The Imaging Sphere Goniophotometer

Imaging Sphere Collage

Fast view angle analysis of LEDs, small light sources & flat panel displays

The Imaging Sphere from Radiant Imaging is an innovative, ultra-fast goniophotometer based upon a ProMetric imaging photometer for instananeous angular analysis of light sources, and displays. With the Imaging Sphere, you measure the light distribution for all angles instantaneously. The Imaging Sphere captures the full hemispherical angular luminous intensity and colour variation of small light sources in seconds. For displays, the Imaging Sphere rapidly measures view angle as well as luminance and colour variation with direction of view for one spot on the display at a time. The Imaging Sphere also functions as a high speed BRDF scatterometer (IS-SA) for characterising the reflectance and transmittance properties of materials.

Three Models, All Incredibly Fast

For emissive measurements, the Imaging Sphere is available in three versions. The IS-LI measures the far field angular luminous intensity versus angle from LEDs and other small light source. For individual LEDs, the IS-LI TE is a lower cost alternative to the full size IS-LI and conforms to the 100mm measurement distance specified in CIE 127, condition B. The IS-VA measures the near field luminance versus angle from flat panel displays. The measurement capabilities of the three versions are summarised in the table below. If the speed of the Imaging Sphere sounds too good to be true (goniophotometers have traditionally been very slow and extremely expensive), all will be revealed in our technical briefing.

Main Specifications	IS-LI TE	IS-LI	IS-VA
Suitable for	Individual LEDs	Individual & Lensed LEDs Small Light Sources	Flat Panel Displays
Luminous Intensity vs. Angle	•	•
Luminance vs. Angle			•
Colour vs. Angle *	•	•	•
Demountable ProMetric Camera		•	•
Dome Diameter	200mm	550mm	550mm
Max Sample Diameter	10mm	22.5mm	N/A
ProMetric CCD Camera(s)	10-bits	14-bits	14-bits
		16-bits	16-bits
CCD Resolution	1392 x 1024 pixels	512 x 512	512 x 512
		1024 x 1024	1024 x 1024
		1536 x 1024	1536 x 1024
Dynamic Range **	0.05 - 10⁵cd	0.005 - 10⁵cd	0.1 - 10⁶ cd/m² ***
Angular Range	0 - 360° azimuth	0 - 360° azimuth	0 - 360° azimuth
	0 - 85° elevation	0 - 85° elevation	0 - 85° elevation
Angular Resolution	0.5°	0.5° (512 pixel camera)	0.5° (512 pixel camera)
		0.25° (1024 pixel cameras)	0.25° (1024 pixel cameras)
Min Measurement Time	1 sec (photopic)	1 sec (photopic)	1 sec (photopic)
	5 sec (colour)	5 sec (colour)	5 sec (colour)

*     The Imaging Sphere can measure the chromaticty and colour temperature variation with angle if the ProMetric
       imaging photometer specified has colour capability - this is optional on all models.
**   The specified dynamic range requires the use of optional ND filters
*** For a 20mm sample area

The Imaging Sphere for Measuring the View Angle of Individual LEDs

The IS-LI TE is our latest Imaging Sphere designed to provide a more affordable choice for those wishing to test the luminous intensity and view angle performance of individual LEDs up to 10mm diameter in accordance with CIE 127, condition B. The IS-LI TE is available with either a photopic or colorimetric response which enables the colour variation from white LEDs to be analysed. The ProMetric imaging photometer built into the IS-LI TE is a hybrid between the CCD sensor of the PM-1000 and the CIE filter wheel used in the PM-1200. The ProMetric camera used in the IS-LI TE is permanently installed; in the case of the IS-LI and IS-VA, the camera can be demounted and used for spatial light source measurements as well.

Imaging Sphere Software (model IS-LI) Showing Results for a White LED

The Imaging Sphere for Measuring the View Angle of Small Light Sources

The IS-LI is our full sized Imaging Sphere for measuring the luminous intensity of LEDs and other small light sources up to 22.5mm diameter. The IS-LI is available with either a photopic or colorimetric response which enables the colour variation from white LEDs to be analysed. The IS-LI is available with a choice of 14 and 16-bit, cooled ProMetric imaging photometer with pixel resolutions from 512 x 512 up to 1024 x 1024. The ProMetric camera used in the IS-LI can be demounted and used for spatial light source measurements as well (realignment is necessary when mounting the camera back onto the Imaging Sphere and an optional ProMetric software licence is required).

The Imaging Sphere for Measuring the View Angle of FPDs

The IS-VA is our full sized Imaging Sphere for measuring the view angle of flat panel displays. Unlike our FPMS goniophotometer which measures the luminance from an entire FPD for one angle at a time, the IS-VA measures the hemispherical view angle for one spot on a display at a time. Compared with traditional conoscopic techniques, the Imaging Sphere is much less expensive and can record measurement spots of up to 40mm diameter at up to 85° elevation. Conoscopic measurements are rendered less accurate when their small measurement spot approaches the typical LCD pixel size.

The IS-VA is also available with a choice of 14 and 16-bit, cooled ProMetric imaging photometer with pixel resolutions from 512 x 512 up to 1024 x 1024. The ProMetric camera used in the IS-VA can be demounted and used for display spatial uniformity measurements as well (realignment is necessary when mounting the camera back onto the Imaging Sphere and an optional ProMetric software licence is required).

Imaging Sphere Software (model IS-VA) Showing A Contrast Ratio Measurement for an FPD