Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J1/00—Photometry, e.g. photographic exposure meter
  • G01J1/10—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void
  • G01J1/20—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle
  • G01J1/22—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle using a variable element in the light-path, e.g. filter, polarising means
  • G01J1/24—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle using a variable element in the light-path, e.g. filter, polarising means using electric radiation detectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
  • F21V9/40—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters with provision for controlling spectral properties, e.g. colour, or intensity
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/005—Diaphragms
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems

Definitions

• the present invention relates to a method for the continuous variation of the luminance of an illuminable image area, which variation is produced with a diaphragm arrangement which acts on a light beam directed onto this image area, and an apparatus for carrying out this method.
• Such methods and devices are used in many optical devices and are of particular importance in lighting technology.
• such lighting devices are used in medicine and for the technical inspection of cavities, by means of which the necessary examinations and manipulations can also be carried out without direct visual contact, for example together with technical or medical endoscopes.
• Such lighting devices preferably additionally contain a heat protection filter, which is arranged between the light source and the entrance of the fiber optics, in order to avoid the entry of heat radiation into the fiber optics.
• Such lighting devices are therefore also referred to as cold light sources.
• the luminous flux or the luminous intensity of the light source can be controlled by changing the supply voltage or the phase angle of the supply voltage.
• the color temperature of the light source and consequently also the color of the illuminated object are changed, which is particularly disadvantageous is when the image of the mirror instrument is to be photographed or taken with a television camera.
• the range in which the light intensity can be changed with a gray wedge is, however, limited and, in particular, does not allow the light to pass through unhindered and thus the maximum illumination of the cavity.
• An iris diaphragm changes the diameter of the light bundle and thus the light entry and exit angles in or out of the fiber optics, and with a sector or fan diaphragm a sector remains in the light bundle even when fully open and prevents, similar to the gray wedge, the maximum possible illumination of the cavity.
• the conventional sickle or slit diaphragms also enable the control of the light flow of a fiber optic light source at a constant color temperature.
• the angular distribution of the light at the light guide exit is significantly less dependent on the diaphragm position, so that for visual applications the constancy of the illuminance distribution on the object is fully sufficient.
• the use of the sickle screen can also be problematic.
• a cold light source and a method for brightness control are described in DE-A-33 * 39 '522.
• the method described in this document uses a control element for regulating the light output and a pulse width control circuit for stabilizing the light source and cannot prevent the color temperature from changing sensitively when regulating the light intensity.
• ÜS-A-4 '233' 650 a diaphragm arrangement of three rings is disclosed, with which the light beam can be covered sector by sector.
• the light intensity can thus be continuously regulated without changing the color temperature.
• the spatial angular distribution of the light beam and thus also the spatial angular distribution of the luminance of the illuminated object become asymmetrical, which leads to inhomogeneities of the brightness in the observation field, in particular in the case of electronic image evaluation, since this angular distribution leads to slight smearing and cropping the total reflection condition, the mean polar angular distribution, which corresponds to the light guide from the projection system, ie Lamp, condenser, aperture, is offered on the entry side.
• a change in the angular distribution on the entry side of the light guide immediately results in a change in the distribution of the illuminance over the object.
• the light flow from the light source should not be impeded when the opening is fully open, and neither the color temperature of the light source nor the spatial angular distribution of the light bundle entering or leaving the fiber optics should be changed when the lighting is changed, and the light losses should be reduced to a minimum .
• the new lighting method enables the light falling on the entrance surface of the fiber optic to be changed continuously without influencing the color temperature or the light entry angle and without impeding the maximum possible light flow.
• the light beam is no longer covered with a gap, i.e. Wedge or sickle, but through several columns at the same time.
• a gap i.e. Wedge or sickle
• the diaphragm arrangement is arranged on a rotatable disc having a plurality of mutually parallel sickle openings, which open into an aperture opening that is open to the entire light beam.
• FIG. 1 shows a schematic plan view of an illumination device for carrying out the method according to the invention
• Fig. 2 is a schematic representation of the conventional
