Making a Homebuilt Pump Cavity
Learning to build a pump cavity allows a frugal holographer to utilize many surplus components. The requirements of a pump cavity are:
- Concentrate light on the active medium.
- Dissipate the heat generated inside the cavity.
- Electrically isolate the flash tube.
- 1 Calculating the Ellipse
- 2 Material Selection
- 3 Polishing the Reflective Surface
- 4 Plating
- 5 Making the Ellipse
- 6 Designing and Fabricating End Plates
- 7 Electrical Considerations
- 8 Water Cooling
Calculating the Ellipse
The lower the ratio of height to width of the ellipse the more efficient the pumping will be. Since the rod and the flash lamp are placed at their respective foci this meens that the rod and the lamp must be as close together as feasible.
Aditional space must be allowed for mounting and machining considerations.
- Great Thermal Conductivity
- Easy to plate
- Poor Reflectivity Requires Plating
- Does not take a good polish requiring polishing after plating
- Great thermal conductivity
- Very good reflectivity for Ruby systems
- Takes a very good polish
- If not coated the surface can tarnish
- Not the best reflectivity for pumping Nd:YAG
- Inexpensive and commonly available
- Very hard
- Polishes well
- Plates easily
- Low thermal conductivity
- Difficult to machine
- Very chemical resistant
- Must be plated
Polishing the Reflective Surface
Polishing the cavity is like doing any other polishing. You start at the finest grit that will remove the deepest scratch. Once the surface has a uniform scratch pattern you move to a finner grit. Making a fitting for your drill is the fastest way to polish a tube.
- Coarse (less than 400 grit)
- 400 grit
- 600 grit
- 800 grit
- Red Polish
- White Polish