Kraken-Optical-Simulator (KrakenOS)
Email: joel@astro.unam.mx
Collaborators:
Carlos Guerrero P., Morgan Rhaí Najera Roa, Anais Sotelo B., Ilse Plauchu F., José A. Araiza
It would be appreciated if a reference to the following work, for which this package was originally build, is included whenever this code is used for a publication: (https://www.spiedigitallibrary.org/journals/optical-engineering/volume-61/issue-1/015101/KrakenOS-Python-based-general-exact-ray-tracing-library/10.1117/1.OE.61.1.015101.short)
KrakenOS (Kraken - Optical Simulator) is a python library based in Numpy, Matplotlib, PyVTK and PyVista libraries, it provides a three-dimensional optical systems visualization and ray tracing. This tool has been programed on the object-oriented paradigm. KrakenOS focuses on performing sequential and non-sequential exact ray tracing, it permits to define all the parameters of the optical elements or even the mathematical function to describe their shape, it also allows adding optical properties to 3D solid elements in STL format and use glass catalogs. The library permit to control and modifying the position of the surfaces in a three-dimensional space, this allows generating off-axis systems. It also has several tools such as the calculation of wavefront aberrations in terms of Zernike polynomials, Seidel sums, Entrance and exit pupil calculation and paraxial optics.
install KrakenOS
pip install KrakenOSPrerequisites
The library has been tested with the following packages and versions, these are also installed with the previous instruction.
• Python '3.7.4'
• numpy '1.18.5'
• scipy '1.7.1'
• pyvista '0.25.3'
• pyvtk '0.5.18'
• matplotlib '3.4.3'
• vtk '8.2'
• csv '1.0'
to install prerequisites
pip install pyvista
pip install PyVTK
pip install vtk
pip install numpy
pip install scipy
pip install matplotlib
pip install csv342• Or clone the repository and place the directory “KrakenOS” in the same path where the code to be executed is located.
⚠ WARNING: If you prefer clone the repositoy instead of using pip install KrakenOS, modify the first line in the file /KrakenOS/SetupClass.py from pip = True to False.
pip = False⚠ WARNING: The before mentioned modification is not required in last version, the file /KrakenOS/SetupClass.py do not have the option pip = True.
Surfaces and the optical system
The library has been simplified to the point of having only two classes of objects for the definition of a system, these are surf and system. The surf object contains all the relevant information of every optical interface, in this way, every optical interface is an object of the surf class, all interfaces, from the object plane to the image plane, contain attributes of size, shape, material or orientation.
A little fun before class ... and objects
"""Examp Doublet Lens Pupil"""
# Loading the library
import KrakenOS as Kos# Creating an object of the surf class for the object plane
P_Obj = Kos.surf()
P_Obj.Thickness = 100
P_Obj.Glass = "AIR"
P_Obj.Diameter = 30.0
# Creating a surface for the first face in BK7 Glass
L1a = Kos.surf()
L1a.Rc = 92.847
L1a.Thickness = 6.0
L1a.Glass = "BK7"
L1a.Diameter = 30.0
# Creating a surface for the second face in F2 Glass
L1b = Kos.surf()
L1b.Rc = -30.716
L1b.Thickness = 3.0
L1b.Glass = "F2"
L1b.Diameter = 30
# Creating a surface for the third interface to air
L1c = Kos.surf()
L1c.Rc = -78.197
L1c.Thickness = 97.376 - 40
L1c.Glass = "AIR"
L1c.Diameter = 30
# Creating a surface to exemplify a pupil
pupila.Rc = 30
pupila.Thickness = 40.
pupila.Glass = "AIR"
pupila.Diameter = 5
pupila.Name = "Pupil"
pupila.DespY = 0.
