Attempting to change field type to object height from angle
Greetings! I am trying to use the image simulator but instead with object height to get a better idea of what to expect with the lenses I am using. After having built my system using a field type of angle, I have not been able to switch it or use “Convert to” to get object type. I am quite new to this software and unsure how to resolve this issue (in order to produce a simulated image using object height). I am receiving the “Can’t use object height at infinite conjugates” error. Does anyone have any suggestions?
Below is attached the file.
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Hello nmattu60,
Thank you for sharing your file. One piece of advice for future reference, you can generate an archive of your file in OpticStudio by pressing File..Create Archive. This creates a *.ZAR file, which contains all the files that are necessary for somebody else to run your file. If you simply share the *.ZOS file, some data might not be conveyed with that file. A typical example is with user-defined CAD parts. If you have a CAD object as a *.STEP file, this file is not embedded in the *.ZOS file, but it will be in the *.ZAR.
Going back to you problem, I think it has more to do with what you call object height. Your system is at infinite conjugates, as suggested by the error message. That means your object is located at infinity, and by definition, it cannot have a height. Let me try to explain with an example. Suppose we have a paraxial lens with a focal length of 50 mm, if I place an object at 100 mm from this lens, I will have an image 100 mm after the lens and the magnification is minus one (object is the same size but reversed). This is the depiction of the situation:
In OpticStudio, by default, the left-hand side is the object-side and the right-hand side is the image side. In orange is the paraxial lens. This is what we call a finite-conjugate system. Meaning, a point in the object surface maps onto a point in the image surface. In this case, it makes sense to talk about object height. This is simply the height in the object surface from which the rays emerge.
Imagine that we are increasing the object distance, the rays emitted from the object will become more parallel to one-another. This is the situation when the object-to-lens distance is changed to 300 mm:
In the extreme case where the object-to-lens distance is set to inifnity, the rays become parallel and they all converge in the image space at a focal distance away from the lens (or 50 mm in this case):
Now that the rays are starting parallel to one another, there is no notion of object height anymore, because the rays don’t meet to a single point in the object space.
I hope that makes sense, a physicist or mathematician can give you a more theoretical explanation, but that’s how I would explain it as an engineer.
In your case, what do you call the object height?
Take care,
David
Thank you very much! I think I completely misunderstood the term object height. Everything is resolved now. Thank you!
