Customers trust Optimax to create high-quality optics and deliver them fast, and our freeforms are no exception. Designing with freeforms requires fewer elements, lighter weight and increased flexibility for your system.
Freeform optical shapes or optical surfaces are gaining popularity with lens designers and optical system integrators. Now, there are optical fabrication processes that include generation, high-speed VIBE polishing, sub-aperture figure correction, surface smoothing and testing of freeform surfaces.
Optimax is a leading producer in freeform optics from glass, fused silica, crystals and ceramics for UV, Visible and IR applications using proprietary techniques for low scatter surfaces.
Freeforms are optical shapes or optical surfaces that are designed with little to no symmetry. Manufacturing a freeform is similar to that of a highly complex asphere; surface form and local slope change are all factors that influence the complexity of the shape and the manufacturing process used.
To learn more about freeforms we invite you to visit Optimax's Resources & Tools and read our Technical Papers on the topic.
Specifying a freeform begins by defining the surface. An optical fabricator needs a clear description of the desired final optic; equation, cloud of points or a 3D model.
Optimax utilizes deterministic CNC machine tools for predictable removal rates and adherence to tight tolerances. To control centration, precision tools maintain the optical axis.
Attribute |
Tolerancing Limit* |
| Diameter (mm) | +0, -0.010 |
| Center Thickness (mm) | ± 0.050 |
| Irregularity – Interferometry (HeNe fringes) |
0.1** |
| Irregularity – Profilometry (μm) | ±1.0 |
| Wedge Lens – ETD (mm) |
TBD |
| Surface Roughness (Å RMS) | 10 |
Based on Form Error Tolerance
Form Error > 2μm Lower Resolution Profilometry (2-D)1 |
||
|---|---|---|
Attribute |
Minimum |
Maximum |
| Diameter (mm) | 3 | 250 |
| Local Radius (mm) | -8 (Concave) | ∞ |
| Sag (mm) | 0 | 502 |
| Departure (mm) | 0.01 | 20 |
| Included Angle (°) | 0 | 120 |
Form Error 0.5 – 2μm Higher Resolution Profilometry (2-D)1 |
||
Attribute |
Minimum |
Maximum |
| Diameter (mm)3 | 3 | 250 |
| Local Radius (mm) | -12 (Concave) | ∞ |
| Sag (mm) | 0 | 252 |
| Departure (mm) | 0.01 | 20 |
| Included Angle (°) | 0 | 150 |
Form Error < 0.5μm Interferometry with Stitching (3-D) |
||
Attribute |
Minimum |
Maximum |
| Diameter (mm)3 | 3 | 250 |
| Local Radius (mm) | -13 (Concave) | ∞ |
| Sag (mm) | 0 | 252,4 |
| Departure (mm) | 0.002 | 1 |
| Included Angle (°) | 0 | 120+5 |
Attribute |
Minimum |
Maximum |
| Diameter | 3mm | 500mm |
| Wavelength | 193nm | 6000nm |
| Use Environment | Vacuum | >95% RH |
| Durability | Moderate abrasion | Severe abrasion |
| Measurement | — | 68°, s, p, average polarization |
| Laser Damage Threshold | — | 1064nm: >30J/cm2@10ns, >1MW/cm2CW |
| Layers | 1 | 200 |
Above are manufacturing limits and tolerances specific to thin film coating. For more detailed information, please contact sales@optimaxsi.com.
Rod or Arbor |
||
|---|---|---|
Attribute |
Minimum |
Maximum |
| Length (mm) | 3 | 5001 |
| Width (mm) Radius dependent | 2 | < 2x Radius |
| Cylinder Radius (mm) – Convex Only | 2 | 150 |
X-Y |
||
| Attribute | Minimum | Maximum |
| Length (mm) | 3 | 300 |
| Width (mm) | 2 | 300 |
| Cylinder Radius (mm) | 10 | ∞ |
| Concave sag to flat (mm) | 0.1002 | =Radius |
Attribute |
Minimum |
Maximum |
| Diameter (mm) | 3 | 300 |
| Thickness | 1 | 150 |
| Aspect Ratio1 | 1 | 502 |
Based on Form Error Tolerance
Attribute |
Minimum |
Maximum |
| Diameter (mm) | 3 | 400 |
| Radius (mm) | ±1 | ∞2 |
| Aspect Ratio (Diameter/Center Thickness) | <1:1 | 30:1 |
| Included Angle (°) | 0 | 2103 |
Here are manufacturing limits and tolerances specific to optical aspheres, prisms, cylinders and spheres. For more detailed information on any attribute, please contact sales@optimaxsi.com.
