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How to tilt optics after non sequential component?

  • 11 March 2022
  • 3 replies
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I have a equilateral prism which I want to use in my setup. The prism is off the shelf. I got its zemax file (PS852-Zemax.zar) from Thorlabs and it is defined as non sequential object with a source diode and rectangular  volume. 

I inserted that prism in my setup by using only the rectangular volume NSC data from the provided zemax file.  

I figured that I would need to tilt the prism to make the rays parallel to the bottom face. However when I tilt the prism, the rest of the sequential optics do not get tilted. For example look at the orange highlighted surface after the prism. I have shown the local axis of all the surfaces as well.

 

I am unable to insert a coordinate break in the line right after the NSC in lens data editor in order to tilt rest of the optics. Any idea on how to tilt the optical axis after Non sequential object is tilted? 

I have attached the PS852-Zemax.zar Prism file from Thorlabs as well as the zemax file showing the above setup.

I’m new to working with NSC. Any help would be highly appreciated.

Thank you

Swati

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Best answer by David.Nguyen 15 March 2022, 12:10

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Userlevel 7
Badge +2

Hi Swati,

 

I’m not entirely sure what you are trying to achieve. I’ve downloaded your file, and you seem to be tilting the prism through the non-sequential component. I’d suggest not to do so, if you want to tilt the whole system after the prism. Instead, you can have a Coordinate Break before the non-sequential component and apply the tilt there.

If you do so, you’ll notice the prism tilt around a point on its left:

This is because the prism is located a Z = 30.0 in the non-sequential component. If you want to rotate about the local axis of the rectangular volume, you can add a dummy surface before the coordinate break that moves 30.00 forward to the point of rotation, which becomes the prism local axis, and apply the rotation before returning 30.00 backward to continue the raytrace.

Be careful how you set your entrance and exit ports though.

I hope this helps.

Take care,

 

David

Userlevel 4
Badge +1

David has made a very good point. If you want to change the coordinate system for all subsequent elements, you should use a coordinate break before the NSC component.

In this case, you also do have the option to change the exit port by putting parameter values on the NSC component in the Lens Data Editor, in the Exit Loc and Exit Tilt cells. You could also put a Coordinate Break after the exit port to tilt subsequent surfaces. Since tilting the prism 20 degrees won’t tilt the beam by 20 degrees, you will probably want to do one of these options even if you do put the CB before the NSC component just to get the system aligned properly.

Userlevel 1

Good.

 

Here I am facing one issue with coordinate break, when I use CB to tilt my aspheric lens about y axis 180 degree, rays disappear. Initially the aspheric surface faced towards the object ray (Seq source), but when i tilt it about y axis 180 degree, the flat surface face towards the object. I have found that this happens only in aspheric system, other system works well with CB. 

 

Any possible solution ? Why aspheric lenses do so ?

Thanks 

Ebi

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