JPH01209651A - High luminance arc discharge light source utilizing magnetic field or electric field for arc position control - Google Patents

Abstract

PURPOSE: To permit a high luminance arc discharge by controlling the offset of an arc by the action of a magnetic field to be controlled, which is generated in an arc region so as to offset a portion of the arc. CONSTITUTION: An electromagnetic field B having a component perpendicular to an arc 14 is generated in a region of the arc 14, and the magnetic field B for offsetting a portion of the arc 14 is controlled to adjust the offset of the arc 14. When an arc lamp 20 is employed in an optical system, the offset of the arc 14 can be utilized to regulate a light beam direction, a light beam focus or a light beam intensity. Moreover, the arc lamp 20 can be activated by using a DC power source or an AC power source having a prescribed frequency, thus making possible a high intensity arc discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, a high intensity arc discharge lamp is controlled by application of a magnetic field to an arc within the arc discharge lamp.

By varying the magnetic field in a controlled manner, the position of the arc within the arc lamp is controlled. Control of an arc accompanied by a magnetic field will be explained with reference to FIGS. 1A to 1D. In each of FIGS. 1A-1D, a bright arc discharge is formed between a pair of electrodes 10 and 12. In FIGS. It will be appreciated that an arc is formed in an arc tube containing a filler material that ionizes and forms an arc discharge upon application of an appropriate operating voltage, metal halide lamps in which a distinct arc is formed between a pair of electrodes, mercury vapor, etc. Magnetic fields can be used to control the position of the arc in lamps, high pressure canadium lamps, or other arc discharge lamps. The details of the configuration of the arc discharge lamp will be omitted for simplicity. This is because they are well known in the art and do not form an essential part of the present invention.

An arc 14 without any applied magnetic field is illustrated in FIG. 1A. An arc axis 16 is defined as a straight line between electrodes 10 and 12. When the arc discharge lamp is operated with the arc axis 16 in a horizontal orientation,
The arc 14 arcs upward as a result of convective currents within the arc tube.

Referring to FIG. 1B, a magnetic field B is applied to the arc 14, causing the arc to be deflected from the position shown in FIG. 1A. The arc 14 consists of a plasma of charged particles and has a current i associated with it between the electrodes 10 and 12. The magnetic field B interacts with the current i and a force F8 is generated on the charged particles of the arc 14. The resulting force Fa is perpendicular to the direction of the current i and the direction of the magnetic field B. In general, the magnetic field can have any desired direction, but must have at least a component perpendicular to the arc 14, since the perpendicular component determines the force FB of the arc 14. Additionally, a magnetic field must be exposed to the area of the arc 14 to interact with the charged particles moving within the arc. According to the well-known principles of electromagnetism, the force Fe is given by Fa = 1 l B sin θ (where i is the plasma current and l is the
2, B is the applied magnetic field, and θ is the angle between the plasma current i and the magnetic field B). As illustrated in FIG. 1B, arc 14 is biased downwardly to coincide with arc axis 16. In FIG. 1C, the magnitude of the magnetic field is increased so that arc 14 is biased below arc axis 16. It will be appreciated that the ends of arc 14 terminating in electrodes 10 and 12 are not biased by the magnetic field; the portion between the ends of arc 14 is the portion that is biased.

Although the applied magnetic field B is illustrated in FIGS. 1B and 1C as resisting upward curvature of the arc due to convective currents, the arc tube can have any desired orientation; It will be appreciated that the magnetic field B can also have any desired orientation for the arc, under conditions having at least a component perpendicular to the arc 14. By increasing or decreasing the magnitude of the magnetic field B, the deflection of the arc 14 is controlled from its normal position in the manner described in detail below.

In order for the magnetic field to produce a fixed arc deflection in the arc lamp, it is necessary that the magnetic field and the arc current have a fixed instantaneous directional relationship. This is easily accomplished in the case of DC lamps where both the direction of the arc current and the direction of the magnetic field are fixed except when movement of the arc is desired.

In the case of alternating current arc lamps, the current direction is continuously changing and it is necessary to apply a magnetic field with a similar frequency and fixed phase with respect to the arc current.

Thus, the magnetic field and arc current follow each other such that a fixed excursion occurs. If this relationship is not maintained, an effective expansion motion of the beam will occur.

