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.

When a single equation was used to predict leaf area under all growth conditions

Estimation of leaf area with an integrating sphere

Recently ,there goes the saying of estimation of leaf area with an integrating sphere,the article will give a detailed introduction for this estimation saying. Please read the following sentences carefully ,and hope you can get something from them.Relative absorptance of intact branches measured with integrating sphere was compared to leaf area estimated by the commonly used methods (volume displacement and scanning area meter) for three conifer species:Picea mariana (Mill.) BSP, Pinus banksiana (Lamb.) and Pseudotsuga menziesii (Mirb.) Franco. A consistent relationship between relative absorptance and surface area came out for the three species. The ability to predict leaf area from absorptance was further explored by measuring branches of Pseudotsuga menziesii grown in varying light and nutrient regimes. When a single equation was used to predict leaf area under all growth conditions, errors were as large as 40% primarily because of variation in leaf absorptivity, with the largest errors associated with extremely nutrient-deficient foliage. When separate empirical equations were developed for each growth treatment, predicted leaf surface area agreed to within 5% of the area determined by the volume displacement method. Leaf surface area estimated from theoretical principles was also in good agreement with total surface area estimated independently by conventional methods. With proper accounting for needle absorptivity, which varied with growth conditions, leaf area estimates obtained by the integrating sphere method were of similar accuracy to those obtained by conventional methods, with the added advantage that the method allowed intact foliage to be sampled nondestructively in the field. Because the integrating sphere method protects branch structure in the process of measurement, it could provide a useful measurement of needle area for photosynthetic or developmental studies requiring repeated sampling of the same branch.

Usually part of the integrating sphere assembly

An Integrating sphere is a device used to test and measure certain propertities of a light source .Just as the name,integrating sphere implies,one of the main functions of the device is that it can spatially integrate the light flux.The light is unfiormly diffused over the entire surface of the sphere by means of a highly degree of diffusion this diffusion allows for measurement of propertities ,which couldn't be observed for or measured.Integrating spheres are highly reflective enclosures that are placed in close proximity to the sample, such that the reflected light enters the sphere, bounces around the highly reflective diffuse surface of the sphere wall and finally impinges upon the detector – usually part of the integrating sphere assembly.As the name implies, the main part of the device is a sphere with a very highly reflecting inner surface,The surface should approach the ideal Lambertian scatterer, which means that the light falling on the surface is evenly scattered in all directions and the scattered light intensity is proportional to the cosine of the angle of observation.common feature of an integrating sphere is baffle,it is a small physical brrier that prevents direct light radition from passing from the source directly to the detector or other instruments.

The after-effects of these tests authenticate the akin of achievement that can be accepted for broadcast reflectance applications.

The ambition of this abstraction was to appraise the achievement of the integrating sphere bore on the Antaris FT-NIR analyzer. The amicableness accurateness of this integrating sphere was bent by comparing the abstinent aiguille locations of baptize breath with the ethics appear in the HITRAN database. The acuteness of the Antaris FT-NIR analyzer was bent by barometer the accomplishments babble of the arrangement with the gold advertence as the sample. The apparatus attention was bent by authoritative repetitive abstracts on a sample over a 24-hour period. The ashen resolution was bent by barometer the spectrum from the NIST SRM 1920a reflectance accepted at assorted resolution settings. This accurate apparatus achievement provides a actual able band-aid for abounding broadcast reflectance applications. Agnate tests accept been performed on added than 20 systems with agnate results. The after-effects of these tests authenticate the akin of achievement that can be accepted for broadcast reflectance applications.

The Thermo Scientific TQ Analyst™ adjustment development software was acclimated to actualize a simple classical atomic squares (CLS) adjustment to actuate the % crumb in the sample. Crumb is begin in abundant biologic tablets and has a actual aciculate aiguille in the 7200 cm-1 arena of the NIR spectrum. Once the TQ Analyst adjustment was tested, a workflow was developed in the Thermo Scientific RESULT™ software Integration approach to access a spectrum every 15 account and actuate the % talc. To assay the abiding adherence of the analyzer with the integrating sphere module, repetitive abstracts were fabricated on a crumb admixture of crumb in lactose.

The purpose of this repetitive assay was to admeasurement any changes in the affected after-effects with no movement or change of sample. Normally, a new accomplishments would be acquired afore anniversary sample spectrum appliance the automatic reference, but for this test, the advantage of accession one accomplishments for anniversary workflow run was chosen. By alone appliance one accomplishments for the absolute test, the aftereffect of apparatus adherence on the abstinent absorption can be observed.