pupila.Nm_Poss=[-10,10]
# Creating a surface for image plane
P_Ima = Kos.surf()
P_Ima.Rc = 0.0
P_Ima.Thickness = 0.0
P_Ima.Glass = "AIR"
P_Ima.Diameter = 20.0
P_Ima.Name = "P_Ima"
P_Ima.Nm_Poss=[-10,10]Creating a list with all the surfaces and loading the default grass catalogs (See user manual)
A = [P_Obj, L1a, L1b, L1c, pupila, P_Ima]
config_1 = Kos.Setup()# Creating the system with previus information
Doblete = Kos.system(A, config_1)Creating a ray container
Rays = Kos.raykeeper(Doulet)Defining parameters to configure pupil on surface 4 (Again.., see user manual)
W = 0.4
sur = 4
AperVal = 10
AperType = "EPD"
Pup = Kos.PupilCalc(Doublet, sur, W, AperType, AperVal)
# Configuring field and ray array type
Pup.Samp = 3
Pup.Ptype = "fan"
Pup.FieldType = "angle"
Pup.FieldY = 2.0Generating and tracing rays
# ray origin coordinates and direction cosines
x, y, z, L, M, N = Pup.Pattern2Field()
# Tracing the rays with a loop
for i in range(0, len(x)):
pSource_0 = [x[i], y[i], z[i]]
dCos = [L[i], M[i], N[i]]
Doblete.Trace(pSource_0, dCos, W)
Rays.push()# Saving rays
# Configuring (-field) and ray array type,.. etc
Pup.FieldY = -Pup.FieldY
x, y, z, L, M, N = Pup.Pattern2Field()
for i in range(0, len(x)):
pSource_0 = [x[i], y[i], z[i]]
dCos = [L[i], M[i], N[i]]
Doblete.Trace(pSource_0, dCos, W)
Rays.push() # Saving rays3D plotting
Kos.display3d(Doblete, Rays,2)
Or for 2D plotting
Kos.display2d(Doblete, Rays,0,1)
surf class Atributes
| class Atribute | Short description |
|---|---|
| surf.Name = "" | Name of the element. |
| surf.NamePos = (0,0) | “Name” position in the 2D diagram. |
| surf.Note = "None" | Useful for adding user notes to a surface. |
| surf.Rc = 0 | Paraxial radius of curvature in millimeters. |
| surf.Cylinder_Rxy_Ratio = 1 | Ratio between the axial and sagittal radius of curvature. |
| surf.Axicon = 0 | Values other than zero an axicon is generated with the angle defined |
| surf.Thickness = 0.0 | Distance between this surface and the next surface. |
| surf.Diameter = 1.0 | Outside diameter of the surface. |
| surf.InDiameter = 0.0 | Internal diameter of the surface. |
| surf.k = 0.0 | Conicity constant for classical conic surfaces, k = 0 for spherical, k = -1 for parabola, etc. Default value: 0.0 |
| surf.DespX = 0.0 | Displacement of the surface in the X, Y and Z axis |
| surf.DespY = 0.0 | |
| surf.DespZ = 0.0 | |
| surf.TiltX = 0.0 | Rotation of the surface in the X, Y and Z axis |
| surf.TiltY = 0.0 | |
| surf.TiltZ = 0.0 | |
| surf.Order = 0 | Define the order of the transformations. |
| surf.AxisMove = 1 | Defines what will happen to the optical axis after a coordinate transformation. |
| surf.Diff_Ord = 0.0 | Diffraction order. |
| surf.Grating_D = 0.0 | Separation between the lines of the diffraction grating. |
| surf.Grating_Angle = 0.0 | Angle of the grating lines in the plane of the surface |
| surf.ZNK = np.zeros (#) | Zernike polynomials coefficients |
| surf.ShiftX = 0 | Offset the surface function on the X or Y axis. |
| surf.ShiftY = 0 | |
| surf.Mask = 0 | (0) Do not apply mask, (1) Use mask as aperture, (2) Use mask as obstruction. Default value: 0 |
| surf.Mask_Shape = Object_3D | Form of the mask to apply on surface |
| surf.AspherData = np.zeros (#) | Asphericity coefficients. |
| self.ExtraData = [f, coef] | User-defined function for optical surface |
| Surf.Error_map = [X, Y, Z, SPACE] | Error map array |
| surf.Drawing = 1 | 1 for drawn in the 3D plot, 0 to omit. |
| surf.Color = [0,0,0] | Element color for 3D Plot. [R,G,B] |
| surf.Solid_3d_stl = "None" | Path to the 3D solid STL file. |
system class atributes and methods
| class Atribute | Short description | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| system.Trace (pS, dC, wV) | Sequential ray tracing. | ||||||||||||
| pS = [1.0, 0.0, 0.0] – Ray origin coordinates | |||||||||||||
| dC = [0.0,0.0,1.0] - The directing cosines | |||||||||||||
