There are generally three ways to express the light distribution curve: one is the polar coordinate method, the other is the rectangular coordinate method, and the third is the equal light intensity curve.
A. Polar coordinate light distribution curve:
On the metering plane passing through the center of the light source, the light intensity values of the lamps at different angles are measured. Starting from a certain direction, the light intensity of each angle is marked with a vector with the angle as a function, and the connection to the top of the vector is the polar coordinate light distribution curve of the lighting fixture. If the luminaire has a rotationally symmetrical axis, only the light intensity distribution curve on a photometric surface passing through the axis can be used to illustrate the spatial distribution of its light intensity.
If the light distribution of the luminaire in space is asymmetric, the light intensity distribution curves of several photometric planes are needed to explain the spatial distribution of its light intensity.
B. Rectangular coordinate light distribution curve:
For condensing lamps, because the beam is concentrated in a very narrow solid angle, it is difficult to express the spatial distribution of its light intensity in polar coordinates, so the right-angle light distribution curve representation method is used, and the vertical axis represents the light intensity map. I. Use the horizontal axis to indicate the projection angle of the light beam. If it is a luminaire with a symmetrical axis of rotation, only one light distribution curve is needed to represent it, and if it is an asymmetric luminaire, it needs multiple light distribution curves to represent it.
C. Light intensity curve chart:
The curve connecting the tops of the vectors with equal light intensity is called the equal intensity curve, and the values of the adjacent light intensity curves are arranged in a certain proportion, and the graph composed of a series of equal intensity curves is called equal intensity curve. Graphs, commonly used graphs include circular graphs, rectangular graphs and positive arc graphs. Since the rectangular network diagram can not only illustrate the light intensity distribution of the lamps, but also the regional distribution of the light quantity, the current isoluminous intensity curve diagrams used by the cast-light lamps are all rectangular network diagrams, and we will not introduce them here.
