arctan(U/Q), in radians (ALMA definition).

Method Detail

values

public static StokesParameter[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (StokesParameter c : StokesParameter.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static StokesParameter valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

getDefault

public static StokesParameter getDefault()

Returns a default stokes parameter.

Returns:

a default stokes parameter.

fromString

public static StokesParameter fromString(String text)

Returns the stokes parameter represented by text.

For details about the transformation, see EnumerationUtility.enumFromString(Class, String).

Parameters:

text - a text representation of a stokes parameter.

Returns:

the stokes parameter represented by text.

getStokesFor

public static SortedSet<StokesParameter> getStokesFor(PolarizationType p1,
                                                      PolarizationType p2)

Returns a set of stokes parameters than can be created from the given polarizations. The returned set will never be null, but will be empty if no Stokes Parameters can be created from the polarizations.

It is permissible to have one or both of the parameters be null. If both are null the returned set will be empty. If one is null and the other is not the returned set will have one element. For example if p1 is null and p2 is PolarizationType.R, the returned set will contain only RR.

Parameters:

p1 - a polarization to be combined with p2 to form Stokes parameters.

p2 - a polarization to be combined with p1 to form Stokes parameters.

Returns:

a set of stokes parameters than can be created from the given polarizations.