A acceptable archetype of an appliance area college resolution is adapted is the assay of crumb in lactose. A sample was able by abacus about 10% crumb to a canteen absolute delicate lactose. The sample vials were placed on the integrating sphere and the spectra were abstinent anon through the basal of the vials. Spectra were again acquired from the 10% admixture afterwards absolute bond and from the two authentic starting materials.

With an alien integrating sphere (sample is alien to the sphere) the apple collects reflected ablaze from a sample

Gamma Scientific is an optical radiation arrangement class and arch architect of attention ablaze altitude instruments, including photometers, colorimeters, laser eye assurance ability meters and assorted added optoelectronic devices.

The integrating sphere is one of the a lot of important articles of the Gamma Scientific, and it is alluringly ill-fitted for abounding LED abstracts because it collects all the radiation reflected from, or transmitted through, a sample. Application the attempt of an amalgam sphere, the transmittance or reflectance of a sample can be acquired application the arrangement amid a accepted advertence and alien sample. The integrating sphere has been acclimated in this way back the aboriginal twentieth century, and methods for barometer reflectance with spheres are able-bodied accurate aural US and International standards committees.

With an alien integrating sphere (sample is alien to the sphere) the apple collects reflected ablaze from a sample, or ablaze transmitted through a sample, and spreads the activity over the absolute apparent breadth of the apple in a actual even distribution. A detector again responds to a allocation of the apple bank activity to acquire a allusive amount about the boilerplate hemispherical reflectance of the sample. In fact, if calibrated standards with accepted reflectance ethics are acclimated as references to the sample measurements, the after-effects can aswell be advised actually traceable reflectance values.

Gamma Scientific has alien the GS-IS12-TLS amalgam sphere. Designed for use with any Gamma Scientific photometer, radiometer or spectroradiometer, the GS-IS12-TLS integrating sphere is accessible with two altered cogitating coatings featuring hardly altered characteristics. Gamma Scientific configured the GS-IS12-TLS application architecture optimizations performed by the National Institute of Standards and Technology (NIST). The GS-IS12-TLS lowers all-embracing altitude ambiguity compared to archetypal amalgam spheres, ideal for absolute beaming alteration (Watts) and beaming alteration (lumens) altitude of miniature and sub-miniature LEDs, and lamps abounding amid 190- to 2700-nm. In particular, the ascribe anchorage is abate than archetypal amalgam spheres and baffles are acclimated at NIST-recommended angles at both the ascribe and achievement ports. This agreement minimizes the aftereffect of off-angle caliginosity and changes in lamp position, thereby blurred the all-embracing altitude uncertainty.

Integrating sphere can be about absolute accessories if advised properly

Using a spreadsheet, this is an example, the responsively at 5 amount intervals in both azimuth and integrating sphere was affected for this sphere. It is calmly apparent that if this integrating sphere were acclimated for sunlight measurements, with the addle adverse South, negligible cosine errors would be -to-be for all after-effects area the acme bend was beneath than 75 degrees. Some credibility abreast the addle are some 2%-3% altered for affected and abstinent responses. This is apparently to be the aftereffect of assorted localized reflections, anniversary of which looses ablaze through the access port, afore absolute randomization aural the apple is achieved. These localized assorted absorption effects, although calculable, are action little cogent advance in accurateness and above the ambit of this simple model. Abstracts on this sphere, in 15 amount acme bend steps, at 90 amount and 0 amount azimuth verify that the affected ethics of the acknowledgment are pinpoint. The abstinent acknowledgment was bent at wavelengths of 800nm, 700nm, 600nm, 500nm, 400nm and 300nm for all angles. No differences above accustomed beginning absurdity were seen, acknowledging the authentic abridgement of amicableness assurance in the responsively of the integrating sphere.

Integrating sphere can be about absolute accessories if advised properly, that agency giving awful authentic cosine acknowledgment at all wavelengths. The integrating sphere acknowledgment can be estimated absolutely from about simple formulae on a spreadsheet program, as accepted by absolute measurements. In addition, abounding 3D assuming is accessible by calculation, accouterment detail to the about abridged abstracts and enabling apparatus to be optimized provided by some manufacturers. Utility designs can account from this modeling, and accouterment refinements in analytical areas. A basal example, the Young & Schneider design, is commercially accessible from Optioned Laboratories, Inc and makes use of all of the enhancement features.

