Pro Lite Technology

PLMS Medium Integrating Sphere Photometers

Labsphere PLMS-1000 Medium Integrating Sphere Photometer

Measure the flux of LEDs, lamps & small luminaires

Further Information Case Studies
» PLMS Medium Datasheet » Testing LED Optics
» Testing LED Arrays
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Labsphere's PLMS-1000 and PLMS-2000 are bench-top photometers with integrating sphere sizes of 10 and 20-inches respectively which are used for measuring the luminous flux of lamps, individual LEDs, small clusters of LEDs and compact luminaires.

Measure Total & Forward Flux

The PLMS-1000 can accomodate light sources of up to 100W and up to 3 x 3cm, whereas the PLMS-2000 is suitable for sources of up to 400W measuring up to 5 x 5cm. Each sphere is based upon a convenient, latch-free, clamshell-type interior access integrating sphere painted with Labsphere's Spectraflect diffuse reflectance coating. A height-adjustable sample platform with tapped holes and electrical feed-through allows simple mounting of the device under test in the centre of the sphere for 4π flux measurements. A 2-inch port is also fitted that allows the 2π forward (or partial) flux from externally mounted samples to be measured. A port plug (blanking plate) coated with Spectraflect is supplied to seal the external source port when not in use.

Accurate & Reproducible Readings

The Labsphere LMS-100 and LMS-200 integrating spheres used in the PLMS photometers fully comply with CIE Publication No. 84, IESNA LM78, IESNA LM79 for 4π flux and the ANSI flashlight standard. All of which means that you can count on your PLMS photometer to yield accurate, reproducible results.

Not Just Any Sphere - This is a Labsphere Integrating Sphere

The LMS-100 and LMS-200 integrating spheres benefit from Labsphere's 30 years of experience. The 10-inch LMS-100 is equipped with a 1-inch port for the optional auxiliary lamp, a 2-inch port for use with externally mounted samples, a 1-inch port adjacent to the south pole for electrical feed-trough for the device under test and a further 1-inch port for mounting an optional temperature probe. Removeable port plugs are supplied for all port openings. The photodetector attaches to a ½-inch port equipped with a cosine diffuser. The integrating sphere is equipped with baffles also coated with Spectraflect to screen the auxiliary lamp port, the detector port and the external source port. The 20-inch LMS-200 differs only in that the photodetector attaches to a 3-inch satellite sphere which provides for an improves cosine response and reduced angular sensitivity compared to the cosine diffuser fitted to the LMS-100.

Please note that the baffle which screens the detector port is designed to block light from samples mounted in the geometric centre of the sphere; care should therefore be taken when measuring samples that exceed the maximum size recommended and advice sought from Pro-Lite.

Not Just a Sphere Either

At the heart of each PLMS system is the LMS integrating sphere. In addition, each system is equipped with a socket for the calibration lamp, a silicon detector with photopic response, a standard lamp of spectral flux, a stabilised power supply for the calibration lamp and Labsphere's SC-6000 integrating sphere photometer readout unit. The system includes a calibration certificate for the standard lamp, a cable to connect the lamp power supply to the bulkhead connector on the sphere frame (which in turn routes the electrical supply to the sample platform in the centre of the sphere) and a further cable that interfaces to the sphere at one end and is supplied with bare wires at the other to allow the operator to route power to the device under test from their own power supply. Pro-Lite also provides an on-site installation service and training course; for details, see: training courses.

Auxiliary Correction for Accurate Measurements

Integrating sphere photometers are calibrated by substitution. The lamp standard of spectral or luminous flux is placed inside the sphere and the photometer responsivity determined. The measured responsivity takes account not just of the light emitted from the standard lamp, but also the light absorbed. When a sample is placed within the sphere, the degree of absorption may well be different, particularly so if the the device under test is an LED in a housing with lens, reflector, heat sink or drive electronics attached. The presence of all of this hardware causes the self absorption of the sample to be much higher than from the standard lamp, with the result that the flux from the sample is under recorded.

There is, however, a very simple solution to this error. This is called auxiliary correction and involves the use of a low power, uncalibrated "auxiliary" lamp mounted on the wall of the sphere. 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. Both the PLMS-1000 and PLMS-2000 are available with an optional auxiliary correction lamp and companion power supply that can be used to fully correct for self absorption errors.

Moreover, if the sphere is used for forward flux measurements with externally mounted samples, the auxiliary lamp can also solve the problem of readings being too high. With a sample placed at the external source port, light that would have escaped and been lost through this port during the sphere calibration can now reflect back from the device under test and cause an over-estimation of the sample flux. In this case, the auxiliary lamp is used to guage the relative reflectance of the sample compared to the open port and to yield the appropriate correction factor.

Specifications & Ordering Information

PLMS Medium Sphere Photometers

PLMS-1000

PLMS-2000

Product Code

AS-02477-100

AS-02478-100

Integrating Sphere Dia.

10-inches (25cm)

20-inches (50cm)

Max. Lamp Power

100W

400W

Dynamic Range

0.6 ... 2,000 lumens

2 .... 6,500 lumens

Max. Recommended Sample Size

3 x 3cm

5 x 5cm

System Configuration

Integrating Sphere

LMS-100

LMS-200

Lamp Standard

SCL-600

SCL-600

Lamp Socket, Bayonet

LMP-1100

LPM-2100

Lamp Power Supply

LPS-100-0260

LPS-100-0260

Detector

SDA-050-P

SDA-050-P

Photometer Readout

SC-6000

SC-6000

Options & Accessories

Auxiliary Correction Lamp

AUX-35

AUX-35

Aux. Lamp Power Supply

LPS-100-0307

LPS-100-0307

Set, Spectral Flux Standards

CSFS-600

CSFS-600

Set, Optical Grade Lamps

OGS-600

OGS-600

Precision 50mm Aperture

PA-200-050 MM

PA-200-050 MM

SMA Optical Fibre Adaptor

SMA-050-SF/SL

SMA-050-SF/SL

Temperature Probe

TP-100

TP-100 

Temp. Probe with Monitor

TPM-100

TPM-100

Horizontal Lamp Mount Bracket

AS-02477-003

AS-02477-003

 

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