"Lumière ponctuelle" is correct, but sounds rather odd and outdated. I have never heard or read it in real life. "Eclairage ponctuel * " or mostly "éclairage dirigé" are the usual names for the concept (the more common opal lamp / condenser lighting system being referred to as "éclairage semi-dirigé"). "Source ponctuelle", as said in the patent, is the common way to refer to the this type of bulb.
* Be aware that "éclairage ponctuel" is mostly used in studio or room lighting, to designate a projector creating a localized spot of light in the scene/room, so using this expression is easily misleading if you don't specify that you are talking about an "agrandisseur à éclairage ponctuel". The expression "éclairage dirigé" is unambiguous.
No problem at all Yes, in French we call it a head too. "Une tête à lumière dirigée" is perfectly correct. "Une tête à source ponctuelle" is equally good.
If you mean a point light Durst head, then you would say "Une tête de Durst L1000 à éclairage dirigé". If you talk about the whole enlarger, then it would be "Un Durst L1000 avec une tête à éclairage dirigé". There is no neutral word in the French grammar: a head, a bulb and light are feminine, an enlarger and lighting are masculine.