Diffusors for changing the measuring Range

Diffusors with reduced Transmission (calibration necessary)

The measuring ranges of specbos 1201 and 1211 for Illuminance mode measurements are given in application note 05. It is possible to order special diffusors with added filters to shift the measuring range towards higher illuminance values:


Filter type


Measuring range Illuminance (Illum. A) Part number for specbos 1211 Part number for specbos 1211UV
OD 0.5 specbos 1201: 60 ... 630 000 lx
specbos 1211/1211UV: 16 ... 95 000 lx
ACC 013 OD0.5 ACC 013UV OD0.5
OD 1.0 specbos 1201: 200 ... 2 Mlx
specbos 1211/1211UV: 50 ... 300 000 lx
ACC 013 OD1.0 ACC 013UV OD1.0
OD 1.5 specbos 1201: 600 ... 6.3 Mlx
specbos 1211/1211UV: 160 ... 950 000 lx
ACC 013 OD1.5 ACC 013UV OD1.5
OD 2.0 specbos 1201: 2 000 ... 20 Mlx
specbos 1211/1211UV: 500 ... 3 Mlx
ACC 013 OD2.0 ACC 013UV OD2.0

Diffusors with increased Transmission (calibration necessary)

A diffusor with increased transmission has a higher error in cosine matching, but there are some applications where this can be tolerated. One example is the measurement of point like sources as vehicle lamps.

Therefore two modified diffusors are offered as accessory for the specbos radiometers - a version with medium transmission and a version with high transmission:

diff kurven 1240

Angular behavior of the medium and high transmission type compared with the standard version

The transmission of the medium version is 20 times higher and the transmission of the high version is 60 times higher than that of the standard diffusor version.

Part numbers: ACC013 Med
  ACC013 High

Special Diffusors

The standard diffusors of specbos 1201/ 1211 allow in axis Irradiance measurements. There exist applications where this restricted set up cannot be used, e.g. if it is necessary to measure the Irradiance on a certain surface.

Therfore there are offered two special kinds of diffusors – a 90° (side view) and fiber extended (remote) diffusors. Additionally the combination of both is available.

90° Diffusor (calibration necessary)

If it is necessary to measure in Irradiance mode perpendicular to the instrument, the 90° diffusor can be used. This diffusor was especially developed for specbos 1211/ 1211UV.

Detail 90grad diff
Part numbers: ACC012 (for specbos 1201/1211)
  ACC012UV (for specbos 1211UV)

Fiber extended Diffusor (calibration necessary)

The Fiber extended diffusor consists of a fiber optic cable and a diffusor part. It will be attached to the instrument and allows the measurement at difficult accessible locations.


Part numbers:

Cable length Part number for specbos 1211 Part number for specbos 1211UV
0.35 m ACC 015-35 ACC 015UV-35
1.00 m ACC 015-100 ACC 015UV-100
3.00 m ACC 015-300 -
5.00 m - ACC 015UV-500

Fiber extended 90° Diffusor (calibration necessary)

This diffusor combines the 90° geometry with the possibility to measure at remote locations. The standard length of the cable is 1 m.

fiber extented 90diffusor400
Part numbers: ACC 019-100 (for specbos 1201/1211)
  ACC 019-100UV (for specbos 1211UV)

Diffusors for restricted Wavelength Ranges (calibration necessary)

There are offered two diffusors combined with UV bandpass filters. Thus the measurement will not be disturbed by the longer wavelength part of the spectrum. The integration time fits to the filter range exposure and the stray light will be reduced.


Diffusor for specbos 1211UV with short pass filter SP 322 (wavelength range 230 … 320 nm) has the

Part number: ACC 020 SP

Diffusor for specbos 1211UV with filter combination (wavelength range 230 … 400 nm) has

Part number: ACC 020 combi