THORLABS KURIOS-VB1, Руководство пользователя

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Kurios
®
Liquid Crystal Tunable Filters Chapter 6: Technical Terminology
Rev G, September 3, 2019
Page 25
Chapter 6 Technical Terminology
6.1. Bandwidth
Thorlabs’ KURIOS ® tunable filter defines the passband bandwidth as the Full Width at Half Maximum (FWHM). This
is the spectral width between the two points where the filter’s transmission reaches half of the peak value. The
KURIOS filter’s bandwidths are dependent on wavelength and optical design, and therefore different models and
bandwidth modes (for KURIOS-VB1) have different bandwidth values.
6.2. Center Wavelength
The center wavelength of the KURIOS tunable filter is the center point wavelength between half maximum points.
Note that the center wavelength is not necessarily the same as the peak wavelength (the wavelength with highest
transmission), and there may be a slight offset between them.
6.3. Transmission
The transmission refers to the peak transmission of the passband profile with a given center wavelength. The
transmission value is measured with an incident light beam linearly polarized parallel to the transmission axis of the
filter. The KURIOS tunable filter transmission is wavelength-dependent.
6.4. Passband
The passband is defined as the range between the first local minimum values on either side of the center
wavelength. The passband spectral range is approximately from [Center Wavelength - 1.2 * FWHM] to [Center
Wave 1.2 * FWHM].
6.5. Out-of-Band Blocking
Out-of-Band Blocking is the maximum transmittance measured from the entire operating wavelength range, but
outside of the passband range. The KURIOS filter defines blocking range transmittance with optical density
OD > 2, which corresponds to transmittance of less than 1%.
Figure 22 Illustration of Technical Terminology
6.6. Switching Speed
KURIOS tunable filters take a certain time to switch between two wavelengths. The switching time depends on the
initial and final wavelength. The switching time data is calibrated for each filter and is saved in its EEPROM memory.
This switching time matrix map gives the switching time as a function of the initial wavelength and the final
wavelength. Note that when switching from longer wavelengths to shorter wavelengths, the switching time is shorter
than switching in the opposite direction. This is due to properties of liquid crystal optics.