The polar detector is a spherical shaped detector that displays radiant intensity data on a polar plot. It can show both power and tristimulus (i.e. true color) data from NSC rays that hit the detector. This type of detector can be considered a “far-field” detector, as opposed to other detector types that display data in spatial coordinates (near-field). For source characterization, far-field intensity data is often the most informative way to display the intensity profile; polar plots are the most intuitive way to look at angular data.



The polar detector has the following unique parameters:
• Maximum Angle: the maximum polar angle in degrees from 0 to 180. As this is a polar angle, a sphere can be defined.
• Radial Size: the maximum radial size of the detector. This determines the radius of the spherical detector.
• #P pixels: the number of polar pixels from 10 to 721.
• #A pixels: the number of azimuthal pixels from 12 to 720.
• Mirroring: allows the detector to exploit symmetry in the incident rays, if appropriate. This is supported for most detector types.

Note that the vertex of the polar detector will be located a distance equal to the radius from the detector’s local coordinate origin. The suggested method for placing the detector is to center it on the source that is being measured. In this case, the radial size determines the distance of the detector vertex from the source and the angular size determines the lateral extent of the detector (the angle it subtends from the source). To fully characterize a source, the detector should be placed and sized to collect all rays from the source.

A unique optimization operand, NSDP, is supported for optimizing data on a polar detector. The syntax for the NSDP operand is as follows:

NSDP   Surf   Det#   Pix#   Data

Surf defines the non-sequential group surface (1 in pure NSC), Det# defines the desired polar detector from which to report data (it can also be used to clear one or all detectors), Pix# defines the specific pixel or computed value to return and Data defines whether to return power, flux, radiometric/photometric intensity, chromaticity or tristimulus data. For a detailed description of NSDP capabilities, see the optimization chapter in the ZEMAX user’s guide.

The ZEMAX programming language also has a numeric function, NSDP(), that returns the same data as the optimization operand. This function allows you to return any desired data from a polar detector in a macro. See Chp. 22 of the manual for more information on this function.