conic.h follow-up: figure-error control, StdReflecFunc-only reflectivity, normal and sourceDist fixes

mcstas-comps/contrib/Conics_EH.comp

@@ -41,6 +41,8 @@
 * alpha: [AA]           Slope of reflectivity for reflectivity curve approximation
 * W: [AA^-1]             Width of supermirror cut-off
 * transmit: [1]         Fraction of statistics to assign to transmitted beam - NOT YET IMPLEMENTED
+* sigma_m: [rad]        RMS meridional slope (figure) error of the mirror surfaces
+* sigma_s: [rad]        RMS sagittal slope (figure) error of the mirror surfaces
 * mirr_thick: [m]       Thickness of mirror shell surfaces - NOT YET IMPLEMENTED
 * %End
 *
@@ -51,7 +53,7 @@ DEFINE COMPONENT Conics_EH
 SETTING PARAMETERS (
     rmin=0.0031416, rmax=0.05236,focal_length_u=10, focal_length_d=10, le=0.25, lh=0.25,
     int nshells=4, m=1, mirr_thick=0, int disk=1, vector radii=NULL,
-    R0 = 0.99, Qc = 0.021, W = 0.003, alpha = 6.07, transmit = 0)
+    R0 = 0.99, Qc = 0.021, W = 0.003, alpha = 6.07, transmit = 0, sigma_m=1e-6, sigma_s=250e-6)
 
 SHARE
 %{
@@ -106,6 +108,10 @@ INITIALIZE
       addHyperboloid (focal_length_d, focal_length_d + 2.0 * cH, pi, 0, lh, m, R0, Qc, alpha, W, &s);
     }
   }
+  for (i = 0; i < s.num_c; i++) {
+    s.c[i].figerr_m = sigma_m;
+    s.c[i].figerr_s = sigma_s;
+  }
   if (disk) {
     addDisk (pm->zs, 0.0, rConic (pm->ze, *pm), &s);
   }

mcstas-comps/contrib/Conics_HE.comp

@@ -41,6 +41,8 @@
 * alpha: [AA]           Slope of reflectivity for reflectivity curve approximation
 * W: [AA^-1]             Width of supermirror cut-off
 * transmit: [1]         Fraction of statistics to assign to transmitted beam - NOT YET IMPLEMENTED
+* sigma_m: [rad]        RMS meridional slope (figure) error of the mirror surfaces
+* sigma_s: [rad]        RMS sagittal slope (figure) error of the mirror surfaces
 * mirr_thick: [m]       Thickness of mirror shell surfaces - NOT YET IMPLEMENTED
 * %End
 *
@@ -51,7 +53,7 @@ DEFINE COMPONENT Conics_HE
 SETTING PARAMETERS (
     rmin=0.0031416, rmax=0.05236,focal_length_u=10, focal_length_d=10, le=0.25, lh=0.25,
     int nshells=4, m=1, mirr_thick=0, int disk=1, vector radii=NULL,
-    R0 = 0.99, Qc = 0.021, W = 0.003, alpha = 6.07, transmit = 0)
+    R0 = 0.99, Qc = 0.021, W = 0.003, alpha = 6.07, transmit = 0, sigma_m=1e-6, sigma_s=250e-6)
 
 SHARE
 %{
@@ -106,6 +108,10 @@ INITIALIZE
       addEllipsoid (-focal_length_u - 2.0 * cH, focal_length_d, pi, 0, le, m, R0, Qc, alpha, W, &s);
     }
   }
+  for (i = 0; i < s.num_c; i++) {
+    s.c[i].figerr_m = sigma_m;
+    s.c[i].figerr_s = sigma_s;
+  }
   if (disk) {
     addDisk (pm->zs, 0.0, rConic (pm->ze, *pm), &s);
   }

