By using the same cuvette for all trials of a particular experiment or by matching a set of cuvettes.

The Colorimeter actually uses polystyrene cuvettes to desigh. Fifteen of these cuvettes and lids are supplied with the Colorimeter. The cuvettes have a volume of approximately 4 mL. Two opposite sides of the cuvette are ribbed and are not intended to transmit the light from the LED. The two smooth surfaces are intended to transmit light. It is important to position the cuvette correctly in the Colorimeter, with a smooth side facing the arrow at the back of the slot, and with the ribbed edges facing left and right. The light travels from the LED at the top, through the cuvette, to the detector below the slot. Just like most spectrophotometer sample tubes, individual plastic cuvettes vary slightly in the amount of light they absorb.You may choose to ignore these differences. For most lab exercises, this variation will not have a noticeable effect on experimental results. For best results, variation in light absorbed by individual cuvettes can be controlled either by using the same cuvette for all trials of a particular experiment or by matching a set of cuvettes.

Lisun Group Product: LSG-1900 Moving Detector Goniophotometer

LSG-1900 Moving Detector Goniophotometer completely meets LM-79 Clause9.3.1requirement. The LSG-1900 is an automatic light distribution intensity 3D curve testing system for measuring light. The measuring distance is from5mto30m. It can measure all types of lighting sources, LED or HID luminaires such as indoor and outdoor luminaires, roadway luminaires, street lamps, flood lights and other kinds of luminaires.

Measurement:

Luminous Intensity Data, Luminous Intensity Distribution, Zonal Luminous Flux, Luminaries Efficiency, Luminance Distribution, Coefficient Of Utilization, Luminance Limitation Curves Glare, Maximum Ratio of Distance to Height, Equal Illuminance Diagrams, Curves of Luminaires VS Lighting Area, Lsocandela Diagrams, Efficient Luminescence Angle Etc.

Features:

Many national patents pending on hardware and software.

CIE Class A & Constant temperature photo detector (Class L detector can be optional).

High degree of intelligent and test function is complete.

The rotation motor is from Japan MITSUBISHI MOTORS and it uses Germanic Angle decode system, it will help smoothly and high accuracy rotation. It is very stable when start and stop.

The working principles are according to IESNA and CIE. This instrument is specially recommended by LM-75, LM-79 and CIE121-1996.

With some optional instruments, it has good expanding functions

The position and working state remain the same as it is under working.

Special collimation device with laser cross line, conveniently and accurately fix the position of the tested luminaries.

Specifications:

The tested luminaire rotates around the mirror with an angle of (γ)±180°(or 0-360°) and the tested luminaire rotates around itself with an angle of (C)±180°(or 0-360°).

The accuracy of angle: 0.1° Resolution of angle: 0.01°

Accuracy of photometry: CIE class A (Standard Class) or Class L.

The test result can be exported as CIE, IES, LDT and other format files. This kind of format files can be transferred by other illumination and luminaire design software such as DiaLux.

RS-232Cstandard interface can be connected to PC, English version software can run in WinXP or Win7

Detailed information about goniophotometer console

This component contains all of the system’s electrical and electronic controls. Main power switches and a test lamp voltage adjustment are included in the goniophotometer console. A hand-held control box is also attached to the unit on a long cable so the test operator can walk around the lab and manually position the luminaire during test set-up. A remote Yokogawa power analyzer meter is installed which incorporates a large digital display of volts, amps and watts.

The goniophotometer measures the exact lamp characteristics by use of remote sensing leads to the test luminaire. An option for measurement of Power Factor and Total Harmonic Distortion is available. An additional benefit of this system is that the power measurements on the ballast secondary of a high intensity discharge lamp are also facilitated.Readingsare transmitted to the computer and displayed so that all electrical monitoring can be done from the computer station. Automated voltage or power adjustment controlled throughout the test by the computer is also available as an option.

Detailed information for integrating sphere materials

Integrating sphere is important for the measurement but how many people have a clear understanding of its material? How many people know its component in a detailed way? I think it remains to be debated. Now please fix your attention on the following articles, and it is bound to surprise you.

The integrating sphere‘s lining optical properties greatly affect its measurement accuracy. Different coatings must be used at visible, infrared and ultraviolet wavelengths. High-powered light sources may heat or damage the coating, so an integrating sphere will be rated for a maximum level of incident power. Different kinds of coating materials are used. Early experimenters used a deposit of magnesium oxide. Barium sulfate has a useful flat reflectance over the visible spectrum. Finely-deposited gold is used for infrared measurements. Various proprietary PTFE compounds are also used for visible light measurements.

The theory of an integrating sphere assumes a uniform inside surface. Ports for detectors and sources must be small, not more than 5% of the surface area of the integrating sphere, for the theoretical assumptions to be valid. Unused ports in commercially built spheres may have matching plugs made up, with the interior surface of the plug coated with the same material as the rest of the integrating sphere. A baffle may be inserted in the integrating sphere so that the direct path of light from a source to a detector is blocked, since this light will have non-uniform distribution.

LSG-2000 Goniophotometer with Rotating Mirror - Lisun Group

LSG-2000 Goniophotometer with Rotating Mirror (Moving Mirror Goniophotometer) completely meet LM-79 Clause 9.3.1. The LSG-2000 is an automatic light distribution intensity 3D curve testing system for measuring light. The measuring distance is from 5m to 30m. It can measure all types of lighting sources, LED or HID luminaires such as indoor and outdoor luminaires, roadway luminaires, street lamps, flood lights and other kinds of luminaires.





