Optical constants

Refractive index of E-FD13 (HOYA)

E-FD13: n,k 0.365–1.014 µm

Data: formula 3 + tabulated k
Range: 0.365–1.014 µm
Temperature: 293 K
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength. Note: k data cover 370-1550 nm only; k = 0 elsewhere in the n range 365.01-1013.98 nm.

At one wavelength

Refractive index n: 1.74076
Extinction coefficient k: 2.34385e-08

Permittivity ε₁: 3.03026
Permittivity ε₂: 8.16018e-08

Absorption coefficient α: 0.00501254 cm⁻¹
Penetration depth δ = λ/(2πk): 3.98999e+09 nm

Abbe number V_d: 27.76
Chromatic dispersion dn/dλ: -0.133972 µm⁻¹

Group index n_g: 1.81949
Group velocity dispersion: 272.914 fs²/mm

Dispersion parameter D: -1488.89 ps/(nm·km)
Photon energy: 2.11001 eV

ε = (n + ik)², α = 4πk/λ, n_g = n − λ dn/dλ, GVD = λ³/(2πc²) d²n/dλ², D = −(λ/c) d²n/dλ². Group-velocity dispersion is given for formula data only.

Use it in Lightsmith

Load this data in Python, simulate in one more line

pip install lightsmith

import lightsmith as ls

# E-FD13 (HOYA): E-FD13
hoya_e_fd13 = ls.fetch_refractiveindex("specs", "HOYA-optical", "E-FD13", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(hoya_e_fd13.range_nm)  # (365.01, 1013.98) nm
eps = hoya_e_fd13.eps([633])  # complex permittivity

Downloads the original record once (pinned to the imported snapshot) and caches it.

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_4df613407411/lightsmith"
hoya_e_fd13 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(hoya_e_fd13.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (hoya-e-fd13/hoya).

# ... load hoya_e_fd13 as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=hoya_e_fd13)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=1000, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength

Same spec runs with DDA, FDTD, BEM or T-matrix: ls.compare(sim, ["mie", "dda"]).

Materials guide Open a sphere of it in Studio Quick start Ask the community

Lightsmith is open source (MIT): Mie, T-matrix, BEM, DDA, FDTD, RCWA, TMM, mode solvers and inverse design behind one spec, on CPU or GPU. GitHub.

Dispersion formula

Polynomial (formula 3), λ in µm

n^{2} = 2.9205906 - 0.013681618 λ^{2.0} + 0.03256776 λ^{- 2.0} + 0.0028725519 λ^{- 4.0} - 0.00024277107 λ^{- 6.0} + 2.6614514 \times 10^{-5} λ^{- 8.0}

Valid from 0.36501 to 1.01398 µm.

Coefficients as stored

C_i	Value
C1	2.9205906
C2	-0.013681618
C3	2.0
C4	0.03256776
C5	-2.0
C6	0.0028725519
C7	-4.0
C8	-0.00024277107
C9	-6.0
C10	2.6614514e-05
C11	-8.0

Comments and conditions

General glass Type

Conditions

temperature: 293 K

Properties

thermal dispersion: type: formula A, coefficients: -3.40517e-07 0.0 0.0 0.0 0.0 0.0
nd: 1.74077
Vd: 27.76
glass code: 741278
density: value: 3110
thermal expansion: value: 9.1e-06, temperature range: 243 343; value: 1.1e-05, temperature range: 293 573
dPgF: 0.0093
resistance: acid: 1.0; stain: 1.0; climatic: 1.0

Thermo-optic coefficient

Schott thermal-dispersion model (reference temperature 293.0 K): dn/dT = -1.97e-07 K⁻¹ at 633 nm

Notes on the source data (kept exactly as published):

k data cover 370-1550 nm only; k = 0 elsewhere in the n range 365.01-1013.98 nm

References

HOYA Zemax catalog 2017-04-01 (obtained from http://www.hoya-opticalworld.com)

Cite

HOYA Zemax catalog 2017-04-01 (obtained from http://www.hoya-opticalworld.com); Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

Computed on 421 wavelengths, the same grid as the API and the library

CSV comma separated TXT tab separated YAML n, k Full database record original YAML All quantities CSV JSON metadata