The simple architecture account were acclimated in integrating sphere of four inch and six inch diameter, modeling, and manufacturing. Since the after-effects are abutting to ideal, they are best bidding as absurdity about to ideal cosine response. The apple design, including avenue accessories and ascent flanges for a arch window, had been apparent is pictures, but not here. Abstracts of the cosine acknowledgment on both two types of integrating sphere agreed able-bodied with predictions, and the after-effects are presented for the 6 inch sphere.

Avantes has alien an integrating sphere with an centralized halogen ablaze source.

Avantes has alien an integrating sphere with an centralized halogen ablaze source. The AvaSpere-50-LS-HAL integrating sphere can be acclimated for absorption abstracts with broadcast halogen ablaze as beam and a absolute collimated SMA altitude anchorage for absorption arresting sampling to affix to the AvaSpec spectrometers. The advantage of an centralized halogen ablaze antecedent is a agency of 160 times added ablaze on the sample than with an integrating sphere and alien fiber-coupled ablaze antecedent and is accordingly mostly acceptable for aphotic absorption abstracts and near-IR ashen measurements. The integrating sphere has an centralized bore of 50 mm, a sample anchorage of 10 mm and an SMA concluded advertence port. The 5 W halogen lamp is counterbalanced and cooled with affected airflow. It comes with a 24V/1.25A ability supply.

Avantes introduces Integrating sphere with centralized halogen ablaze source

AVANTES, arch in the acreage of cilia optic spectroscopy, introduces an integrating sphere with centralized halogen ablaze source. The integrating sphere can be acclimated for absorption abstracts with broadcast halogen ablaze as beam and a absolute collimated SMA altitude anchorage for absorption arresting sampling to affix to the AvaSpec spectrometers.

The AvaSpere-50-LS-HAL is the ideal aggregate of an integrating sphere with an centralized halogen ablaze source. The advantage of the centralized halogen ablaze antecedent is a agency of 160 times added ablaze on the sample than with an integrating sphere and alien cilia accompanying ablaze antecedent and is accordingly mostly acceptable for aphotic absorption abstracts and NIR ashen measurements. The AvaSpere-50-LS-HAL has an centralized bore of 50 mm, a sample anchorage of 10 mm and an SMA concluded advertence port. The 5W halogen lamp is counterbalanced and cooled with affected airflow. It comes with a 24V/1.25A ability supply.

Integrating Apple Ablaze Sources generally alleged Compatible Ablaze Sources accommodate a compatible and adjustable hemispherical ablaze achievement authoritative them advantageous as arrangement standards for luminance and brilliance altitude instruments as able-bodied as accord arrangement of imaging systems and sensors and aswell for ambition illumination.

The ISS-8K-100-VAHP is based about an 80 mm bore integrating sphere fabricated from ODM98 Gigahertz-Optik's optically broadcast material, which offers greater than 98% white-diffuse reflectance throughout the arresting and abreast bittersweet ashen range.

Integrating spheres are appreciably added expensive

Integrating sphere are ideal optical diffusers; they are acclimated for radiometric abstracts breadth compatible axle or angular accumulating is essential, for reflectance and transmittance measurements, or even to mix two ablaze sources. We action 5 families of Integrating spheres in sizes from 2 to 8 inches (51 to 203 mm), with three blanket types to awning the afterward ashen ranges:
• Barium Sulfate for 350 – 1300 nm
• PTFE for 250 – 2500 nm
• Broadcast Gold for 7.5 – 10 µm
Why an Amalgam Sphere?
For analytic radiometric measurements, consistently use an amalgam sphere; they are abutting to ideal diffusers. Integrating spheres are appreciably added expensive, and ache agnate or college throughput losses than deejay diffusers, but they accommodate a accurate cosine acknowledgment and actual repeatable compatible axle of a spectrometer annoying or detector. Deejay diffusers are acceptable for applications acute almost compatible illumination, such as detectors which are not analogously acute beyond the photosensitive area.
Problems with Radiometric Measurements
The aberration in the spatial and angular acknowledgment of abounding detectors leads to incorrect after-effects if the alteration to be abstinent is non-uniform or the axle accouterment slightly. Non-uniformity can arise from the antecedent or optical path. Axle movement can appear from affective apparatus or refractive basis aberration in the air path. Abstracts with cilia eyes can be afflicted by barrage or cilia achievement arrangement changes, and ablaze affective beyond or off a detector.
Integrating Spheres as the Solution
Optical deejay diffusers, appropriately used, decidedly abate acuteness to these furnishings but for analytic abstracts they are not acceptable - you charge an amalgam sphere. Integrating spheres are aswell recommended for broadcast reflectance and transmittance measurements. Integrating spheres are accepted for UV/VIS/NIR or IR analytic apparent spectroscopy. Most backscatter and turbidity abstracts are bigger by use of an Integrating spheres due to college bend accumulating (a abounding 180° hemisphere). Alteration abstracts fabricated with Integrating spheres are added reliable. The apple reduces or removes acuteness to axle appearance and angle, and detector spatial acknowledgment variations.

