Medical headlamp optical arrangement permitting variable beam width
A medical headlamp having a front from which light is selectively emitted. The headlamp includes a beam origination portion that produces a light beam and an iris assembly, positioned in front of the beam origination portion, having a user accessible actuator and an iris, responsive to the actuator to block a user selectable portion of the light beam. The iris is also responsive to the actuator to block none of the light beam, for maximum efficiency, when a user so selects.
1. A medical headlamp having a front surface from which a lamp light beam is emitted, comprising:
(a) a high efficiency light source assembly including a high efficiency light source producing a first light beam and a dome lens substantially placed immediately in front of said high efficiency light source;
(b) an annular light block, defining an annulus and placed about said dome lens so that said lens protrudes through said annulus to block a peripheral portion of said first light beam, thereby creating a second light beam extending from said light block, said second light beam having a crisper boundary than said first light beam;
(c) an optical assembly positioned to receive light from said high efficiency light source and produce said lamp light beam emitted from said front surface of said medical headlamp;
(d) a housing supporting said light source and said optical assembly and an electrical conductor connected to said light source, for supplying electricity to said light source; and
(e) wherein said optical assembly includes an adjustable iris assembly in front of said annular light block and including a user accessible actuator, moveable over a range of motion, and an iris that is adjustable by said actuator, either to be retracted, thus leaving unaffected said second light beam from said light block, or to be tightened to block a portion of said second light beam from said annular light block, thus producing a thinner lamp light beam.
2. The medical headlamp of claim 1 , wherein said high efficiency light source is a light emitting diode.
3. The medical headlamp of claim 1 , wherein said optical assembly includes a prime lens and an exit lens.
4. The medical headlamp of claim 3 , wherein a portion of said actuator's range of motion retracts and tightens said iris over a range that does not block said light beam from said light block, and over said portion of said actuator's range of motion said exit lens is moved forward or backward by said actuator.
5. The medical headlamp of claim 3 , wherein said exit lens is not moved by said user accessible actuator.
6. The medical headlamp of claim 5 , wherein said exit lens is focused on said iris.
7. The medical headlamp of claim 3 , wherein said exit lens is a doublet lens.
8. The medical headlamp of claim 1 , wherein when said iris is expanded to leave said light beam unaffected, said headlamp light beam has a circular edge wherein light intensity decreases by 20 dB over 0.5° from a position inside said headlamp light beam to a position outside said headlamp light beam.
9. The medical headlamp of claim 1 , wherein more than 70% of the light produced by said high efficiency light source is emitted in said lamp light beam.