E-FD13 (HOYA), E-FD13: n and k versus wavelength
λ (µm)	n	k
0.36501	1.818475	0
0.365946	1.817635	0
0.366884	1.816804	0
0.367825	1.815981	0
0.368768	1.815168	0
0.369713	1.814363	0
0.37	1.814121	5.269700e-06
0.370661	1.813566	5.065076e-06
0.371612	1.812778	4.771033e-06
0.372565	1.811998	4.476237e-06
0.37352	1.811226	4.180684e-06
0.374477	1.810461	3.884374e-06
0.375438	1.809705	3.587305e-06
0.3764	1.808956	3.289473e-06
0.377365	1.808215	2.990878e-06
0.378333	1.807482	2.691517e-06
0.379303	1.806756	2.391389e-06
0.38	1.806239	2.175700e-06
0.380275	1.806037	2.143621e-06
0.38125	1.805325	2.030052e-06
0.382228	1.80462	1.916191e-06
0.383208	1.803922	1.802038e-06
0.38419	1.803232	1.687593e-06
0.385176	1.802547	1.572854e-06
0.386163	1.80187	1.457821e-06
0.387153	1.801199	1.342493e-06
0.388146	1.800534	1.226869e-06
0.389141	1.799876	1.110949e-06
0.39	1.799315	1.010900e-06
0.390139	1.799224	1.004309e-06
0.391139	1.798579	9.568140e-07
0.392142	1.797939	9.091968e-07
0.393147	1.797305	8.614576e-07
0.394155	1.796678	8.135959e-07
0.395166	1.796056	7.656115e-07
0.396179	1.79544	7.175041e-07
0.397195	1.79483	6.692734e-07
0.398213	1.794225	6.209190e-07
0.399234	1.793626	5.724406e-07
0.4	1.793181	5.360900e-07
0.400258	1.793032	5.320254e-07
0.401284	1.792444	5.158605e-07
0.402313	1.791861	4.996541e-07
0.403345	1.791283	4.834061e-07
0.404379	1.790711	4.671165e-07
0.405416	1.790143	4.507851e-07
0.406455	1.789581	4.344119e-07
0.407497	1.789024	4.179967e-07
0.408542	1.788471	4.015393e-07
0.40959	1.787924	3.850398e-07
0.41064	1.787381	3.684980e-07
0.411693	1.786843	3.519138e-07
0.412748	1.786309	3.352870e-07
0.413806	1.78578	3.186176e-07
0.414867	1.785256	3.019055e-07
0.415931	1.784736	2.851505e-07
0.416998	1.784221	2.683526e-07
0.418067	1.78371	2.515116e-07
0.419139	1.783203	2.346274e-07
0.42	1.7828	2.210600e-07
0.420213	1.7827	2.201879e-07
0.421291	1.782202	2.157828e-07
0.422371	1.781708	2.113666e-07
0.423454	1.781218	2.069389e-07
0.42454	1.780732	2.025000e-07
0.425628	1.78025	1.980496e-07
0.426719	1.779772	1.935878e-07
0.427813	1.779298	1.891146e-07
0.42891	1.778828	1.846300e-07
0.43001	1.778362	1.801338e-07
0.431113	1.777899	1.756261e-07
0.432218	1.77744	1.711068e-07
0.433326	1.776985	1.665760e-07
0.434437	1.776534	1.620335e-07
0.435551	1.776086	1.574794e-07
0.436668	1.775641	1.529136e-07
0.437787	1.775201	1.483361e-07
0.43891	1.774763	1.437469e-07
0.44	1.774343	1.392900e-07
0.440035	1.774329	1.392211e-07
0.441163	1.773899	1.370154e-07
0.442295	1.773472	1.348040e-07
0.443429	1.773048	1.325870e-07
0.444566	1.772627	1.303643e-07
0.445705	1.77221	1.281359e-07
0.446848	1.771796	1.259018e-07
0.447994	1.771385	1.236619e-07
0.449143	1.770977	1.214163e-07
0.450294	1.770572	1.191650e-07
0.451449	1.770171	1.169078e-07
0.452606	1.769772	1.146449e-07
0.453767	1.769377	1.123762e-07
0.45493	1.768984	1.101017e-07
0.456097	1.768595	1.078213e-07
0.457266	1.768208	1.055351e-07
0.458438	1.767824	1.032430e-07
0.459614	1.767443	1.009451e-07
0.46	1.767319	1.001900e-07
0.460792	1.767065	9.943258e-08
0.461974	1.766689	9.830299e-08
0.463158	1.766317	9.717050e-08
0.464346	1.765947	9.603511e-08
0.465536	1.76558	9.489681e-08
0.46673	1.765215	9.375559e-08
0.467927	1.764853	9.261145e-08
0.469126	1.764494	9.146437e-08
