diff --git a/tests/data/beamsplitter/beamsplitter_transmittance.csv b/tests/data/beamsplitter/beamsplitter_transmittance.csv
new file mode 100644
index 0000000..e12aeac
--- /dev/null
+++ b/tests/data/beamsplitter/beamsplitter_transmittance.csv
@@ -0,0 +1,5 @@
+wavelength,spectral transmittance
+201,1
+202,1
+203,1
+204,0.9
diff --git a/tests/test_BeamSplitter.py b/tests/test_BeamSplitter.py
index 184bdf0..4fb5d8a 100644
--- a/tests/test_BeamSplitter.py
+++ b/tests/test_BeamSplitter.py
@@ -11,7 +11,8 @@ class TestBeamSplitter(TestCase):
 
     def setUp(self):
         self.target = FileTarget("data/target/target_demo_1.csv")
-        self.splitter = BeamSplitter(self.target, "data/lens/lens_transmittance.csv", 0.5, temp=300 * u.K)
+        self.splitter = BeamSplitter(self.target, "data/beamsplitter/beamsplitter_transmittance.csv", 0.5,
+                                     temp=300 * u.K)
 
     def test___init__(self):
         self.assertEqual(self.splitter.calcNoise(),