Free-form surface
"Free-form surface" is a general term that refers to smoothly curved surfaces without restrictions such as symmetry. They are defined in a wide variety of ways, for example analytic functions such as XY polynomials and polysurfaces modeled using 3D CAD. Due to the flexibilities, by using it on the lens surface and reflection surface of an optical element, significant effects can be expected in off-axis optical systems and optical systems with different characteristics, such as improving optical characteristics, reducing the number of optical elements, and miniaturizing units.
A free-form surface does not generally have axial symmetry, so it cannot be processed with an ultra-precision lathe, which is usually imaged as a lens processing machine. For free-form surface processing, it is necessary to use an ultra-precision multi-axis machine with 3 or 5-axis configuration.
In order to achieve the sub-micron form accuracy required for optical elements, not only the processing machine itself, but also the design of rotary tools, the selection of the optimum processing path, the maintenance of CAM(Computer-aided manufacturing) software, and the temperature control to ensure positioning stability and anti-vibration environment over a few hours to a few days periood of processing time are indispensable. As similar quality is required for measureent of shape and correction processing, it is the super difficult process comparing to processing of rotation symmetric surfaces by ultra precision lathe.
Nalux has been designing and manufacturing optical elements with free-form surfaces for many years, and holds many design patents and manufacturing technologies.
Our Capabilities in Processing
- Mold processing, Optical design considering the molding process, Optimization at the product design stage
- Stabilization of finishing process for a long term period(against temperature, vibration, etc.)
- High-precision evaluation technology and correction technology
Product example
f-theta lens for laser beam printer
An f-theta lens has a distortion characteristic expressed by the relational expression y=f-theta, “y” is the image height, “f” is the focal length, and “theta” is the half angle of view (angle of incidence). These lenses are used in scanning optics for laser beam printers.
Since 1989, Nalux has been producing plastic free-form surface f-theta lenses for laser printers. Conventional scanning optical systems for laser printers required a combination of multiple glass spherical lenses and long cylindrical lenses. By adopting a free-form surface, the degree of freedom in aberration correction has been improved, greatly contributing to a reduction in the number of lenses used in the scanning optical system. We have contributed to the miniaturization and cost reduction of laser beam printers.
Our Specific Capabilities in fΘ Lens
- Consistent support from optical design and product analysis to mold processing, production, and quality assurance
- Product design considering birefringence due to internal strain and changes in optical properties due to moisture absorption
- Quality assurance by original function evaluation equipments
Free-form mirror・prism
A free-form surface mirror is an optical element that reflecting surface is a free-form surface. In an off-axis reflective optical system, it is difficult to control aberrations with rotationally symmetrical optical elements, so the adoption of free-form surfaces is indispensable. Nalux had long been A free-form surface mirror is an optical element that reflecting surface is a free-form surface. In an off-axis reflective optical system, it is difficult to control aberrations with rotationally symmetrical optical elements, so the adoption of free-form surfaces is indispensable. Nalux had long been producing free-form prisms for camera viewfinders for many years. In recent years, camera viewfinders are seldomly used because of digitization, but reflective optical elements that use free-form surface mirrors and prisms, such as HUDs (head up display) and AR glasses, are still used in many products.
Reflective optical elements are also characterized by the fact that they can be used in wavelength bands that cannot be transmitted by resin, and that chromatic aberration does not occur. Nalux also manufactures reflective optical system units using multiple free-form surface mirrors.
roducing free-form prisms as camera viewfinders for many years. In recent years, camera viewfinders have become digitalized and their use has decreased dramatically, but reflective optical elements that use free-form surface mirrors and prisms, such as HUDs (head up display) and AR glasses, are still used in many products.
Reflective optical elements are also characterized by the fact that they can be used in wavelength bands that cannot be transmitted by resin, and that chromatic aberration does not occur. Nalux also manufactures reflective optical system units using multiple free-form surface mirrors.
Our Specific Capabilities in Free form Mirror
- Can be manufactured up to about 200 mm diagonal
- Surface roughness Ra5nm or less (Surface roughness depends on mirror shape. Please contact us for details.)
- Capabilites of high reflection coating, half mirror coating, etc.