0.470329	1.764137	9.031435e-08
0.471535	1.763783	8.916138e-08
0.472744	1.763432	8.800545e-08
0.473956	1.763083	8.684656e-08
0.475171	1.762736	8.568470e-08
0.47639	1.762392	8.451986e-08
0.477611	1.76205	8.335204e-08
0.478836	1.761711	8.218122e-08
0.48	1.761391	8.106800e-08
0.480063	1.761374	8.100166e-08
0.481294	1.76104	7.971337e-08
0.482528	1.760708	7.842178e-08
0.483765	1.760378	7.712688e-08
0.485006	1.76005	7.582866e-08
0.486249	1.759725	7.452711e-08
0.487496	1.759402	7.322222e-08
0.488746	1.759081	7.191399e-08
0.489999	1.758763	7.060240e-08
0.491255	1.758447	6.928745e-08
0.492515	1.758132	6.796913e-08
0.493778	1.75782	6.664742e-08
0.495044	1.757511	6.532233e-08
0.496313	1.757203	6.399385e-08
0.497586	1.756897	6.266195e-08
0.498861	1.756594	6.132664e-08
0.5	1.756325	6.013500e-08
0.500141	1.756292	6.002764e-08
0.501423	1.755993	5.904803e-08
0.502709	1.755695	5.806592e-08
0.503997	1.7554	5.708128e-08
0.50529	1.755106	5.609411e-08
0.506585	1.754815	5.510442e-08
0.507884	1.754525	5.411219e-08
0.509186	1.754238	5.311741e-08
0.510492	1.753952	5.212009e-08
0.511801	1.753668	5.112021e-08
0.513113	1.753386	5.011776e-08
0.514429	1.753106	4.911274e-08
0.515748	1.752828	4.810515e-08
0.51707	1.752551	4.709497e-08
0.518396	1.752277	4.608220e-08
0.519725	1.752004	4.506684e-08
0.521057	1.751733	4.404887e-08
0.522393	1.751464	4.302830e-08
0.523733	1.751196	4.200510e-08
0.525076	1.75093	4.097928e-08
0.526422	1.750666	3.995084e-08
0.527772	1.750404	3.891975e-08
0.529125	1.750143	3.788602e-08
0.530481	1.749884	3.684965e-08
0.531842	1.749627	3.581061e-08
0.533205	1.749371	3.476891e-08
0.534572	1.749117	3.372454e-08
0.535943	1.748865	3.267749e-08
0.537317	1.748614	3.162776e-08
0.538695	1.748365	3.057533e-08
0.540076	1.748117	2.952021e-08
0.541461	1.747871	2.846238e-08
0.542849	1.747626	2.740184e-08
0.544241	1.747383	2.633858e-08
0.545636	1.747142	2.527260e-08
0.547035	1.746902	2.420388e-08
0.548438	1.746663	2.313242e-08
0.549844	1.746426	2.205821e-08
0.55	1.7464	2.193900e-08
0.551254	1.746191	2.198900e-08
0.552667	1.745957	2.204537e-08
0.554084	1.745724	2.210188e-08
0.555505	1.745493	2.215853e-08
0.556929	1.745264	2.221533e-08
0.558357	1.745035	2.227228e-08
0.559789	1.744808	2.232937e-08
0.561224	1.744583	2.238661e-08
0.562663	1.744359	2.244400e-08
0.564106	1.744136	2.250153e-08
0.565552	1.743915	2.255921e-08
0.567002	1.743695	2.261704e-08
0.568456	1.743476	2.267501e-08
0.569913	1.743259	2.273314e-08
0.571374	1.743043	2.279141e-08
0.572839	1.742828	2.284984e-08
0.574308	1.742615	2.290841e-08
0.575781	1.742403	2.296713e-08
0.577257	1.742192	2.302601e-08
0.578737	1.741983	2.308503e-08
0.580221	1.741774	2.314421e-08
0.581709	1.741567	2.320354e-08
0.5832	1.741362	2.326302e-08
0.584695	1.741157	2.332265e-08
0.586195	1.740954	2.338244e-08
0.587697	1.740752	2.344238e-08
0.589204	1.740551	2.350247e-08
0.590715	1.740351	2.356272e-08
0.59223	1.740152	2.362312e-08
0.593748	1.739955	2.368367e-08
0.59527	1.739759	2.374438e-08
0.596797	1.739564	2.380525e-08
0.598327	1.73937	2.386627e-08
0.599861	1.739177	2.392745e-08
0.6	1.73916	2.393300e-08
0.601399	1.738986	2.457179e-08
0.602941	1.738795	2.527588e-08
0.604487	1.738606	2.598178e-08
0.606037	1.738418	2.668949e-08
0.607591	1.73823	2.739901e-08
