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Top Hat Beam Shaping Lens FBS2

Top Hat Beam Shaping Lens FBS2

FBS2 beam shapers generate small and homogeneous square Top Hat spots in the focal plane. Each FBS2 is made for a fixed input beam diameter with a ±5% tolerance. Lenses for wavelengths and beam diameters other than standard can be produced on request.

1736 $
delivery Estimated delivery time: 1 - 1 week
Products
Specifications
Operation Instructions
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Description
Operation Wavelength
Input Beam Diameter @ 1/e²
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Code Operation Wavelength Input Beam Diameter @ 1/e² Price Delivery Add to cart
FBS2-1064-1.0 1064 nm 1.0 mm 1736 $ 1 - 1 week
FBS2-1064-1.5 1064 nm 1.5 mm 1736 $ 1 - 1 week
FBS2-1064-2.0 1064 nm 2.0 mm 1736 $ 1 - 1 week
FBS2-1064-2.5 1064 nm 2.5 mm 1736 $ 1 - 1 week
FBS2-1064-3.0 1064 nm 3.0 mm 1736 $ 1 - 1 week
FBS2-1064-3.5 1064 nm 3.5 mm 1736 $ 1 - 1 week
FBS2-1064-4.0 1064 nm 4.0 mm 1736 $ 1 - 1 week
FBS2-1064-4.5 1064 nm 4.5 mm 1736 $ 1 - 1 week
FBS2-1064-5.0 1064 nm 5.0 mm 1736 $ 1 - 1 week
FBS2-1064-5.5 1064 nm 5.5 mm 1736 $ 1 - 1 week
FBS2-1064-6.0 1064 nm 6.0 mm 1736 $ 1 - 1 week
FBS2-1030-1.0 1030 nm 1.0 mm 1736 $ 1 - 1 week
FBS2-1030-1.5 1030 nm 1.5 mm 1736 $ 1 - 1 week
FBS2-1030-2.0 1030 nm 2.0 mm 1736 $ 1 - 1 week
FBS2-1030-2.5 1030 nm 2.5 mm 1736 $ 1 - 1 week
FBS2-1030-3.0 1030 nm 3.0 mm 1736 $ 1 - 1 week
FBS2-1030-3.5 1030 nm 3.5 mm 1736 $ 1 - 1 week
FBS2-1030-4.0 1030 nm 4.0 mm 1736 $ 1 - 1 week
FBS2-1030-4.5 1030 nm 4.5 mm 1736 $ 1 - 1 week
FBS2-1030-5.0 1030 nm 5.0 mm 1736 $ 1 - 1 week
FBS2-1030-5.5 1030 nm 5.5 mm 1736 $ 1 - 1 week
FBS2-1030-6.0 1030 nm 6.0 mm 1736 $ 1 - 1 week
FBS2-532-1.0 532 nm 1.0 mm 1736 $ 1 - 1 week
FBS2-532-1.5 532 nm 1.5 mm 1736 $ 1 - 1 week
FBS2-532-2.0 532 nm 2.0 mm 1736 $ 1 - 1 week
FBS2-532-2.5 532 nm 2.5 mm 1736 $ 1 - 1 week
FBS2-532-3.0 532 nm 3.0 mm 1736 $ 1 - 1 week
FBS2-532-3.5 532 nm 3.5 mm 1736 $ 1 - 1 week
FBS2-532-4.0 532 nm 4.0 mm 1736 $ 1 - 1 week
FBS2-532-4.5 532 nm 4.5 mm 1736 $ 1 - 1 week
FBS2-532-5.0 532 nm 5.0 mm 1736 $ 1 - 1 week
FBS2-532-5.5 532 nm 5.5 mm 1736 $ 1 - 1 week
FBS2-532-6.0 532 nm 6.0 mm 1736 $ 1 - 1 week
FBS2-515-1.0 515 nm 1.0 mm 1736 $ 1 - 1 week
FBS2-515-1.5 515 nm 1.5 mm 1736 $ 1 - 1 week
FBS2-515-2.0 515 nm 2.0 mm 1736 $ 1 - 1 week
FBS2-515-2.5 515 nm 2.5 mm 1736 $ 1 - 1 week
FBS2-515-3.0 515 nm 3.0 mm 1736 $ 1 - 1 week
FBS2-515-3.5 515 nm 3.5 mm 1736 $ 1 - 1 week
FBS2-515-4.0 515 nm 4.0 mm 1736 $ 1 - 1 week
FBS2-515-4.5 515 nm 4.5 mm 1736 $ 1 - 1 week
FBS2-515-5.0 515 nm 5.0 mm 1736 $ 1 - 1 week
FBS2-515-5.5 515 nm 5.5 mm 1736 $ 1 - 1 week
FBS2-515-6.0 515 nm 6.0 mm 1736 $ 1 - 1 week
FBS2-355-1.0 355 nm 1.0 mm 1736 $ 1 - 1 week
FBS2-355-1.5 355 nm 1.5 mm 1736 $ 1 - 1 week
FBS2-355-2.0 355 nm 2.0 mm 1736 $ 1 - 1 week
FBS2-355-2.5 355 nm 2.5 mm 1736 $ 1 - 1 week
FBS2-355-3.0 355 nm 3.0 mm 1736 $ 1 - 1 week
FBS2-355-3.5 355 nm 3.5 mm 1736 $ 1 - 1 week
FBS2-355-4.0 355 nm 4.0 mm 1736 $ 1 - 1 week
FBS2-355-4.5 355 nm 4.5 mm 1736 $ 1 - 1 week
FBS2-355-5.0 355 nm 5.0 mm 1736 $ 1 - 1 week
FBS2-355-5.5 355 nm 5.5 mm 1736 $ 1 - 1 week
FBS2-355-6.0 355 nm 6.0 mm 1736 $ 1 - 1 week
FBS2-343-1.0 343 nm 1.0 mm 1736 $ 1 - 1 week
FBS2-343-1.5 343 nm 1.5 mm 1736 $ 1 - 1 week
FBS2-343-2.0 343 nm 2.0 mm 1736 $ 1 - 1 week
FBS2-343-2.5 343 nm 2.5 mm 1736 $ 1 - 1 week
FBS2-343-3.0 343 nm 3.0 mm 1736 $ 1 - 1 week
FBS2-343-3.5 343 nm 3.5 mm 1736 $ 1 - 1 week
FBS2-343-4.0 343 nm 4.0 mm 1736 $ 1 - 1 week
FBS2-343-4.5 343 nm 4.5 mm 1736 $ 1 - 1 week
FBS2-343-5.0 343 nm 5.0 mm 1736 $ 1 - 1 week
FBS2-343-5.5 343 nm 5.5 mm 1736 $ 1 - 1 week
FBS2-343-6.0 343 nm 6.0 mm 1736 $ 1 - 1 week

