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Goniophotometer is divided into vertical goniophotometer and horizontal distribution Photometer. Goniophotometer is the main measuring equipment for the light distribution performance test of lamps, which can be used to measure the spatial light intensity distribution, total luminous flux and lamp efficiency of lamps or light sources. Goniophotometer system consists of: precision turntable and control system, spectral analysis system, standard lamp, alignment system, computer processing system and other parts.
Goniophotometer needs to be used with a larger dark room, use low reflectivity materials in the room to avoid reflected light entering the probe. Since the measurement system is easily affected by the ambient temperature, it is critical to keep the temperature of the light source itself stable. The goniophotometer reads angle by angle, which is very time-consuming. If you only need to measure the luminous flux parameters of the lamp, there are no strict requirements for the measurement distance.
According to the different arrangements of the measuring light path, two measurement schemes can be used to measure the luminous flux: illuminance integration method and light intensity integration method:
1. Illuminance integration method. There is no limit on the measuring distance and the required measuring space is small. As long as the illuminance can be measured, accurate total luminous flux can be obtained even at short distances. It can be measured using a compact goniophotometer, which measures the illumination distribution of the light source in space and integrates the entire space to obtain the total luminous flux. Because it is not sensitive to the measurement distance and the installation position of the light source, and can avoid the use of reflectors, it can achieve high measurement accuracy. It is the method recommended by CIE to realize the benchmark unit of luminous flux.
2. Light intensity integration method. The light intensity integration method measures the light intensity distribution of the light source in space and integrates the entire space to obtain the total luminous flux. Measuring light intensity distribution requires sufficient distance. The object to be measured can be approximately regarded as a point light source, and the light intensity can be measured using the inverse square distance relationship.
Goniophotometers are mainly divided into several types: lamp rotating type, detector rotating type, and lamp fixed type.
Operating principle:
Luminous intensity can be obtained by rotating the lighting device in different directions at a fixed distance for illuminance (far-field) or illuminance (near-field) measurements. With sufficient angular step size and range, the luminous flux of a lighting device can be calculated by summing all luminous intensities in each measurement direction. A goniometer is an instrument with a rotating axis used to measure the luminous flux and luminous intensity distribution of a lighting device or light source.
Based on the luminous intensity distribution, properties of the lighting application can be inferred, such as transverse/vertical iso-illuminance curves or cone diagrams. According to the measurementThe way the lighting equipment is rotated during the process and the photometric data obtained during this measurement system, the types of goniometers can basically be divided into Group 1, Group 2 and Group 3, also known as Class A, Class B and Class C , the difference is as follows:
Class A is suitable for automotive lighting that characterizes relatively limited beams. Type A goniometers have a fixed horizontal axis and a moving axis perpendicular to the central axis. Measurements are made by rotating the light source around a horizontal axis while keeping the other axis in a fixed position (rotation vs height).
Class B is suitable for monitors and floodlights. Type B goniometers have a fixed vertical axis and a moving horizontal axis. Measurements are made by rotating the light source around a vertical axis while keeping the other axis in a fixed position (height vs rotation).
Class C is suitable for general lighting systems. Type C goniometers are a highly specialized type with a fixed vertical axis and a moving horizontal axis. Measurements are made on the C-plane or on the conical surface. Type C goniometers are the same as Type B except that the light source is rotated by 90°.
The definition of light distribution curve:
1. The light distribution curve, also called the luminous intensity distribution curve, actually represents the distribution of light emitted by a lamp or light source in space. distribution, a persistent curve. It can record the luminous flux, number of light sources, power, power factor, size of the lamp, efficiency of the lamp, including the manufacturer and model of the lamp. Of course, the most important thing is to record the light intensity of the lamps in all directions.
2. Classification of light distribution curves:
Light distribution curves can usually be divided into: axial symmetry, symmetry and asymmetric light distribution according to their symmetry properties.
Axial symmetry: Also known as rotational symmetry, it means that the light distribution curves in all directions are basically symmetrical. General downlights and industrial and mining lamps have such light distribution.
Symmetry: When the c0° and c180° cross-section light distribution of the lamp is symmetrical, and when the c90° and c270° cross-section light distribution is symmetrical, such a light distribution curve is called symmetrical light distribution
Asymmetric: refers to c0 °- 180° and c90°- 270° any section with asymmetrical light distribution.
According to the beam angle, the light distribution curve can usually be divided into:
narrow light distribution (< 20°)
medium light distribution (20°> 40°)
wide light distribution ( > 40°)
In fact, there is no strict definition. Each manufacturer has slightly different definitions of wide, medium and narrow
There are usually two expression methods for light distribution curve testing:
Polar coordinate representation:
The method in
is usually used to describe the light distribution of indoor and road luminaires. It is very vivid to represent the light center of the lamp with the origin of the polar coordinates, to represent the magnitude of the intensity with a vector in a certain direction, and to represent the angle of the polar coordinatesRepresents the angle between the light intensity vector and the optical axis.
Rectangular coordinate representation:
This method is usually used to describe the light distribution of floodlights and lamps and light sources with very narrow light distribution. The origin of the rectangular coordinate is used to represent the light center, the abscissa is used to represent the direction angle, and the ordinate is used to represent the light intensity.
LSG-6000 rotating probe vertical goniophotometer (full space goniophotometer) fully meets the requirements of LM-79-19, EN13032-1 clause 6.1.1.3 goniophotometer type 4, CIE S025, SASO2902 , IS16106 and GB and other requirements for optical parameter testing. LSG-6000 is the latest upgraded product of LSG-5000 and LSG-3000 in response to the requirements of Clause 7.3.1 of the LM-79-19 standard. It can automatically test 3D light intensity distribution curves, and the test distance can be designed according to customer needs. It can meet the testing requirements of various light sources, such as LED light sources, plant lighting, HID light sources, indoor and outdoor lighting, street lights and floodlights, etc.
LM-79 vertical goniophotometer system LSG 6000
