RS-50 VF Projection Light Source

The RS-50VF source is primarily used for generating irradiance levels at distances from 6 to 30 meters or for uniformly illuminating areas of up to 50 cm or more in diameter. The calibration of the source is given at a specified distance from the exit pupil. Beyond 6 meters the source has the characteristics of a point source, and approximate illuminance and irradiance levels may be generated using the inverse square law.

The RS-50VF may also be used uncalibrated to illuminate various materials of interest. The correlated color temperature of the RS-50VF source is set at CIE Illuminant A at 2856 ± 20K. The area of illumination may be varied by changing the field apertures.  An RS-4 Series Constant Current Power Supply (sold separately) is used for ultra-stable, constant-current power.


  • Calibrate spectroradiometers, radiometers, and photometers
  • Measure reflectance and transmittance
  • Illuminate various materials
  • Perform calibration reports in units of luminance, illuminance, radiance and irradiance


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Robust, Reliable Light Source Solutions

  • NIST-traceable calibration for Luminous Intensity (cd), Illuminance (lux), and Irradiance (W/cm2)
  • Light delivery system with variable focal distance
  • Illuminant A spectrum curve
  • 2856K night-time color standard
  • Tungsten-halogen lamps for stable output

In addition to our exceptional technical and functional capabilities, Gamma Scientific is ISO/IEC 17025 accredited by NVLAP (NVLAP lab code 200823-0).

RS-50VF Light Source Specifications

Calibrated Wavelength Range

380 to 830 nm                                                           (300 to 1100 on request)

Luminous Intensity

2700 cd


12 lux at a distance of 15m                                     (1.1 fc) at 2856 ± 20 K

Uniformity of Illuminated Area

± 4% over 460 mm diameter

Exit Pupil Size

25 mm with symmetrical distribution on the optical axis

Illuminated Area at 15 m

300 mm diameter                                                     (Standard)

460 mm diameter


127 mm (5 in) L x 127 mm (5 in) W x 310 mm (12.2 in) H            

2.7 kg (6.3 lb)

NIST Traceable Calibration

Luminous Intensity (cd)          Illuminance (lux)          Irradiance (W/cm2)


RS-4 Power Supply (purchased separately)

Operating Mode

Constant Current

Measurement Technique

Poggendorf Comparison Method


Null type (zero center)

Output Current

10A maximum

Voltage Compliance

15 V maximum

Current Accuracy, Long Term

>  99.95%

Set Accuracy Error

> 0.02%

Temperature Drift

 < 50 ppm per °C

Temperature Range

15 to 35°C

Thermal Drift After 8 min. Warmup

< 0.01%


± 0.02% change for line voltage change of of 10V

Current Ramp On/Off Time

< 30 seconds


220W maximum

Line Voltage

100 to 240 VAC   50/60 Hz

Relative Humidity

Up to 99% (non-condensing)


254 mm (10 in) L x 216 mm (8.5 in) W x 89 mm (3.5 in) H           2 kg (4.4 lbs)

Specifications are subject to change without notice.

Related Products

The Gamma Scientific RS-4 power supply is a precise, current-regulated power supply intended for use in light measurement applications.

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