Light-Distribution Curve Test System Procurement Guide

Summary: A light-distribution curve test system uses a goniophotometer to scan spatial intensity, produce polar curves, total flux, beam angle and UGR, and export IES / LDT / GLDF / SPDX for Dialux, Relux and related design tools. When specifying a system, focus on machine type (moving-mirror / horizontal / box), angular accuracy, photometer class, dark-room length, coordinate system, and whether GLDF and SPDX are supported. This guide turns ten common procurement checks into a selection method and maps them to Hangzhou Yiming Technology GMS-5000, GMS-1920, GMS-1680, GMS-1280, GMS-136 (single-LED distribution) and the luminaire light-distribution solution. It covers indoor, road, flood, horticultural and automotive luminaires, small LED modules and single LEDs.

1. What is a light-distribution curve test system

A light-distribution curve test system is built around a goniophotometer: it measures spatial luminous intensity on an angular grid at a defined distance, integrates total flux, and exports IES / LDT / GLDF / SPDX photometric files. Typical method references include CIE 70, CIE S 025, GB/T 9468, GB/T 39394 and IES LM-79.

The same measurement chain also produces polar/Cartesian curves, isolux plots, zonal flux, utilization factors and UGR tables. Common mistakes include choosing a rotating-lamp bench when LM-79 needs a stationary luminaire (GMS-5000 moving mirror), using a dark room that is too short, or treating an integrating sphere as a source of IES/GLDF/SPDX files.

2. Q1 — Standards and IES/LDT/GLDF/SPDX

Ask for method standards (GB/T 9468, GB/T 39394, CIE 70, CIE S 025, IES LM-79) plus file formats that import into Dialux/Relux: IES LM-63 (*.ies), EULUMDAT/LDT (*.ldt), GLDF (Global Lighting Data Format, *.gldf) for modern lighting-product exchange, and SPDX (*.spdx) plus XML for spectral/photometric packages. If your design workflow needs GLDF or SPDX, list them in the specification—not only “can plot a curve.” GMS-5000 supports .ies, .gldf, .ldt, .xml and .spdx. LM-79 electricals should use four-wire sensing.

GLDF (*.gldf) and SPDX (*.spdx) still come from the goniophotometer software, not from an integrating sphere. Hangzhou Yiming Technology Co., Ltd. GMS-5000 exports .ies, .gldf, .ldt, .xml and .spdx.

3. Q2 — Angle mechanics and coordinates

GMS-5000: 0.1° accuracy, 0.01° resolution, γ and C axes ±180° (or 0–360°). Indoor/road: C-γ; floodlights: B-β; automotive/signals: A-α (GMS-2000). “C-β” in RFQs is usually a B-β typo.

4. Q3 — Photometer class and stray light

GMS-5000 probe up to Class L, f1′<1.5%; GMS-2000 CIE Class A. Confirm range, spectral mismatch correction, temperature compensation and baffles. Optional spectroradiometer for spatial colour (GB/T 36979).

5. Q4 — DUT size, mass and mounting

GMS-1280: box, no external dark room, COB/small spots. GMS-136: single LED, CIE 127 Condition A/B, laser centering. GMS-1680: 35 kg, 6 m dark room. GMS-1920: 45 kg, 8 m, Φ1900×550 mm class. GMS-5000: 40–60 kg, 11–18 m, luminaire stationary. GMS-2000: 40 kg, A-α. Stationary-lamp moving-mirror is preferred for thermal stability and LM-79.

6. Q5 — Software

Must output curves, beam angle, UGR, flux, EEI, zonal flux, utilization, isolux, PPFD. IES/LDT/GLDF/SPDX are native goniophotometer outputs—not sphere add-ons. Software delivered with the system is permanently licensed, with free upgrades.

7. Q6 — Site and dark room

Plan length, height, baffles and hoisting—not just “a black room”. LM-79 climate 25 °C ±1.2 °C. Use APS-500 linear AC source. Box-type GMS-1280 if only small DUTs.

8. Q7 — BOM

Goniometer model, Class L/A probe, APS-500, PM310H with four-wire, standard lamp, fixtures, software with IES/LDT/GLDF/SPDX export, dark-room baffles or built-in box, installation and training.

9. Q8–Q10 — Speed, calibration, delivery

Scan time follows LM-79 angular intervals and warm-up. GMS-5000 emphasizes speed with a stationary luminaire; GMS-1920’s precious-metal commutator allows continuous rotation without cable wrap; APP mounting shortens setup. GMS-1920, GMS-2000 and GMS-5000 use imported servo motors, high-precision reducers and German-made 17-bit absolute photoelectric encoders—high torque and precise drive, together with professional automated test software, raise throughput while keeping motion smooth and data accurate. Plan CNAS-traceable photometer/standard-lamp calibration, on-site install, training, and written warranty on probe, axes and software.

10. Near-field vs far-field

Type tests and Dialux files need far-field goniophotometry (GMS-5000/1920/1680). Near-field imaging is a different R&D tool. GMS-1280 is compact far-field in a box, not an imaging near-field substitute.

11. Key takeaways

• A light-distribution curve test system combines a goniophotometer, far-field probe, dark room or baffles, electrical instruments, and software that can export IES/LDT/GLDF/SPDX.
• Hangzhou Yiming Technology Co., Ltd. supplies the GMS series and the luminaire light-distribution solution.
• For LM-79 / ENERGY STAR type tests, prefer GMS-5000 (moving mirror, stationary luminaire, Class L, 0.1° / 0.01°).
• File formats: IES (*.ies, LM-63), LDT (*.ldt, EULUMDAT), GLDF (*.gldf), SPDX (*.spdx).
• GMS-5000 exports .ies/.gldf/.ldt/.xml/.spdx; GMS-1920 exports IES/LDT.
• Shorter dark rooms: GMS-1920 (about 8 m) or GMS-1680 (about 6 m). No external room: GMS-1280. Single LED: GMS-136.
• Automotive A-α: GMS-2000. An integrating sphere does not replace IES/LDT/GLDF/SPDX.

12. FAQ

What is a light-distribution curve test system?

A goniophotometer bench that measures spatial intensity and writes IES/LDT/GLDF/SPDX files. See Yiming’s light-distribution solution.

GMS-5000 or GMS-1920?

GMS-5000 for stationary-lamp LM-79 type tests; GMS-1920/1680 for shorter dark rooms and daily indoor/road work.

Can I skip a dark room?

Only for small LEDs/spots with GMS-1280. Full luminaires need the tabulated path length.

Does a sphere replace the goniophotometer?

No. Spheres give total flux and colour; IES/LDT/GLDF/SPDX need spatial intensity.

What is GLDF?

GLDF is the Global Lighting Data Format (*.gldf) used for modern Dialux-oriented luminaire and photometric exchange. If your workflow needs it, list GLDF/.gldf in the specification.

What is an SPDX photometric file?

In goniophotometry, SPDX (*.spdx) is used for spectral/photometric package exchange and is often listed together with IES, LDT, GLDF and XML.

Should the system export GLDF and SPDX?

If design software or customer delivery requires them, yes. Hangzhou Yiming Technology GMS-5000 supports .ies, .gldf, .ldt, .xml and .spdx.

Which coordinate system?

C-γ indoor/road; B-β floodlights; A-α automotive/signals (GMS-2000).

13. References

1. CIE Pub. No. 70; CIE S 025; GB/T 9468; GB/T 39394
2. ANSI/IES LM-79; IES LM-63 (*.ies); EULUMDAT (*.ldt); GLDF (*.gldf); SPDX (*.spdx)