0.609148	1.738044	2.811035e-08
0.61071	1.737859	2.882352e-08
0.612276	1.737675	2.953851e-08
0.613846	1.737493	3.025534e-08
0.61542	1.737311	3.097400e-08
0.616998	1.73713	3.169451e-08
0.61858	1.73695	3.241687e-08
0.620166	1.736772	3.314108e-08
0.621756	1.736594	3.386714e-08
0.62335	1.736417	3.459507e-08
0.624948	1.736242	3.532486e-08
0.626551	1.736067	3.605652e-08
0.628157	1.735893	3.679006e-08
0.629768	1.735721	3.752548e-08
0.631382	1.735549	3.826279e-08
0.633001	1.735378	3.900198e-08
0.634624	1.735209	3.974308e-08
0.636251	1.73504	4.048607e-08
0.637883	1.734872	4.123097e-08
0.639518	1.734705	4.197777e-08
0.641158	1.734539	4.272649e-08
0.642802	1.734374	4.347713e-08
0.64445	1.73421	4.422970e-08
0.646102	1.734047	4.498420e-08
0.647759	1.733885	4.574063e-08
0.64942	1.733723	4.649899e-08
0.65	1.733667	4.676400e-08
0.651085	1.733563	4.635523e-08
0.652754	1.733403	4.572615e-08
0.654428	1.733245	4.509545e-08
0.656106	1.733087	4.446314e-08
0.657788	1.73293	4.382921e-08
0.659474	1.732774	4.319365e-08
0.661165	1.732618	4.255646e-08
0.662861	1.732464	4.191764e-08
0.66456	1.732311	4.127718e-08
0.666264	1.732158	4.063508e-08
0.667972	1.732006	3.999133e-08
0.669685	1.731855	3.934594e-08
0.671402	1.731705	3.869888e-08
0.673123	1.731555	3.805017e-08
0.674849	1.731407	3.739979e-08
0.67658	1.731259	3.674775e-08
0.678314	1.731112	3.609404e-08
0.680053	1.730966	3.543865e-08
0.681797	1.73082	3.478157e-08
0.683545	1.730676	3.412282e-08
0.685298	1.730532	3.346237e-08
0.687055	1.730389	3.280023e-08
0.688816	1.730246	3.213640e-08
0.690583	1.730105	3.147086e-08
0.692353	1.729964	3.080362e-08
0.694128	1.729824	3.013466e-08
0.695908	1.729684	2.946399e-08
0.697692	1.729546	2.879160e-08
0.699481	1.729408	2.811749e-08
0.7	1.729368	2.792200e-08
0.701275	1.729271	2.782000e-08
0.703073	1.729134	2.767612e-08
0.704875	1.728998	2.753187e-08
0.706683	1.728863	2.738725e-08
0.708495	1.728729	2.724226e-08
0.710311	1.728595	2.709690e-08
0.712132	1.728462	2.695117e-08
0.713958	1.72833	2.680506e-08
0.715789	1.728198	2.665858e-08
0.717624	1.728067	2.651172e-08
0.719464	1.727937	2.636449e-08
0.721309	1.727808	2.621688e-08
0.723158	1.727679	2.606889e-08
0.725012	1.72755	2.592052e-08
0.726871	1.727423	2.577177e-08
0.728735	1.727296	2.562264e-08
0.730603	1.727169	2.547312e-08
0.732477	1.727044	2.532323e-08
0.734355	1.726919	2.517294e-08
0.736237	1.726794	2.502228e-08
0.738125	1.72667	2.487123e-08
0.740018	1.726547	2.471978e-08
0.741915	1.726425	2.456796e-08
0.743817	1.726303	2.441574e-08
0.745724	1.726181	2.426313e-08
0.747636	1.72606	2.411013e-08
0.749553	1.72594	2.395674e-08
0.75	1.725912	2.392100e-08
0.751475	1.725821	2.335580e-08
0.753402	1.725702	2.261760e-08
0.755334	1.725583	2.187750e-08
0.75727	1.725465	2.113551e-08
0.759212	1.725348	2.039161e-08
0.761159	1.725231	1.964580e-08
0.76311	1.725115	1.889808e-08
0.765067	1.724999	1.814845e-08
0.767028	1.724884	1.739689e-08
0.768995	1.72477	1.664341e-08
0.770967	1.724656	1.588799e-08
0.772943	1.724543	1.513064e-08
0.774925	1.72443	1.437135e-08
0.776912	1.724317	1.361011e-08
0.778904	1.724205	1.284691e-08
0.78	1.724144	1.242700e-08
0.780901	1.724094	1.244133e-08
0.782903	1.723983	1.247316e-08
0.784911	1.723873	1.250508e-08
0.786923	1.723763	1.253708e-08
