How to make telescope design as Black Box

How to share the telescope design data without sharing the intellectual property of the original designer to the end user, How to protect our works using a design black box? Look at this!

Simply sending telescope design information such as ray-traceable data files in order to let customer perform their work might expose the intellectual property of the designer. We share a way to this problem through the Black Box export tool. Using the Black Box tool allows surfaces to retain all of the information needed to trace real rays at whatever field point, wavelength, and conjugate is desired without allowing those surfaces to be viewed or edited; however, they cannot be individually analyzed or optimized.

The Black Box Lens Surface contains all the information needed to trace real rays with any specification, exactly as if the full telescope design data were present in the Lens Data Editor. Yet, the original data is hidden from view, unable to be edited. We will use this telescope design example to describe the creation and to use of Black Box Lens files.

Converting a design to a Black Box Lens Surface is usually done when the telescope design is complete, although it can be done at any stage in the design cycle. We normally add two extra dummy surfaces to define the first and last surfaces in the range of surfaces to export. These would usually be positioned at mechanical datums (any maybe represent the extent of the mechanical housing holding the optics, for example) or at pupil locations.

In this telescope design example (which can be downloaded from the bottom of this article), it is intended to export the eye piece lenses in this telescope system. Dummy surfaces have been added to represent the mechanical housing that holds the lenses.

Prior to export, all surfaces in the intended range of the telescope design should have fixed apertures placed on them, because when we play the lens back. Convert Semi-Diameters to Circular Apertures of the Apertures tool in the LDE Toolbar is a useful tool. Any aperture type except the User Defined Aperture (UDA) can be used to define the mechanical extents of each lens within the exported region.

We normally leave the option ‘Create and load test file’ checked, so that the software will not only create the Black Box file of the telescope design, but will also delete the surfaces in the specified range, load the black box, and save the file. This makes it easy to ensure that the Black Box file really does represent the exported file, and is an important quality assurance step. The new telescope design black box file will be automatically loaded. And you can confirm that the ray-trace results are exactly the same between the original and Black Box versions of the file.

There are some consequences inherent in the nature of a ‘black box’, some of which are obvious and some maybe not. In this telescope design, for example, Rays hit the front surface of a Black Box and emerge from the back surface exactly as if they had been ray-traced through the equivalent surfaces in the Lens Data Editor, but without exposing any of the surface data. Things that may or may not surprise you include:

  • The data for all surfaces inside the Black Box is hidden, and therefore cannot be accessed by analysis features, optimization operands or ZPL commands. You cannot, for example, tolerance a black box file, or perform thermal analysis. It is a black box and it cannot be altered once created. The surfaces outside the Black Box can of course be analyzed, optimized, toleranced, etc. as normal.
  • Usually OpticStudio distinguishes between rays that hit apertures and are clipped, rays that totally internally reflect, and rays that miss a surface because there is no valid ray-surface intercept location, and gives different error codes for each case. When tracing a Black Box, all OpticStudio knows is that the ray went in but did not come out, and a ‘Ray Miss’ error is generated. Note that if the chief ray is not traceable (as in a telescope with a central obscuration, for example) wavefront calculations will not be possible as there is no chief-ray reference data.
  • No ray data can be generated on any surface inside the Black Box, so the Object, Stop and Image surfaces cannot be inside the Black Box. OpticStudio requires direct access to all the ray data on these three surfaces.
  • Physical optics analysis is not appropriate for black-box optics, as only output ray data is available. FFT and Huygens PSF/MTF, etc. all work as normal.
  • The range of surfaces exported may include Coordinate Breaks and surface tilts/decenters, but the first and last surfaces must be within the same coordinate system so that the input and output planes are only separated by a thickness.

In this telescope design, the thickness of the Black Box surface is reported in the Lens Data Editor, as it is needed for the placement of subsequent surfaces. This does not disclose any details of the internal eye piece design, it simply gives the distance between the input and output planes.

An alternative to the Zemax Black Box tool is the Zernike surface, we will share it in the future, hope it will help you.

The design file used in this particle is attached, please download it here. How to make your telescope design as Black Box How to make your telescope design as Black Box_BB

Reference  Source:

  1. Laikin, Milton. Lens Design. CRC Press, 2007.
  3. Zemax Optical Design Program User’s Guide, Zemax Development Corporation


    The material used in this knowledge sharing, is only for research, academic, non-profit educational or personal use, the blog owner has strived to credit the original sources, but cannot warrant the accuracy of copyrights or completeness of the information sources.