diff --git a/Laser_utils.py b/Laser_utils.py
new file mode 100644
index 0000000000000000000000000000000000000000..0af4c88ed419096a910bb2a75ed49de97695584c
--- /dev/null
+++ b/Laser_utils.py
@@ -0,0 +1,15 @@
+def positionToDelay(data, key, origin=0, invert = False, reflections=1):
+    ''' converts a motor position in mm into optical delay in picosecond
+        Inputs:
+            data: dataset containing delay stage motor position
+            key: key of the delay stage
+            origin: motor position of time zero in mm
+            invert: bool, inverts the sign of delay if True
+            reflections: number of bounces in the delay stage
+
+        Output:
+            delay in picosecond
+    '''
+    c_ = 299792458 *1e-9 # speed of light in mm/ps
+    x = -1 if invert else 1
+    return 2*reflections*(data[key]-origin)*x/c_
\ No newline at end of file
diff --git a/__init__.py b/__init__.py
index 654b00fd8ddd17321acbc7a68a6d4afe987560bb..9266141c5314b51d023361e26c8767c64864bf26 100644
--- a/__init__.py
+++ b/__init__.py
@@ -2,3 +2,4 @@ from ToolBox.Load import *
 from ToolBox.xgm import *
 from ToolBox.XAS import *
 from ToolBox.knife_edge import *
+from ToolBox.Laser_utils import *