Pro Lite Technology

PLMS Large Integrating Sphere Photometers

Labsphere PLMS-4000 Large Integrating Sphere Photometer

Measure the flux of lamps, LED clusters and large luminaires

Further Information Case Studies
» PLMS Large Datasheet » Testing LED Optics
» Testing LED Arrays
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» Integrating Spheres » PLMS Large Drawing
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» Spectrometer system for LED analysis  

Labsphere's PLMS-4000, PLMS-6500 and PLMS-7600 are photometers with integrating sphere sizes of 40, 65 and 76 inches respectively (102, 165 & 193cm) which are used for measuring the luminous flux of LED clusters, large luminaires and almost any type of lamp, including arc, incandescent, HID and fluorescent.

Measure Total & Forward Flux

The PLMS-4000 can accomodate light sources of up to 1,500W and up to 10 x 10cm, whereas the PLMS-6500 is suitable for sources of up to 4000W measuring up to 18 x 18cm. For the very largest samples, the PLMS-7600 is rated to 5,000W and can accomodate samples measuring up to 21 x 21cm. For tubular lamps, or linear arrays of LEDs, the maximum sample size is 60, 86 and 130cm respectively. Each sphere is also fitted with a 2-inch external source port which permits unobstructed mounting of board-mounted or heat-sinked devices for forward and partial flux measurements. A port plug (blanking plate) is supplied to seal the external source port when not in use. This port can be enlarged on a custom basis to accomodate larger samples, for example downlighters.

Accurate & Reproducible Readings

The Labsphere LMS-400, LMS-650 and LMS-760 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 series integrating spheres benefit from Labsphere's 30 years of experience. The LMS-400 integrating sphere features convenient, clamshell-type interior access and stands on a rugged, floor-mounted extruded aluminium frame with locking castors. The LMS-650 and LMS-760 hemispheres are rail mounted and separate in parallel to provide interior access. All three spheres are painted with Labsphere's Spectraflect integrating sphere coating which exhibits high, diffuse reflectance.

Each sphere is equipped with a 1-inch port for the optional auxiliary lamp, the 2-inch port for use with externally mounted samples, two 1-inch ports adjacent to the south and north poles for electrical feed-through 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 3-inch satellite sphere which provides for an optimal cosine response and reduced angular sensitivity.

The lamp mount is a telescopic design so a quick twist adjusts the position of the lamp. The height-adjustable sample platform features tapped holes and electrical feed-through which allows simple mounting of the device under test in the centre of the sphere for 4π flux measurements. With lamp mounts fitted at both the north and south poles, the test lamp can be held in either a base up or a base down orientation. Exchangeable baffles give optimal detector screening efficiency. The 1-inch base ports allow for an additional cable feedthrough for assembled fixtures. The quick-connect internal and external electrical contacts allow for effortless substitution between different samples. 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 Large Photometers

PLMS-4000

PLMS-6500

PLMS-7600

Product Code

AS-02479-100

AS-02480-100

AS-02481-100

Integrating Sphere Dia.

40" (1.02m)

65" (1.65m)

76" (1.93m)

Max. Lamp Power (W)

1500

4000

5000

Dynamic Range (lm)

10 ... 30,000

20 ... 70,000

30 ... 100,000

Max. Sample Size      

   2D (cm)

10 x 10

18 x 18

21 x 21

   Linear/Tubular (cm)

60

86

130

System Configuration     

Integrating Sphere 

LMS-400

LMS-650

LMS-760

Lamp Standard

SCL-1400

SCL-1400

SCL-1400

Lamp Socket

AS-02236-000

AS-02236-000

AS-02236-000

Lamp Power Supply

LPS-150-0268

LPS-150-0268

LPS-150-0268

Detector

SDA-050-P

SDA-050-P

SDA-050-P

Photometer Readout

SC-6000

SC-6000

SC-6000

Options & Accessories

Auxiliary Correction Lamp

AUX-100

AUX-100

AUX-100

Aux. Lamp Power Supply

LPS-100-0833

LPS-100-0833

LPS-100-0833

Set, Spectral Flux Standards

CSFS-1400

CSFS-1400

CSFS-1400

Set, Optical Grade Lamps

OGS-1400

OGS-1400

OGS-1400

Precision 50mm Aperture

PA-200-050 MM

PA-200-050 MM

PA-200-050 MM

SMA Optical Fibre Adaptor

SMA-050-SF/SL

SMA-050-SF/SL

SMA-050-SF/SL

Temperature Probe

TP-100

TP-100

TP-100

Temp. Probe with Monitor

TPM-100

TPM-100

TPM-100

Horizontal Lamp Mount Bracket

AS-02477-003

AS-02477-003

AS-02477-003

Fluorescent Tube Lamp Holder

AS-01312-010

AS-01591-010

AS-01476-010

 

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