mcstas-comps/contrib/Conics_PH.comp

@@ -39,6 +39,8 @@
 * alpha: [AA]           Slope of reflectivity for reflectivity curve approximation
 * W: [AA^-1]             Width of supermirror cut-off
 * transmit: [1]         Fraction of statistics to assign to transmitted beam - NOT YET IMPLEMENTED
+* sigma_m: [rad]        RMS meridional slope (figure) error of the mirror surfaces
+* sigma_s: [rad]        RMS sagittal slope (figure) error of the mirror surfaces
 * mirr_thick: [m]       Thickness of mirror shell surfaces - NOT YET IMPLEMENTED
 *
 * %L
@@ -52,7 +54,7 @@ DEFINE COMPONENT Conics_PH
 SETTING PARAMETERS (
     rmin=0.325,rmax=0.615, focal_length=10.070, lp=0.84, lh=0.84,
     int nshells=4, m=1, mirr_thick=0, int disk=1, vector radii=NULL,
-    R0=0.99, Qc=0.021, W=0.003, alpha=6.07, transmit=0)
+    R0=0.99, Qc=0.021, W=0.003, alpha=6.07, transmit=0, sigma_m=1e-6, sigma_s=250e-6)
 
 SHARE
 %{
@@ -99,6 +101,10 @@ INITIALIZE
     pm = addParaboloid (focal_length + 2.0 * cH, pi, -lp, 0, m, R0, Qc, alpha, W, &s);
     addHyperboloid (focal_length, focal_length + 2.0 * cH, pi, 0, lh, m, R0, Qc, alpha, W, &s);
   }
+  for (i = 0; i < s.num_c; i++) {
+    s.c[i].figerr_m = sigma_m;
+    s.c[i].figerr_s = sigma_s;
+  }
   if (disk) {
     addDisk (pm->zs, 0.0, rConic (pm->ze, *pm), &s);
   }

mcstas-comps/contrib/Conics_PP.comp

@@ -41,6 +41,8 @@
 * alpha: [AA]           Slope of reflectivity for reflectivity curve approximation
 * W: [AA^-1]             Width of supermirror cut-off
 * transmit: [1]         Fraction of statistics to assign to transmitted beam - NOT YET IMPLEMENTED
+* sigma_m: [rad]        RMS meridional slope (figure) error of the mirror surfaces
+* sigma_s: [rad]        RMS sagittal slope (figure) error of the mirror surfaces
 * mirr_thick: [m]       Thickness of mirror shell surfaces - NOT YET IMPLEMENTED
 * %End
 *
@@ -51,7 +53,7 @@ DEFINE COMPONENT Conics_PP
 SETTING PARAMETERS (
     rmin=0.0031416, rmax=0.05236, focal_length_u=10.070, focal_length_d=10.070, lp1=0.84, lp2=0.84,
     int nshells=4, m=1, mirr_thick=0, int disk=1, vector radii=NULL,
-    R0 = 0.99, Qc = 0.021, W = 0.003, alpha = 6.07, transmit = 0)
+    R0 = 0.99, Qc = 0.021, W = 0.003, alpha = 6.07, transmit = 0, sigma_m=1e-6, sigma_s=250e-6)
 
 SHARE
 %{
@@ -95,6 +97,10 @@ INITIALIZE
     pm = addParaboloid (-focal_length_u, pi, -lp1, 0, m, R0, Qc, alpha, W, &s);
     addParaboloid (focal_length_d, pi, 0, lp2, m, R0, Qc, alpha, W, &s);
   }
+  for (i = 0; i < s.num_c; i++) {
+    s.c[i].figerr_m = sigma_m;
+    s.c[i].figerr_s = sigma_s;
+  }
   if (disk) {
     addDisk (pm->zs, 0.0, rConic (pm->ze, *pm), &s);
   }

