Design of custom prisms in Zemax OpticStudio
Prisms are vital components in optics due to their ability to manipulate light, separate wavelengths, correct aberrations, and facilitate a range of optical applications and effects. Their unique properties and versatility make them indispensable in various fields, including science, technology, medicine, and everyday optical devices.
Zemax OpticStudio supports two distinct ray tracing modes, Sequential and Non-Sequential. If the prism is part of a larger sequential optical system, where the light path is well-defined and the interactions between components are mostly deterministic, then using sequential components to model the prism is the most appropriate approach.
On the other hand, if the prism is part of a non-sequential optical system, where the light path is not well-defined and the interactions between components are mostly stochastic or probabilistic, then using non-sequential components to model the prism is the most appropriate approach.
However, there are situations where it becomes necessary to combine these two techniques. This design may be referred to as a “mixed” or “hybrid” system. Using a Mixed-Mode system in Zemax OpticStudio, you can harness the advantages of both sequential and non-sequential modes to effectively model prisms and their interactions within complex optical systems.
In the following parts, the design of prisms using sequential and mixed modes will be discussed and demonstrated using Zemax OpticStudio.
Sequential Mode
For the design of the system in sequential mode, a Porro prism (Figure 1) was used.
To construct the desired system, the “Coordinate Break” surface type should be chosen in Zemax for the axis rotation (Figure 2).
The lens material K8 (substitute for Schott Glass BK7) glass was chosen. The size of the base of the prism is 25 by 100 mm. Mirror surfaces 4 and 7 (see Figure 2) are tilted 45 degrees about the X-axis. In addition, a 15 mm square rectangular aperture was attached to surfaces 4, 7, as well as to the surface 2.
As a result, the following optical system of the Porro prism was designed (Figure 3).
Mixed Mode
For the design of the system in mixed mode, a Half Penta Prism was used (Figure 4).
In order to use a custom prism, a “.pod” file was made (the file has been saved to “{Zemax}\Samples\Non-Sequential\Prisms” folder in order to be automatically imported by Zemax) with the calculated coordinates of the prism vertices (Figure 5b). The file also contains additional characteristics that determine the beam path in the optical system. When calculating the coordinate vertices, it is important to consider that in Zemax OpticStudio, the optical axis is represented by the Z-axis of the coordinate system (Figure 5a).
In the indicators, the value -1 means that the prism material is opaque and does not transmit light. In contrast, the value 1 means that the material is reflective and reflects the light. The value 0 indicates that the material is transparent and does not interact with the light at all (Figure 5b).
A Mixed-Mode system refers to a sequential optical system that incorporates non-sequential objects, also known as NSC groups (Figure 6). To trace rays through such a system, Entry and Exit Ports are required in order to define the starting and ending points of the NSC group. Additional information on modeling a mixed sequential-non-sequential system can be found in Zemax Knowledgebase.
As a result, the following optical system of the Half Penta Prism was designed (Figure 7).
Conclusion
To sum up, Zemax OpticStudio provides flexibility to model prisms using both sequential and non-sequential approaches. By understanding the characteristics and requirements of the optical system, you can determine the most suitable mode and effectively simulate prisms within complex optical setups.