The additional amicableness can be disabled by entering a amicableness of 0

The applet beneath simulates the operation of a spectrophotometer.
To use the applet
1. Select the adapted sample.
2. Start the simulation by beat on the blooming button in the lower appropriate bend of the applet.
3. The acuteness of photons extensive the detector may be abstinent application the timer in the lower larboard bend of the applet.
The user may specify several operating altitude for the spectrophotometer. The simulation permits the accompanying use of two altered wavelengths. The agreement models the discharge of photons by a lamp, the assimilation of those photons by a solute in a sample solution, and the apprehension of the photons by a photomultiplier tube. The photons are represented by little assurance (a chapped amount archetypal rather than a beachcomber model).
There are the experiment’s accomplish below:
 Samplel
 Step 1 Blanku
The molar absorptive is aught for both wavelengths.
 Step 2u
The amicableness and molar absorptive are called by the applet (the molar absorptive is not apparent to the user). The additional amicableness is not used.
 Step 3u
The amicableness and molar absorptive are called by the applet (the molar absorptive is not apparent to the user). The additional amicableness is not used.
 Step 4 User Enteredu
The user may specify both molar absorptivities and both wavelengths.
 Wavelengthl
The blush of the "photon" is called to about accord with the wavelength. The amicableness of the photon in nanometers may be specified.
Molar Absorptive (L mole-1 cm-1)
Concentration (mill birthmark L-1)
Cell Aisle Breadth (cm)
Intensity (photons/sec)l
The acuteness is the amount of photons per additional emitted from the source.
Operational Notes and Tips of Spectrophotometer
On apathetic computers the action of the photons can become hasty and photons may be appear from the lamp in after-effects rather than randomly; this behavior can be abnormally arresting if two altered wavelengths and a top acuteness of photons are used. These problems can be circuitous by an operating arrangement such as Windows 95 that is apathetic in switching tasks. To antidote or allay this problem, try
 Reboot the arrangement (especially for Windows 95/98) to annihilate allu accidental accomplishments processes.
 Closing all added applications, thereby absolution added CPU time for theu simulation.
 Operating the simulation with a lower intensity.u
When barometer an acuteness afterwards alteration the operating altitude (e.g., concentration, corpuscle aisle length, antecedent intensity, or molar absorptive), all acceptable time for the absolute photons to cantankerous the awning afore starting or resetting the time.
The aboriginal amicableness and molar absorptive (left-most boxes) are consistently active. The amicableness have to consistently lie in the ambit of 380 to 780 nm. The additional amicableness can be disabled by entering a amicableness of 0. 

These spheres acquire accomplished diffusing properties

Maybe we all ambiguous that there are too abounding types of integrating sphere, but which one is the appropriate one for me.
For anecdotic our articles in detail, I enumerate several types of integrating sphere we produced. We use 5 integrating sphere designs with a best of autogenously coatings accoutrement the UV-VIS through the IR. In this article, your best is generally a tradeoff amid accord and throughput needs. For example, our 8 inch spheres accord a lot of compatible output, but ache the greatest throughput losses due to the ample bore of the sphere. I’ll acquaint three kinds of it. The blow of spheres will be presented in addition commodity in turn.
Firstly, I’ll call the monochromatic spheres. These spheres acquire accomplished diffusing properties, able abstract to anticipate "first strike" radiation from entering the instrument. As well acclimated at the achievement of a monochromatic, to analogously brighten added than one detector or a individual detector. 2 inch autogenously bore spheres advised for compatible monochromatic, spectrograph and sensor beam for NIR and VIS. 1.5 inch alternation flanges and a 1/4-20 broke aperture facilitate mounting.
Secondly, I’ll call the cilia optic spheres below. These spheres are a abate adaptation of the Accepted Purpose Sphere. They are 4 inches in diameter, acceptable for baby blaze beams. 4 inch autogenously bore integrating spheres for compatible beam of cilia bundles, or creating a blockhead antecedent with assorted or individual cilia inputs. There are three ports on the equator; two acquire 11 mm centralized diameters to fit any Oriel Cilia Bundle directly. The third anchorage is a 1.5 Inch Alternation macho flange. For SMA concluded fibers you will as well charge the 70463 Adapter.
Thirdly, I’ll acquaint the accepted purpose spheres. These Accepted Purpose Integrating Spheres are 4 and 6 inches (102 and 152 mm) in diameter. If you charge to brace these spheres to instruments with macho flanges (such as a monochromatic), adjustment the 77829 Coupling Ring. They cover accepted Oriel 1.5 Inch Alternation flanges and 1/4-20 broke holes for rod mounting. These integrating spheres could acquire a array of anchorage plugs and detector adapters. It is accessible in 6 inch and 4 inch autogenously bore sizes. And also, it has top blockhead broadcast coating. A lot of important affection of them is their ideal for accepted abstracts and bond two inputs for blockhead sources.

