The model 3211 series is a diffused Photometric sensor designed to meet CIE 127 requirements, with a precision aperture / filter / diffuser combination that delivers a CIE V (λ) f1′ < 2.0%. These products are ideally suited for LED measurement applications per CIE 127 condition A & B, including luminous intensity and cd. The matched photometric filter and cosine diffuser lowers the error in spectral matching, particularly in the blue and violet portion of the spectrum.  The integrated cosine filter significantly reduces directional sensitivity for ease of use.

Our wide range of optical power meters, photometric and radiometric sensors is complemented by ISO/IEC 17025 accreditation by NVLAP (NVLAP lab code 200823-0), resulting in unmatched performance and custom configuration as required.

  • Luminous Flux Measurements (lm)
  • Illuminance Measurements (lux)
  • Luminous Intensity Measurements (cd)

Key Specifications                                          Part No. U68224

CIE V (λ) Function

 f1’  ≤ 2.5%

Detector Information

Silicon   1.0 cm2 active area

Rise Time

3 µ sec

Dynamic Range(1)

1 x 10-2 to 5 x 105 lux

Typical Response(1)

3.2 x 10-9 A/lux


ISO17025, NIST Traceable


2 meter, included

Compatible with the UDT Handheld and Benchtop series Optical Meters and Integrating Spheres.

(1) Stand alone with cosine receptor. Value may differ when used with integrating sphere, or with cosine receptor removed.


UDT Model 3211 Photometric Sensor