New condenser for upright to use LED PCB

This merge request updates the upright condenser to match the new condenser for the inverted microscope. It enables use of either 5mm LED or the circular OpenFlexure LED PCB

From #270 (closed):

This would involve:

• Make the Z position parametric, closing #227 (closed)
• Split the upright condenser into two parts - a part similar to the inverted condenser (but without the mounting) and an "lid" that includes the objective mounting wedge to connect to the Z axis.
• Add in the holes to the "lid" to allow the existing 5mm LED holder to fit there
• Increase the size of the void under the condenser (i.e. at the top of the lid) to allow use of the illumination PCB
• Add a lug to the condenser that enables the existing mounting screws to be used, possibly in the opposite direction (i.e. screwing through clearance holes in the condenser, into tapped holes in the lid/mounting.

---

also required:

• renders for building the illumination
• instructions

closes #270 (closed)
closes #227 (closed)

openscad/libs/upright_illumination.scad

@@ -23,17 +23,19 @@ use <./z_axis.scad>
 //     }
 // }
 
+// the condenser lens is 5mm focal length and the body is 30mm long
+// seems to be formed from:
+//    condenser_lens_assembly_z() (22mm) + condenser_lens_diameter()/2 (6.5mm) 
+//    + lens base thickness (1mm) + gripper (1.5mm)
+// effective lens position at 30 - 1.5 mm
+sample_z = key_lookup("sample_z", default_params());
+function  upright_condenser_platform_height() = sample_z - 5 - (condenser_lens_assembly_z() + 6.5 -1.5 );
 
 // Module to create a platform with a fitting wedge for the z-axis
 // and a mounting face for the condenser adn cut-out for a 5mm LED or LED PCB
 module upright_condenser_platform_separate(params, base_r){
-    sample_z = key_lookup("sample_z", params);
-    // the condenser lens is 5mm focal length and the body is 30mm long
-    // seems to be formed from:
-    //    condenser_lens_assembly_z() (22mm) + condenser_lens_diameter()/2 (6.5mm) 
-    //    + lens base thickness (1mm) + gripper (1.5mm)
-    // effective lens position at 30 - 1.5 mm
-    platform_h = sample_z - 5 - (30 - 1.5);
+    
+    platform_h = upright_condenser_platform_height();
     assert(platform_h > upper_z_flex_z(params), "Platform height too low for z-axis mounting");
     
     // Make a platform with a dovetail on the side and a platform on the top
@@ -151,7 +153,7 @@ function upright_condenser_lug_x() = 12;
 // for use with upright microscope
 // 5mm LED or LED PCB
 module upright_condenser_separate(){
-    condenser(lens_assembly_z= 30, include_mounting = false, basic_condenser = true);
+    condenser(lens_assembly_z= condenser_lens_assembly_z(), include_mounting = false, basic_condenser = true);
     lens_d=condenser_lens_diameter();
     base_r = condenser_base_r(lens_d);
     difference(){