diff --git a/optika/sensors/_materials/_materials.py b/optika/sensors/_materials/_materials.py
index 9b56eb9e..a6d1b12e 100644
--- a/optika/sensors/_materials/_materials.py
+++ b/optika/sensors/_materials/_materials.py
@@ -126,29 +126,40 @@ def absorbance(
     if not isinstance(chemical_substrate, optika.chemicals.AbstractChemical):
         chemical_substrate = optika.chemicals.Chemical(chemical_substrate)
 
-    result = optika.materials.layer_absorbance(
-        index=1,
+    layer_oxide = optika.materials.Layer(
+        chemical=chemical_oxide,
+        thickness=thickness_oxide,
+        interface=optika.materials.profiles.ErfInterfaceProfile(
+            width=roughness_oxide,
+        ),
+    )
+
+    layer_substrate = optika.materials.Layer(
+        chemical=chemical_substrate,
+        thickness=thickness_substrate,
+        interface=optika.materials.profiles.ErfInterfaceProfile(
+            width=roughness_substrate,
+        ),
+    )
+
+    _, transmissivity_oxide = optika.materials.multilayer_efficiency(
         wavelength=wavelength,
         direction=direction,
         n=n,
         layers=[
-            optika.materials.Layer(
-                chemical=chemical_oxide,
-                thickness=thickness_oxide,
-                interface=optika.materials.profiles.ErfInterfaceProfile(
-                    width=roughness_oxide,
-                ),
-            ),
-            optika.materials.Layer(
-                chemical=chemical_substrate,
-                thickness=thickness_substrate,
-                interface=optika.materials.profiles.ErfInterfaceProfile(
-                    width=roughness_substrate,
-                ),
-            ),
+            layer_oxide,
         ],
+        substrate=layer_substrate,
     )
 
+    absorption = chemical_substrate.absorption(wavelength)
+
+    decay = np.exp(-absorption * thickness_substrate)
+
+    transmissivity_total = transmissivity_oxide * decay
+
+    result = transmissivity_oxide - transmissivity_total
+
     return np.real(result)