| wV = 0.4 - Wavelength | |||||||||||||
| system.NsTrace (pS, dC, wV) | Non-Sequential ray tracing | ||||||||||||
| Prx = system.Parax (w) | Paraxial optics calculations | ||||||||||||
| system.disable_inner | Enables the central aperture. | system.enable_inner | Disables the central aperture. | system.SURFACE | Returns the surfaces the ray passed through. | system.NAME | Returns surface names that the ray passed through | system.GLASS | Returns materials that the ray passed through. | system.XYZ | [X, Y, Z] ray coordinates from its origin to the image plane. | system.OST_XYZ | [X, Y, Z] coordinates of ray intersections with respect to a coordinate system at its vertex, even if this vertex has a translation or rotation. |
| system.DISTANCE | List of distances traveled by the ray. | system.OP | List of optical paths. | system.TOP | Total optical path. | system.TOP_S | List of the ray's optical path by sections. | ||||||
| system.ALPHA | List the materials absorption coefficients | ||||||||||||
| system.BULK_TRANS | List the transmission through all the system. absorption coefficients are considered. | ||||||||||||
| system.S_LMN | Surface normal direction cosines [L, M, N]. | ||||||||||||
| system.LMN | Incident ray direction cosines [L, M, N]. | ||||||||||||
| system.R_LMN | Resulting ray direction cosines [L, M, N]. | ||||||||||||
| system.N0 | Refractive indices before and after each interface | ||||||||||||
| system.N1 | Refractive indices after each interface. This is useful to differentiate between index before and after an iteration. Example: | ||||||||||||
| N0 = [n1, n2, n3, n4, n5] and N1 = [n2, n3, n4, n5, n5] | |||||||||||||
| system.WAV | Wavelength of the ray (µm) | ||||||||||||
| system.G_LMN | [L, M, N] Direction cosines that define the lines of the diffraction grating on the plane. | ||||||||||||
| system.ORDER | Ray diffraction order. | ||||||||||||
| system.GRATING_D | Distance between lines of the diffraction grating.Units (µm) | ||||||||||||
| system.RP | Fresnel reflection coefficients for polarization P. | ||||||||||||
| system.RS | Fresnel reflection coefficients for polarization S. | ||||||||||||
| system.TP | Fresnel transmission coefficients for polarization P. | ||||||||||||
| system.TS | Fresnel transmission coefficients for polarization S. | ||||||||||||
| system.TTBE | Total energy transmitted or reflected by element. | ||||||||||||
| system.TT | Total energy transmitted or reflected total. | ||||||||||||
| system.targ_surf (int) | Limits the ray tracing to the defined surface | ||||||||||||
| system.flat_surf (int) | Change a surface to flat. |
User manual and examples
Very important, read the included user manual (KrakenOS_User_Manual.pdf) and the set of useful examples:
• Examp_Axicon.py
• Examp_Axicon_And_Cylinder.py
• Examp_Diffraction_Grating_Reflection.py
• Examp_Diffraction_Grating_Transmission.py
• Examp_Doublet_Lens_ParaxMatrix.py
• Examp_Doublet_Lens.py
• Examp_Doublet_Lens_3Dcolor.py
• Examp_Doublet_Lens_CommandsSystem.py
• Examp_Doublet_Lens_Cylinder.py
• Examp_Doublet_Lens_NonSec.py
• Examp_Doublet_Lens_Pupil.py
• Examp_Doublet_Lens_Pupil_Seidel.py
• Examp_Doublet_Lens_Tilt_Nulls.py
• Examp_Doublet_Lens_Tilt.py
• Examp_Doublet_Lens_Tilt_non_sec.py
• Examp_Doublet_Lens_Zernike.py
• Examp_ExtraShape_Micro_Lens_Array.py
• Examp_ExtraShape_Radial_Sine.py
• Examp_ExtraShape_XY_Cosines.py
• Examp_Flat_Mirror_45Deg.py
• Examp_MultiCore.py
• Examp_ParaboleMirror_Shift.py
• Examp_Perfect_lens.py
• Examp_Ray.py
• Examp_Solid_Object_STL.py
• Examp_Solid_Object_STL_ARRAY.py
• Examp_Sourse_Distribution_Function.py
• Examp_Tel_2M.py
• Examp_Tel_2M_Error_Map.py
• Examp_Tel_2M_Pupila.py
• Examp_Tel_2M_Spyder_Spot_Diagram.py
• Examp_Tel_2M_Spyder_Spot_RMS.py
• Examp_Tel_2M_Spyder_Spot_Tilt_M2.py
• Examp_Tel_2M_Atmospheric_Refraction.py
• Examp_Tel_2M_Wavefront_Fitting.py
Enjoy it!!