Top Hat
Efficient conversion of laser beams into a very uniform intensity top hat profile
Osela’s beam shaping technology is based on free form aspheric cylinder lens. Our in-house optical manufacturing capability is very flexible. It allows for optimization of input beams of varied sizes and efficient transformation to top hat/flat top profile of desired dimension. This optical element has the added advantage of having a very weak dependency on wavelength and can be easily integrated into existing optical systems. CV uniformity down to 1% can be readily achievable.
Top Hat vs Gaussian
Laser beams typically have a Gaussian intensity distribution which has a high peak intensity at the center with fading edges. This profile is not advantageous for some applications. Osela’s aspheric cylinder base optics converts the optical intensity into a top hat profile, flattening the peak thereby creating a uniform profile with no losses on the edges.
See below comparisons of a Top Hat profile having 50 um region of interest as typically used in Flow Cytometry and other laser induced fluorescence and scatter applications. One can clearly see that the Top Hat profile provides both high uniformity without sacrificing contained power.
- 50 um ROI
- Contained Power > 75
- Top Hat Uniformity < 3
- 50 um ROI
- Contained Power > 75
- Top Hat Uniformity ≈20
- 50 um ROI
- Contained Power ≈20
- Top Hat Uniformity < 3
Achromatic
The optical element has a very weak dependency to wavelength. This allows it to be easily integrated with multi-wavelength optical systems.
High Transmission Efficiency
Based on an all glass single element aspherical cylinder, allowing for an efficiency close to 100%.
No High Frequency Noise
The uniformity profile created has slow variations unlike other technologies that have high ripple and high frequency noise.
High Edge Steepness
The technology allows for the profile created to have a sharp fall off, making use of every photon.
Flexible Dimensions
The Top Hat profiles can be designed for many different sizes and is scalable to fit your applications. Dimensions available from a few microns to multiple millimeters.
Flexible Aspect Ratio
The aspect ratio of the Top Hat axis vs the Gaussian axis is flexible and the technology comes with many options to choose from.
No internal focusing
The technology maps a Gaussian to Top Hat profile without creating an internal focus, allowing for large input beam optical power.
Real Technology Example
Here a real profile example of an Osela Laser projector with Top Hat profile technology. The 405nm, 300 mW laser projects a Top Hat beam at a 90 mm standoff distance. The Top Hat has a dimension of 255 um with a Cv uniformity of 2.39% and contained energy within useful region of 78.91%. The Gaussian dimension is 9 um.
Expertises
Gaussian to Top Hat Illumination
Use of customized acylindrical lensing allows for creation of Top Hat projections with the highest uniformity and efficiency available on the market. The beam shaping can be tailored for specific laser input beam characteristics for maximum repeatability and performance. The refractive based technology has > 98% efficiency and transmission, with capabilities to create micron size Top Hat dimensions. Fiber coupled solutions are also available.
Optical coating
Osela’s manufacturing facility in Montreal, Canada is well setup with internal AR coating capabilities in both thermal and e-beam technologies. The recipes developed over the years contribute to optimal transmission performance, from wavelengths spanning the UV to IR across all of our products. Our intelligent deposition technology has allowed us to develop unique optical solutions, such as specialized mirrors, filters and masks.
Optical glass grinding and polishing
For more the 25 years, our specialists have developed a solid expertise in diode based laser modules in combination with an extensive knowledge of glass polishing and grinding. Our unique optical shaping process converts raw glass to precision shaped lenses for generating uniform laser lines and Top Hat profiles. Our in-house capabilities allow us to create optimized lenses for each specific laser diode’s optical characteristics. This ensures high repeatability and performance for our customers.
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