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While many of the readers of this page will have started their career in optics dealing with traditional diffuse reflectance coatings and materials such as Opal glass, Eastman 6080, G-E Sphere paintª, or even fumed magnesium oxide, this page will serve to update that knowledge to the best coatings and materials available. This page will guide the newcomer to the best possible coating for their application, taking into consideration the wavelength range of interest, the desired reflectance, functional consideration of environmental and physical properties, as well as any limitations that are inherent with any reflectance coating or material.

While Labsphere is not the only company to produce optical coatings and reflective materials, we are unique to the field in that we supply such a wide range of such materials. Labsphere products cover the spectral range from the deep ultraviolet to the far-infrared in reflectance ranges from 99% to less than 1%.Labsphere produces standards for color analysis, grey scale, and fluorescence. All of these materials have been intensely studied for their BRDF properties, environmental stabilty, and physical properties.

This page should be considered a 'work-in-progess' as we are continually improving and developing innovative new reflectnace products. Current research projects include new fluorescent materials, diffuse selectively reflective and fluorescent coatings, alternative mid to far-IR diffuse reflectance materials, and new low reflectance coatings for the UV-Vis-NIR-mid-IR.

We hope you find this page useful and informative and, as always, we appreciate your comments and suggestions.

Diffuse Reflectance Coatings
Traditionally, diffuse reflectance coatings have been used to improve the performance of integrating spheres for lamp measurement photometers and uniform light sources. These materials have also been used as remote sensing targets. Labsphere produces a number of such coatings. Spectraflectª and Duraflectª are predominantly used for the Vis-NIR region of the spectra, though both can be used in the UV under certain conditions. InfraGold(2) and Infragold-LF(3) are used for near to mid-IR and mid to far-IR applications, respecively. In the past four years, Labsphere's patented Spectralon® technology has increased the efficiency of devices dependent on high reflectance, lambertian devices in the UV-Vis-NIR region. Applications are as varied as diffuse reflectors for line illuminators for film processing, well plates for increasing the sensitivity of fluorescence measurements, and for lamp measurement photometry in the UV. All of these materials have certain physical and spectral properties that make them ideal for most diffuse reflectance applications.

Reflectance Standards
Labsphere reflectance standards have become the standard of choice the world round. Spectralon® grey scale is used as the standard reference materials of national laboratories in the United States and Great Britain, and is used as a linearity standard in most commercial NIR spectrometers. The base material, Spectralon SRS-99, is the white standard of choice in UV-Vis-NIR reflectance spectroscopy along with remote sensing applications due to its environemtal stability. A particular, highly purified and documented form of this materials known as Space Grade Spectralon®, is the standard of choice on low-earth orbit imaging systems. A related material, Spectralon® SRS-99L, is used as a reflective diffuser in many solid-state lasers.

Infragold and Infragold-LF are widely used as diffuse reflectance materials and targets for near- to far-IR spectrometer systems. These materials are chemically stable and highly lambertian over a wide wavelength range.

Fluorescent Standards
Labsphere offers two types of fluorescent standards. The first type, Spectralon-based materials named Spectralon® SFS- materials, exhibit a high degree of photolytic and environmental stability. These materials are inorganic fluor based, UV activated materials. These have found uses in typical applications for fluorescent standards- paper whiteness, optical whitening agents, and the like. More recently, applications in fluorescence microscopy and as remote fluorescent targets have been developed. These materials are still very much in their infancy in terms of applications, with more applications and materials being developed on a regular basis.

The second type of fluorescent standard is used in the traditional application of determining instrument stability for users concerned with optical brightness and flourescent whitening agents (FWA's) in paper and textiles. Supplied to Labsphere and calibrated by F.T.Simon, Inc., the FTS-Fluorescent Standards are a new addition to Labsphere's product line.

Wavelength Calibration Standards
Typically, to calibrate spectrophotometers for wavelength accuracy, spectrocopists have used holmium oxide or dydimium oxide filters. The reflectance equivalent of these materials are available under appelation of Spectralon WCS These materials are used in reflectance spectrometers to assure the accuracy of the monochromator or position of peaks in a diode array spectrometer.

Specular Standards
When the reflectance of specular or mirror-like materials is performed, the best technique is to use a similar materials as a standard. Labsphere offers Specular Reflectance Standard (SPRS) standards. These standards are aged, magnesium fluoride coated first surface aluminum mirrors for the calibration of other specular materials in hemispherical geometry.

Transmittive Diffusers
Diffusers are used to give a lambertian response to a detector, either in a sphere system or as a solar collector. Typical transmittive diffusers such as opal glass or ground quartz are either not transmittive in part of the spectra (as is opal glass in the UV) or not particularly lambertian in response (typical of ground quartz). Spectralon SDM diffusers have the ability to transmit UV and also act as an extremely lambertian diffuser over a wide spectral range. These materials can also be tailored for either high or low transmittance to fit particular applications.

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