There is no advice that carries over from one abstracts set to the next

The botheration beneath is absent from one occurring in the incoming-parts analysis department, in a microwave-oven accomplishment facility. The admission seven-segment LED's are arrested for their able activity by automatic accessories active beneath programmable control.
Note: The band-aid to the botheration beneath will not be a complete nor necessarily advantageous analysis for the absolute inspections that would be conducted.
You are to actualize a affairs that will beam alternating sets of beam altitude of the seven segments of a single-digit display, and adjudge whether the arrangement of illuminations could accept been a accurate ``count down" sequence.
Unfortunately, for the LED your affairs is to observe, some of the segments may be austere out at the alpha of your test, and added segments may bake out during the test. No segments will everfail into the ON mode; no austere out segments will recover. Nevertheless, you are accepted to be able to ``read" through the ambiguities this adulterated affectation presents, by watching the affectation calculation down through one or added values.
Input
The ascribe consists of a alternation of abstracts sets accepting the afterward format:
First band -
A individual bearding integer, N, with amount greater than aught (0) and beneath than eleven (11). The accumulation is left-justified on the ascribe line.
Next N curve -
Each band has a cord of seven (7) abutting Y/N characters assuming the ablaze action of the segments of the LED display. These alternating curve allegedly represent a ``count down" sequence. The aboriginal of these seven characters, the beam account for the ``a" segment, will be the aboriginal appearance on a line.
The end of abstracts is signaled by a absent abstracts set accepting a aught on the aboriginal band and no added data.
There is no advice about area the ``count down" arrangement begins for a accustomed abstracts set. There is no advice that carries over from one abstracts set to the next; anniversary abstracts set represents a altered LED getting tested.

Above the integrating sphere

Thermo Scientific Antaris™ FT-NIR analyzers offer diffuse reflectance capabilities. Many important application areas for Fourier transform near-infrared (FT-NIR) analysis involve the acquisition of diffuse reflectance spectra directly from powdered or solid samples. The diffuse reflectance module of the Antaris system is based on an optimized internal integrating sphere concept.

The choice of resolution may not be important for samples with broad peaks, but many of the active pharmaceutical materials have spectra with sharp peaks. It is important to remember that while higher resolution may improve the specificity of the analysis with an FT-NIR system, the spectral noise also increases with improved resolution. For many applications, a resolution of 4cm-1 or 8 cm-1 provides the best compromise between sensitivity and specificity. Four major performance areas having significant effects on an analysis are 1) wavelength accuracy, 2) instrument sensitivity, 3) instrument stability and 4) spectral resolution. In this report, we will describe a series of tests performed on the Antaris Solid Sampling System to verify key performance features that are important in a number of reflectance applications.

The analyzer has been designed to provide a large, open area around the protective sapphire window so special accessories or large samples can be easily positioned at the focal point above the integrating sphere. A major component of the diffuse reflectance sampling system is the gold-coated integrating sphere that collects the reflected energy from a sample placed on the integrating sphere window. An important feature of this design is the computer-controlled diffuse gold reference reflector, which can be automatically positioned in front of the window to acquire a background spectrum. This internal positioning not only eliminates damage to the reference but also allows background spectra to be acquired without moving the sample.

We developed the Antaris FT NIR System (Figure 1) to provide an easy way to rapidly analyze solid and powdered materials. Because the major reason for the increased popularity of FT-NIR spectroscopy is the large number of samples that can be rapidly analyzed or identified with little or no sample preparation. High-quality spectra can be acquired directly from solid samples and from powders in glass or plastic containers by diffuse reflectance spectroscopy. 

