The luminous intensity of any luminaire is different in all directions in space. We can use data or graphs to record the distribution of luminous intensity of the luminaire in space. Usually we use the ordinate to represent the luminous intensity distribution of the luminaire, with the origin of the coordinate As the center, the luminous intensity in each direction is marked with a vector, and the endpoints of the vector are connected to form a light intensity distribution curve, also called a light distribution curve.
Because the shape of most lamps is an axisymmetric rotating body, the distribution of luminous intensity in space is also axisymmetric. Therefore, it is sufficient to take any plane through the axis of the lamp and use the light intensity distribution curve in this plane to show the distribution of the lighting lamps in the entire space. If the spatial distribution of the luminous intensity of the lighting fixture is asymmetric, such as a long-strip fluorescent lamp, the light intensity distribution curves of several photometric planes need to be used to illustrate the spatial light distribution. Take the plane perpendicular to the long axis of the luminaire and passing through the sag line of the luminaire center as the C0 plane, and the plane perpendicular to the C0 plane and passing through the sag line of the luminaire's center as the C90 plane. At least the light intensity distribution of the two planes C0 and C90 should be used to illustrate the spatial light distribution of asymmetric lamps.
In order to facilitate the comparison of the light distribution characteristics of various lighting fixtures, it is uniformly stipulated that an imaginary light source with a luminous flux of 1000 lumens (lm) is used to provide light intensity distribution data. Therefore, the actual luminous intensity should be the luminous intensity value provided by the photometric data multiplied by the ratio of the actual luminous flux of the light source to 1000.
The light intensity distribution of lighting fixtures is realized by using reflectors, translucent prisms, grids or diffusers of the fixtures to control the light. The reflector is the basic light control part of the lamp. The higher its reflectance, the stronger the regular reflection and the more remarkable the light control ability. Anodized or polished aluminum oxide and stainless steel plates are commonly used mirror-emitting materials. According to the law of regular reflection, the geometric shape and size of the aluminum reflector are carefully designed. When installing, pay attention to the precise positioning of the light source to obtain various required light distributions. The grille mainly plays the role of shielding the light source and reducing direct glare. The light distribution through the grid is generally narrow.
