diff --git a/src/kat.h b/src/kat.h
index 30c4f1bf81ee325f1231b334397a4b7b2775b3db..caa998f18254bdb03ba99fb02ed167da3168bf8a 100755
--- a/src/kat.h
+++ b/src/kat.h
@@ -635,6 +635,8 @@ typedef struct surface_merged_map {
     /** True if a transmission map is merged into this */
     bool hasTransmissionMaps;
     
+    double map_amplitude;
+    
     knm_workspace_t knm_ws;
     
 } surface_merged_map_t;
@@ -770,6 +772,8 @@ typedef struct mirror {
     double r_aperture; //!< physical size of mirror, infinite if set to 0
     aperture_type_t aperture_type;
     
+    double map_amplitude;
+
     double x_off;
     double y_off;
     double Rcx; //!< radius of curvature in x plane (tangential)
diff --git a/src/kat_knm_mirror.c b/src/kat_knm_mirror.c
index fa2ecda3bbbb2d75a41bdc619248e37645e22d35..a9706e6fa069f848a10d33b7225134e62d4d7da6 100644
--- a/src/kat_knm_mirror.c
+++ b/src/kat_knm_mirror.c
@@ -1272,9 +1272,9 @@ void compute_mirror_knm_integral(mirror_t *mirror, double nr1, double nr2, bitfl
 
     recompute = recompute | (map->_nr1 != nr1);
     recompute = recompute | (map->_nr2 != nr2);
-
     recompute = recompute | (map->_angle != mirror->angle);
                 
+    recompute = recompute | !eq(mirror->map_amplitude, map->map_amplitude);
     recompute = recompute | !ceq(mirror->knm_q.qxt1_11, map->mirror_knm_q.qxt1_11);
     recompute = recompute | !ceq(mirror->knm_q.qxt2_11, map->mirror_knm_q.qxt2_11);
     recompute = recompute | !ceq(mirror->knm_q.qyt1_11, map->mirror_knm_q.qyt1_11);
@@ -1666,10 +1666,10 @@ void compute_mirror_knm_integral(mirror_t *mirror, double nr1, double nr2, bitfl
                         ipfile = NULL;
                     }
 
-                    knm->k11[n][m] = results[0];
-                    knm->k12[n][m] = results[1];
-                    knm->k21[n][m] = results[2];
-                    knm->k22[n][m] = results[3];
+                    knm->k11[n][m] = z_by_x(results[0], mirror->map_amplitude);
+                    knm->k12[n][m] = z_by_x(results[1], mirror->map_amplitude);
+                    knm->k21[n][m] = z_by_x(results[2], mirror->map_amplitude);
+                    knm->k22[n][m] = z_by_x(results[3], mirror->map_amplitude);
                     
                     // If we have a mode matched beam we are able to calculate the transposed
                     // elements by applying a simple phase factor
@@ -1704,7 +1704,7 @@ void compute_mirror_knm_integral(mirror_t *mirror, double nr1, double nr2, bitfl
     map->_lambda = init.lambda;
     map->_nr1 = nr1;
     map->_nr2 = nr2;
-
+    map->map_amplitude = mirror->map_amplitude;
     map->mirror_knm_q.qxt1_11 = mirror->knm_q.qxt1_11;
     map->mirror_knm_q.qxt2_11 = mirror->knm_q.qxt2_11;
     map->mirror_knm_q.qyt1_11 = mirror->knm_q.qyt1_11;
diff --git a/src/kat_read.c b/src/kat_read.c
index 4104de98f7c0241715903ac8f8bbd5da9895be86..0e44830f0e173d89d061c8c2605a048e332a51a2 100755
--- a/src/kat_read.c
+++ b/src/kat_read.c
@@ -10584,7 +10584,14 @@ int assign_mirror_parameter(component_param_t *component_param) {
         strcpy(component_param->unit, " [deg]");
         *component_param->lborder = 0;
         *component_param->uborder = 0;
-        
+    } else if (strcasecmp("map_amp", component_param->parameter) == 0){
+        *component_param->xparam = &(mirror->map_amplitude);
+        mirror->rebuild = 1;
+        inter.rebuild |= 1;
+        strcpy(component_param->unit, " [real]");
+        *component_param->lborder = -1;
+        *component_param->uborder = 1;
+
     } else if (strcasecmp("dither_f", component_param->parameter) == 0) {
         *component_param->xparam = &(mirror->dither_f);
         strcpy(component_param->unit, " [Hz]");