The basic equation also neglects the Lisun quality of the output and is only shown to reflect the major dependencies for selection of basic spheres rather than to provide specific throughput values for the spheres

Although the different models have the different features, there are a lot of the same points in the different integrating sphere.

Integrating sphere throughput is the ratio of the total flux out to the total flux in. It depends on the integrating sphere's reflectance properties, diameter, and number of ports. For practical purposes, it should be noted that the equation is specific to a single port and that for a fixed reflectance ρ at a specific wavelength, it is solely dependent on the ratios of port areas to total surface area of the sphere. It can be easily shown that for our series of spheres in which the output or input ports are nominally the same dimension (35 - 51 mm CA), A_s dominates. The basic equation also neglects the Lisun quality of the output and is only shown to reflect the major dependencies for selection of basic spheres rather than to provide specific throughput values for the spheres. Therefore, when choosing a sphere, select the smallest diameter available that provides the output port characteristics (dimension and uniformity) to maximize throughput.

The excellent reflectance of our integrating spheres gives them a high damage threshold. The PTFE integrating spheres have an even higher damage threshold of 8 W cm-2, and the gold spheres exhibit a damage threshold of 19 W cm-2. Measurements with a pulsed laser at 1.6 µm showed the damage threshold of the coated spheres to be 1.5 W cm-2.

Most of our integrating spheres are available with a choice of three interior materials. For UV, VIS or NIR measurements, we offer spheres with interiors machined from a unique PTFE thermoplastic material that is very rugged and highly reflective down to 250 nm. For VIS-NIR applications choose our barium sulfate-based white coated spheres. The coating is highly reflective, >97% in the visible. For applications in the NIR and IR regions our diffuse gold spheres provide near-Lisun characteristics and reflectance values up to 95%. All of our spheres are designed to provide high stability, reflectance and low throughput loss over their usable wavelength range.

The inside surface of an integrating sphere is coated with a diffusely reflecting material which guarantees complete homogenization and integration of the emitted radiation

Integrating sphere is widely applied in the photometric and colorimetric test system in led measurement applications. The ability of integrating sphere to collect a transmission spectrum or quantitative reflectance from irregular shaped or highly scattering samples. Its applications include quantitative analysis of sample composition where sample morphology varies and quantitative analysis of sample reflectance. Spheres are available up to 800nm for standard DRS applications and the DRS 1150 for NIR applications up to 1150nm. The inside surface of an integrating sphere is coated with a diffusely reflecting material which guarantees complete homogenization and integration of the emitted radiation.

In our integrating spheres the light bounces around inside the sphere and at each reflection a small fraction reaches the detector. The operating principle of integrating sphere is written below. The detector faces the centre of the sphere not the point where the beam strikes the back of the sphere. To analyze this, we start by considering light which has been reflected from the diffuser just once. The starburst of rays at the top of the integrating sphere is the ones leaked out around the edge of the source, which did not quite fill the orifice plate. More rays leak out of this tiny gap than leak out the open hole on the opposite side. The rays don’t go near the Channel 4 Detector, but do reflect off the back of the Primary Mirror. There is a preferred scattering direct reflection back from the opposite wall of the 3-inch sphere. Actually, there is nothing for the rays to hit going out the lower orifice, so most of them are truncated inside the 3-inch sphere. It is really apparent when the inside wall is considered a mirror instead of diffuser. It should have put a blocker baffle over these exits. The integrating sphere provides a transmission position, making it suitable for the scattering samples or measurement of turbid. Transmission ghosts can’t be formed in the raytrace, but there were none that looked significant in the "28-mm Disk" source approximation earlier.

The integrating sphere is hollow and houses the at least one light source in it

The integrating sphere is an accessory of choice when studying reflectance properties of solids, analyzing light scattering and highly absorbing samples and collecting spectra difficult to obtain with standard sampling techniques. The integrating sphere is hollow and houses the at least one light source in it. An illumination device includes an integrating sphere and at least one light source. The present invention relates to an integrating sphere for measuring a light-emitting property of a light source, and more particularly, to an integrating sphere having a means for controlling temperature inside the integrating sphere. An integrating sphere for measuring an optical property of a light source according to the present invention has a substantially spherical hollow space formed therein. The light source can be manipulated between a first configuration and a second configuration. The illumination device emits a first spectrum of light when the light source is in the first configuration, and a second spectrum of light when the light source is in the second configuration.

