HMS-Series "Half Moon" Spectroradiometers
Novel integrating hemispheres for testing solid state lighting
Labsphere's HMS-series of "Half Moon" integrating hemisphere systems are novel spectroradiometers that are ideally suited to measuring the forward flux from solid state lighting. By mounting the sample and its drive electronics outside of the sphere, thermal management problems are much reduced and measurement speed and accuracy are improved. The HMS series are available with hemispheres of 31cm (12-inches), 50cm (20-inches) and 103cm (40-inches) diameter. A CDS-series spectrometer controlled from LightMtrX software provides for ease-of-use, instant acquisitions and powerful analysis.
Two Hemispheres - One Real & One Virtual
The integrating sphere has been used since 1894 to collect the 4π steradian output of lamps and other sources of light placed in its geometric centre. The combination of spherical surface and diffuse high reflectance coating creates a uniform radiance field within the sphere which can be sampled by a photodetector. The Labsphere Half Moon systems comprise half an integrating sphere and a plane mirror bisecting the equator. From within the "sphere" one would see a real hemisphere looking in one direction and a mirror image of the real hemisphere looking in the opposite direction. The result? A uniform radiance field with higher brightness, faster measurement times and half the footprint of a full sphere.
Improved Accuracy with Solid State Lighting
A Half Moon spectroradiometer provides an ideal solution for measuring the foward (2π) flux from solid state lighting (SSL). The device under test is placed at a port in the centre of the plane mirror which means that the body of the luminaire, the heat sink and any drive electronics remain outside of the chamber and don't absorb light. This results in improved accuracy compared with placing the sample within a full sphere. With the sample placed outside of the sphere, stabilisation times are reduced, as the device under test will reach thermal equilibrium more quickly.
Accurate Flux Measurements Regardless of the Lamp Type
The HMS-series spectroradiometers employ a CDS-2100 array spectrometer which features a back-thinned, TE-cooled CCD sensor that provides accurate luminous flux and colour temperature measurements regardless of spectral power distribution of the device under test. Unlike an ordinary filter photometer, the CDS-2100 measure the spectral radiant flux and apply the CIE standard photopic observer function in software. The result is accurate lumen readings regardless of the type of lamp used in the device under test.
Instantaneous Lumen, CCT and CRI Data
The CDS-2100 array spectrometer not only promotes measurement accuracy, it also provides instantaneous spectral acquisitions. Unlike tradition scanning spectroradiometers that record the spectral power one wavelength at a time, an array spectrometer records a complete spectrum in an instant – the measurement time varies with the power of the device under test, but the typical scan time is under one second. LightMtrX software takes care of the photometric and colorimetric computations, providing lumens, chromaticity and colour temperature data in a flash.
Forward Flux Standard
In accordance with the recommendations given in IES LM 79-08 for measurementS of 2π flux from solid state lighting, each Half Moon system is supplied with a standard of forward spectral flux. The FFS-100 series of forward flux standards mount onto the sample port of the hemisphere and are driven by an LPS-series, current regulated lamp power supply.
LightMtrX Software for System Control
Each Half Moon spectroradiometer system is controlled from LightMtrX software. Labsphere's LightMtrX is quite simply the easiest to use software yet released for performing spectroradiometric, photometric and colorimetric measurements of light sources. LightMtrX features user-defined "methods", an auxiliary correction capability and the ability to perform electrical and optical testing in conjunction with a Keithley 2400 series SourceMeter.
Auxiliary Correction for Accurate Measurements
Half Moon spectroradiometers are calibrated by substitution. The lamp standard of forward flux is placed at the sample port opening on the plane mirror and the spectroradiometer responsivity determined. The measured responsivity takes account not just of the light emitted from the standard lamp, but also the light reflected back into the hemisphere upon reillumination. When a sample is placed at the same port, the degree of reflectance may well be different which results in the measuired flux from the sample being over recorded. The simple solution to this error is called auxiliary correction and involves the use of a low power, uncalibrated "auxiliary" lamp mounted on the wall of the hemisphere. This lamp is used to guage the relative absorption of the standard lamp compared with the device under test and to yield a correction factor that can be applied to subsequent readings of the luminous flux for the particular type of sample under test. All of the HMS Half Moon spectroradiometer systems are supplied as standard with an auxiliary correction lamp and companion power supply that can be used to fully correct for self absorption errors.
Also Measure Intensity & Illuminance
In addition to measuring forward flux, you can add the capability of measuring luminous intensity and illuminance to your Half Moon spectroradiometer system. Optional sensor heads can be attached to the optical fibre feed to the spectrometer that provide for alternative types of photometric measurements. The E-1000 irradiance sensor is an integrating sphere-based head with a near-perfect cosine response that is used for measurements of the spectral irradiance of light sources. The I-1000 & I-2000 intensity sensor heads provide for measurements of the spectral radiant intensity of individual LEDs in accordance with CIE publication number 127, condition A & B.
Specifications & Ordering Information
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