diff --git a/esbo_etc/classes/optical_component/AHotOpticalComponent.py b/esbo_etc/classes/optical_component/AHotOpticalComponent.py
index 080ef58..cfefca7 100644
--- a/esbo_etc/classes/optical_component/AHotOpticalComponent.py
+++ b/esbo_etc/classes/optical_component/AHotOpticalComponent.py
@@ -3,7 +3,7 @@ from esbo_etc.classes.ITransmissive import ITransmissive
 from esbo_etc.classes.SpectralQty import SpectralQty
 from abc import abstractmethod
 import astropy.units as u
-from esbo_etc.lib.helpers import gb_factory
+from astropy.modeling.models import BlackBody
 from typing import Union, Callable
 
 
@@ -12,8 +12,9 @@ class AHotOpticalComponent(AOpticalComponent):
     Abstract super class for an optical component with thermal emission
     """
     @abstractmethod
-    @u.quantity_input(wl_bins='length', temp=[u.Kelvin, u.Celsius])
-    def __init__(self, parent: ITransmissive, emissivity: SpectralQty, temp: u.Quantity):
+    @u.quantity_input(wl_bins='length', temp=[u.Kelvin, u.Celsius], obstruction_temp=[u.Kelvin, u.Celsius])
+    def __init__(self, parent: ITransmissive, emissivity: SpectralQty, temp: u.Quantity, obstruction: float = 0,
+                 obstructor_temp: u.Quantity = 0 * u.K, obstructor_emissivity: float = 1):
         """
         Initialize a new optical component with thermal emission
 
@@ -25,16 +26,26 @@ class AHotOpticalComponent(AOpticalComponent):
             The spectral emissivity coefficient for the optical surface.
         temp: Quantity in Kelvin / Celsius
             Temperature of the optical component
+        obstruction : float
+            The additional obstruction factor of the optical component. 0 means the component is not obstructed, 1
+            denotes a completely obstructed component with therefore no incoming flux. It is important to note, that
+            the obstruction factor reflects the obstruction of the optical component additionally to the obstruction
+            factors of the prior elements in the beam.
+        obstructor_temp : Quantity in Kelvin / Celsius
+            Temperature of the obstructing component.
+        obstructor_emissivity : float
+            Emissivity of the obstructing component.
         """
         # Initialize super class
-        super().__init__(parent)
+        super().__init__(parent, obstruction=obstruction, obstructor_temp=obstructor_temp,
+                         obstructor_emissivity=obstructor_emissivity)
         if temp > 0 * u.K:
             # Create noise from black body model
             if isinstance(emissivity, SpectralQty):
-                bb = gb_factory(temp)
+                bb = self._gb_factory(temp)
                 self._noise = SpectralQty(emissivity.wl, bb(emissivity.wl)) * emissivity
             else:
-                bb = gb_factory(temp, emissivity)
+                bb = self._gb_factory(temp, emissivity)
                 self._noise = bb
         else:
             self._noise = 0
@@ -49,3 +60,24 @@ class AHotOpticalComponent(AOpticalComponent):
             The noise created by the optical component
         """
         return self._noise
+
+    @staticmethod
+    @u.quantity_input(temp=[u.Kelvin, u.Celsius])
+    def _gb_factory(temp: u.Quantity, em: Union[int, float] = 1):
+        """
+        Factory for a grey body lambda-function.
+
+        Parameters
+        ----------
+        temp : Quantity in Kelvin / Celsius
+            The temperature fo the grey body.
+        em : Union[int, float]
+            Emissivity of the the grey body
+
+        Returns
+        -------
+        bb : Callable
+            The lambda function for the grey body.
+        """
+        bb = BlackBody(temperature=temp, scale=em * u.W / (u.m ** 2 * u.nm * u.sr))
+        return lambda wl: bb(wl)
diff --git a/esbo_etc/lib/helpers.py b/esbo_etc/lib/helpers.py
index ed4cd80..f889d19 100644
--- a/esbo_etc/lib/helpers.py
+++ b/esbo_etc/lib/helpers.py
@@ -27,27 +27,6 @@ def error(msg: str, exit_: bool = True):
         sys.exit(1)
 
 
-@u.quantity_input(temp=[u.Kelvin, u.Celsius])
-def gb_factory(temp: u.Quantity, em: Union[int, float] = 1):
-    """
-    Factory for a grey body lambda-function.
-
-    Parameters
-    ----------
-    temp : Quantity in Kelvin / Celsius
-        The temperature fo the grey body.
-    em : Union[int, float]
-        Emissivity of the the grey body
-
-    Returns
-    -------
-    bb : Callable
-        The lambda function for the grey body.
-    """
-    bb = BlackBody(temperature=temp * u.K, scale=em * u.W / (u.m ** 2 * u.nm * u.sr))
-    return lambda wl: bb(wl)
-
-
 def isLambda(v: object):
     """
     Check if a object is of type lambda