In an arc lamp operated from a DC power supply, the arc current i
has constant magnitude and direction. In this case, the application of a DC magnetic field results in a fixed deflection of the arc 14. The direction of the deflection is perpendicular to the direction of the arc current and the applied magnetic field. The magnitude of the deflection is a function of the magnitude of the applied magnetic field.

For arc lamps operated from an AC power source, the arc current varies in a sinusoidal manner and the DC magnetic field causes a sinusoidally varying force to be applied to the arc. The effect is that the arc oscillates rapidly and appears to the human eye as unwidened or expanded. In order to obtain a fixed excursion of the arc with an alternating arc current, it is necessary to apply a magnetic field with a time variation similar to the arc current. For example, when the arc current varies sinusoidally, a constant direction and magnitude excursion is produced by a magnetic field having a frequency similar to the arc current and being phase locked with respect to the arc current. This can actually be achieved by activating the lamp and the magnetic field from the same alternating current source. Arc excursion can be varied by changing the magnitude of the alternating magnetic field and maintaining a fixed phase and similar frequency for the arc current. The direction of arc excursion can be reversed by reversing the phase of the magnetic field with respect to the arc current.

In various cases, as will be explained in more detail below, it is desirable to extend the arc so that it is wider than normal in order to change the focus of the light beam. Expansion of the arc 14 can be accomplished as illustrated in FIG. 1D by applying an alternating magnetic field to an arc having a direct current, or by applying a direct magnetic field to an arc having an alternating current. Alternatively, an alternating current arc can be extended by an alternating magnetic field having a frequency different from that of the arc current. In each case, the resulting force on the beam is time-varying, resulting in a time-varying arc excursion that manifests as arc expansion motion. The magnetic fields required for alternating current and direct current arcing currents are summarized in Table 1.

Table 1 Arc current Since the deflection is fixed Magnetic field of arc expansion Magnetic field for operation Alternating current The same as for arc current Frequency of arc current and fixed Alternating current or direct current of a frequency different from the frequency Alternating current or direct current Direct current Direct current AC magnetic An optical system utilizing an arc lamp with an arc biased to is illustrated in FIG. An arc lamp 20, such as a metal halide arc lamp, is oriented with its arc axis 22 in a horizontal direction. Arc lamp 20 may be a metal halide lamp. The power source for arc lamp 20 has been omitted from FIG. 2 for simplicity.

This is because arc lamp power supplies are well known in the art. An image of the arc 21 of the arc lamp 20 is focused by a lens 24 on an aperture plate member having an aperture 28. - In an exemplary embodiment, the second
The illustrated optical system is a projection optical system in which a projection lens 29 projects an image of the aperture 28 to form a beam pattern 30 on a projection screen (not shown). Optical axis 34 passes through arc 21, lens 24, aperture 28 and projection lens 29.

A magnetic device 32 generates a magnetic field parallel to the optical axis 34. The magnetic field biases the arc 21 upwardly or downwardly in a direction perpendicular to the optical axis 34. As a result, the image of arc 21 is biased with respect to aperture 28 and the intensity of beam pattern 30 changes.

In a preferred example, arc lamp 20 is energized by a 60 hertz AC power source. Magnetic device 32 comprises a conductive coil 40 oriented in a plane perpendicular to optical axis 34 and positioned close to arc 21 . Coil 40 comprises multiple turns of electrical conductor coupled to control unit 44 through transformer 42 . Control unit 44 receives 60 hertz AC power and provides current to coil 40 controlled by control signals. The magnitude of the magnetic field produced by coil 40 is a function of the alternating current supplied through the coil. Therefore, the control signal directly controls the position of the arc 21 and the intensity of the beam pattern 30. Control unit 44 may be a variable transformer or any other suitable device for controlling the current supplied to coil 40.

Another optical system is illustrated in FIG. 3 that utilizes an arc lamp having an arc that is controllably biased by a magnetic field. Arc lamp 50 is oriented such that its arc axis coincides with optical axis 52. In the arc lamp 50, the arc 54 inside the arc lamp 50 is a reflector (standardly an elliptical reflector).
is positioned so that it is at the focal point of Reflector 56 reflects a portion of the light from arc lamp 50 to form a light beam 58 in the direction of optical axis 52 . The light beam 58 illuminates an aperture plate member 6o having an aperture 62. A portion of the light beam 58 passes through an aperture 62 and is focused by a projection lens 64. A focused light beam can be used for projection.

