# Source code for sympy.physics.gaussopt

# -*- encoding: utf-8 -*-
"""
Gaussian optics.

The module implements:

- Ray transfer matrices for geometrical and gaussian optics.

See RayTransferMatrix, GeometricRay and BeamParameter

- Conjugation relations for geometrical and gaussian optics.

See geometric_conj*, gauss_conj and conjugate_gauss_beams

The conventions for the distances are as follows:

focal distance
positive for convergent lenses
object distance
positive for real objects
image distance
positive for real images
"""

from __future__ import print_function, division

from sympy import (atan2, Expr, I, im, Matrix, oo, pi, re, sqrt, sympify,
together)
from sympy.utilities.misc import filldedent

###
# A, B, C, D matrices
###

[docs]class RayTransferMatrix(Matrix): """ Base class for a Ray Transfer Matrix. It should be used if there isn't already a more specific subclass mentioned in See Also. Parameters ========== parameters : A, B, C and D or 2x2 matrix (Matrix(2, 2, [A, B, C, D])) Examples ======== >>> from sympy.physics.gaussopt import RayTransferMatrix, ThinLens >>> from sympy import Symbol, Matrix >>> mat = RayTransferMatrix(1, 2, 3, 4) >>> mat Matrix([ [1, 2], [3, 4]]) >>> RayTransferMatrix(Matrix([[1, 2], [3, 4]])) Matrix([ [1, 2], [3, 4]]) >>> mat.A 1 >>> f = Symbol('f') >>> lens = ThinLens(f) >>> lens Matrix([ [ 1, 0], [-1/f, 1]]) >>> lens.C -1/f See Also ======== GeometricRay, BeamParameter, FreeSpace, FlatRefraction, CurvedRefraction, FlatMirror, CurvedMirror, ThinLens References ========== .. [1] http://en.wikipedia.org/wiki/Ray_transfer_matrix_analysis """ def __new__(cls, *args): if len(args) == 4: temp = ((args[0], args[1]), (args[2], args[3])) elif len(args) == 1 \ and isinstance(args[0], Matrix) \ and args[0].shape == (2, 2): temp = args[0] else: raise ValueError(filldedent(''' Expecting 2x2 Matrix or the 4 elements of the Matrix but got %s''' % str(args))) return Matrix.__new__(cls, temp) def __mul__(self, other): if isinstance(other, RayTransferMatrix): return RayTransferMatrix(Matrix.__mul__(self, other)) elif isinstance(other, GeometricRay): return GeometricRay(Matrix.__mul__(self, other)) elif isinstance(other, BeamParameter): temp = self*Matrix(((other.q,), (1,))) q = (temp[0]/temp[1]).expand(complex=True) return BeamParameter(other.wavelen, together(re(q)), z_r=together(im(q))) else: return Matrix.__mul__(self, other) @property
[docs] def A(self): """ The A parameter of the Matrix. Examples ======== >>> from sympy.physics.gaussopt import RayTransferMatrix >>> mat = RayTransferMatrix(1, 2, 3, 4) >>> mat.A 1 """ return self[0, 0]
@property
[docs] def B(self): """ The B parameter of the Matrix. Examples ======== >>> from sympy.physics.gaussopt import RayTransferMatrix >>> mat = RayTransferMatrix(1, 2, 3, 4) >>> mat.B 2 """ return self[0, 1]
@property
[docs] def C(self): """ The C parameter of the Matrix. Examples ======== >>> from sympy.physics.gaussopt import RayTransferMatrix >>> mat = RayTransferMatrix(1, 2, 3, 4) >>> mat.C 3 """ return self[1, 0]
@property
[docs] def D(self): """ The D parameter of the Matrix. Examples ======== >>> from sympy.physics.gaussopt import RayTransferMatrix >>> mat = RayTransferMatrix(1, 2, 3, 4) >>> mat.D 4 """ return self[1, 1]
[docs]class FreeSpace(RayTransferMatrix): """ Ray Transfer Matrix for free space. Parameters ========== distance See Also ======== RayTransferMatrix Examples ======== >>> from sympy.physics.gaussopt import FreeSpace >>> from sympy import symbols >>> d = symbols('d') >>> FreeSpace(d) Matrix([ [1, d], [0, 1]]) """ def __new__(cls, d): return RayTransferMatrix.__new__(cls, 1, d, 0, 1)
[docs]class FlatRefraction(RayTransferMatrix): """ Ray Transfer Matrix for refraction. Parameters ========== n1 : refractive index of one medium n2 : refractive index of other medium See Also ======== RayTransferMatrix Examples ======== >>> from sympy.physics.gaussopt import FlatRefraction >>> from sympy import symbols >>> n1, n2 = symbols('n1 n2') >>> FlatRefraction(n1, n2) Matrix([ [1, 0], [0, n1/n2]]) """ def __new__(cls, n1, n2): n1, n2 = map(sympify, (n1, n2)) return RayTransferMatrix.__new__(cls, 1, 0, 0, n1/n2)
