819C Series modular integrating sphere bodies feature four ports located at 0, 90 and 180 degrees, as well as at the north pole. The baffle is located between the 0- and the 90-degree ports. The 0-degree port is plugged with a port plug and the 180-degree port is used as the input. A fourth sphere port adds functionality to an integrating sphere but also diminishes the uniformity of the light distribution inside the sphere. We offer a wide variety of integrating sphere accessories that mount to the port frames, allowing the sphere to be customized for multiple applications.

Newport offers accessories that are compatible with our integrating spheres to build a complete integrating sphere system. Various adapters are available to change port frame diameter, reduce an input port's clear aperture, measure fiber optic power, connect lens tubes and mount sensors. Port plugs to block an unused sphere port are also available.

The 819C series integrating sphere is ideal for applications that require use of the 180° port. A detector is typically mounted on the 90° port, while the source beam may enter the sphere through either the 0° or 180° port, depending on the application. Common applications include measuring total collimated laser beam power (including the collimated output of an optical fiber), measuring transmitted radiation from an irradiated sample and measuring reflected radiation from an irradiated sample. For more details about these applications, please see our Integrating Sphere Fundamentals and Applications tutorial.

The diffuse gold coatings on gold spheres exhibit superior reflectance characteristics in the long IR region when compared with coatings on existing barium sulfate and PTFE integrating spheres. The typical reflectance of gold is >94% up to 20 µm, while reflectance deteriorates rapidly after 2500 nm for both barium sulfate and PTFE. This makes gold spheres an ideal choice for mid- to far-IR applications.

Diffuse gold coating is an electrochemically plated, diffuse gold-metallic coating that exhibits high reflectance over the near-infrared and infrared wavelength range from 0.7 to 20 µm. Gold spheres and barium sulfate spheres are constructed in the same manner, except that the external flat surface and port frames on the gold spheres are also gold-plated. Gold spheres are ideal for infrared laser applications. Diffuse gold coatings remain stable at temperatures well above 100°C, while a barium sulfate coating may lose its reflectance at high temperatures. With a damage threshold four times greater than PTFE and high thermal limit characteristics, gold spheres are an excellent choice for high power applications.

Among the factors in selecting the size of an integrating sphere is the physical limitation of the measurement setup that will be used. Generally, as the sphere diameter grows, the “integration” property of the sphere improves, the port size can be larger and higher input power can be accommodated. However, with the increasing attenuation of the setup, the throughput will be decreased.