Measurement:
Luminous Intensity Data, Luminous Intensity Distribution, Zonal Luminous Flux, Luminaries Efficiency, Luminance Distribution, Coefficient Of Utilization, Luminance Limitation Curves Glare, Maximum Ratio of Distance to Height, Equal Illuminance Diagrams, Curves of Luminaires VS Lighting Area, Lsocandela Diagrams, Efficient Luminescence Angle Etc.

Features:
Many national patents pending on hardware and software.
CIE Class A & Constant temperature photo detector (Class L detector can be optional).
High degree of intelligent and test function is complete.
The rotation motor is from Japan MITSUBISHI MOTORS and  it uses Germanic Angle decode system, it will help smoothly and high accuracy rotation. It is very stable when start and stop.
The working principles are according to IESNA and CIE. This instrument is specially recommended by LM-75, LM-79 and CIE121-1996.
With some optional instruments, it has good expanding functions
The position and working state remain the same as it is under working.
Special collimation device with laser cross line, conveniently and accurately fix the position of the tested luminaries.

Specifications:The tested luminaire rotates around the mirror with an angle of (γ)±180°(or 0-360°) and the tested luminaire rotates around itself with an angle of (C)±180°(or 0-360°).
The accuracy of angle: 0.1° Resolution of angle: 0.01°
Accuracy of photometry: CIE class A (Standard Class) or Class L.
The test result can be exported as CIE, IES, LDT and other format files. This kind of format files can be transferred by other illumination and luminaire design software such as DiaLux.
RS-232C standard interface can be connected to PC, English version software can run in WinXP or Win7

LSG-2000 can be used with a USB CCD Spectrometer to test spatial CCT Distribution and other Spectral color parameters. We call this system "Goniospectroradiometer (LSG-2000CCD)".
Please refer to this document: A Near-field Goniospectroradiometer for LED Measurements
PDF version: A Near-field Goniospectroradiometer for LED Measurements

If you want to test light sources - integrating sphere and goniophotometer are very important instruments

Light Measurement: Integrating Sphere and Goniophotometer

Integrating sphere and Goniophotometer mesurement.
The integrating sphere can measure the total light output of a lamp quickly without inaccuracy.but there is certain requirement for the position of the lamp when it is being tested,for example,the lamp being tested has to be placed in the center of the integrating sphere. Moreover,there is a light meter on one side of the integrating sphere ,it is used to measure the light output of the lamp. There is a baffle between the lamp and the light meter which is to stop the light meter from seeing any direct light from the lamp.The inside of the integrating sphere (including the baffle) is coated with a very white paint ,the white paint can reflect all wavelengths equally. This allows us to get the correct measurement values we want.
It is crucial that there is nothing else in the integrating sphere besides the lamp and the baffle. If anything else is placed in the sphere, like a fixture, would absorb some of the light. So that is to say,something  besides the lamp and baffle is placed in the sphere, not all of the light reaches the light meter and this leads to wrong meter readings. This means that we can only obtain "bare lamp" readings in the   integrating sphere. The integrating sphere cannot measure the light output of the lamp in fixture (which the goniophotometer can).

Integrating sphere introduction

The recent years has witnessed the fast development of Integrating sphere, it is one of the most important device for spectral and luminous flux measurement of light source. it is widely applied in the photometric and colorimetric test system in led measurement applications.The inside surface of an integrating sphere is coated with a diffusely reflecting material which guarantees complete integration and homogenization of the emitted radiation.The Integrating sphere is an important instrument of optical measurement for enabling high sensitivity measurements. The sphere is made of a sintered PTFE, which is >98% reflective in the visible.

Each of the integrating spheres can couple to our spectrometers to measure the total integrated reflectance of surfaces placed against the sphere's sample port.Integrating spheres generally function as a light collector. The collected light can be used as a diffuse illumination source or as a measurement source.In the Avantes line of integrated spheres the spheres are mostly used as measurement source. The basic principle of operation is that light enters the integrating sphere through the sample port, goes through multiple reflections and is scattered uniformly around the interior of the sphere. The detection fiber optics are SMA-coupled to the port at the side of the sphere which is viewing illumination on a baffle, independent of the angular properties of the light at the sample port. The baffle prevents first reflections to enter the detection fiber.

A compact and affordable luminaire goniophotometer

A compact and affordable luminaire goniophotometer which generates standard IESNA & EULUMDAT photometric files The PM-NFMS from Radiant Imaging combines a motorised goniometer stage with a ProMetric CCD imaging photometer to perform a near-field angular analysis of the luminance and colour from LEDs, luminaires and solid state lighting.

 

ProSource software then scales this to far-field luminous intensity data from which standard photometric files are generated.So-called photometric data defines how much light a luminaire emits and into what directions; lighting designers then use this standardised data format with all kinds of commercially-available lighting design programmes to determine the number and positioning of luminaires in order to create the desired illuminance.

The Integrating Sphere system has been designed and constructed according to the specifications detailed in the following paragraphs.

The Integrating Sphere  system has been designed and constructed according to the specifications detailed in the following paragraphs. The inside wall of the sphere is coated with a material that is nearly a Lambertian diffuser and at the same time has a high directional hemispherical diffuse reflectance! The sphere has entrance, sample, and reference ports, all centered on a great circle of the sphere,. There is also a detector port, with its center located along the normal to the great circle. An integrating-sphere system is designed and constructed for measuring a variety of optical properties in the IR spectral range. Integrating spheres are also applied to an averaging device for detectors. Due to the helpful propertities of an integrating sphere, an averaging sphere’s entrance port can be significantly larger and spatially uniform. The benefits of using an integrating sphere for detecting light more accurately are used in the design of system and development of the method. The measurement of absolute transmittance, reflectance, and absorptance of specular samples is described and demonstrated.