Choose definitions to view the definitions of our filters

Dielectric interference filters
consist of two or more dielectric layers, which are separated by a suitable number of distance coatings.

The attributes of a filter are dependent on the number of layers, the reflection of each layer and the thickness of the distance coating.

The range of self blocking of a filter is determined by the width of the layers and amounts in the visible area about 100 nm at the short and longwave side.
By cementing with blocking filters ( 13-layers, 16-layers) and, or with color glasses, the blocking can be extended to any desired range. The blocking range should not reach much farther than the sensivity of the transceiver, since additional blocking weakens the transmission of the filter band.

4-layer filter
This type is already very close to the ideal rectangular form. It possesses 3 adjacent zeros of reflection, which cause the wide plateau shape wave form of the transmission maximum.

Flank steepness: tW/HW ~ equal 3

Halfbandwidths of 3 nm to about 20 nm can be produced in the visible area.

6-layer filter
The rectangular form has been achieved even better here.
This type possesses 5 zeros of reflection,thereby increasing the number of waves of the transmission maximum to 5.

Flank steepness: tW/HW ~ 1.3

Halfband width varies from about 20nm to 60nm.

13-layer filter
This filter type is used as a bandpass filter and a blocking filter.

Its flank steepness is about 1.1 for tW/HW

The transmission averages about 90%.


16-layer filter
This is an extension of the 13-layer filter. It is also used as a bandpass filter and a blocking filter.

Halfbandwidths of more than 200 nm are depending on wavelength are possible

Dependence on incidence
At obliquer angles of incidence the maximum of transmission moves to shorter wavelengths.
The shifting is a function of the angle of incidence, the refractive index of the distance coating and the wavelength. Filters for use up to 25 angle of incidence can be produced with a HW of >= 10nm.

The relation reads


Temperature dependence
The centre wavelength is dependent on the temperature. A rise of the temperature rise of about 20 C will cause a shift to longer wavelengths of about 0.15 - 0.2 nm

Durability
Admissible temperature range: -30 to +50 C. At 50 C a relative humidity of 80% should not be exceeded.


Service
Filter sizes
You can get round or square filters up to 50,8 mm . Further sizes are available on request
Special production
Our flexible production methods allow us to produce filters of any desired wavelength in the range of 300 up to 2000 nm.

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