For applications requiring an aberration-free image in focus plane, with a high precision, HOLO/ORdeveloped a new optimized focusing module to be used with our Beam Shapers.
A standard focusing lens (or objective) is normally optimized for focusing a Gaussian beam and is not optimized to work with a Beam Shaper. Thus, the use of standard focusing lens with Beam-Shapers often causes aberrations of the Top-Hat image and requires special design of a focusing lens or module. These aberrations will normally occur at small focal lengths, short wavelength and large input beam.
In order to solve this problem, HOLO/OR designed a focusing module (with focal length 50 [mm]) adapted to our Beam Shaper working at 355 [nm].
The module contains 5 lenses, and the Top-Hat output is obtained at the back focal length of the module.
HOLO/OR offers customization of the module for other wavelengths and focal length.
The focusing module presents the following features:
- Free-aberrations module
- Focal lengths: 30 and 50 [mm]
- Wavelength (optimized): 355 [nm]
- Material: Fused Silica
- Max. input beam size = 12 [mm]
- Optional - Objective correction collar
Typical set-up
Focusing Module optimized for Beam Shaper
Comparison between Square Top-Hats result at image plane obtained by different focusing elements / objectives:
Ideal Lens (Theoretical only)
Aspheric lens
Standard Focusing Module
HOLO/OR’s Focusing Module
Simulation results for a Square Top-Hat 100x100[µm2] in size, with (from left to right): perfect lens (not real lens) for ideal spot, aspheric lens, standard focusing module not optimized for use with a Beam Shaper and Holo/Or’s focusing module optimized for use with Beam Shapers.
Table parameters of Beam Shaping Focusers:
| Part Number | Focal Length (mm) | Outer Diameter (mm) | Max input beam (mm) | Material | Module length (mm) | Zemax Black Box |
| Objective-001-U | 50 | 45 | 12 | Fused Silica | 38.5 |  |
| Objective-002-U | 30 | 45 | 12 | Fused Silica | 31 | |
