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
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.
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.
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.
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%.
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
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 >=
The relation reads
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
range: -30 to +50° C. At 50° C a relative humidity of 80% should
not be exceeded.
You can get round or square filters up to 50,8 mm . Further sizes
are available on request
Our flexible production methods allow us to produce filters of any
desired wavelength in the range of 300 up to 2000 nm.