diff --git a/image_analysis/geom_refinement/CMakeLists.txt b/image_analysis/geom_refinement/CMakeLists.txt
index a81b8b54..0143b49a 100644
--- a/image_analysis/geom_refinement/CMakeLists.txt
+++ b/image_analysis/geom_refinement/CMakeLists.txt
@@ -6,6 +6,8 @@ ADD_LIBRARY(JFJochGeomRefinement STATIC
         AssignSpotsToRings.h
         XtalOptimizer.cpp
         XtalOptimizer.h
+        RotOptimizer.cpp
+        RotOptimizer.h
 )
 
 TARGET_LINK_LIBRARIES(JFJochGeomRefinement Ceres::ceres Eigen3::Eigen JFJochCommon)
diff --git a/image_analysis/geom_refinement/SimpleRotXtalOptimizer.cpp b/image_analysis/geom_refinement/SimpleRotXtalOptimizer.cpp
new file mode 100644
index 00000000..6dfc47f4
--- /dev/null
+++ b/image_analysis/geom_refinement/SimpleRotXtalOptimizer.cpp
@@ -0,0 +1,94 @@
+// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
+// SPDX-License-Identifier: GPL-3.0-only
+
+#include "SimpleRotXtalOptimizer.h"
+
+#include <Eigen/Dense>
+
+static bool SimpleRotXtalOptimizerInternal(
+    SimpleRotXtalOptimizerData &data,
+    const std::vector<SpotToSave> &spots,
+    float tolerance)
+{
+    Coord vec0 = data.latt.Vec0();
+    Coord vec1 = data.latt.Vec1();
+    Coord vec2 = data.latt.Vec2();
+
+    const double tol_sq = tolerance * tolerance;
+
+    std::vector<Eigen::Vector3d> obs;
+    std::vector<Eigen::Vector3d> exp;
+
+    // Collect reflections
+    for (const auto &pt : spots) {
+        if (!data.index_ice_rings && pt.ice_ring)
+            continue;
+
+        Coord recip = data.geom.DetectorToRecip(pt.x, pt.y);
+
+        double h_fp = recip * vec0;
+        double k_fp = recip * vec1;
+        double l_fp = recip * vec2;
+
+        double h = std::round(h_fp);
+        double k = std::round(k_fp);
+        double l = std::round(l_fp);
+
+        double d2 =
+            (h - h_fp)*(h - h_fp) +
+            (k - k_fp)*(k - k_fp) +
+            (l - l_fp)*(l - l_fp);
+
+        if (d2 > tol_sq)
+            continue;
+
+        obs.emplace_back(h_fp, k_fp, l_fp);
+        exp.emplace_back(h, k, l);
+    }
+
+    if (obs.size() < data.min_spots)
+        return false;
+
+    const int N = static_cast<int>(obs.size());
+
+    // Build linear system A * omega = b
+    Eigen::MatrixXd A(3*N, 3);
+    Eigen::VectorXd b(3*N);
+
+    for (int i = 0; i < N; i++) {
+        const auto &h = obs[i];
+        const auto &e = exp[i];
+
+        // Cross-product matrix of h_obs
+        A.row(3*i + 0) <<   0.0, -h.z(),  h.y();
+        A.row(3*i + 1) <<  h.z(),  0.0, -h.x();
+        A.row(3*i + 2) << -h.y(),  h.x(),  0.0;
+
+        b.segment<3>(3*i) = e - h;
+    }
+
+    // Solve least squares
+    Eigen::Vector3d omega = A.colPivHouseholderQr().solve(b);
+
+    // Optional sanity check
+    if (!omega.allFinite())
+        return false;
+
+    if (omega.norm() > 0.05) {
+        return false;
+        // > ~3 degrees — warn or reject
+    }
+
+    // Apply small-angle rotation to lattice
+    // TODO: data.latt.RotateSmallAngle(omega);
+
+    return true;
+}
+
+bool SimpleRotXtalOptimizer(SimpleRotXtalOptimizerData &data, const std::vector<SpotToSave> &spots) {
+
+    if (!SimpleRotXtalOptimizerInternal(data, spots, 0.3))
+        return false;
+    SimpleRotXtalOptimizerInternal(data, spots, 0.2);
+    return SimpleRotXtalOptimizerInternal(data, spots, 0.1);
+}
diff --git a/image_analysis/geom_refinement/SimpleRotXtalOptimizer.h b/image_analysis/geom_refinement/SimpleRotXtalOptimizer.h
new file mode 100644
index 00000000..2587e0cb
--- /dev/null
+++ b/image_analysis/geom_refinement/SimpleRotXtalOptimizer.h
@@ -0,0 +1,24 @@
+// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
+// SPDX-License-Identifier: GPL-3.0-only
+
+#ifndef JFJOCH_ROTOPTIMIZER_H
+#define JFJOCH_ROTOPTIMIZER_H
+
+#include <vector>
+#include "../common/SpotToSave.h"
+#include "../common/CrystalLattice.h"
+#include "../common/GoniometerAxis.h"
+
+struct SimpleRotXtalOptimizerData {
+    DiffractionGeometry geom;
+    CrystalLattice latt;
+    int64_t min_spots = 8;
+
+    bool index_ice_rings = true;
+    float max_time = 1.0;
+    double rotation[3] = {0,0,0};
+};
+
+bool SimpleRotXtalOptimizer(SimpleRotXtalOptimizerData &data, const std::vector<SpotToSave> &spots);
+
+#endif //JFJOCH_ROTOPTIMIZER_H
\ No newline at end of file