0.788941	1.723654	1.256916e-08
0.790964	1.723545	1.260132e-08
0.792992	1.723437	1.263357e-08
0.795025	1.723329	1.266589e-08
0.797063	1.723222	1.269830e-08
0.799107	1.723116	1.273080e-08
0.8	1.723069	1.274500e-08
0.801156	1.723009	1.250858e-08
0.80321	1.722903	1.208839e-08
0.805269	1.722798	1.166712e-08
0.807334	1.722693	1.124477e-08
0.809404	1.722589	1.082133e-08
0.811479	1.722485	1.039681e-08
0.81356	1.722382	9.971202e-09
0.815646	1.722279	9.544502e-09
0.817737	1.722176	9.116708e-09
0.819834	1.722074	8.687817e-09
0.821936	1.721972	8.257826e-09
0.824043	1.721871	7.826733e-09
0.826156	1.721771	7.394535e-09
0.828274	1.72167	6.961228e-09
0.83	1.721589	6.608200e-09
0.830398	1.72157	6.611369e-09
0.832527	1.721471	6.628327e-09
0.834662	1.721372	6.645329e-09
0.836802	1.721273	6.662375e-09
0.838947	1.721175	6.679464e-09
0.841098	1.721077	6.696597e-09
0.843255	1.72098	6.713774e-09
0.845417	1.720883	6.730995e-09
0.847584	1.720787	6.748260e-09
0.849758	1.72069	6.765569e-09
0.85	1.72068	6.767500e-09
0.851936	1.720595	6.782917e-09
0.854121	1.720499	6.800309e-09
0.856311	1.720404	6.817745e-09
0.858506	1.72031	6.835226e-09
0.860707	1.720216	6.852752e-09
0.862914	1.720122	6.870323e-09
0.865127	1.720029	6.887939e-09
0.867345	1.719936	6.905599e-09
0.869569	1.719843	6.923306e-09
0.871798	1.719751	6.941057e-09
0.874033	1.719659	6.958855e-09
0.876274	1.719567	6.976697e-09
0.878521	1.719476	6.994586e-09
0.880774	1.719385	7.012520e-09
0.883032	1.719295	7.030501e-09
0.885296	1.719205	7.048527e-09
0.887566	1.719115	7.066600e-09
0.889842	1.719025	7.084719e-09
0.892123	1.718936	7.102884e-09
0.894411	1.718847	7.121096e-09
0.896704	1.718759	7.139355e-09
0.899003	1.718671	7.157661e-09
0.9	1.718633	7.165600e-09
0.901308	1.718583	7.176011e-09
0.903619	1.718496	7.194406e-09
0.905936	1.718409	7.212848e-09
0.908258	1.718322	7.231337e-09
0.910587	1.718235	7.249874e-09
0.912922	1.718149	7.268458e-09
0.915263	1.718063	7.287090e-09
0.917609	1.717978	7.305770e-09
0.919962	1.717892	7.324498e-09
0.922321	1.717807	7.343273e-09
0.924686	1.717723	7.362097e-09
0.927056	1.717638	7.380969e-09
0.929433	1.717554	7.399890e-09
0.931816	1.717471	7.418859e-09
0.934206	1.717387	7.437876e-09
0.936601	1.717304	7.456943e-09
0.939002	1.717221	7.476058e-09
0.94141	1.717138	7.495222e-09
0.943824	1.717056	7.514436e-09
0.946244	1.716974	7.533698e-09
0.94867	1.716892	7.553010e-09
0.95	1.716848	7.563600e-09
0.951102	1.716811	7.572374e-09
0.953541	1.716729	7.591790e-09
0.955985	1.716648	7.611256e-09
0.958437	1.716568	7.630772e-09
0.960894	1.716487	7.650338e-09
0.963358	1.716407	7.669954e-09
0.965828	1.716327	7.689620e-09
0.968304	1.716247	7.709337e-09
0.970787	1.716168	7.729104e-09
0.973276	1.716089	7.748922e-09
0.975771	1.71601	7.768791e-09
0.978273	1.715931	7.788710e-09
0.980781	1.715852	7.808681e-09
0.983296	1.715774	7.828703e-09
0.985817	1.715696	7.848776e-09
0.988345	1.715618	7.868901e-09
0.990879	1.715541	7.889077e-09
0.993419	1.715463	7.909306e-09
0.995967	1.715386	7.929586e-09
0.99852	1.715309	7.949918e-09
1	1.715265	7.961700e-09
1.00108	1.715232	7.970302e-09
1.00365	1.715156	7.990738e-09
1.00622	1.71508	8.011227e-09
1.0088	1.715004	8.031768e-09
1.01139	1.714928	8.052362e-09
1.01398	1.714852	8.073009e-09

