Uniform Integrating Sphere Light Source in Accordance with EMVA 1288
- Integrating sphere light source with homogeneous light field for applications of camera calibration based on LEDs and tungston lamp
- 300 mm Ø sphere diameter, 63.5 mm Ø diameter port
- LED illuminant (UV or other like red, green, blue, white possible)
- Remote or manual aperture for intensity adjustment
- Control electronics with precision power supplies. Traceable calibration.
Integrating sphere light sources provide a luminous field with very good uniformity of the luminance or radiance distribution. Hence they are commonly referred to as Uniform Light Sources. One of their main uses is the pixel sensitivity adjustment of digital image sensors and cameras. In photographic technology this is known as white balance. As part of the adjustment, sensitivity differences of individual pixels or pixel groupings are detected and corrected by uniform illumination of all the pixels. To detect possible linearity errors, white balance is performed at different intensities.
White balance compact wide-angle cameras
Digital image processing is a prerequisite for many applications such as the autonomous movement of vehicles, mobile robots and driverless transport systems. The image is often captured by compact wide-angle cameras, which as safety-critical sensors, require a white balance at different intensities and operating conditions. If the integrating sphere light source has to be arranged at a significant distance from the camera due to the measuring setup which may involve climatic chambers for example, the required uniform light field can be very large. An alternative is to project the homogeneous light field of the integrating sphere through a solid, light-conducting medium right up to the camera optics.
The model shown here corresponds to an example configuration. Gigahertz OptiGmbH is an expert in putting together your individual configuration to meet your requirements. So you can contact us with your special requirements!
The 30 cm integrating sphere is coated with ODP97 (Bariumsulfate), offers monitor detector and a 63.5 mm entrance optic. Other configurations are possible on request.
LED and tungston light source
In the light sources are different LEDs and a tungston light source integrated. The LEDs can be operated individually and together. E.g. a RGB LEDs is support on request for fulfilling the specifications of the EMVA 1288 standard of the European Machine Vision Association. The dynamic range of LEDs in CW operation is relatively low. The integrating sphere light source therefore offers, in addition to the current setting, a aperture for intensity adjustment with constant LED current. Standard is a manual variable aperture, remote control is possible on request.
Short and long term luminance stability
For the best possible short-term and long-term stability of the luminance, the LEDs are operated in current mode. In addition, the intensity is measured by a monitor detector. The LED control and regulation is done by the optional control electronics. It offers four precision power supplies as well as a touch-screen display and RS232, USB and Ethernet interfaces for manual or remote operation. Same is given for the tungston lamp.
The luminance calibration of the uniform light source is carried out in Gigahertz-Optik‘s calibration laboratory for optical radiation measurements. In addition to the calibration of luminance, the spectral radiance and luminance distributions are confirmed in the calibration certificate.
Light source with LED and tungston lamp