[WIP] Window delay stage

.gitignore

@@ -2,4 +2,4 @@
 *.aux
 *.log
 *.pdf
-*.synctex.gz
+*.synctex.gz

tic500/adapter-plate.scad

@@ -0,0 +1,92 @@
+// mount tic500 to optical breadboard
+
+$fn=50;
+inch = 25.4;
+
+// center to center dimensions
+mw = 2*inch;  // mounting width
+mh = 1*inch;  // mounting width
+bw = 1.5*inch - 5.1 - 2.5;  // board width
+bh = 1.05*inch - 5.0;  // board height
+
+// hole diameters
+md = 0.28*inch;  // mounting hole diameter
+bd = 0.09*inch;  // board hole diameter
+
+module roundedRect(size, radius) {
+  x = size[0];
+  y = size[1];  // what was I thinking again??
+
+  z = size[2];
+  linear_extrude(height=z)
+  hull() {
+    // place 4 circles in the corners, with the given radius
+    translate([(-x/2)+radius, (-y/2)+radius, 0])
+    circle(r=radius);
+    translate([(x/2)-radius, (-y/2)+radius, 0])
+    circle(r=radius);
+    translate([(-x/2) + radius, (y/2)-radius, 0])
+    circle(r=radius);
+    translate([(x/2)-radius, (y/2)-radius, 0])
+    circle(r=radius);
+  }
+}
+
+
+module counterSunk(position, radius) {
+  union() {
+    translate(position)
+    translate([0,0,-0.1])
+    union() {
+      cylinder(3.2, radius, radius, 8, center=false);
+      translate([0,0,0.1])
+      cylinder(3.5, 0, 3.5, center=false);
+    }
+  }
+}
+
+module place_tic500(pos, rot=0){
+    translate(pos)
+    color("red", 0.3)
+    //flip downward facing
+    rotate([180, 0, 0])
+    // center board holes and move downward
+    translate([-(0.75+0.05)*inch, -0.5025*inch, 0.125 * inch])
+    import("tic_t500_crude.stl");
+}
+
+
+// plate itself
+difference() {
+  // positive rectangle
+  roundedRect([mw + 0.5*inch, mh + 0.5*inch, 3], 5, center=false);
+  // four table mounting holes
+  translate([-mw/2, -mh/2, -0.1])
+  cylinder(3.2, md/2, md/2, 8, center=false);
+  translate([-mw/2, mh/2, -0.1])
+  cylinder(3.2, md/2, md/2, 8, center=false);  
+  translate([mw/2, -mh/2, -0.1])
+  cylinder(3.2, md/2, md/2, 8, center=false);  
+  translate([mw/2, mh/2, -0.1])
+  cylinder(3.2, md/2, md/2, 8, center=false);
+  // four board holes
+  union() {
+    counterSunk([bw/2, bh/2, 0], bd/2);
+    counterSunk([-bw/2, bh/2, 0], bd/2);
+    counterSunk([bw/2, -bh/2, 0], bd/2);
+    counterSunk([-bw/2, -bh/2, 0], bd/2);
+  }
+  // negative cutouts
+  translate([0,0,-0.1])
+  linear_extrude(height=5)
+  offset(r=3){
+    offset(r=-6){
+      union(){
+        square([mw,bh-0.5*inch], center=true);
+        square([bw-0.5*inch,mh], center=true);
+      }
+    }
+  }
+}
+
+place_tic500();