Optical transmission calculator

Free-standing sample in vacuum, normal incidence

Transmittance T: —
Reflectance R: —

Fresnel reflection calculator

R_p: —
R_s: —
R = (R_p+R_s)/2: —
Phase φ_p: —
Phase φ_s: —
Brewster angle θ_B: —
Critical angle θ_C: —

E-FD13 (HOYA): all datasets

FD (Dense flint)

E-FD13 n,k 0.365–1.014 µm default

About E-FD13 (HOYA)

HOYA Corporation is a global technology company based in Japan, known for its diverse range of products in the fields of healthcare and optics. In the optical industry, HOYA is particularly recognized for its high-quality optical glass and lens technologies. The company produces a wide array of optical products, from eyeglass lenses with advanced coatings to specialized glass materials used in cameras, telescopes, and other precision optical instruments. HOYA's expertise extends to various types of optical glass, including low-dispersion and high-refractive-index materials, which find applications in situations requiring exceptional optical clarity and performance. Beyond its contributions to optics, HOYA has also ventured into medical technologies, making it a multi-faceted company with a broad impact. With a commitment to innovation and quality, HOYA has earned a reputation as a leader in its field, consistently delivering products that set industry standards for performance and reliability. Their expansive portfolio and technological prowess make them a go-to provider for both consumer and industrial optical solutions.

More about E-FD13 (HOYA) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/specs/hoya/optical/E-FD13.yml
ID: ds_4df613407411
API: /v1/datasets/ds_4df613407411

Plot