A magnetic device 68 that generates a magnetic field perpendicular to the optical axis 52 includes an electrically conductive coil 70 positioned near the arc.

Preferably, the plane of the coil 70 is perpendicular to the optical axis 52. A coil 70 includes multiple turns of electrical conductor and is coupled through a transformer 72 to a control unit 74 . Control unit 74 receives AC power from a suitable source and supplies current to coil 70 under the control of control signals. The current supplied to coil 7o creates a magnetic field in arc 5 that causes arc 54 to be biased with respect to the focal point of reflector 56.
Generated in area 4. The deflection of arc 54 in turn causes beam 58 to change direction and shift with respect to aperture 62. As a result, the intensity of beam pattern 64 is varied as a function of the magnetic field applied to arc 54.

A vehicle headlight incorporating a high intensity arc discharge lamp and means for arc deflection using a controllable magnetic field is illustrated in FIGS. 4-6. Arc lamp 80 is positioned at focal point 83 of reflector 84 . During normal use, the arc lamp 80
The arc 86 in 0 is positioned horizontally and perpendicular to the axis 82 of the reflector 84. A headlight lens 88 is positioned on axis 82 in front of reflector 84 . When the reflector 84 is a parabolic reflector,
Arc lamp 80, reflector 84 and headlight lens 8
8 produces a substantially collimated light beam 90 suitable for illuminating the path ahead of the vehicle.

A coil 92 is mounted within reflector 84 in close proximity to arc lamp 80 . Coil 92 is comprised of multiple turns of electrical conductor oriented such that a magnetic field is generated parallel to axis 82 and through arc lamp 80 . When arc lamp 80 is activated by AC power, coil 92 is supplied with AC current from control unit 96 through transformer 94 .

As mentioned above, the alternating current supplied through coil 92 should be of similar frequency and phase locked with respect to the arc current of arc lamp 80. As explained below, by varying the current supplied to coil 92, arc 86 is biased upward or downward about the focal point and the direction of beam 90 is directed upward or downward. A control unit 96 receives AC power from a suitable power source, typically a vehicle DC/AC converter, and controls the current through the coil 92 in response to control inputs from a sensor or switching means 98.

In a preferred example, the arc lamp 80 is an oblong shaped 4
It is a 5 Watt metal halide arc lamp. This lamp has a total length of about 4 cm, an arc length of about 5 mm, and operates with 90 volts AC and 0.
．． Requires 5 amps. A preferred coil 92 utilizes approximately 30 turns of 24 gauge 0.022 inch diameter enamelled wire wrapped around an insulating sleeve 99. Referring to FIG. 6, lamp leads 80a, 80b and coil leads 92a, 92b.
is connected through sleeve 99 and reflector 84 and to a suitable power source.

The operation of the vehicle headlights illustrated in FIGS. 4-6 in producing upper and lower beams is illustrated in FIGS. 7A and 7B. In FIG. 7A, arc 86 is aligned with axis 8.
In this example, the light beam 90 is directed parallel to the axis 82 by a reflector 84,
Arc 86 is maintained at focal point 83 by magnetic field B supplied by coil 92. Referring to FIG. 7B, arc 86 is displaced upwardly with respect to focal point 83. In this example, the upward displacement is caused by removal or turn-off of the applied magnetic field. Light beam 90 is directed here at a downward angle with respect to axis 82 by reflector 84 . Thus, a high position beam and a low position beam controlled by the magnetic field B from the coil 92 are provided.

It will be appreciated that the selection of magnetic fields to generate the high and low positions is a matter of design choice. As an alternative to the configuration described above, the application of a magnetic field causes the arc 86 to move to the focal point 8.
3 as shown in FIG. 7B, while removal of the magnetic field positions the arc 86 at the focal point 83 as shown in FIG. 7A. Furthermore, the high and low positions can be set by two different magnitudes of magnetic fields, rather than the on and off states.

Another important feature is that the vehicle headlights disclosed herein are not limited to high and low beams. Instead, the angle between light beam 90 and axis 82 can be varied continuously between upper and lower limits depending on the desired operation. - In the example, beam 9
0 is controlled between high and low beam positions by a photocell or footswitch or hand switch that senses the headlights of an approaching vehicle. In another example, the direction of light beam 90 is controlled by a level sensor mounted on the vehicle. The level sensor detects out-of-level (out-of-level) signals when the vehicle rises or falls or leans from side to side when going around a corner.
-of-1 level) provides an instruction signal. The out-of-level indication signal is provided to control unit 96 so that the direction of light beam 90 is adjusted as desired. Any other desired sensor, switch means or control device
It will be appreciated that it can be used to control the direction of light beam 90.