mcstas-comps/contrib/FlatEllipse_finite_mirror.comp

@@ -17,7 +17,7 @@
 * The component relies on an updated version of conic.h from MIT.
 *
 * %P
-* sourceDist: [m]   Distance used for calculating the spacing of the mirrors
+* sourceDist: [m]   Distance used for calculating the spacing of the mirrors, 0: use LStart
 * LStart:     [m]   Left focal point
 * LEnd:       [m]   Right focal point
 * lStart:     [m]   z-Value of the mirror start
@@ -86,7 +86,7 @@ SHARE
   double*
   get_r_at_z0 (int number, double z_0, double r_0, double z_extract, double LStart, double LEnd, double lStart, double lEnd) {
     int n = number;
-    double* r_zExtracts = malloc (n * sizeof (double_t)); /* n is an array of 10 integers */
+    double* r_zExtracts = malloc (n * sizeof (double)); /* n is an array of 10 integers */
     if (!r_zExtracts) {
       fprintf (stderr, "NMO comp function get_r_at_z0: malloc() failed. Exit! \n");
       exit (-1);
@@ -143,6 +143,9 @@ DECLARE
 
 INITIALIZE
 %{
+  if (sourceDist == 0) { // default: mirror spacing is calculated for a source at the left focal point
+    sourceDist = LStart;
+  }
   if (rfront_inner_file && strlen (rfront_inner_file) && strcmp (rfront_inner_file, "NULL") && strcmp (rfront_inner_file, "0")) {
     if (Table_Read (&rsTable, rfront_inner_file, 1) <= 0) { /* read 1st block data from file into pTable */
       exit (fprintf (stderr, "FlatEllipse_finite_mirror: %s: can not read file %s\n", NAME_CURRENT_COMP, rfront_inner_file));
@@ -163,9 +166,6 @@ INITIALIZE
     rfront_inner = get_r_at_z0 (nummirror, 0, r_0, lStart, sourceDist, LEnd, lStart, lEnd);
     // calculate the r-distances of all mirrors at the entry of the NMO, we will need this later
   }
-  if (sourceDist == 0) { // obsolete?
-    sourceDist = LStart;
-  }
   silicon = (mirror_width == 0) ? 0 : -1; // neutron starts in air by default
 
   // Load Reflectivity Data File TODO

mcstas-comps/contrib/Mirror_conic.comp

@@ -29,9 +29,9 @@
 *          unaffected. Compare with Mirror(transmit=1).
 * conic=1: the mirror is a conic.h ConicSurf cylinder of (very large) radius 1 km,
 *          handled by reflectNeutronConic(), which always reflects and weights by R.
-*          Compare with Mirror(transmit=0). Note that reflectNeutronConic() absorbs
-*          neutrons beyond m times the critical angle of Ni (hard cut-off) and
-*          applies a small hard-coded figure error to the surface normal.
+*          Compare with Mirror(transmit=0). A Gaussian figure (slope) error can be
+*          applied via sigma_m and sigma_s; the default is 0 here, whereas the
+*          Conics_* components default to the conic.h values of 1 and 250 urad.
 *
 * Example: Mirror_conic(length=1, yheight=0.1, m=2)
 *
@@ -44,13 +44,15 @@
 * m: [1]           m-value of material
 * W: [AA^-1]       Width of supermirror cut-off
 * conic: [1]       0: use FlatSurf/reflectNeutronFlat(), 1: use ConicSurf/reflectNeutronConic()
+* sigma_m: [rad]   RMS meridional slope (figure) error, conic=1 only
+* sigma_s: [rad]   RMS sagittal slope (figure) error, conic=1 only
 *
 * %E
 *******************************************************************************/
 
 DEFINE COMPONENT Mirror_conic
 
-SETTING PARAMETERS (length=1, yheight=0.1, R0=0.99, Qc=0.021, alpha=6.07, m=2, W=0.003, int conic=0)
+SETTING PARAMETERS (length=1, yheight=0.1, R0=0.99, Qc=0.021, alpha=6.07, m=2, W=0.003, int conic=0, sigma_m=0, sigma_s=0)
 
 SHARE
 %{
@@ -78,6 +80,8 @@ SHARE
     c->alpha = par[2];
     c->m = par[3];
     c->W = par[4];
+    c->figerr_m = par[5];
+    c->figerr_s = par[6];
     c->type = PARA;
   }
 %}
@@ -95,7 +99,7 @@ INITIALIZE
      coordinates; the local mirror plane x=0 is mapped to x=xshift. */
   xshift = 1e3;
 
