Pre-Collimator Chemical Milling for X-ray Telescopes

Combining Chemical Milling with wire Electrical Discharge Machining (EDM), Mindrum Precision will build a precollimator (PC) faster and more cost effective than current methods. Space-based x-ray telescopes currently involve the use of a PC to shield the optics from stray light. Each PC requires extensive build time from highly skilled technicians. The PC cylindrical aluminum ribs (or blades) are individually attached to alignment frames. This hands-on "place/weld/measure and repeat" process is ineffective for the thousands of ribs. Build times have exceeded a year, and sometimes the PC still failed to perform. Some telescopes scrap the PC early to avoid these complications and accept the limitations in performance. Eliminating the hands-on time with CNC unattended wire EDM automates the build, but can't reach the thin walls required. Chemical milling of this large, complex structure is an innovation which will bring fast and affordable PC to market. Current chemical milling uses HF and HNO3 acids to etch thin films of Titanium. However, etching is traditionally done on thin sheets. Mindrum Precision process will investigate etching of this complex material. New concentration levels, etch times, and agitation methods will be explored to achieve a uniform etch along the entire length of the numerous 3" slots. Mindrum Precision will combine wire EDM with Chemical Milling to rapidly make affordable precollimators for future telescopes.