Reflector 84 need not be parabolic, but can be oval, spherical, or any other shape. As illustrated in FIG. 8, arc lamp 91 can be oriented such that the arc axis coincides with axis 93 of reflector 95. In this case, the coil is positioned either to the left or right of the arc lamp 91 to obtain a magnetic field perpendicular to the axis 93 and an upward or downward arc deflection.
'Alternatively, two (or more) coils 100, 101 can be used for biasing the arc.

As illustrated in FIG. 8, coils 100 and 101
are positioned on opposite sides of arc lamp 91. The coils 100, 101 are rectangular or otherwise shaped so that interference between the arc lamp 91 and the reflector 95 is minimized as much as possible. A similar power supply or a separate power supply can be used to energize coil too, 101. However, the above relationship between arc current and magnetic field must be maintained. Standardly,
The size and shape of the reflector depends on the size of the arc lamp,
The selection is complementary to the shape and orientation.

According to another feature of the invention, a magnetically controlled arc lamp can be utilized to focus or defocus the light beam, as illustrated in FIG. An arc lamp 102 is connected to an axis 10 at a focal point 106 of a reflector 108.
4. Arc 1 in arc lamp 102
10 is oriented perpendicular to axis 104. When no magnetic field is applied, the arc 110 is relatively small and dense and a focused light beam 112 is generated. To defocus and expand the light beam, a magnetic field is applied to the arc 1 as illustrated in FIG. 1D and as described above.
10 is applied. In order to expand the light beam rather than deflect it in some fixed direction, the magnetic field must be time-varying with respect to the arc current; if a DC arc lamp is used, the magnetic field is alternating; When arc lamps are utilized, the magnetic field is direct current or alternating current at a different frequency than the arc current. The required magnetic field is provided by a coil 114 positioned at axis 104 to generate a magnetic field through arc 110 along axis 104. The magnetic field causes an expanding motion of the arc, as indicated by reference numeral 116, to defocus and produce an expanded light beam 118.

Arc excursion has been described in terms of the force exerted by a magnetic field on the moving charged particles of an arc. Arc deflection can also be achieved by applying an electric field, as illustrated in FIG. An arc 130 is formed between the pair of electrodes 132,134. at least arc 13
An electric field E having a component perpendicular to
is applied to the area of the arc 130. When a voltage is applied between bias plate members 136 and 138, an electric field E is generated therebetween. Biasing plate members 136, 138 may have any convenient size or shape to generate the desired electric field E in the region of arc 130. Electric field E biases arc 130 in a manner similar to an applied magnetic field (the force is perpendicular to applied magnetic field B), except that the force on arc 130 is parallel to electric field E. The arc excursion configuration illustrated in FIG. 10 can be utilized in the optical systems illustrated in FIGS. 2-9 and described above.

Although preferred examples of the present invention have been described above, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the technical idea of the present invention.

Figure 1A is a schematic diagram illustrating the upward curving motion of the arc due to convection current.

FIGS. 1B to 1D are schematic diagrams illustrating deflection of an arc due to a magnetic field.

FIG. 2 is a schematic diagram of a high-intensity arc discharge light source with controllable intensity.

FIG. 3 is a schematic diagram of a high-intensity discharge light source whose intensity can be controlled.

FIG. 4 is a side view of a vehicle headlight whose beam direction is magnetically controlled.

FIG. 5 is a plan view of the vehicle headlight of FIG. 4 with the reflector removed.

FIG. 6 is a partially cut-away perspective view of a vehicle headlight with magnetically controlled beam direction.

7A and 7B are side views of the vehicle headlight of FIG. 4 illustrating the high and low beams.

FIG. 8 is a simplified perspective view of a vehicle headlight in which the arc lamp is aligned with the axis of the reflector.

FIG. 9 is a schematic diagram of a spotlight whose focus adjustment is controlled magnetically.

FIG. 10 is a schematic diagram illustrating the deflection of an arc due to an electric field.

The main names indicated by each reference number in the figure are listed below.

