Innovative design improves the sphere's accuracy and repeatability when used to measure the power of divergent lasers and other difficult to measure sources of optical radiation
Pro-Lite Technology, a specialist photonics distributor, has announced the availability of the LPM-040-SF laser power measurement integrating sphere from Labsphere.
The LPM-040-SF features an innovative design which improves the sphere's accuracy and repeatability when used to measure the power of divergent lasers and other difficult to measure sources of optical radiation with outputs of up to 80 degrees divergence and powers of up to 15W in the wavelength range 250-2500nm.
Typical applications include measurements of the total radiant flux of lasers, projectorised sources, optical fibres, laser diodes, LEDs, VCSELs and laser diode stacks or bars.
Sources of optical radiation that exhibit high powers, large beams, extended source sizes, high divergence or dynamic beam displacement present a significant challenge to those wishing to determine their power in an accurate, repeatable fashion.
The integrating sphere provides a simple solution to these problems and offers an increased accuracy alternative to regular optical power meters used with otherwise difficult to measure sources.
Compared with a bare photodiode detector, the integrating sphere captures the full beam from such sources and reduces the effect of the non-uniform spatial response that many detectors exhibit.
Sphere response is polarisation-insensitive and serves to attenuate the optical beam onto a photodetector, allowing much higher power sources to be measured with sensitive, fast response silicon, germanium or InGaAs photodiodes.
To function correctly, a sphere for total flux measurements should be designed to take account of the size, position, divergence, any beam displacement and the power levels of the source under test.
The LPM-040-SF is designed to address these requirements and comprises a 100mm diameter integrating sphere with a 25mm diameter input port and a detector port located in a non-radial position just below the entrance.
A photodiode mounted at the detector port is constrained to view a small area of sphere wall just above the entrance port which prevents it from receiving both direct illumination and indirect radiation from an extended area of sphere wall that the incoming beam illuminates.
The response of the LPM-040-SF is highly insensitive to changes in beam direction, divergence or pointing for solid angles of illumination of up to 80 degrees.
The sphere provides attenuation of approximately 10,000:1 which allows powers of up to 15 watts to be measured.
The LPM-040-SF is coated with Labsphere's Spectraflect diffuse, high reflectance coating which provides spectrally non-selective reflectance of up to 98% in the wavelength range 250-2500nm.
The sphere is compatible with a range of interchangeable silicon, germanium and InGaAs photodiode detectors for power measurements in the range from 200-1800nm.
Calibrations are offered in watts over this range, with all calibrations performed using standards that are traceable to Nist.