[docs]class CurvedRefraction(RayTransferMatrix): """ Ray Transfer Matrix for refraction on curved interface. Parameters ========== R : radius of curvature (positive for concave) n1 : refractive index of one medium n2 : refractive index of other medium See Also ======== RayTransferMatrix Examples ======== >>> from sympy.physics.gaussopt import CurvedRefraction >>> from sympy import symbols >>> R, n1, n2 = symbols('R n1 n2') >>> CurvedRefraction(R, n1, n2) Matrix([ [ 1, 0], [(n1 - n2)/(R*n2), n1/n2]]) """ def __new__(cls, R, n1, n2): R, n1, n2 = map(sympify, (R, n1, n2)) return RayTransferMatrix.__new__(cls, 1, 0, (n1 - n2)/R/n2, n1/n2)
[docs]class FlatMirror(RayTransferMatrix): """ Ray Transfer Matrix for reflection. See Also ======== RayTransferMatrix Examples ======== >>> from sympy.physics.gaussopt import FlatMirror >>> FlatMirror() Matrix([ [1, 0], [0, 1]]) """ def __new__(cls): return RayTransferMatrix.__new__(cls, 1, 0, 0, 1)
[docs]class CurvedMirror(RayTransferMatrix): """ Ray Transfer Matrix for reflection from curved surface. Parameters ========== R : radius of curvature (positive for concave) See Also ======== RayTransferMatrix Examples ======== >>> from sympy.physics.gaussopt import CurvedMirror >>> from sympy import symbols >>> R = symbols('R') >>> CurvedMirror(R) Matrix([ [ 1, 0], [-2/R, 1]]) """ def __new__(cls, R): R = sympify(R) return RayTransferMatrix.__new__(cls, 1, 0, -2/R, 1)
[docs]class ThinLens(RayTransferMatrix): """ Ray Transfer Matrix for a thin lens. Parameters ========== f : the focal distance See Also ======== RayTransferMatrix Examples ======== >>> from sympy.physics.gaussopt import ThinLens >>> from sympy import symbols >>> f = symbols('f') >>> ThinLens(f) Matrix([ [ 1, 0], [-1/f, 1]]) """ def __new__(cls, f): f = sympify(f) return RayTransferMatrix.__new__(cls, 1, 0, -1/f, 1) ### # Representation for geometric ray ###
[docs]class GeometricRay(Matrix): """ Representation for a geometric ray in the Ray Transfer Matrix formalism. Parameters ========== h : height, and angle : angle, or matrix : a 2x1 matrix (Matrix(2, 1, [height, angle])) Examples ======= >>> from sympy.physics.gaussopt import GeometricRay, FreeSpace >>> from sympy import symbols, Matrix >>> d, h, angle = symbols('d, h, angle') >>> GeometricRay(h, angle) Matrix([ [ h], [angle]]) >>> FreeSpace(d)*GeometricRay(h, angle) Matrix([ [angle*d + h], [ angle]]) >>> GeometricRay( Matrix( ((h,), (angle,)) ) ) Matrix([ [ h], [angle]]) See Also ======== RayTransferMatrix """ def __new__(cls, *args): if len(args) == 1 and isinstance(args[0], Matrix) \ and args[0].shape == (2, 1): temp = args[0] elif len(args) == 2: temp = ((args[0],), (args[1],)) else: raise ValueError(filldedent(''' Expecting 2x1 Matrix or the 2 elements of the Matrix but got %s''' % str(args))) return Matrix.__new__(cls, temp) @property
[docs] def height(self): """ The distance from the optical axis. Examples ======== >>> from sympy.physics.gaussopt import GeometricRay >>> from sympy import symbols >>> h, angle = symbols('h, angle') >>> gRay = GeometricRay(h, angle) >>> gRay.height h """ return self[0]
@property
[docs] def angle(self): """ The angle with the optical axis. Examples ======== >>> from sympy.physics.gaussopt import GeometricRay >>> from sympy import symbols >>> h, angle = symbols('h, angle') >>> gRay = GeometricRay(h, angle) >>> gRay.angle angle """ return self[1] ### # Representation for gauss beam ###