010 Electrode 012 Electrode 014 Arc 016 Arc axis 020 Arc lamp 021 Arc 022 Arc axis 024 Lens 026 Aperture plate 028 Aperture 029 Projection lens 030 Beam pattern 034 Optical axis 040 Coil 044 Control unit 050 Arc lamp 052 Optical axis 054 Arc 056 Reflector 058 Light beam 062 Aperture 064 Projection lens 068 Magnetic device 070 Coil 072 Transformer 074 Control unit 080 Arc lamp 080a, b Lamp lead 082 Axis 083 Jiayu 084 Reflector 086 Arc 088 Lens 090 Collimated light beam 091 Arc lamp 092 Coil 093 Axis 094 Transformer 095 Reflector 096 Control unit 098 Sensor, switching means 099 Insulating sleeve 100 Coil 101 Coil 104 Axis 106 Past 108 Reflector 110 Arc 112 Light beam 116 Arc spread 118 Defocusing light beam 130 Arc 132 Electrode 134 Electrode 136 Biasing plate 138 Biasing plate B Magnetic field F, force/'

Claims (36)

[Claims] (1) an arc lamp for generating a high-intensity arc between a pair of electrodes; and a magnetic means for generating a magnetic field in the area of the arc, the magnetic field being such that a portion of the arc a high intensity arc discharge light source comprising: magnetic means having at least a component perpendicular to the arc so as to be biased by the arc; and means for controlling the deflection of the arc by controlling the magnetic field. (2) the arc lamp is activated by an alternating current power source of a predetermined frequency; the magnetic means includes means for generating an alternating current magnetic field of the predetermined frequency; and the magnetic field and the alternating current power source have a fixed phase relationship. The light source according to claim 1, having: 3. The light source of claim 1, wherein said arc lamp is activated by a DC power source and said magnetic means includes means for generating a DC magnetic field. (4) The light source according to claim 3, wherein the control means includes means for changing the magnitude of the DC magnetic field so as to change the deflection of the arc. (5) The light source according to claim 2, wherein the control means includes means for changing the magnitude of the alternating magnetic field so as to change the deflection of the arc. (6) The light source according to claim 2, wherein the control means includes means for changing the phase of the alternating current magnetic field with respect to the phase of the alternating current power supply that activates the arc lamp. (7) The magnetic means comprises a conductive coil near the arc and means for supplying a current through the coil, and the conductive coil generates the magnetic field perpendicular to the plane of the arc. Light source listed. 8. The light source of claim 7, wherein said coil is oriented to generate said magnetic field perpendicular to said arc. (9) The light source according to claim 8, wherein the arc lamp is a metal halide arc lamp. 10. The light source of claim 2, wherein the arc lamp is oriented in a substantially horizontal direction during normal use. 11. The light source of claim 1, wherein said magnetic field has a fixed instantaneous directional relationship with the direction of current in said arc such that said magnetic field produces a fixed arc excursion of short duration. 12. The light source of claim 1, wherein said magnetic field has a time-varying instantaneous directional relationship with the direction of current in said arc such that said magnetic field produces a time-varying arc excursion. (13) positioned to reflect a portion of the light from the arc lamp to form a beam of light, thereby
13. The light source of claim 12, wherein the light beam includes reflecting means for focusing and defocusing the light beam as the magnetic field changes. (14) An arc lamp that generates a high-intensity arc between a pair of electrodes, and a magnetic means for generating a magnetic field in the region of the arc, the magnetic field being such that a portion of the arc is deflected by the magnetic field. magnetic means having at least a component perpendicular to the arc; means for defining an aperture; means for focusing an image of the arc onto the aperture; and controlling the magnetic field to control the aperture. and means for controlling the intensity of light passed therethrough. (15) the arc lamp is activated by an alternating current power supply having a predetermined frequency; the magnetic means includes means for generating an alternating current magnetic field having the predetermined frequency; and the magnetic field and the alternating current power supply have a fixed phase. Related claim 1