-  double par[5] = { R0, Qc, alpha, m, W };
+  double par[7] = { R0, Qc, alpha, m, W, sigma_m, sigma_s };
   mirror_conic_init (&fs, &cs, xshift, length, yheight, par);
 %}
 

mcstas-comps/contrib/NMO.comp

@@ -19,7 +19,7 @@
 * NMO.comp contains no actual code, uses INHERIT of all sections from FlatEllipse_finite_mirror
 *
 * %P
-* sourceDist: [m]   Distance used for calculating the spacing of the mirrors
+* sourceDist: [m]   Distance used for calculating the spacing of the mirrors, 0: use LStart
 * LStart:     [m]   Left focal point
 * LEnd:       [m]   Right focal point
 * lStart:     [m]   z-Value of the mirror start

mcstas-comps/examples/Tests_optics/Test_Conics_pairs/Test_Conics_pairs.instr

@@ -12,18 +12,18 @@
 * %D
  * Example instrument that shows some ways of using the Conics pair components
 *
- * %Example: Test_Conics_pairs OPTIC=1 Detector: psd_i_I=6.91402e-13
- * %Example: Test_Conics_pairs OPTIC=1 Detector: psd_i_reflections_2_I=6.91402e-13
- * %Example: Test_Conics_pairs OPTIC=2 fs=100000 Detector: psd_i_I=2.85546e-21
- * %Example: Test_Conics_pairs OPTIC=2 fs=100000 Detector: psd_i_reflections_2_I=2.85515e-21
- * %Example: Test_Conics_pairs OPTIC=3 Detector: psd_i_I=6.91402e-13
- * %Example: Test_Conics_pairs OPTIC=4 ssize=1e-4 Detector: psd_i_I=8.66267e-09
- * %Example: Test_Conics_pairs quadratic=1 Detector: psd_i_I=5.03026e-13
- * %Example: Test_Conics_pairs quadratic=1 fs=8 fi=6 Detector: psd_i_I=1.26085e-12
- * %Example: Test_Conics_pairs OPTIC=2 quadratic=1 fs=100000 Detector: psd_i_I=2.09716e-21
- * %Example: Test_Conics_pairs OPTIC=3 quadratic=1 Detector: psd_i_I=5.03026e-13
- * %Example: Test_Conics_pairs OPTIC=3 quadratic=1 fs=8 fi=6 Detector: psd_i_I=9.00287e-13
- * %Example: Test_Conics_pairs OPTIC=4 quadratic=1 ssize=1e-4 Detector: psd_i_I=6.56678e-09
+ * %Example: Test_Conics_pairs OPTIC=1 Detector: psd_i_I=6.71864e-13
+ * %Example: Test_Conics_pairs OPTIC=1 Detector: psd_i_reflections_2_I=6.71864e-13
+ * %Example: Test_Conics_pairs OPTIC=2 fs=100000 Detector: psd_i_I=2.75574e-21
+ * %Example: Test_Conics_pairs OPTIC=2 fs=100000 Detector: psd_i_reflections_2_I=2.75574e-21
+ * %Example: Test_Conics_pairs OPTIC=3 Detector: psd_i_I=6.71864e-13
+ * %Example: Test_Conics_pairs OPTIC=4 ssize=1e-4 Detector: psd_i_I=8.42691e-09
+ * %Example: Test_Conics_pairs quadratic=1 Detector: psd_i_I=4.93027e-13
+ * %Example: Test_Conics_pairs quadratic=1 fs=8 fi=6 Detector: psd_i_I=1.2236e-12
+ * %Example: Test_Conics_pairs OPTIC=2 quadratic=1 fs=100000 Detector: psd_i_I=2.03618e-21
+ * %Example: Test_Conics_pairs OPTIC=3 quadratic=1 Detector: psd_i_I=4.93027e-13
+ * %Example: Test_Conics_pairs OPTIC=3 quadratic=1 fs=8 fi=6 Detector: psd_i_I=8.80918e-13
+ * %Example: Test_Conics_pairs OPTIC=4 quadratic=1 ssize=1e-4 Detector: psd_i_I=6.41135e-09
 *
 * %P
 * OPTIC: [ ]     Flag to choose between 1: EH pair, 2: PH pair, 3: HE pair, 4: PP pair
@@ -38,13 +38,15 @@
 * rmin: [m] Radius of the innermost shell
 * rmax: [m] Radius of the outermost shell
 * quadratic: [ ] Use the quadratic shell-radius mode instead of the radii vector
+* sigma_m: [rad] RMS meridional slope (figure) error of the mirrors
+* sigma_s: [rad] RMS sagittal slope (figure) error of the mirrors
 *
 * %L
 * <reference/HTML link>
 *
 * %E
 *******************************************************************************/
-DEFINE INSTRUMENT Test_Conics_pairs(int OPTIC=1, ssize=1e-6, fs=10, fi=10, R0=0.99, m=3, W=0.003, alpha=6.07, int nshells=4, rmin=0.0031416, rmax=0.05236, int quadratic=0)
+DEFINE INSTRUMENT Test_Conics_pairs(int OPTIC=1, ssize=1e-6, fs=10, fi=10, R0=0.99, m=3, W=0.003, alpha=6.07, int nshells=4, rmin=0.0031416, rmax=0.05236, int quadratic=0, sigma_m=1e-6, sigma_s=250e-6)
 