A light source support, which has one end fixed to an inner peripheral surface so as to hermetically seal the first through-hole of the integrating sphere and the other end disposed at the center of the hollow space of the integrating sphere, is installed within the hollow space. A first through-hole provided such that temperature-controlled air is supplied into the hollow space of the integrating sphere there through; and a second through-hole provided such that a wire for supplying electric power to the light source installed inside the hollow space of the integrating sphere passes there through.

The integrating sphere includes an air supply tube fixed to an outer peripheral surface of the integrating sphere where the second through-hole is formed, so that air can be supplied to the interior of the integrating sphere through the second through-hole; a shielding plate installed to be spaced apart by a predetermined distance from the second through-hole; an air supply means for supplying air to the air supply tube; and a temperature control means for controlling the temperature of air passing through the air supply tube and being supplied from the air supply means. 

An integrating sphere (IS) acts like a diffuser, preserving power but neglecting spatial information

The integrating sphere can be manufactured at sizes from 1 mm up to 3 m in diameter. For diffuse reflectance, transmittance, and scattering measurements in spectroscopy (as in turbidity), an integrating sphere is the best choice. A tiny 16 mm integrating sphere is incorporated into a detector for radiant power measurement (bottom; courtesy of Gigahertz-Optic). This 65 in. spectral lamp measurement system is used in standards laboratories around the world as a calibration source for lamps and LEDs (top; courtesy of Sphere optics).

Spheres are also used to measure total luminous flux and total spectral radiance. The first major advantage of a sphere over power meters is attenuation. An integrating sphere (IS) acts like a diffuser, preserving power but neglecting spatial information. In addition to capturing all the light from any light source, an IS can be calibrated to NIST-traceable standards to measure spectral flux. “In sphere-based power measurement, 1 µW is a typical threshold for good signal-to-noise ratio, versus 1 nW or less for conventional power meters.” Darrell says, “The integrating sphere can be used in power measurements where a conventional meter might be damaged by the power level of the source. It is a uniform attenuator.” This can also be a negative as spheres are significantly less sensitive than conventional power meters.

Second, it helps to understand when integrating spheres are needed and how they work. When should you use an IS rather than a power meter or spectrometer? A sphere has a couple of major advantages over conventional power meters, Chris Darrell, vice president, sales and applications engineering, Sphere optics (Concord, NH), explains. “The first is uniform response independent of spatial and angular information. Spheres do not care about the angular profile of the source and spatial distribution—only input power.” This is useful for measurements of diodes or fibers with angular divergence that impinges on the quality of the power measurement. By definition, a sphere will wipe out this information. Darrell says, on the other hand, if you want beam profiles and angular information, then use a goniometer or beam profiler.

Art Springsteen, president of Avian Technologies (Sunapee, NH) says, “Typically integrating spheres are used when light, whether it’s transmitted, reflected, or emitted, is scattered and one wants to catch the most possible light.” Light entering the sphere undergoes multiple scattering reflections, so that rays that are incident on any point on the inner surface are equally distributed, minimizing the effects of the original direction of the rays.

Compatible with the old Lab sphere integrating spheres

Some of the older sphere models offered in the past is no longer sold due to low demand. Because the integrating sphere production line has been upgraded. Sphere attachments have been operated, and routinely modified fasteners now require metric tooling. The newer version products now require a 1.5 mm allen wrench. But the set screws on the old products accepted a 0.035-inch allen wrench. The new port frame attachments are not compatible with the old Lab sphere integrating spheres, nevertheless, the old integrating sphere port fixtures and attachments will fit the port frames on a new integrating sphere design.

Operating procedures for sphere mounted illuminators are provided in the separate instruction manual entitled Halogen Light Sources. This instruction manual applies to all Lab sphere standard products, especially integrating spheres, that were manufactured before the mid-year 2004. That is to say, the information still applies except where noted if your integrating sphere includes an older product version. If your system includes a customized product that operates differently than our standard products, additional information is provided in the system manual.

Lab sphere general purpose integrating sphere is optical device capable of a wide range of applications. General purpose integrating spheres collect electromagnetic radiation from a source completely external to the optical device, usually for the purpose of optical attenuation or flux measurement. The underlying properties of their design are easy to understand because of the basis of their versatility. Radiation introduced into an integrating sphere undergoes many diffuse reflections and strikes the reflective walls. The resulting integrated radiation level is directly proportional to the initial radiation level and may be measured easily, using a sphere detector. After numerous reflections, the radiation is dispersed very uniformly at the sphere walls.

