The integrating spheres have 5 ports: input port with 1.5 inch series male flange, 1.0 Inch sample port, in-line with input port, detector port with 1.5 inch series male flange, 1.0 inch specular exclusion/inclusion port (for light trap or plug)

Reflectance and transmittance spheres are 8 inch interior diameter integrating sphere. The integrating spheres have 5 ports: input port with 1.5 inch series male flange, 1.0 Inch sample port, in-line with input port, detector port with 1.5 inch series male flange, 1.0 inch specular exclusion/inclusion port (for light trap or plug). Additional 2.0 inch port at North Pole for center mounted samples or comparison measurement technique. The 70679 and 70682 are for diffuse hemispherical reflectance and total transmittance and measurement of specular using a 8/D geometry (8 degree beam incidence/Diffuse collection). The 70679 is good for the VIS-NIR regions and the 70682 is good for UV-VIR-NIR (Note the ID of the 70682 is ~7.0”).

The spring loading allows you to quickly insert and remove the sample and the 70496 White Spectral Calibration Disk. Light, which is reflected from the sample strikes the port and is turned 8 degrees to the specular exclusion port. A reflectance sample holder with 0.5 inch (13 mm) deep cell, 1 inch (25 mm) diameter holds the sample at 8° to the beam. The holder is spring loaded so that rectangular irregular shapes or square with dimensions up to 2 inches (51 mm) can be held against the sphere wall. The clear aperture is 0.7 inch (18 mm). If a light trap is used in the exclusion port, the specular portion of the sample’s reflectance is subtracted from the measurement. The sample must fill the aperture. If a plug is at the exclusion port, the light is re-captured in the sphere. One extra port plug is included for the north pole port and one exclusion port plug is included with the integrating sphere.

Conversely, if a light trap is used at this port opposite the sample, then the normal transmitted beam is excluded by the trap (normal or diffuse excluded transmittance – allows “haze” characterizations). If a plug is used at the 1.0 inch port opposite the sample (former input port), then all energy is included in the measurement (total transmittance). If the 0° Sample Holder (also included with the 70682 R/T and70679 Spheres) is used at the input beam and the sample port is placed behind the sample port, then you can qualify diffuse, normal or total transmittance of samples.

Measured with the same custom-made integrating sphere

An integrating sphere is an optical sphere internally coated with a reflective material such that light shining into its input port would be complete diffused and uniform by the time it reaches its output port. An integrating sphere has an input port and an output port which is typically mated to a monochromator, sample chamber, or detector. A baffle between the output and input port is optionally available to assure no input light directly reaches the output port without first being diffused by the internal reflective coating. The light source can be placed inside the integrating sphere and sometimes it is used as a sample chamber itself. Due to the many reflective bounces a ray of light has to take before reaching the output port, efficiency is typically around 30%, although this can be more accurately estimated following an approximated equation in the Product Details section. Various internal reflective coatings can also be chosen (depending on spectral region required) and baffles and additional ports can also be ordered. The light that reaches the output port is completely diffused meaning it can reach the output port at any reflective angle.

A multifunctional setup based on the absolute integrating sphere method for measuring luminous flux of light emitting diodes (LEDs) is presented. The total luminous flux in 4pi and 2pi geometries and partial luminous flux with variable cone angle can be measured with the same custom-made integrating sphere. This assumes you can collect all light from all angles as normally you would then have to ratio the solid angle of collection to the light collected at all angles as well. If you are calculating the light that gets collected into a monochromator or detector, use the area of the monochromator or detector slit and not the actual output port area. A complete calibration procedure of the constructed integrating sphere photometer is presented as well as comparison measurements with a goniophotometer. The number of baffles of the sphere and area of ports was minimized. Only one absolute calibration of the integrating sphere photometer is needed for measuring LEDs in all three geometries. The sphere has three ports: an auxiliary port, a detector port, and a main port, located in the same hemisphere. The main port is used for the calibration of the sphere as well as for the LED under test. The spatial nonuniformity correction is needed only for LEDs with low directivity or having significant minor beams. The other hemisphere is free of ports. The expanded uncertainty (k=2) for the measurement setup varies between 4.6% and 1.2% depending on the measurement color, geometry, and the angular spread of the LED light beam.

A hole or "port" in the integrating sphere allows this uniform illumination to be used in an optical system

An integrating sphere is a hollow spherical shell coated on the inside with a highly reflecting diffuse coating. It is available with light traps, port reducers, 0°/8° sample adapters, sample holders and detector mounts. The integrating sphere produces illumination that has extremely uniform irradiance and radiance. A good working model of an integrating sphere is to consider the port to be a hole in a wall, and, at a totally arbitrary distance behind it, another wall of infinite extent and radiance. A hole or "port" in the integrating sphere allows this uniform illumination to be used in an optical system.

The projected solid angle from any point on a sphere to any element of area on the integrating sphere is the same, regardless of location. This fact combined with the diffuse coating and the multiple reflections cause any light introduced into the sphere to produce uniform radiance of and irradiance on the wall of the sphere. The irradiance at the wall of an integrating sphere is incident from a full hemisphere. The radiance at the exit of an integrating sphere extends to a full hemisphere (π projected steradians). The specular component may be included or excluded in the measurement, by the use of a trap or reflectance piece at the relevant port.

Bentham is a company which manufactures a range of integrating spheres for measuring diffuse transmission and reflection. The following part is writing about brief introduction fof two products.

The DTR6 or DTR4 is its product of integrating spheres, coupled with a monochromatic source and detection electronics, allow the determination of the diffuse transmittance and diffuse reflectance of a sample. The monochromatic probe is imaged onto the place of the port appropriate to the measured reflectance, transmittance or quantity. In the case of reflectance, the sample is placed at the reflectance port. In the case of diffuse transmittance, the sample is placed at the transmittance port, the integrating sphere collects all light transmitted into the hemisphere behind the sample.

According to this principle-the integrating sphere collects the scattered light

The good news is that this problem can be solved. Optical absorption, used to assess the concentration of dissolved matter, could be measured through a standard spectrometer arrangement using an input light source and a detector behind the sample. According to this principle-the integrating sphere collects the scattered light and keeps it within the measurement system; the light bounces around the cavity and will eventually contribute to the detected signal-researchers find a method to solve the difficulty. Researchers at North West Water (Warrington, England) have developed a method that overcomes both problems. In the technique, the water flows in an unconstrained stream through an integrating sphere. Within the integrating sphere, optical absorption is measured independent of scattering and this combination of scattering-independent and window-free absorption measurement offers a highly reliable industrial instrument.

Another difficulty arises is the sample also contains particles and bubbles. The only practical restriction is that the input beam makes at least one reflection off the surface of the sphere before reaching the detector; if not, the directly transmitted light would dominate the detected power. It is possible to avoid this interference by making the measurement in an integrating sphere. Scattering from these contribute to the reduction in the light reaching the detector. The light loss through scattering out of the beam path is indistinguishable from absorption in a simple system.

The integrating sphere is an optical instrument. You can find this measurement is so good for anything, like it doesn’t have any weakness. But in a drinking-water treatment plant, it is important to measure both dissolved materials and particles to ensure that the water meets quality standards. Many dissolved materials can be detected by their optical absorption; however, absorption measurement is made difficult by interference from scattering caused by particles. In addition, the cuvette windows of a standard measurement system are often fouled, which reduces instrument reliability.