Learning Forum

[gt21]

Greetings, Ansys community!

I have two questions:

1) I want to simulate an optical system tracking the propagation of a Gaussian beam. I am starting with an input beam with Aperture Type: Entrance Pupil diameter, and Gaussian Apodization Type. The requirement of the system is to have a specific waist at a particular surface (center of an AOM), which I can achieve in two ways: one is to define the entrance pupil diameter that of the desired beam diameter (240 um), and the other one (which visually looks closer to the actual situation) is to focus a larger input beam into the AOM, adjusting the entrance pupil diameter such that I get the desired paraxial waist at the AOM. Which method is recommended? I realized that even though I use Gaussian apodization, the propagation in the Layout is that of rays whose density folows a Gaussian distribution at the input. Below I have attached, on the left, the PSF resulting by inputing a beam diameter of 240 um exactly at the AOM, and on the right that resulting by focusing a beam of diameter of 600 um with a 300 mm lens into the AOM (diameter of 242 um).

 

2) In the first case above, I define three fields by angle to simulate the bandwidth of the AOM, and the angle I define at the input (STOP) is that measured by the merit function RAED. However, in the second case, when the STOP is not at the input (since the AOM is a certain distance away such that a beam can be focused into it), the angles of the fields I define, are not those I measure at this surface. To fix this, I adjust the angle of the fields such that RAED reads what I need it to read. Is this an acceptable approach? Below, notice that the angle defined at the STOP (surface 6) is not that measured with RAED.

 

 

[Niki Papachristou]

Hi Subscriber,

Thank you for your questions!

Without exploring your file, it is hard to identify what is "acceptable and unacceptable" on your design this is also is directly linked to what your application requires as well as to what you want to achieve.

I would highly recommend to go through the Knowledge base articles for Gaussian Beams, these cover all the ways of modelling this tyoe of beams with ZOS.

Kind Regards,

Niki