principal plane

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prin·ci·pal plane

the theoretic plane of a compound lens system. See: principal point.


In geometrical optics, a straight line representing the direction of propagation of light.
axial ray A ray that is coincident with the axis of an optical system.
chief ray A ray joining an object point to the centre of the entrance pupil of an optical system (Fig. R2). See pencil of light.
emergent ray A ray of light in image space either after reflection (reflected ray) or after refraction (refracted ray).
extraordinary ray See birefringence.
incident ray A ray of light in object space that strikes a reflecting or refracting surface.
marginal ray A ray joining the axial point of an object to the edge or margin of an aperture or pupil (Fig. R2).
ordinary ray See birefringence.
paraxial ray A light ray that forms an angle of incidence so small that its value in radians is almost equal to its sine or its tangent. (i.e. sin θ = θ or tan θ = θ. These are approximate expressions referred to as the paraxial approximation (or the gaussian approximation). See paraxial optics; paraxial region; gaussian theory.
principal ray A ray joining the extreme off-axis object point to the centre of the entrance pupil or aperture (Fig. R2).
ray tracing Technique used in optical computation consisting of tracing the paths of light rays through an optical system by graphical methods or by using formulae. Nowadays, computer methods are used. See sign convention.
Fig. R2 Rays of light incident to the eye (E, centre of the entrance pupil of the eye)enlarge picture
Fig. R2 Rays of light incident to the eye (E, centre of the entrance pupil of the eye)

Table R1 Differences between the sine and the tangent values of various angles (in degrees and radians). The error is calculated between the sine value and the value in radians and between the value in radians and the tangent value
angle (deg)angle (rad)sine
tangent valueerror (%) sine errorerror (%) tangent error
0.50.008 7270.008 7270.008 7270.000.00
10.017 4530.017 4520.017 4550.010.01
20.034 9070.034 8990.034 9210.020.04
30.052 3600.052 3360.052 4080.050.09
40.069 8130.069 7560.069 9270.080.16
50.087 2660.087 1560.087 4890.130.25
60.104 7200.104 5280.105 1040.180.37
70.122 1730.121 8690.122 7850.250.50
80.139 6260.139 1730.140 5410.330.65
100.174 5330.173 6480.176 3270.511.03
150.261 7990.258 8190.267 9491.152.35
5200.349 0660.342 0200.363 9702.064.27
300.523 5990.500 0000.577 3504.7210.27
References in periodicals archive ?
Figure 11 shows Surface A as a three-dimensional view supplemented by a plan view, the latter clearly indicating the rotation a of the principal plane of symmetry.
It is interesting to note that a purely real root can still be found even when the principal plane of symmetry of each surface is no longer parallel with the G- or H-axes.
12 is the optimized radiation patterns of the principal planes.
The patterns of the principal planes are close to the desired pattern.
The radiation patterns must be quasi-isotropic in all the principal planes and, in many applications, should have a wide frequency bandwidth.
Figure 1 shows the free-space 840 MHz vertically and horizontally polarized radiation patterns in the principal planes of a conventional helical antenna, which is mounted on a cellular telephone and vertically orientated.
The measured radiation patterns of the proposed wideband CP antenna in two principal planes (x-z plane and y-z plane shown in Fig.
The radiation pattern of the antenna in two principal planes for excitation of Probe1 and Probe2 is illustrated in Figs.
For such antennas, the cross-polar level is low in the principal planes so the total power S([Theta],[Phi]) is almost equal to the power in the co-polar component.
Figures 10 and 11 show a comparison of the simulated and measured gain patterns in the elevation and azimuth principal planes.
Mesh density can be made finer or coarser by increasing (or decreasing) the number of cells between the principal planes.
The main-beam patterns and the half-power beamwidths are nearly the same at both frequencies for both principal planes to within 10 percent.