Wide Beam Imager
The Ophir Wide Beam Imager: WB-I a compact, calibrated accessory for beam profiling cameras, provides a way to measure both size and power distribution of a divergent and large diameter beam coming from sources such as VCSEL, LED as well as parallel beams. It employs a 45mm diffusive plate onto which the beam from the light source is projected. This image is then reduced by 8 times and is reimaged onto the camera focal plane. VCSELs, LEDs and fiber lasers are used in many sensitive applications. To guarantee the high quality of the devices, it is essential to analyze the beam profile, but those wide, divergent beams place specific requirements on the measurement system:
- The apertures of conventional beam profilers are too small to collect the entire spot of large or divergent light sources.
- Diverging beams cannot be accurately measured with regular detectors because the quantum efficiency of the detector is highly dependent on the angle of incidence. Compact, ruggedized, and portable design of WB-I enables on-site service of beam profiling of VCSELs and LED systems at the customer site as well as operation at production lines and R&D labs.
- Divergent beams measurement significantly improved due to the possibility of up to 70° angle measurement, compared to 15°of standard beam profiler sensors.
- WB-I accessory, together with the camera and the BeamGage software, provides real-time beam shape analysis and visualization of changes of the beam shape due to different currents can be easily detected.
- Variable attenuation, via set of interchangeable filters or iris enables measuring wide range of light sources of different emitting powers.
Designated for R&D, Production and Service in following fields: Data Telecommunication, Automotive, Remote sensing, Face and gesture recognition
Typical light sources: VCSELs, LED, Wide laser beams, fibers
Typical measurements: Far Field energy distribution, Divergence, LIV sweep test VCSELs (beam profile vs current (A))
The WB-I accessory comes in 2 versions: UV-VIS-NIR (350-1100 nm) or SWIR (900-1700nm) designated for Eye- Safe, IR applications. The WB- I is purchased without camera. For a complete solution that includes BeamGage Professional imaging and analysis software, high-resolution camera can be added.
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Application example
VCSEL energy distribution directly depends on parameters such as current, pulse width and repetition rate and temperature of the device. Therefore, it is essential to measure the angle distribution of VCSELs at various stages of the manufacturing process as well as in R&D and field service. VCSEL behavior on the LIV sweep test: VCSELs are in a so called “LED mode” when there is only a low current applied. Once the current applied to the VCSEL rises, its beam profile changes to “Laser mode”:
| Model | Wide Beam Imager Wide | Beam Imager SWIR |
| Wavelengths | 350(1)-1100nm | 900-1700nm |
| Active area(2) | Ø45mm | Ø45mm |
| Beam sizes (2), (3) | 10mm– 45mm | 10mm– 45mm |
| Angle of incidence | <70° | >70° |
| Minimum detail(4), (5) | 0.5mm | 0.5mm |
| Lowest measurable signal | 100μW/cm²(6) | 3μW/cm² (With Iris fully opened at 1550nm) |
| Maximum power exposure CW(7) | 200W unlimited, 1000W for 1 minute | 50W unlimited time |
| Maximum energy exposure(8) | For ns pulses 1.5J/cm² | N/A |
| CCD recess supported | 4.5mm CCD recess camera | 17.5 mm (C-Mount) |
| Dimensions | L=258mm X Ø57mm | L=265mm X Ø57mm (Ø73mm Iris control) |
| Weight (with camera and support) | 0.5 kg (0.7 kg) | 0.6 kg (0.8 kg) |
| Part number | SP90553 | SP90605 |
| Notes: | (1) Camera response down to 350nm. Below this, flourescence of screen will be imaged | |
| (2) Limited to 43 mm in Y direction by camera sensor | ||
| (3) 5mm possible with reduced accuracy | ||
| (4) For low contrast artefacts, due to blur effect (~0.8mm) | ||
| (5) Small diameter evaluation error is < 5%, decreases proportionally with increased diameter | ||
| (6) With two ND1 filters mounted on camera | ||
| (7) For WB-I: 80% of the light is diffused inside system, 20% is backward scattered, WB-I SWIR: 50% of the light is diffused inside system, 50% is backward scattered | ||
| (8) At 1.064μm. For wavelengths below 0.9μm, derate to 40% of above , for <0.4μm to 20% | ||
