Gentec-EO, a provider of laser beam measurement instruments, has announced a new beam sampler for kilowatt-level lasers. The BA32-1KW is enabling technology that allows camera-based beam profiling for high power lasers. This water-cooled beam splitter is ideal for inline beam profiling in a variety of high-power applications, from military to industrial materials processing and R&D.

The BA32-1KW beam splitter measures laser beam profiles with power from milliwatts to 1 kW, and at power densities of up to 10 MW/cm2. This device attenuates extremely high power density beams with an attenuation ratio of 1:1900. This enables the use of very sensitive laser beam profilers to measure beam shape, focal spot and even beam waist. The BA32-1KW can also be equipped with a power meter at the second residual beam window to monitor the laser’s power simultaneously with the beam profiling.

POLARIZATION-NEUTRAL ATTENUATION

The BA32-1KW operates by reflecting a fraction of the incoming laser beam into the camera through the front surfaces of a pair of orthogonally oriented wedges. This reflects the beam in three directions: approximately 0.05% to the beam profiler camera, 7.4% to the power meter sensor, and 92% to the working beam. The result is uniform attenuation of any beam shape, from Gaussian to flat-top and even doughnut. 

The BA series optical attenuators use Fresnel reflection on two optical wedges to pick off a small percentage of the input beam. Since the wedges are oriented orthogonally, the S and P polarization states are switched when the reflected beam hits the second wedge, and the difference in reflectance between the two states cancels out. The incoming beam polarization state and irradiance are thus preserved. The wavefront distortion is negligible and the laser output power stability is not affected.

IN-LINE POWER MEASUREMENT

A common application for beam samplers is picking off a portion of a beam in order to track changes in beam power vs time using a detector. This information may be used as part of a feedback loop to regulate power, or could simply be used to log power in order to normalize experimental results at a later time. With approximately 92% of the beam that is transmitted, a laser process can keep running while its power and beam profile are monitored.

HIGH-QUALITY OPTICS FOR UV & BROADBAND APPLICATIONS

The BA32-1KW contains two optical wedges with excellent surface quality and flatness, to provide a transmitted beam with very low wavefront error. Its wedges are made of UV Grade Fused Silica, a colorless silica glass of extremely high purity, providing maximum transmission from 200 to 2100 nm. This glass combines a very low thermal expansion coefficient with good optical qualities, and excellent transmittance in the ultraviolet region. It will not fluoresce under UV light and has extremely high laser damage thresholds. This beam sampler comes with screw-on caps for each aperture to keep the optics dust-free and clean. Accessories to mount a power detector and beam profiler are sold separately.

MANAGE THE LASER POWER

CMOS sensors have low saturation levels as well as low damage thresholds. It is thus very important that you control your laser power to get the best measurement possible and avoid damaging the BEAMAGE camera.

MANY POSSIBLE USES

• Monitor power and beam profile simultaneously
• Polarization insensitive beam-splitter with no back-reflections
• Optical pick-off for use with our energy or power detectors
• Attenuator for our high sensitivity detectors like M6 series and PH series

MODULAR CONCEPT

The “sampled beam” port can be connected to the Beamage via the included adaptor tube. The adaptor tube is also compatible with our ND filters for additional attenuation (recommended for small beams at high power). An ND4 filter is always included with the purchase of a Beamage profiling camera. 

Inline monitoring of high power laser beams.

 Specifications:

• Spectral range: 200 - 2100 nm
• Equivalent attenuation: 1/1900 @ 1064 nm
• Integrated power detector: Compatible with UP55 series (not included)
• Optical wedges material: UV Fused Silica (uncoated)
• Residual beam deviation: 3.6° @ 1064 nm
• Polarization correction: Yes (pair of orthogonal wedges)

Damage Thresholds:

• Maximum average power density: 10 MW/cm²
• Maximum energy density: 10 J/cm²
• Maximum power: 1000 W
• Aperture diameter: 32 mm

Physical:

• Dimensions: 145H x 250W x 132D mm
• Weight: 5.5 kg
• Mounting thread: SM2