Reimaging UV Laser Beam Profiling

Kevin Kirkham, Sr. Manager, Product Development, Ophir-Spiricon

• Wavelengths from 190 to 360 nm
• Spot sizes from 150 μm to 30 mm*
• Energy density from 50 μJ/cm² to 0.6 J/cm²**

* Maximum measurable spot size is 4 times the CCD active area up to a maximum of 30mm diameter.

** Laser fluence exceeding 30 mJ/cm² requires optional beam splitter: BEAM SPLITTER FOR X4 UV, P/N SPZ17007

Three types of C-mount UV accessories are offered: 4X expander, 4X reducer, and 1:1 UV imaging system. The UV beam profiling accessories attach directly to Cmount type cameras with 4.5 or 12.5 mm sensor spacing. Each comes with its own spatial calibration value so that Ophir’s BeamGage beam profiling software results can accurately reflect the magnification of the reimaging optics.

The c-mount UV conversion re-imaging products consist of four main components:

1. Conversion crystal. This crystal is specially doped Nd:YAG and is cut and polished to be very thin, <50 um.
2. Filter blocks a UV light that was not converted to visible.
3. Visible image is relayed to the image plane with the use of some lenses.
4. Camera sensor plane (not provided) converts visible image to an electronic one.

Available UV conversion / re-imaging systems include: 4x reduction, 4x expansion, or 1:1 re-imaging of the UV profile. Converter uses C-mount adapter threads to connect to camera. The converter design requires a CS (4.5 mm) or SP (12.5 mm) camera. They will not work with C-mount (17.5 mm sensor spacing) cameras.

In addition to the three C-mount options, we offer solarized glass and doped YAG crystal UV conversion targets for use with our CCTV lens reimaging options. These conversion materials require one of our CCTV lenses and mounting hardware to construct a laser beam re-imaging system. Crystal UV imaging plates are more spatially uniform and exhibit higher sensitivity than the solarized glass converter plates. The extra cost is well worth the fidelity of the image in applications where accuracy of the beam profile is important. This especially true if the goal is to measure Top Hat uniformity.

Our unmounted UV conversion materials include:

20mm Round & 30mm Round, SUMITA Conversion Crystal.

• P/N SPF01177 – 20 mm Diameter UV Imaging conversion plate. For customers that have own imaging system. Converts UV image to visible for beam intensities 50 μJ/ cm² to 10 mJ/cm².
• P/N SPF01150 – 30 mm Diameter UV Imaging conversion plate - For customers that have own imaging system. Converts UV image to visible for beam intensities 50 μJ/ cm² to 10 mJ/cm².

50 x 50 mm, and 100 x 100 mm Rectangular, Solarized Glass Plates.

• P/N SP90082 – 50 x 50 mm UV conversion plate – not suitable for <200 nm wavelengths. For customers that have own imaging system. Converts UV image to visible for beam intensities 1 mJ/cm² to 20 mJ/cm². Not suitable for 193 nm.
• P/N SP90083 – 100 x 100 mm UV conversion plate – not suitable for <200 nm wavelengths. For customers that have their own imaging system. Converts UV image to visible for beam intensities 1 mJ/cm² to 20 mJ/cm². Not suitable for 193 nm.

Ophir-Spiricon offers three families of UV converter products for the indirect measurement of UV laser beam profiles:

• C-mount turnkey systems: 4x reduction, 1:1 and 4x expansion
  • Highest cost, ease of use, high performance
• Doped YAG crystal converter plates for use with imaging systems, CCTV lens.
  • Mid cost, mid to high performance
• Solarized glass converter plates for use with imaging systems, CCTV lens.
  • Low cost, low performance