[docs]class BeamParameter(Expr): """ Representation for a gaussian ray in the Ray Transfer Matrix formalism. Parameters ========== wavelen : the wavelength, z : the distance to waist, and w : the waist, or z_r : the rayleigh range Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.q 1 + 1.88679245283019*I*pi >>> p.q.n() 1.0 + 5.92753330865999*I >>> p.w_0.n() 0.00100000000000000 >>> p.z_r.n() 5.92753330865999 >>> from sympy.physics.gaussopt import FreeSpace >>> fs = FreeSpace(10) >>> p1 = fs*p >>> p.w.n() 0.00101413072159615 >>> p1.w.n() 0.00210803120913829 See Also ======== RayTransferMatrix References ========== .. [1] http://en.wikipedia.org/wiki/Complex_beam_parameter """ #TODO A class Complex may be implemented. The BeamParameter may # subclass it. See: # https://groups.google.com/d/topic/sympy/7XkU07NRBEs/discussion __slots__ = ['z', 'z_r', 'wavelen'] def __new__(cls, wavelen, z, **kwargs): wavelen, z = map(sympify, (wavelen, z)) inst = Expr.__new__(cls, wavelen, z) inst.wavelen = wavelen inst.z = z if len(kwargs) != 1: raise ValueError('Constructor expects exactly one named argument.') elif 'z_r' in kwargs: inst.z_r = sympify(kwargs['z_r']) elif 'w' in kwargs: inst.z_r = waist2rayleigh(sympify(kwargs['w']), wavelen) else: raise ValueError('The constructor needs named argument w or z_r') return inst @property
[docs] def q(self): """ The complex parameter representing the beam. Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.q 1 + 1.88679245283019*I*pi """ return self.z + I*self.z_r
@property
[docs] def radius(self): """ The radius of curvature of the phase front. Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.radius 0.2809/pi**2 + 1 """ return self.z*(1 + (self.z/self.z_r)**2)
@property
[docs] def w(self): """ The beam radius at 1/e^2 intensity. See Also ======== w_0 : the minimal radius of beam Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.w 0.001*sqrt(0.2809/pi**2 + 1) """ return self.w_0*sqrt(1 + (self.z/self.z_r)**2)
@property
[docs] def w_0(self): """ The beam waist (minimal radius). See Also ======== w : the beam radius at 1/e^2 intensity Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.w_0 0.00100000000000000 """ return sqrt(self.z_r/pi*self.wavelen)
@property
[docs] def divergence(self): """ Half of the total angular spread. Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.divergence 0.00053/pi """ return self.wavelen/pi/self.w_0
@property
[docs] def gouy(self): """ The Gouy phase. Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.gouy atan(0.53/pi) """ return atan2(self.z, self.z_r)
@property
[docs] def waist_approximation_limit(self): """ The minimal waist for which the gauss beam approximation is valid. The gauss beam is a solution to the paraxial equation. For curvatures that are too great it is not a valid approximation. Examples ======== >>> from sympy.physics.gaussopt import BeamParameter >>> p = BeamParameter(530e-9, 1, w=1e-3) >>> p.waist_approximation_limit 1.06e-6/pi """ return 2*self.wavelen/pi ### # Utilities ###
[docs]def waist2rayleigh(w, wavelen): """ Calculate the rayleigh range from the waist of a gaussian beam. See Also ======== rayleigh2waist, BeamParameter Examples ======== >>> from sympy.physics.gaussopt import waist2rayleigh >>> from sympy import symbols >>> w, wavelen = symbols('w wavelen') >>> waist2rayleigh(w, wavelen) pi*w**2/wavelen """ w, wavelen = map(sympify, (w, wavelen)) return w**2*pi/wavelen
[docs]def rayleigh2waist(z_r, wavelen): """Calculate the waist from the rayleigh range of a gaussian beam. See Also ======== waist2rayleigh, BeamParameter Examples ======== >>> from sympy.physics.gaussopt import rayleigh2waist >>> from sympy import symbols >>> z_r, wavelen = symbols('z_r wavelen') >>> rayleigh2waist(z_r, wavelen) sqrt(wavelen*z_r)/sqrt(pi) """ z_r, wavelen = map(sympify, (z_r, wavelen)) return sqrt(z_r/pi*wavelen)
[docs]def geometric_conj_ab(a, b): """ Conjugation relation for geometrical beams under paraxial conditions. Takes the distances to the optical element and returns the needed focal distance. See Also ======== geometric_conj_af, geometric_conj_bf Examples ======== >>> from sympy.physics.gaussopt import geometric_conj_ab >>> from sympy import symbols >>> a, b = symbols('a b') >>> geometric_conj_ab(a, b) a*b/(a + b) """ a, b = map(sympify, (a, b)) if abs(a) == oo or abs(b) == oo: return a if abs(b) == oo else b else: return a*b/(a + b)