 DECLARE
 %{
@@ -102,7 +104,7 @@ COMPONENT psd_o0 = PSD_monitor(xwidth=0.12, yheight=0.12, restore_neutron=1,
 	filename="psd_o0")
 AT(0,0,fs) RELATIVE PREVIOUS
 
-COMPONENT cEH = Conics_EH(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cEH = Conics_EH(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length_u=fs, focal_length_d=fi, radii=radii, le=0.25, lh=0.25, disk=1
 )
 WHEN(OPTIC==1 && !quadratic) AT(0,0,fs) RELATIVE ss
@@ -111,7 +113,7 @@ EXTEND
   number_of_reflections = SCATTERED - 1;
 %}
 
-COMPONENT cEH_quadratic = Conics_EH(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cEH_quadratic = Conics_EH(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length_u=fs, focal_length_d=fi, rmin=rmin, rmax=rmax, le=0.25, lh=0.25, disk=1
 )
 WHEN(OPTIC==1 && quadratic) AT(0,0,fs) RELATIVE ss
@@ -120,7 +122,7 @@ EXTEND
   number_of_reflections = SCATTERED - 1;
 %}
 
-COMPONENT cPH = Conics_PH(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cPH = Conics_PH(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length=fi, radii=radii, lp=0.25, lh=0.25, disk=0
 )
 WHEN(OPTIC==2 && !quadratic) AT(0,0,fs) RELATIVE ss
@@ -129,7 +131,7 @@ EXTEND
   number_of_reflections = SCATTERED - 1;
 %}
 
-COMPONENT cPH_quadratic = Conics_PH(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cPH_quadratic = Conics_PH(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length=fi, rmin=rmin, rmax=rmax, lp=0.25, lh=0.25, disk=0
 )
 WHEN(OPTIC==2 && quadratic) AT(0,0,fs) RELATIVE ss
@@ -138,7 +140,7 @@ EXTEND
   number_of_reflections = SCATTERED - 1;
 %}
 
-COMPONENT cHE = Conics_HE(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cHE = Conics_HE(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length_u=fs, focal_length_d=fi, radii=radii, le=0.25, lh=0.25, disk=1
 )
 WHEN(OPTIC==3 && !quadratic) AT(0,0,fs) RELATIVE ss
@@ -147,7 +149,7 @@ EXTEND
   number_of_reflections = SCATTERED - 1;
 %}
 
-COMPONENT cHE_quadratic = Conics_HE(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cHE_quadratic = Conics_HE(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length_u=fs, focal_length_d=fi, rmin=rmin, rmax=rmax, le=0.25, lh=0.25, disk=1
 )
 WHEN(OPTIC==3 && quadratic) AT(0,0,fs) RELATIVE ss
@@ -156,7 +158,7 @@ EXTEND
   number_of_reflections = SCATTERED - 1;
 %}
 
