High reflectance materials for UV to NIR wavelengths

Most of our integrating spheres are available with a choice of three interior materials. For VIS-NIR applications choose our barium sulfate-based white coated spheres. The coating is highly reflective, with greater than 97% reflectance at visible wavelengths.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 applications in the NIR and IR regions, our diffuse gold spheres provide near-Lambertian characteristics and reflectance values up to 95%. All of our spheres are designed to provide high reflectance, stability and low throughput loss over their usable wavelength range.

Reflectance and throughput of 4 inch PTFE and BaSO4Spheres. A gold sphere has a 95% reflectance from 5 to 10 µm.

High Damage Threshold

The excellent reflectance properties of these spheres give them a high damage threshold. Measurements with a pulsed laser at 1.6 µm showed the damage threshold of the coated spheres to be 1.5 W cm-2. The PTFE 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.

Reflectance of diffuse gold coating.

Uniform Light Source Spheres

Place one of these integrating spheres at the output of a light source to create a uniform Lambertian broadband emitter. These spheres are utilized in applications where uniformity is critical. Typical radiance uniformity is within 1-2% of the average over the exit port as long as the field of view of the imaging system remains aimed at the baffle within the sphere. Irradiance uniformity at the port is also better than 1-2%.For a tunable, uniform light source, couple the sphere to the input of a monochromator or motorized filter wheel. To make a uniform calibration source with several orders of luminance range, attach a filter wheel with neutral density filters to the sphere's input. These models feature an 8-inch interior diameter. The input port of each sphere has a standard Oriel 1.5-inch series male flange so it can be mated to an Oriel light source. The output port is a 2-inch [51 mm] diameter port frame, allowing samples to be easily mounted. Use a model 77829 coupling ring to connect these spheres to an Oriel monochromator.

Reflectance and Transmittance Spheres

The 70679NS and 70682NS are used for measurement of specular and diffuse hemispherical reflectance and total transmittance using an 8/D geometry (8-degree beam incidence/diffuse collection). The 70679NS may be used from 350 to 1300 nm and has an 8-inch diameter. The 70682NS functions from 250 to 2500 nm, with a 7-inch inner diameter. These spheres have five ports:

  • Input port with 1.5 inch series male flange
  • Inch sample port, in-line with input port
  • Detector port with 1.5 inch series male flange
  • Inch specular exclusion/inclusion port for light trap or plug
  • Additional 2.0 inch port at north pole for comparison measurement technique or center mounted samples (custom holder required)
Two sample holders are provided, each with a 1-inch [25 mm] diameter. The 0.5 inch [13 mm] deep cell holds the sample at a 0° or 8° angle to the beam. The clear aperture is 0.7 inch [18 mm]. The holder is spring loaded so that square, rectangular or irregular shapes with dimensions up to 2 inches [51 mm] can be held against the sphere wall. The sample must fill the aperture. The spring loading allows users to quickly insert and remove the sample. When the 8° sample holder is utilized, light is reflected from the sample strikes the port and is turned 8 degrees to the specular exclusion port. If a plug is at the exclusion port, the light is re-captured in the sphere (specular inclusion, total reflectance 8/D). If a light trap is used in the exclusion port, the specular portion of the sample’s reflectance is subtracted from the measurement (specular excluded, diffuse only reflectance 8/D) allowing characterization of "gloss". If the 0° sample holder is used at the sample port and the input beam is placed behind the sample port, then normal or total transmittance of samples may be quantified. One exclusion port plug is included with the sphere and one extra port plug is included for the north pole port. If a plug is used at the 1.0-inch port opposite the sample, then all energy is included in the measurement (total transmittance). If a light trap is used at this port opposite the sample, then the normal transmitted beam (specular transmission) is excluded by the trap. Diffuse or normal excluded transmittance allows for characterization of "haze".