SPOT GEOMETRY

 

Top Hat width approximately 2 * λ * f / d, with f = focal length, d = beam diameter @1/e2
Efficiency up to 90%
Homogeneity ca. ± 2.5% (rel. to average intensity of the Top Hat plateau)
Side modes (strongest) ~16.5x weaker than line plateau (< 1.5% of input energy)
Depth of focus (DOF) ~60% of the Rayleigh length

 

SUBSTRATE SPECIFICATIONS

 

Material Fused silica
Transmission >99%
Damage threshold @ 10 ns 10 J/cm² @ 1064 nm
5 J/cm² @ 532 nm
3 J/cm² @ 355 nm
Dimensions ⌀25.4 x 3 mm

REQUIREMENTS FOR OPERATION

 

Input beam Gaussian beam TEM00, M² of 1.4 or better
Apertures within the optical setup Clear aperture along the whole beam path should be at least 2.2x larger than the beam diameter @ 1/e²

 

INTEGRATION INTO BEAM PATH

 

Alignment

Alignment in lateral direction (translation) is necessary.
Rotation around the optical axis helps to align the orientation of the Top Hat.

Recommended mount: 840-0240 X-Y translation positioner.

Optical equipment Required: focusing optics. Top Hat is generated in the focal plane of this optic.
Useful: beam expander for adjustment of the beam diameter (effective beam diameter to the FBS2 design input beam diameter) and for adjustment of the beam diameter to the desired spot size.
Helpful: beam profiler to check the profiles while aligning.

