diff --git a/esis/flights/f1/optics/gratings/rulings/_rulings.py b/esis/flights/f1/optics/gratings/rulings/_rulings.py
index 2174bad..3afdaf8 100644
--- a/esis/flights/f1/optics/gratings/rulings/_rulings.py
+++ b/esis/flights/f1/optics/gratings/rulings/_rulings.py
@@ -102,7 +102,7 @@ def ruling_design(
             width=0.1,
             num_distribution=num_distribution,
         ),
-        diffraction_order=1,
+        diffraction_order=-1,
     )
 
 
diff --git a/esis/flights/f1/optics/models.py b/esis/flights/f1/optics/models.py
index d4d92b7..1e0c24d 100644
--- a/esis/flights/f1/optics/models.py
+++ b/esis/flights/f1/optics/models.py
@@ -5,6 +5,7 @@
 import optika
 import esis
 from . import primaries
+from . import gratings
 
 __all__ = [
     "design_full",
@@ -144,7 +145,7 @@ def design_full(
         angle_output=8.057 * u.deg,
         sag=optika.sags.SphericalSag(
             radius=na.UniformUncertainScalarArray(
-                nominal=radius_grating,
+                nominal=-radius_grating,
                 width=radius_grating * error_radius_grating,
                 num_distribution=num_distribution,
             ),
@@ -161,8 +162,8 @@ def design_full(
                 period_max=2 * u.um,
             ),
         ),
-        material=optika.materials.Mirror(),
-        rulings=esis.flights.f1.optics.gratings.rulings.ruling_design(
+        material=gratings.materials.multilayer_design(),
+        rulings=gratings.rulings.ruling_design(
             num_distribution=num_distribution,
         ),
         num_folds=num_folds,
diff --git a/esis/optics/_gratings.py b/esis/optics/_gratings.py
index fad99c1..91fe506 100644
--- a/esis/optics/_gratings.py
+++ b/esis/optics/_gratings.py
@@ -95,6 +95,11 @@ def width_border_inner(self) -> u.Quantity | na.AbstractScalar:
     def clearance(self) -> u.Quantity | na.AbstractScalar:
         """minimum distance between adjacent physical gratings"""
 
+    @property
+    def transformation(self) -> na.transformations.AbstractTransformation:
+        rotation = na.transformations.Cartesian3dRotationX(180 * u.deg)
+        return super().transformation @ rotation
+
     @property
     def surface(self) -> optika.surfaces.Surface:
         angle_aperture = self.angle_aperture
diff --git a/esis/optics/_models.py b/esis/optics/_models.py
index 707119c..fce38b8 100644
--- a/esis/optics/_models.py
+++ b/esis/optics/_models.py
@@ -123,7 +123,7 @@ def _wavelength_test_grid(self) -> na.AbstractScalar:
         d = grating.rulings.spacing_(position).length
         a = self.angle_grating_input
         b = self.angle_grating_output
-        result = (np.sin(a) + np.sin(b)) * d / m
+        result = np.abs((np.sin(a) + np.sin(b)) * d / m)
         return result.to(u.AA)
 
     @property