Photolithographic method for making helices for traveling wave tubes and other cylindrical objects

Apparatus for making a helix for a slow wave structure of a traveling wave tube comprising:

• a mandrel,
• means for supporting the mandrel for rotation about its axis,
• means for rotating said mandrel,
• energy source means for directing an energy beam at said mandrel,
• said energy source including means for shaping said beam into a selected configuration at said mandrel, and
• means for shifting said energy source means along said mandrel.

A method for making a helix derived device comprising the steps of:

• forming an elongated cylindrical mandrel,
• applying a coating of photo resist to said mandrel,
• processing said photo resist to form a pattern of photo resist having a plurality of helical turns that wind around said mandrel to provide a first helical pattern between adjacent ones of said helical turns, and a second helical pattern in registration with said helical turns of said photo resist,
• applying a pattern of device material to said mandrel in registration with one of said first and second helical patterns,
• removing said pattern of photo resist from said mandrel and pattern of device material, and
• removing said mandrel from said device material.