A wide range of imaging applications do not require the unique illumination capabilities of a laser but still demand for more precise control than a constant halogen illumination can offer. LED illumination has clear advantages over the alternatives. Known spectral characteristics together with low heat dissipation and the ability to work in pulsed mode come in a cost-efficient package for various fields of applications.
LaVision offers LED solutions for different purposes. All LED's can be used in constant or pulsed mode synchronized to other devices and events by DaVis software. The LED units are triggered or modulated by TTL signals up to 100 kHz.
Standard colors are white and blue. The linear LED illumination units contain high power LEDs and are focused for efficient usage of the light. White illumination is highly efficient and matches any camera‘s sensitivity curve well. Blue illumination is advantageous when high temperatures or flames give a strong background radiation of visible or infrared wavelengths.
To eliminate glare and specular reflections from the specimen surface and greatly improve usability and result quality.
Metallic or shiny surfaces can create unwanted specular reflections which can confuse the correlation algorithms. Such reflections may not be visible at the start of a test but as the specimen deforms, the local light incidence changes and these bright spots can occur. The polarization light upgrade kit includes the necessary filters for the standard LED illumination units. In combination with optical filter rings for the camera lenses this configuration significantly reduces this effect thus improving data quality.
Covered by Patent EP1739403B1
If the specimen has a reflective surface, complex geometry, or undergoes large deformation during the experiment, shadows or reflections may occur on the specimen surface. This can make image evaluation difficult.
An alternative approach to white light illumination is Ultra-Violet (UV) light. When UV light is combined with a matching filter for the camera it is possible to avoid the potential issues described above. In order to use UV light the specimen surface must be prepared with a suitable speckle pattern: this can be achieved with fluorescent paint matched to the light characteristics. UV speckle is robust and stable over time irrespective of the specimen’s movement, and through the use of a matched filter, changes in ambient lighting do not affect the image quality.
LaVision’s UV LED Panel offers a compact light capable of illuminating small or large areas together with matched camera filters and speckle application kit.
Designed expressly to meet the requirements of high speed imaging. With a light intensity of up to 2.39 million lux (Ø 6.5 cm field of view at 20 cm distance) this halogen spot light is ideal for high speed experiments, using cameras with extremely short exposure time. The special cooled halogen illumination concentrates an intense amount of light over a long time period with less object warming. For short imaging tasks, the heating effect is negligible.
Strain experiments with high-speed cameras require large amounts of light in a short time. The LED-Flashlight 300 provides an array of 72 high-power LEDs in an area of 300 x 100 mm². It is much more compact, made up only by the LED module itself and a small power supply, allowing easy transportation and mounting. The incoherent white light ensures high image quality with constant homogeneous brightness in time and space. The amount of light output is similar to high-repetition-rate lasers at a fraction of the cost. The LEDs are operated above the nominal LED current to generate short pulses at very high light intensities. In the free-trigger mode at lower peak power, the LED-Flashlight 300 can either be used for constant illumination (100 % duty cycle), e.g. for experimental adjustment, or can be triggered with an arbitrary pulse sequence, e.g. for dual-pulse or multi-pulse illumination.
|Size||337 x 117 x 153 mm³|
|Weight||5.3 kg (LED module)
1.6 kg (power supply)
|LEDs||72 white high power, high efficiency LEDs|
|Opening angle||10° (+/- 5°)|
|Working distance||typ. 500 mm – 2000 mm|
|Electrical power||avg. 300 W|
|Efficiency||20 % (free-trigger), 10 % (pulsed-overdrive)|
|Light pulse trigger||0 – 20 kHz, TTL-level|
|Jitter||< 10 ns|
|Mode selection||manual switch or remote (TTL)|
|Safety features||temperature control, LED trigger protection|