Summary:The Universal Detector is the most versatile tool in VirtualLab Fusion to evaluate and output any information about the electromagnetic field. It is capable of providing information in different domains (spatial domain and spatial frequency domain) and coordinate systems (field and detector position coordinate systems). In addition, by using very flexible built-in or custom add-ons, it can further evaluate the information of the incident light to calculate any physical quantity, such as radiometric or photometric. 
How do I find a universal detector? 
Universal detectors can be found directly in the component tree of the Optical Path Editor, and to add them to your system, simply drag and drop them to the desired location. Universal detectors with different modeling profilesThe options available in the Universal Detector depend on whether a Ray Results Profile or a Generic Profile is selected. 
Field quantities (generic profiles).
Portions: To determine which components of the electromagnetic field to detect, at least one component must be selected. Note: VirtualLab Fusion uses EX and EY for propagation, and other components are calculated as needed. Domains: The detector can evaluate and output data in the x-domain (spatial domain) and or k-domain (space-frequency domain). The components are calculated using the paraxial approximation: Determines whether the detector uses a paraxial approximation to calculate the additional components of the electromagnetic field. (See: Paraximal Hypothesis).Summing of interrelated patterns? If this option is activated, the relevant modes are summed before any further evolution or output is performed. It provides three summation options:
Detector window.
The central position and size of the detector window can be defined in terms of the coordinate system and the expansion of each individual mode or the position of the detector. 
The user can also configure whether the samples are processed separately (for each mode) or on mutual meshes. The grid can be specified by periods (sample distance) or grid points (number of sample points). No mesh data.
If propagation uses meshless data, the probe can also visualize this type of data. In addition to the output of meshing information, it is also output in grid-free mode of field sampling, or separately. In addition, the amount (quantity) of the output information can be reduced to just the position and direction (e.g., ray tracing results). Note that this will only apply to a single mode, otherwise coherent summation is disabled. 
Detector add-on - the amount of electromagnetic field.
The add-on is a versatile tool that allows additional calculations of any value based on incident field data (a single physical value or a 2D array). They are organized in the form of a tree because one add-on requires the result of another. By default, the EM Add-on is pre-configured (cannot be removed). It outputs any field component in the x and or k domains. Note that only the field components can be output, which is selected in the Field Quantities tab (and vice versa, it is not necessary to enable the output of all components). In addition, there is an option to output only the amplitude or wavefront phase, as well as a display option. Detector Add-ons - Custom add-onsWhen calculating all add-ons, the user can specify which results to display. Each add-on has its own set of options. They can be passed.
button to enter. The results will be visualized.
The results will not be visualized. 
In this area, detector add-ons can be created or loaded from the officially available database.
button to update the add-on database from lighttrans** via the internet. Detector Add-on - Hierarchy Tree.
By default, the Universal Detector provides electromagnetic field information for all add-ons based on the field components specified in the Field Quantities tab. Some add-ons only require a single component, while others require a full set of 6 components (E and H). In addition, some add-ons require different physical quantities as input (e.g., Poynting vectors). To do this, add-ons can be arranged in a tree. In this example, the Poinkine Vector add-on is applied to the field data to calculate the Pointinin vector in the x-domain. The resulting information can be used to calculate (spectral) irradiance and further processed to calculate brightness. In contrast, radiant flux and efficiency (surface) only require a complete field data set. Therefore, it is positioned in a new branch. Detector Add-ons Read Instructions - Documentation
Each add-on in the official database comes with a reading documentation that explains its functionality and explains the input and output parameters. Released 202301 Add-on overviewThe official database categorizes the available detector add-ons into subcategories. With version 20231 of the releases, the following add-ons are available:Detector add-ons read the instructions for programmable fragments.
With maximum flexibility in mind, any add-on is based on a programmable fragment. A more in-depth introduction to programmable tools in VirtualLab Fusion can be found below: How to Use Programmable Probes and Examples.