Stage lighting fixture
A stage lighting fixture having: a casing having a closed first end and an open second end; a light source housed inside the casing, close to the first end, and which emits a light beam along an optical axis; an optical assembly positioned to intercept the light beam, and having a focal point located between the light source and the optical assembly; and a reflector coupled to the light source; the reflector and the light source being designed and coupled to concentrate the light beam substantially at a work point substantially coincident with the focal point of the optical assembly; and the light source being defined by a short-arc lamp to project a light bar.
1. A stage lighting fixture comprising:
a casing having a closed first end and an open second end;
a short arc lamp which is housed inside the casing, close to the first end, and which emits a light beam along an optical axis;
a reflector coupled to the light source;
an output optical assembly spaced from the reflector and positioned to intercept the light beam, and having a focal point located between the short arc lamp and the optical assembly;
the reflector and the short arc lamp being designed and coupled to concentrate the light beam substantially at a work point substantially coincident with the focal point of the output optical assembly; and
processing means which is configured to process the light beam and is located between the light source and the optical assembly; the processing means comprising at least one light beam processing element being located substantially at the work point.
2. A lighting fixture as claimed in claim 1 , wherein the short-arc lamp comprises a bulb containing two electrodes connected to a power circuit and spaced a first distance apart.
3. A lighting fixture as claimed in claim 2 , wherein the first distance between the electrodes is less than roughly 2 mm.
4. A lighting fixture as claimed in claim 3 , wherein the first distance between the electrodes is roughly 1 mm.
5. A lighting fixture as claimed in claim 1 , wherein the reflector has an outer edge; the work point being located a second distance from the outer edge of the reflector.
6. A lighting fixture as claimed in claim 5 , wherein the second distance is roughly 34.5 mm.
7. A lighting fixture as claimed in claim 1 , wherein the light beam processing elements comprise at least one diffuser glass.
8. A lighting fixture as claimed in claim 1 , wherein the light beam processing elements comprise at least one colour assembly.
9. A lighting fixture as claimed in claim 1 , wherein the light beam processing elements comprise at least one prismatic lens.
10. A lighting fixture as claimed in claim 1 , wherein the light beam processing elements comprise at least one gobo assembly.
11. A lighting fixture as claimed in claim 10 , wherein the gobo assembly comprises at least one disk having a number of gobos for intercepting the light beam; the gobo assembly being positioned so that the gobo in use is located substantially at the work point.
12. A lighting fixture as claimed in claim 1 , wherein the optical assembly is movable to adjust the position of the focal point.
13. A lighting fixture as claimed in claim 1 , wherein the optical assembly comprises a biconcave first lens.
14. A lighting fixture as claimed in claim 13 , wherein the optical assembly comprises a biconvex second lens coupled to the biconcave first lens.
15. A lighting fixture as claimed in claim 14 , wherein the optical assembly comprises a biconvex third lens located a third distance from the biconvex second lens.
16. A lighting fixture as claimed in claim 15 , wherein the third distance is roughly 1 mm.
17. A stage lighting fixture comprising:
a casing having a closed first end and an open second end;
a light source comprising a short arc lamp which is housed inside the casing, close to the first end, and which emits a light beam along an optical axis;
a reflector coupled to the light source; and
an output optical assembly spaced from the reflector and positioned to intercept the light beam, and having a focal point located between the light source and the optical assembly;
the reflector and the light source being designed and coupled to concentrate the light beam substantially at a work point substantially coincident with the focal point of the output optical assembly so as to emit a sharp, substantially cylindrical ‘light bar’ intended to as a narrow, aligned, well defined, highly concentrated light beam.
18. A stage lighting fixture comprising:
a casing having a closed first end and an open second end;
a short arc lamp which is housed inside the casing, close to the first end, and which emits a light beam along an optical axis;
a reflector, which is coupled to the short-arc lamp to direct the light beam along an optical axis; is shaped and spaced apart from the short-arc lamp to concentrate the light beam substantially at a work point located along the optical axis; and
an output optical assembly, which is located at the second end of the casing, is configured to have a focal point located along the optical axis, and is spaced apart from the short-arc lamp so that the focal point coincides with the work point;
wherein the optical assembly comprises a biconcave first lens (L 1 ), a biconvex second lens (L 2 ), a biconvex third lens (L 3 ), and a frame supporting the first, second and third lenses (L 1 , L 2 , L 3 ), whereas the second lens (L 2 ) and the third lens (L 3 ) are spaced apart by a distance, preferably of roughly 1 mm; wherein the first, second and third lenses (L 1 , L 2 , L 3 ) are provided with the following characteristics, where the terms ‘face a’ refers to the beam entry face, and ‘face b’ to the beam exit face of the respective lens:
RADIUS OF
LENS
CURVATURE
THICKNESS
DIAMETER
L1 face a
201.037
5
108
L1 face b
150.063
108
L2 face a
150.063
30.700
108
L2 face b
86.321
108
L3 face a
249.812
19.30
130
L3 face b
249.812
130.