Optimax inspects 100% of all optics. Test data is provided with prototype orders.
Our metrology must match the sophistication of our manufacturing technology. Optimax offers state-of-the-art metrology, including surface profilers and interferometers to verify that parts meet the form error specification. Testing options are form specific, lenses with mild departure from a best-fit sphere have the highest potential for fractional wave precision.
Optimax manufactures a wide variety of optical components. When on-time delivery is crucial, Optimax offers an expedited delivery option with a money back guarantee.
Optimax's R&D department is continuously looking for ways to improve our fabrication process and produce higher quality optics. Our current research projects are designed to meet future market needs.
For more information please see Optimax Innovation or contact sales@optimaxsi.com.
This paper briefly tells the story of the importance of metrology in optics fabrication at Optimax, and highlights Wyko and Jim Wyant’s contribution to early Optimax success
Optimax has developed the HERMES (High End Robotic MSF Elimination System) a robotic platform that uses a machine learning algorithm to smooth parts. Results indicate that HERMES fared well compared to smoothing results of a highly skilled artisan
Freeform surfaces on optical components have become an important design tool for optical designers. Non-rotationally symmetric optical surfaces have made solving complex optical problems easier. The manufacturing and testing of these surfaces has been the technical hurdle in freeform optic’s wide-spread use.
Freeform surfaces are quickly becoming a desired and necessary shape for many refractive and reflective optical systems. In this paper, we will discuss the round-robin study of surface irregularity measurements of a freeform toroidal window.
Freeform applications are expanding and include helmet-mounted displays, conformal optics, and those requiring the extreme precision of EUV. We will discuss the total manufacturing process and highlight the capabilities available today.
This case study will focus on the absolute freeform surface measurement utilizing a custom dual CGH and interferometer set-up, with special emphasis on reference artifacts and surface alignment to measure both the irregularity and the location of the freeform surface simultaneously.
Freeform optical systems are becoming increasingly common due to new design and manufacturing methods. We present an example compact freeform optical system and describe considerations for transfer of the prescription of freeform surfaces for fabrication.
Monolithic multi-surface telescopes combined with freeform optical surfaces provide improvements in optical performance in a smaller footprint as compared to systems with spherical surfaces, while providing superior mechanical stability to traditional telescope assemblies.
This paper will address challenges that have been encountered in the manufacturing, testing, and handling of freeforms as their size expands up to and beyond 500 mm, and provide future work that will address each challenge.
Several challenges associated with part size and shape complexity were solved during the manufacture of the largest extreme freeform shape Optimax has fabricated to date.
Freeform optics have emerged as a new tool for optical designers and integrators. Manufacturing innovations are gradually increasing availability of precision freeform optics.
Optical systems must perform under environmental conditions including thermal and mechanical loading. To predict the performance in the field, an integrated analysis combining optical and mechanical software is required to understand optical performance.
Freeform optical shapes or optical surfaces that are designed with non-symmetric features are gaining popularity. This enabling technology allows for conformal sensor windows and domes that provide enhanced aerodynamic properties.
Conformal windows pose new and unique challenges to manufacturing due to the shape, measurement of, and requested hard polycrystalline materials. Optimax has developed a process for manufacturing conformal windows out of fused silica, glass, zinc-sulfide multispectral, and spinel.
Freeform optical surfaces are gaining popularity with lens designers and optical system integrators as a method to solve complex optical system design problems. Fortunately, advances in optical manufacturing have opened the possibility for designers to manufacture these complex surfaces.
Freeform optical shapes that are designed with non-symmetric features allow for conformal sensor windows and domes that provide enhanced aerodynamic properties as well as environmental and ballistic protection.
Freeform and conformal optics have the potential to dramatically improve optical systems by enabling systems with fewer optical components, reduced aberrations, and improved aerodynamic performance.
For more than 100 years, optical imaging systems were limited to rotationally symmetric lens elements, due to limitations in processing optics. However, the present application of CNC machines has made the fabrication of non-rotationally symmetric lenses, such as freeform surfaces, economical.
Freeform optical shapes or optical surfaces that are designed with non-symmetric features are gaining popularity with lens designers and optical system integrators. Tolerances on a freeform optical design influence the optical fabrication process.
Freeform optical surfaces, which have little to no symmetry, are gaining popularity with lens designers and optical system integrators. Using fiducials properly leads to higher accuracy measurements and allows more control of the surface throughout the manufacturing process.
Proper metrology is required to monitor and verify the freeform fabrication processes to improve capability and precision.
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