tic500/assembled_nema17.scad

@@ -0,0 +1,69 @@
+
+$fn=50;
+inch = 25.4;
+default_color = "aqua";
+
+d_shaft = 5; // shaft diameter
+
+// dimensions
+mw = 4*inch;  // board width
+mh = 2.5*inch;  // board height
+mt = 0.25*inch; // board thickness
+
+motor_stl = "17HS13-0404S-PG27.stl";
+
+stepper_positions = [
+    [-1*inch, 0, 0],
+    [1*inch, 0, 0]
+];
+
+
+module countersunk(diameter, pos){
+    union(){
+        through_hole(diamter, pos);
+    };
+}
+
+module through_hole(diameter,pos){
+    translate(pos)
+    linear_extrude(mt*1.2, center=true)
+    color("red", 0.2)
+    circle(d=diameter);
+}
+
+module place_tic(pos){
+    translate(pos)
+    color("red", 0.2)
+    import("tic_t500_crude.stl");
+    }
+
+module place_stepper(pos){
+    translate([pos[0], pos[1], pos[2]-80])
+    // rotate([180,0,0])
+    color("silver", 0.2)
+    import(motor_stl);
+}
+
+color(default_color)
+difference(){
+    cube([mw, mh, mt], center=true);
+    union(){
+        through_hole(5.5, [-1*inch,0,0]);
+        through_hole(5.5, [1*inch,0,0]);
+        for (center=stepper_positions) {
+            translate(center)
+            for (rot=[0,90,180,270]) {
+                rotate([0, 0, rot])
+                through_hole(3.4,[-14, 0, 0]);
+            }
+        }
+    }
+}
+
+for (pos = stepper_positions){
+    place_stepper(pos);
+}
+
+place_tic([1*inch, 0, 1*inch]);
+
+

tic500/delay_vs_angle.py

@@ -0,0 +1,69 @@
+"""calculate important parameters for window delay stage"""
+
+import numpy as np
+
+
+w = 2e-3   # window length, in m
+n1 = 1.  # refractive index of air
+n2 = 1.45  # refractive index of window material
+
+
+def calculate(alpha, w=w, n1=n1, n2=n2):
+    refracted_angle = np.arcsin(n1 * np.sin(alpha) / n2)
+    beta = alpha - np.arcsin(n1 * np.sin(alpha) / n2)
+    B1 = w / np.cos(refracted_angle)  # length of travel through glass (including refraction)
+    B2 = B1 * np.sin(beta) * np.tan(alpha) # length of travel after glass to meet with wavefront of path C
+    C = w / np.cos(alpha)  # path length through glass without refraction
+    path_difference = 2 * (n2 * B1 + n1 * B2 - n1 * C)
+    return dict(
+        refracted_angle = refracted_angle,
+        beta = beta,
+        B1 = B1,
+        B2 = B2,
+        C = C,
+        path_difference = path_difference,
+    )
+
+def total_reflectivitiy(theta, n1=n1, n2=n2, polarization="p"):
+    c1 = (1- (n1/n2 * np.sin(theta))**2 )**0.5
+    if polarization == "p":
+        top = n1 * c1 - n2 * np.cos(theta)
+        bottom = n1 * c1 + n2 * np.cos(theta)
+    elif polarization == "s":
+        top = n1 * np.cos(theta) - n2 * c1
+        bottom = n1 * np.cos(theta) + n2 * c1
+    else:
+        raise ValueError
+    r = np.abs(top / bottom)**2
+    return 1 - (1 - r)**4
+
+
+if __name__ == "__main__":
+    alpha = np.arange(0, 70, 1.8)
+    # alpha = np.linspace(0, 70, 90)
+    calculations = [a for a in map(calculate, alpha * np.pi / 180)]
+    opt_delay = np.array([a["path_difference"]/3e8 for a in calculations])
+    no_refraction = lambda a: 2 * (n2-n1) *a["C"]
+    approx_delay = np.array([x/3e8 for x in map(no_refraction, calculations)])
+
+    import matplotlib.pyplot as plt
+    fig, (ax1, ax2, ax3) = plt.subplots(figsize=(5,8), nrows=3, sharex=True)
+
+    ax1.plot(alpha, opt_delay * 1e12, lw=2, marker="o")
+    # ax1.plot(alpha, approx_delay * 1e12)
+    ax2.plot(alpha, np.array([2 * a["B1"]*1e3 for a in calculations]), lw=2)
+    ax3.plot(alpha, total_reflectivitiy(alpha * np.pi / 180), lw=2, label="p-pol")
+    ax3.plot(alpha, total_reflectivitiy(alpha * np.pi / 180, polarization="s"), lw=2, label="s-pol")
+
+    ax1.set_ylabel("optical delay (ps)")
+    ax2.set_ylabel("window travel length (mm)")
+    ax3.set_ylabel("total reflective loss fraction")
+    ax3.set_xlabel("incidence angle (deg)")
+    ax1.set_title(f"w={w*1e3} mm, n={n2}")
+    # ax1.set_ylim(0, 10)
+    ax1.set_xlim(30, 70)
+    [ax.grid() for ax in fig.axes]
+    plt.show()
+
+
+

