Added furst_optics.feed_optics.FeedOptic.transformation_image prope…

…rty.

furst_optics/feed_optics/_feed_optics.py

@@ -178,6 +178,20 @@ def transformation(self) -> na.transformations.AbstractTransformation:
         )
         return t_img @ super().transformation @ t_yaw @ t_center
 
+    @property
+    def transformation_image(self):
+        """
+        Coordinate transformation from the global coordinate system
+        and the virtual image of the Sun inside the feed optic.
+        """
+
+        t_img = na.transformations.Cartesian3dTranslation(
+            x=0 * u.mm,
+            y=0 * u.mm,
+            z=self.radius / 2,
+        )
+        return t_img @ self.transformation
+
     @property
     def surface(self) -> optika.surfaces.Surface:
         return optika.surfaces.Surface(

furst_optics/feed_optics/_feed_optics_test.py

@@ -1,5 +1,6 @@
 import pytest
 import astropy.units as u
+import named_arrays as na
 from optika._tests import test_mixins
 import furst_optics._components_test
 
@@ -23,4 +24,7 @@ class TestFeedOptics(
     test_mixins.AbstractTestTranslatable,
     furst_optics._components_test.AbstractTestAbstractRowlandComponent,
 ):
-    pass
+
+    def test_transformation_image(self, a: furst_optics.feed_optics.FeedOptic):
+        result = a.transformation_image
+        assert isinstance(result, na.transformations.AbstractTransformation)