How can a Goniophotometer be used for photometric measurement

Goniophotometers are a devices used to test the luminosity of other devices and appliances. This can help ensure the quality of of the devices to be sold and strengthen the position of the seller or the manufacturer of the products in the market. In this case, the photometric measurements taken and the role of the available manufacturers is vital.

Goniophotometer

A goniophotometer measures the directional light distribution characteristics of lamps and luminaires. It gathers photometric data from various spherical places. It creates a network of photometric information around the object being evaluated. Gonio photometric data is collected using various technologies and presented in a variety of angular coordinate systems.

The measuring of the angular or spatial dispersion of light from a light source is known as gonio photometry. A laser is a powerful light source. The beam is relatively tiny and frequently moves in a nearly straight path. This renders a laser ineffective for everyday use . The ideal isotropic radiator is an incandescent light source. It generates a consistent level of intensity in all directions.

Photometry

The goal of photometry is to measure light while accounting for the sensitivity of the human visual system. Photometry only detects light in the visible spectral range of 360 nm to 830 nm, which is visible to human eyes. Radiometry detects light across the entire spectral range , including ultraviolet and infrared. As a result, photometry is critical for evaluating light sources and objects used in lighting, signaling, displays, and other applications where light is meant to be perceived by humans.

Luminosity measurement

The stability of the tested bulbs, the measuring distance, angle, and brightness are the four essential parameters for determining the luminous intensity distribution. The test light source must be consistent at all times. Exact distance, brightness, and relative rotation angle measurements between the photometer and the tested lights are possible.

Both the huge mirror and the near field detector move in a straight path. Both the far-field detector and the massive mirror are moving at the same time. The luminaires’ burning locations will remain consistent. Light from the luminaires will always be detected by the detector.

To measure the luminous intensity (unit: candela) of LEDs in a far field scenario, a standard photometric bench and photometers can be utilized. This is done far enough away from the test LED to be termed a point source (typically 2 m or longer ). However, in the LED sector, it is usual practice to test LEDs at shorter distances, such as 10 cm to 50 cm. The practice is thought to have begun when LEDs were dim and photometers were not very sensitive.

Even though LEDs are brighter, this behavior persists. Many LEDs do not act like point sources because they have epoxy lenses. As a result, when measuring light intensity across short distances, the inverse-square formula does not apply. The effective center of LED emission may migrate away from the LED’s physical center. When tested at varying distances, the measured luminous intensity changes, especially when the distance is small. This was found to be one of the most significant reasons of variation in light intensity measurements.

The Commission Internationale de l’Eclairage (CIE) issued CIE 127 (1997) and CIE 127:2007, which limited the intervals between LED intensity measurements (100 mm and 316 mm). The aperture of the photometer should be round and one cm2 in size. The distance should be measured from the tip of the LED encapsulation. The measurement axis should be parallel to the LED’s mechanical axis.

Because the result can differ from the genuine (far-field) luminous intensity of the LED, it is known as the CIE Averaged LED Intensity. The two distances are identified by conditions A and B for 316 mm and 100 mm, respectively. The CIE recommendation should be followed for determining the intensity of individual LEDs. This suggestion does not apply to LED clusters, arrays, or fixtures made up of LEDs. When comparing test LEDs to calibrated standard LEDs or a calibrated standard photometer head, spectral mismatch compensation is used .

Goniophotometer manufacturers

Some prominent manufacturers of goniophotometers in the market include

1- LISUN GROUP, based in Shanghai, China. They provide stock and custom manufacturing, as well as distribution and device design.
2- North Sutton, New Hampshire-based Lab sphere Inc. Because it has been in business for a long time and has publicly traded stock, this company is well-known in the market.
3- PAB advanced technologies Ltd., based in Friedberg, Germany. They are both stock and custom gadget producers.
4- Berlin-based PRC Krochmann. They specialize in custom manufacturing.
5- Techno Team Vision USA Inc in Orlando, Florida is a subsidiary of Techno Team Bildverarbeitung GmbH. They also undertake device stock production.
6- Instrument systems GmbH, a subsidiary of Konica Minolta. Line Optronik, also in Berlin, Germany. They produce stock devices.
7- Ilmenau, Germany-based Techno Team Bildverarbeitung GmbH. They also produce stock gadgets.

FAQs

What is the use of goniophotometer?

A goniophotometer is a photometric device. It is used to determine the perceived strength of a light source from various angles. It is mostly used to evaluate the luminous flux of directed light sources such as LEDs and car headlights.

How does a Photogoniometer work?

A goniophotometer is utilized in measuring the distribution of light. This is done by shifting the location of a photometer or goniometer at a precise geometry to determine the luminous intensity or illuminance of a light source, luminaire, self-luminous display, or surface.

What is photometric measurement?

To make sure the equipment complies with legal requirements, photometric measurement comprises assessing the product performance of any light emitting device, including LEDs, lamps, signs, luminaires, and more.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

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