Optical Filters

EURECA supplies a large number of different filter types for various applications. Beside larger OEM volumes most filter types can also be delivered in small numbers or as single pieces.

• Interference filters
  These filters work with destructive interference. The light extinguishes to a very narrow spectral range or it is reflected. The bands can be very steep. As these coatings transmit again in the spectral ranges far from the central wave length, interference filters are mostly constructed as glass-laminate with coloured glasses, which are important for the necessary absorption. The central wave length is dependent on the angle and moves with smaller angles to shorter wave lengths. In general, the filters are used under an angle of 0°. Other angles are possible. Most of the light is reflected by the coating, so these filters are also suitable for higher power, e.g. at lasers. Typical applications are e.g. filters to extract surrounding or stimulation light at applications with lasers or fluorescences.
• Coloured glass filters
  Coloured glasses absorb light of wave lengths in itself and therefore work as a filter. For this reason, they are also called "volume filters". The glass then appears in the colour of the remaining, transmitting light. For the filter effect, the existing of a suitable ione-endowment or chemical relations with corresponding absorption-bands is necessary. For this reason, only some, mostly filters that have a wide band, are realisable. The wave length of the filter effect is independent of the angle, the absorption increases with a smaller angle.
  By the absorption, the filter gets warmer, this can lead to damages at high power.
• Si/Ge filters
  Silicium and Germanium provide a high transmission in the infrared and reflect the visible spectral range. Due to this fact they are also used as filter e.g. for infrared optics.
• Low cost filters
  For very price sensitive applications we offer filters made of plastic.
  These filters can be cut easily and are available for many spectral ranges.
  With laser cutting nearly all dimensions can be realized.