[docs]def geometric_conj_af(a, f): """ Conjugation relation for geometrical beams under paraxial conditions. Takes the object distance (for geometric_conj_af) or the image distance (for geometric_conj_bf) to the optical element and the focal distance. Then it returns the other distance needed for conjugation. See Also ======== geometric_conj_ab Examples ======== >>> from sympy.physics.gaussopt import geometric_conj_af, geometric_conj_bf >>> from sympy import symbols >>> a, b, f = symbols('a b f') >>> geometric_conj_af(a, f) a*f/(a - f) >>> geometric_conj_bf(b, f) b*f/(b - f) """ a, f = map(sympify, (a, f)) return -geometric_conj_ab(a, -f)
geometric_conj_bf = geometric_conj_af
[docs]def gaussian_conj(s_in, z_r_in, f): """ Conjugation relation for gaussian beams. Parameters ========== s_in : the distance to optical element from the waist z_r_in : the rayleigh range of the incident beam f : the focal length of the optical element Returns ======= a tuple containing (s_out, z_r_out, m) s_out : the distance between the new waist and the optical element z_r_out : the rayleigh range of the emergent beam m : the ration between the new and the old waists Examples ======== >>> from sympy.physics.gaussopt import gaussian_conj >>> from sympy import symbols >>> s_in, z_r_in, f = symbols('s_in z_r_in f') >>> gaussian_conj(s_in, z_r_in, f)[0] 1/(-1/(s_in + z_r_in**2/(-f + s_in)) + 1/f) >>> gaussian_conj(s_in, z_r_in, f)[1] z_r_in/(1 - s_in**2/f**2 + z_r_in**2/f**2) >>> gaussian_conj(s_in, z_r_in, f)[2] 1/sqrt(1 - s_in**2/f**2 + z_r_in**2/f**2) """ s_in, z_r_in, f = map(sympify, (s_in, z_r_in, f)) s_out = 1 / ( -1/(s_in + z_r_in**2/(s_in - f)) + 1/f ) m = 1/sqrt((1 - (s_in/f)**2) + (z_r_in/f)**2) z_r_out = z_r_in / ((1 - (s_in/f)**2) + (z_r_in/f)**2) return (s_out, z_r_out, m)
[docs]def conjugate_gauss_beams(wavelen, waist_in, waist_out, **kwargs): """ Find the optical setup conjugating the object/image waists. Parameters ========== wavelen : the wavelength of the beam waist_in and waist_out : the waists to be conjugated f : the focal distance of the element used in the conjugation Returns ======= a tuple containing (s_in, s_out, f) s_in : the distance before the optical element s_out : the distance after the optical element f : the focal distance of the optical element Examples ======== >>> from sympy.physics.gaussopt import conjugate_gauss_beams >>> from sympy import symbols, factor >>> l, w_i, w_o, f = symbols('l w_i w_o f') >>> conjugate_gauss_beams(l, w_i, w_o, f=f)[0] f*(-sqrt(w_i**2/w_o**2 - pi**2*w_i**4/(f**2*l**2)) + 1) >>> factor(conjugate_gauss_beams(l, w_i, w_o, f=f)[1]) f*w_o**2*(w_i**2/w_o**2 - sqrt(w_i**2/w_o**2 - pi**2*w_i**4/(f**2*l**2)))/w_i**2 >>> conjugate_gauss_beams(l, w_i, w_o, f=f)[2] f """ #TODO add the other possible arguments wavelen, waist_in, waist_out = map(sympify, (wavelen, waist_in, waist_out)) m = waist_out / waist_in z = waist2rayleigh(waist_in, wavelen) if len(kwargs) != 1: raise ValueError("The function expects only one named argument") elif 'dist' in kwargs: raise NotImplementedError(filldedent(''' Currently only focal length is supported as a parameter''')) elif 'f' in kwargs: f = sympify(kwargs['f']) s_in = f * (1 - sqrt(1/m**2 - z**2/f**2)) s_out = gaussian_conj(s_in, z, f)[0] elif 's_in' in kwargs: raise NotImplementedError(filldedent(''' Currently only focal length is supported as a parameter''')) else: raise ValueError(filldedent(''' The functions expects the focal length as a named argument''')) return (s_in, s_out, f) #TODO #def plot_beam(): # """Plot the beam radius as it propagates in space.""" # pass #TODO #def plot_beam_conjugation(): # """ # Plot the intersection of two beams. # # Represents the conjugation relation. # # See Also # ======== # # conjugate_gauss_beams # """ # pass