-COMPONENT cPP = Conics_PP(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cPP = Conics_PP(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length_u=fs, focal_length_d=fi, radii=radii, lp1=0.25, lp2=0.25, disk=0
 )
 WHEN(OPTIC==4 && !quadratic) AT(0,0,fs) RELATIVE ss
@@ -165,7 +167,7 @@ EXTEND
   number_of_reflections = SCATTERED - 1;
 %}
 
-COMPONENT cPP_quadratic = Conics_PP(R0=R0,alpha=alpha,W=W,m=m,
+COMPONENT cPP_quadratic = Conics_PP(R0=R0,alpha=alpha,W=W,m=m, sigma_m=sigma_m, sigma_s=sigma_s,
     nshells=nshells, focal_length_u=fs, focal_length_d=fi, rmin=rmin, rmax=rmax, lp1=0.25, lp2=0.25, disk=0
 )
 WHEN(OPTIC==4 && quadratic) AT(0,0,fs) RELATIVE ss

mcstas-comps/examples/Tests_optics/Test_Mirror_conic/Test_Mirror_conic.instr

@@ -21,16 +21,15 @@
 * COMP=2: Mirror, transmit=0           (reference for COMP=3)
 * COMP=3: Mirror_conic, conic=1        (ConicSurf, reflectNeutronConic)
 *
-* COMP=0 and COMP=1 should agree exactly. COMP=3 agrees with COMP=2 except above
-* the cut-off: reflectNeutronConic() absorbs neutrons with grazing angles beyond
-* m times the critical angle of Ni, whereas Mirror keeps the tail of width W.
+* COMP=0 and COMP=1 should agree exactly, and so should COMP=2 and COMP=3 when
+* no figure error is applied (sigma_m=sigma_s=0).
 *
 * %Example: COMP=0 Detector: L_refl_I=8.98208e-07
 * %Example: COMP=1 Detector: L_refl_I=8.98208e-07
 * %Example: COMP=0 Detector: L_trans_I=7.01789e-07
 * %Example: COMP=1 Detector: L_trans_I=7.01789e-07
 * %Example: COMP=2 Detector: L_refl_I=8.9763e-07
-* %Example: COMP=3 Detector: L_refl_I=8.83094e-07
+* %Example: COMP=3 Detector: L_refl_I=8.9763e-07
 *
 * %P
 * COMP:   [1]     Mirror implementation, see description
@@ -43,10 +42,12 @@
 * W:      [AA^-1] Width of supermirror cut-off
 * Lmin:   [AA]    Minimum source wavelength
 * Lmax:   [AA]    Maximum source wavelength
+* sigma_m: [rad]  RMS meridional slope (figure) error, COMP=3 only
+* sigma_s: [rad]  RMS sagittal slope (figure) error, COMP=3 only
 *
 * %E
 *******************************************************************************/
-DEFINE INSTRUMENT Test_Mirror_conic(int COMP=0, theta=1, length=1, m=2, R0=0.99, Qc=0.0217, alpha=6.07, W=0.003, Lmin=1, Lmax=11)
+DEFINE INSTRUMENT Test_Mirror_conic(int COMP=0, theta=1, length=1, m=2, R0=0.99, Qc=0.0217, alpha=6.07, W=0.003, Lmin=1, Lmax=11, sigma_m=0, sigma_s=0)
 
 DECLARE
 %{
@@ -104,7 +105,7 @@ AT (0, 0, length/2) RELATIVE mirror_arm
 ROTATED (0, 90, 0) RELATIVE mirror_arm
 
 COMPONENT mirror_conic_conic = Mirror_conic(length=length, yheight=0.1, conic=1,
-    R0=R0, Qc=Qc, alpha=alpha, m=m, W=W)
+    R0=R0, Qc=Qc, alpha=alpha, m=m, W=W, sigma_m=sigma_m, sigma_s=sigma_s)
 WHEN (COMP==3)
 AT (0, 0, 0) RELATIVE mirror_arm