In addition to Detector Rectangle, Detector Polar, results of which can be viewed via Detector Viewer, OpticStudio Non-Sequential mode also provides an option to set an NSC object as a detector to capture flux or irradiance incident on the object. This feature comes handy when the object you are trying to observe is of an odd shape, for example a CAD object with complex geometry. To use this feature, you need to first go to the Object Properties dropdown and tick the “Object Is A Detector” option. This will turn each triangles used to generate the object into individual pixels to record flux or irradiance. The way to access the Object As detector data is limited. You have following two options:In Detector Viewer, you will not be able to see data displayed in the Graph tab. That's only for native detectors like Detector Rectangle or Detector Polar. For Object as Detectors, you can only access the text listings of the Flux and Irradiance values pixel by pixel in the Text tab of the Detector Viewer window. The intensity detected on each pixel can be displayed in the Shaded Model False Color or Grey Scale to help you visualize it. In order to see this in the Shaded Model, you need to run ray trace first, and then in the Shaded Model, under Settings, you need to choose “Detector: Color pixels by last analysis”, highlighted in red box below. After that you should see pixels light up on this object used as Detector to display flux or irradiance. The color scheme the detector displays in the Shaded Model may be selected under the Object Properties dialog box. By default, the color display represents the Irradiance level, but you can also set it to Flux.   If you would like to know more about how to use the Object Is a Detector option, you can find it explained in the Help System at The Setup Tab > Editors Group (Setup Tab) > Non-sequential Component Editor > Non-sequential Detectors > Objects as Detectors.Additionally, one way to increase the pixel resolution when using Object As Detector is to increase the number of pixels used to render this object. If it’s a native object, you can go to Object Properties\Draw to increase the Drawing Resolution; or if it’s a CAD object, you can decrease the Chord Tolerance. Both will increase the pixel counts therefore provide higher pixel resolution.

OpticStudio provides two methods to compute PSF. One is the FFT PSF. This is where OpticStudio takes the wavefront at the exit pupil and Fourier Transform it to get the PSF. The other is the Huygens PSF. The Huygens PSF uses a very different approach. It samples the wavefront at the exit pupil. Each pupil sampling point then becomes a Huygens wavelet. OpticStudio propagates all these Huygens wavelets individually, either as plane waves or as spherical waves, from exit pupil to the Image surface, and then coherently sums all these Huygens wavelets to get the final PSF irradiance distribution on the Image surface. Huygens PSF is more computationally intensive, but it is also more robust and makes less assumptions. In many systems, the FFT PSF and Huygens PSF may provide similar results, however, there are also cases where they will not agree, simply because the FFT PSF makes two important assumptions: 1. The image surface lies in the far field of the optical beam. This means the computed PSF is only accurate if the image surface is fairly close to the geometric focus for all rays; 2. The chief ray does not form a large angle with the image surface because the FFT PSF computes the PSF on a plane normal to the chief ray. Therefore, if you have a system that has a large amount of defocus, or if you launch rays from a field point where the chief ray forms a large angle (>20 degrees) with the image surface, you should trust Huygens PSF method more. In general, we recommend that when the two methods give different results, the Huygens method is more reliable because it does not make similar assumptions as the FFT PSF.   The Help file provides a detailed description on these two PSF computations at The Analyze Tab (sequential ui mode) > Image Quality Group > PSF > FFT PSFThe Analyze Tab (sequential ui mode) > Image Quality Group > PSF > Huygens PSF  

Mixed mode operation comes handy when modeling Sequential system that includes objects with complex geometries, for example prisms with many facets or CAD objects. In those situations, user can insert a Non-Sequential Component (NSC) surface in the Sequential model and perform mixed-mode ray tracing. The advantage is that though rays are traced non-sequentially within the NSC group, user still has access to many GUI analysis tools only Sequential mode can offer. This mixed-mode ray tracing allows you to take advantage of both Sequential and Non-Sequential ray tracing. However, there are certain rules to follow when running mixed-mode ray tracing. One common error seen when debugging mixed-mode ray tracing issue is the Entry and Exit port location. The NSC objects need to be properly enclosed between the Entry and Exit port. If rays hit the NSC object before reaching the Entry port, or if rays reach the Exit port before hitting all or part of the NSC object, you will not see rays interact with the NSC objects properly. This is because rays need to enter the NSC section through the Entry port, interact with the NSC objects, and then exit the NSC section via the Exit port. Most of the issues seen in mixed-mode ray tracing are caused by the improper placement of the Entry or Exit port. In the Lens Data Editor, if you set the Draw Ports? parameter to 3, OpticStudio will draw both Entry and Exit ports location in the 3D Layout to help you visualize. For example, in this prism setup below, some rays at the bottom right, highlighted in red circle below, miss the Exit port. Therefore you see only part of the beam is able to exit the NSC section and the part that misses the Exit port will be terminated. You can also run a Single Ray Trace to follow one specific ray surface by surface and within the NSC group to troubleshoot its ray path. The Exit port location can be adjusted via the six parameters highlighted in yellow.  A detailed description on things to watch out for when running mixed-mode ray tracing can be found in the help file at The Setup Tab > Editors Group (Setup Tab) > Non-sequential Component Editor > Non-sequential Overview > NSC ray tracing in mixed mode (with entry and exit ports)