tic500/main_plate.scad

@@ -0,0 +1,69 @@
+
+$fn=50;
+inch = 25.4;
+default_color = "aqua";
+
+d_shaft = 5; // shaft diameter
+
+// dimensions
+mw = 4*inch;  // board width
+mh = 2.5*inch;  // board height
+mt = 0.25*inch; // board thickness
+
+motor_stl = "11HS20-0674S-PG27.stl";
+
+stepper_positions = [
+    [-1*inch, 0, 0],
+    [1*inch, 0, 0]
+];
+
+
+module countersunk(diameter, pos){
+    union(){
+        through_hole(diamter, pos);
+    };
+}
+
+module through_hole(diameter,pos){
+    translate(pos)
+    linear_extrude(mt*1.2, center=true)
+    color("red", 0.2)
+    circle(d=diameter);
+}
+
+module place_tic(pos){
+    translate(pos)
+    color("red", 0.2)
+    import("tic_t500_crude.stl");
+    }
+
+module place_stepper(pos){
+    translate([pos[0], pos[1], pos[2]-80])
+    // rotate([180,0,0])
+    color("silver", 0.2)
+    import(motor_stl);
+}
+
+color(default_color)
+difference(){
+    cube([mw, mh, mt], center=true);
+    union(){
+        through_hole(5.5, [-1*inch,0,0]);
+        through_hole(5.5, [1*inch,0,0]);
+        for (center=stepper_positions) {
+            translate(center)
+            for (rot=[0,90,180,270]) {
+                rotate([0, 0, rot])
+                through_hole(3.4,[-14, 0, 0]);
+            }
+        }
+    }
+}
+
+for (pos = stepper_positions){
+    place_stepper(pos);
+}
+
+place_tic([1*inch, 0, 1*inch]);
+
+

tic500/main_plate_nema11.scad

@@ -0,0 +1,86 @@
+
+$fn=50;
+inch = 25.4;
+default_color = "aqua";
+
+d_shaft = 5; // shaft diameter
+
+// dimensions
+mw = 4*inch;  // board width
+mh = 2.5*inch;  // board height
+mt = 0.25*inch; // board thickness
+
+motor_stl = "11HS20-0674S-PG27.stl";
+window_stl = "window_mount_1in.stl";
+
+stepper_positions = [
+    [-1*inch, 0, 0],
+    [1*inch, 0, 0]
+];
+
+
+module countersunk(diameter, pos){
+    union(){
+        through_hole(diameter, pos);
+        translate([pos[0], pos[1], pos[2]+mt/2-6.5])
+        cylinder(7, d1=0, d2=7);
+    };
+}
+
+module through_hole(diameter, pos){
+    translate(pos)
+    linear_extrude(mt*1.2, center=true)
+    circle(d=diameter);
+}
+
+module place_tic(pos){
+    translate(pos)
+    rotate([-90, 0,0])
+    rotate([0, 0, -90])
+    color("red", 0.2)
+    import("tic_t500_crude.stl");
+    }
+
+module place_stepper(pos){
+    translate([pos[0], pos[1], pos[2]-40])
+    rotate([180,0,0])
+    color("silver", 0.2)
+    import(motor_stl);
+}
+
+module place_windows(pos, rot=0){
+    translate(pos)
+    color("green", 0.3)
+    rotate([0, -90, rot])
+    import(window_stl);
+}
+
+color(default_color, 0.5)
+difference(){
+    cube([mw, mh, mt], center=true);
+    union(){
+        for (center=stepper_positions) {
+            // for shaft
+            through_hole(5.5, center);
+            translate([center[0], center[1], center[2]-mt/2-1])
+            cylinder(3.1, d=18.5);
+            translate(center)
+            // for fasteners to steppers
+            for (rot=[0,90,180,270]) {
+                rotate([0, 0, rot])
+                countersunk(3.4,[-11, 0, 0]);
+            }
+        }
+    }
+}
+
+for (pos = stepper_positions){
+    place_stepper(pos);
+}
+
+place_windows([1*inch, 0, mt/2], rot=-45);
+place_windows([-1*inch, 0, mt/2], rot=45);
+
+place_tic([0, 1*inch, -2*inch]);
+
+