The light source according to item 4. 16. The light source of claim 14, wherein said arc lamp is activated by a DC power source and said magnetic means includes means for generating a DC magnetic field. (17) The magnetic means comprises a conductive coil near the arc and means for supplying a current through the coil, and the conductive coil generates the magnetic field perpendicular to the plane of the arc. Light source listed. (18) the arc includes a flow of charged particles constituting an arc current, and the magnetic field has a short-term fixed directional relationship with the direction of the arc current such that the magnetic field produces a short-term fixed arc excursion; 15. The light source according to claim 14, having: 19. The light source of claim 14, wherein said magnetic field has a time-varying instantaneous directional relationship with the direction of current in said arc such that said magnetic field produces a time-varying arc excursion. (20) An arc lamp that generates a high-intensity arc between a pair of electrodes, and a magnetic means for generating a magnetic field in the region of the arc, the magnetic field being such that a portion of the arc is deflected by the magnetic field. a magnetic means having at least a component perpendicular to said arc so as to be directed to said arc; and reflecting means positioned to reflect a portion of the light from said arc lamp to form a beam of light in a predetermined beam direction; and means for controlling said beam direction by controlling a magnetic field. (21) The reflecting means is composed of a parabolic reflector,
21. The light source of claim 20, wherein the arc is positioned at or near the axis of the parabolic reflector. 22. The light source of claim 20, further comprising means for defining an aperture positioned in the path of the light beam. (23) A method for controlling the deflection of an arc in a high-intensity arc discharge lamp, comprising: providing a magnetic field in the region of the arc having at least a component perpendicular to the arc, such that a portion of the arc is deflected by the magnetic field; controlling a magnetic field to control arc deflection in a high intensity arc discharge lamp. (24) energizing the arc lamp with an alternating current power source having a predetermined frequency, the step of providing a magnetic field in the area of the arc includes the step of energizing the arc lamp with an alternating current magnetic field of the predetermined frequency having a fixed phase relationship with respect to the alternating current power source; 24. A method of controlling arc excursion in a high intensity arc discharge lamp as claimed in claim 23, comprising providing: (25) The method for controlling arc deviation in a high-intensity arc discharge lamp according to claim 24, wherein the step of controlling the deviation of the arc comprises the step of changing the deviation of the arc by changing the magnitude of the alternating magnetic field. . (26) providing a magnetic field in the region of the arc comprises providing a magnetic field having a fixed instantaneous directional relationship with the direction of current in the arc such that the magnetic field produces a short term fixed arc excursion; A method for controlling arc excursion in a high intensity arc discharge lamp according to claim 23. (27) The step of providing a magnetic field in the region of the arc comprises providing a magnetic field having a time-varying instantaneous directional relationship with the direction of current in the arc so that the magnetic field produces a time-varying arc excursion. 24. A method for controlling arc excursion in a high-intensity arc discharge lamp according to item 23. (28) positioning an arc lamp at a focal point of a reflector to form a beam of light, the step of controlling deflection of the arc comprising biasing the arc with respect to the focal point to change the direction of the beam of light; 24. A method for controlling arc excursion in a high intensity arc discharge lamp as claimed in claim 23. (29) An arc lamp that generates a high-intensity arc between a pair of electrodes, and means for generating an electromagnetic field in a region of the arc, the electromagnetic field being such that a portion of the arc is caused by the magnetic field. A high intensity arc discharge light source comprising: means having at least a component perpendicular to the arc so as to be biased; and means for controlling the deflection of the arc by controlling the magnetic field. (30) The high-intensity arc discharge light source according to claim 29, wherein the means for generating an electromagnetic field generates a magnetic field. (31) The high-intensity arc discharge light source according to claim 29, wherein the means for generating an electromagnetic field generates an electric field. 32. The high intensity arc discharge light source of claim 29, further comprising optical means positioned to direct a portion of the light from said arc lamp to form a beam of light. (33) an arc lamp for generating a high-intensity arc between a pair of electrodes; an optical means positioned to guide a portion of the light from the arc lamp to form a light beam; means for generating an electromagnetic field in the region of the arc for interacting with the arc and for deflecting the arc from its normal path. (34) The high-intensity arc discharge light source according to claim 33, wherein said optical means comprises a reflector. (35) the optical means defines an aperture;
34. The high intensity arc discharge light source of claim 33, further comprising means for focusing an image of said arc onto said aperture. (36) A method for controlling arc deviation in a high-intensity arc discharge lamp, comprising: providing in the area of the arc an electromagnetic field having at least a component perpendicular to the arc, and a portion of the arc being deflected by the electromagnetic field; controlling an electromagnetic field to control arc deflection in a high intensity arc discharge lamp.