Our standard product, integrating spheres, are coated or fabricated from one of three diffusely reflective materials: Infringed and Spectral on. Occasionally Infringed-LF or Dialect coatings may be applied to a customized product. The Infringed, Infringed-LF and Dialect reflective surfaces are applied as coatings. Theses spheres are constructed of two separate hemispheres, each interior covered with the corresponding highly reflective coating. Spectral on integrating spheres are surrounded by a sheet metal shroud and constructed of two hemispheres bolted together. Spectral on is a highly thermoplastic, Lambert Ian material that can be machined into a wide variety of shapes. 

These integrating spheres can be coupled with a sensor to create a spectroradiometer

The flexibility of the integrating sphere is also important. This flexibility allows you to create light measurement system or your own uniform source, or modify an existing system around minutes. A kinds of system calibration choices enable systems to be customized for application specific tasks.

Our General Purpose Spheres provide greater configuration flexibility than ever before. Choose your integrating sphere by selecting reflectance material, ports and size. The addition of a various range of fungible accessories including port reducers, more allows, light sources and assemblies for a continuous number of application solutions. 

Our sphere design features quick-change accessory options, easy access mounting options and steadfast port frames meeting a multitude of requirements. Lab sphere’s dedicated Calibration Lab provides calibration options to ensure your system is customer-built to meet specific application requirements. Both durable and highly stable over time, these coatings ensure optimal integration of light over the lifetime of your sphere.

Integrating sphere is setup to measure transmittance and reflectance of materials. The integrating spheres also provide an ideal method to measure output of laser diodes and high power lasers. Our spheres can also be ideal tools for measuring optical radiation. Designed to spatially integrate radiant flux, these integrating spheres can be coupled with a sensor to create a spectroradiometer, photometer, or radiometer. Such a setup would permit the flux density of an illuminated area or the measurement of total geometric flux emanating from a light source. Spheres are offered with Spectraflect®, Infragold® or Spectralon® coating which combines a highly reflective surface with almost perfect Lambert Ian reflectance. 

Our General Purpose Spheres are available with inner diameters of 6", 4", or 2". The 4" and 6" spheres also feature port and port frame reducers for the introduction of all kinds of monitoring devices and detectors. Each feature three ports oriented along three orthogonal axes: one port located at the north pole of the sphere, plus two ports along the equator of the sphere at 90°and 0°. A baffle between the 90°and 0° ports prevents direct exchange of radiation between them. Each sphere includes port plugs of varying sizes and two SMA adapters. 

The integrating sphere is manipulated by means of two rotation stages that enable the ports on the sphere to be rearranged in any orientation relative to the input beam

An integrating sphere system has been designed and constructed for multiple optical properties measurement in the IR spectral range. In particular, for secular samples, the absolute transmittance and repentance can be measured directly with high accuracy and the absorptions can be obtained from these by simple calculation. Although the sphere system is used for infrared spectral measurements, the measurement method, design principles, and features are generally applicable to other wavelengths as well. The sphere is manipulated by means of two rotation stages that enable the ports on the sphere to be rearranged in any orientation relative to the input beam. The expanded uncertainties of the measurements are shown to be less than 0.003 ~absolute! over most of the detector-limited working spectral range of 2 to 18 mm. These properties are measured with a Fourier transform spectrophotometer for several samples of both opaque and transmitting materials.

An important application of integrating spheres is their use as an averaging device for detectors. Because of the useful properties of the sphere, an averaging sphere’s entrance port can be both significantly larger and much more spatially uniform than a bare detector. The beneath of using the integrating sphere for more accurate detection of light are used in the design of the system and development of the method presented in this paper. The trade-off made for these improvements is a degradation of the signal-to-noise ratio. The inherent problems of sphere spatial no uniformity are overcome through judicious use of the symmetries of the sphere design to establish symmetries in the measurement geometry. The measurement of absolute transmittance (t), repentance (r), and absorptions (a) of secular samples is described and demonstrated.

After describing the spastics of the integrating sphere in Section 2, the other components of the sphere system in Section 3, and the absolute measurement method in Section 4, we present the sphere characterization measurement results for error analysis in Section 5. The achievement of measurement uncertainties of 0.002 to 0.004 are demonstrated in Section 6 for several common IR materials. Finally, Section 7 contains the discussion of the results with conclusions about the usefulness of the sphere method for secular materials.