Production process

We supply our customers from the development of a specification to the final series product. All design and production steps are realized in-house, even for small series or prototypes only.This service includes the integration of opto-mechanical and opto-electronic parts also.
Our qualified and experienced team is looking forward to new challenges.

RAW MATERIALS

We receive lens blanks made of optical material in the form of round disks or preforms. We use approximately 120 different optical quality glass types, including fused silica, calcium fluorid, germanium, zinc sulfide and filter glasses.

PRE-GRINDING

The lens blanks (round disks or preforms) are pre-grinded with diamond fitted tools, each side separately, since the curvatures are different. On every side an allowance of 0.1 mm to 0.2 mm is maintained for fine-grinding and polishing. 

FINE-GRINDING

Fine grinding of the lens radius will be done with specialized tools, onto which pellelts are glued. Diamond grains sized 5 µm to 25 µm are sintered in these pellets. For prototyping we use special CNC grinding machines with 2 tools, which allow pre- and fine grinding in one single chuck.

POLISHING

We use tools lathed of aluminum, plated with a polyurethane foil, for polishing the radii of the lenses. The foils glued onto the tools are prepared by special counter tools to achieve the required precision. Mainly ceriumoxide is being used as the polishing medium. We use in process interferometric test methods, to perform a contact-free measurement of the accuracy of the lens surface, achieved by adjusting our machines and by adjusting our tools.

CENTERING

After polishing of both radii, the lens has to be centered to its optical axis. For this purpose we transmit a laser beam and precisely align the lens to its optical axis in a centering machine. We use mandrels to fix its position and afterwards we grind its rim centrically using one or two diamond grinding discs. During the same process we also center the chamfers.

MRF TECHNOLOGY

Our latest establishment is a production line for pre-, fine grinding, polishing and MRF polishing technology. The“Magneto-Rheological Finishing” process ensures a zonal correction of smallest deviations from the nominal radius. This technology allows the production of aspheres as well as surfaces with an accuracy of less than lambda/10 under controlled conditions. By investing in hydro speed polishing technology and new measuring technology, the technological possibilities of production of precision lenses and aspherical lenses have been Extended.

COATING

Lens surfaces transmit approx. 96% of the light (due to reflection). For this reason the surface is coated with a thin dielectric film. This coating consists of 5 to 11 layers (in special cases up to 50 layers) and prevents losses on the glass/air (or air/glass) surface. To reduce reflection up to 0.05% the layer has to be adapted to the required wavelength and glass type. Our standard range covers anti-reflective coatings for a wavelength range from 193 nm to 2000 nm.

QUALITY CONTROL

After all production steps the surface quality of our lenses is controlled with a magnifying glass or a microscope. In order to assure the high quality of our products, Sill Optics has been certified according to DIN EN ISO 9001:2008. This motivates all our employees to maintain maximum quality awareness.

HOUSINGS

Sill Optics is equipped with its own CNC grinding center for the production of high precision workpieces. In our modern machine park, consisting of 4 CNC lathes and 2 CNC milling machines, we are able to flexibly produce prototypes and also small or medium batch sizes. Favorable material used is aluminum (RoHS conform), but other materials like titanium are possible as well. After machining, the workpieces receive a black anodized finish, are varnished or treated otherwise to circumvent any optical reflections.

ASSEMBLY

Optical systems (objectives) consist of several lenses that have to be assembled into an objective mount. The lenses must be thoroughly cleaned to avoid any dirt or dust. Attention must be paid to make sure they get centrically set into their mount. Modular systems ensure cost-efficient assembly as well as effective stock keeping. Our assembly department employs 20 skilled technicians. Here, we assemble up to 20000 objectives per year.

TESTING CAPABILITIES

  • Interferometer
  • Wavefront sensor
  • MTF Measurment up to 100 lp/mm
  • Goniometer
  • Autocollimators
  • 3D-Measuring Center
  • Lasers (1064 nm, 633 nm, 532 nm, 355 nm)