FBS - Top-Hat Fundamental Beam Mode Shaper

Without FBS Beam Shaper: Gaussian-profile at focal plane

 

 

 

With FBS Beam Shaper: Top-Hat-profile at focal plane


– FBS works together with focusing system (FS)
– Top Hat size just depends on wavelength (λ) and numerical aperture (NA) of focused beam
– Distance d between FBS and FS up to several meters

 

Intensity distribution at focal plane

Main FBS advantages:
– Smallest achievable Top-Hat size: ≈ always 1,5x of diffraction limited Gaussian-spot @ 1/e²
– Achievable Top Hat profiles: square or round
– Diffraction efficiency: > 95% of energy in Top Hat
– Homogeneity: modulation < ±2.5%
– Depth of focus: similar as for Gaussian beam
– Insensitive to misalignment, ellipticity and input diameter variation: ±5-10%

 

 Without FBS shaper: diffraction limited Gaussian profile

 

 With FBS shaper: near diffraction limited Top Hat profile

 

 


1. Beam shaper directly in front of a focusing optic/objective

By introducing the FBS beam shaper into the beam path in front of a lens/objective the initial diffraction limited Gaussian spot will be transformed into a homogeneous Top-Hat profile.
When a Gaussian TEM00 input beam with a diameter of 5 mm@1/e² is used the diameter of the free aperture along the total beam path have to be at least 11 mm (better 13 mm).
If for example a wavelength with 532 nm, a Gaussian TEM00 input beam with a diameter of 5 mm@1/e² and a focusing lens with f=160 mm is used, ones will get a homogeneous Top Hat profile with a diameter of 34 μm.

2. Beam shaper in front of a beam expander

There is also the possibility to introduce the FBS beam shaper into the beam path in front of a beam expander. This leads to a higher numerical aperture of focused beam and to a smaller Top Hat profile.
Example: A Gaussian beam with a diameter of 5 mm@1/e² illuminates the FBS beam shaper and is afterwards increased by a beam expander to a beam diameter of 8 mm. With an focusing optic with f=50 mm the user can generate a Top Hat with a diameter of 7 μm. The needed free aperture increases with the expanded beam. For a beam with a diameter of 8 mm the free aperture have to be at least 18 mm.

3. Beam shaper within a beam expander

A further and even more flexible possibility is to introduce the FBS beam shaper into the beam path within a beam expander.
The user has the possibility for an easy “fine tuning” of beam diameter at the position of FBS beam shaper by shifting shaper along z-axis.

Scribing of CIGS-solar cells

– Wasted area, reducing efficiency → need of smallest scribing lines
                     – Cut quality influence efficiency → need of small HAZ, no debris, smooth edges
          – High scanning speed for high throughput → need of small pulse overlap

P1 – "Scribing“

Removal of a front contact in ZnO(1 μm)/CIGS/Mo/PI structure. Laser PL10100/SH, 10 ps, 370 mW, 100 kHz, 532 nm; scanning speed 4.3 m/s, single pass.

P3 – "Scribing“

Tilted SEM pictures of the P3 scribe in ZnO(1 μm)/CIGS/ Mo/PI structure. Laser PL10100/SH, 10 ps, 370 mW, 100 kHz, 532 nm; scanning speed 60 mm/s, single pass.

                                     Raciukaitis et. al, JLMN-Vol. 6, No. 1, 2011

EKSMA Optics Top Hat Beam Shaping Lenses
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FBS2 series Top Hat beam shapers are single-piece optical elements that transform a Gaussian laser beam into a square top-hat profile. FBS2 are focal beam shapers, while they generate the top-hat profile at the focal plane of focusing optics. Each FBS2 lens is designed for a fixed input beam diameter (@1/e²) and specific operation wavelength. Beam shaping lens can be easily integrated into the beam path at nearly any position, even in front of or within a beam expander / telescope.

FBS2 generate Top Hat spots with a long depth of focus (DOF). The depth of focus for a flat-top beam is around 60% of the Rayleigh length of a Gaussian spot in a similar optical setup. The Top Hat width is approximately 1.5 times larger than the Gaussian spot size. Within this range, the Top Hat profile is uniform and shows nearly constant peak intensity.

The width of the Top Hat profile generated by FBS2 is approximately 1.5 times larger than the diffraction-limited Gaussian spot size. Top-Hat size depends on the focal length of the focusing optics (f), input laser beam diameter @1/e² (d), and operation wavelength (λ). Output spot size is typically smaller than 100 µm, and can easily be scaled using additional focusing optics.

The approximate size of the Top Hat can be calculated by the formula:

2 * λ * f / d or λ / NA, where NA is the numerical aperture of the focused beam. 

FBS2 beam shaper can be combined with any objective or F-Theta lens