• FIG. 3 shows a schematic illustration of the variation according to the invention of the illuminance of a light beam
• FIG. 6 shows a diagram of the brightness distribution with a double sickle screen according to the invention
• FIG. 7 shows a diagram of the brightness distribution with a five-fold sickle diaphragm according to the invention.
• FIG. 1 schematically shows the top view of a lighting device, the cover of which has been removed.
• the device contains a housing 1 which by means of a Partition 11 is divided into two chambers 12, 13.
• a light source 16 is arranged in the first chamber 12 and adjacent to the center of the partition.
• This light source contains a glass bulb 17 with an incandescent ribbon and a cold light mirror 18, which is transparent to heat radiation.
• the base of the light source is inserted into an opening 19 in the partition. The diameter of this opening is considerably larger than the diameter of the lamp base in order to allow cooling air to flow through.
• a connecting piece 21 for a fiber optic 22 is fastened in the front wall 20 of the housing and practically opposite the lamp.
• the fiber optic can be screwed into the connector, inserted or held with a bayonet catch.
• a cooling element 24, which is provided for guiding cooling air, is arranged on the inside of the front wall and the entry surface 23 of the fiber optics.
• an interference filter 25 is installed in front of the entry surface of the fiber optics, with a coating facing the light source and reflecting IR radiation.
• the cold light mirror 18 on the light source 16 and the interference filter 25 reduce the proportion of IR radiation in the light impinging on and transmitted by the fiber optics. In particular, heating of the fiber optics is to be avoided in this way because with longer exposure to heat the adhesive located between the individual fibers softens and the fiber optics can be adversely affected or even destroyed.
• An aperture 26 according to the invention is installed in the path of the light bundle along the bundle axis 35 between the light source 16 and the interference filter 24.
• the aperture is formed as a circular disc. and on an axis of rotation
• FIG. 2 shows a light bundle 50 which is generated by the light source 16 and in particular by the lamp 17 and the mirror 18 and is directed onto the image surface or. Entry surface 23 of the fiber optics is directed.
• the shadows 52 produced by a conventional diaphragm 26, which greatly reduce the angle of incidence range, are clearly recognizable. For any point P on the image surface 23, the angular range of the incident light beam is greatly narrowed.
• the angular range of the light striking this point P is essentially retained in the method according to the invention, as can be clearly seen from FIG. 3.
• the shadows 53 shown in this embodiment are uniformly distributed over the entire angular range of the light beam and produce a correspondingly uniformly distributed illuminance.
• the diaphragm arrangement is arranged at a distance from the image area 23, at which any point P on this image area 23 can receive light from each aperture opening from each of the partial light beams 55 generated by the diaphragm arrangement 26, the brightness is also evenly distributed over the entire image area 23. Additional inhomogeneities in the luminous flux are compensated for by using a light-mixing fiber-optic bundle.
• FIG. 4 shows a preferred diaphragm 26 with nine crescent-shaped diaphragm openings 61.
• This diaphragm 26 has a first zone 62 through which the light beam 50 can pass unhindered.
• a second zone 63 is large enough to completely interrupt the luminous flux of the entire light bundle 50.
• the crescent-shaped diaphragm openings 61 taper towards this second zone 63 and, by simply rotating the diaphragm disk 26, allow the luminous flux to be varied continuously.
• FIGS. 5, 6 and 7. The effectiveness of this preferred aperture is made clear in FIGS. 5, 6 and 7.
• 80% of the light from a given light beam is shadowed.
• the values for the brightness of the image surface along an intersection axis are shown as value curves.
• their associated two-dimensional distribution is also illustrated as a top view, the blackening corresponding to the brightness values of the diagram. 5 shows the uneven distribution of brightness, as is produced by a conventional sickle screen, clearly.
• a ring structure can also be seen in FIG. 6, as is produced by a double sickle screen according to the invention.
• FIG. 7 shows the brightness distribution of an aperture according to the invention with five crescent-shaped apertures.
• the geometry of the individual diaphragm openings 61 corresponds to the desired requirements and, in particular, linear or logarithmic, wedge-shaped or sickle-shaped diaphragm openings are used.
• several such screens can be arranged one behind the other in order to cooperate in a suitable manner.
• the present method and the associated special diaphragm arrangement are used in particular in lighting technology and for light intensity control in fiber-optic lighting devices, as are described, for example, in CH-A-1255 / 89-7.

Landscapes

• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Microscoopes, Condenser (AREA)
• Medicines That Contain Protein Lipid Enzymes And Other Medicines (AREA)
• Mechanical Light Control Or Optical Switches (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=4267995

Family Applications (1)

Country Status (6)

Cited By (5)

Families Citing this family (7)

Citations (10)

• 1990
  • 1990-12-18 CH CH4003/90A patent/CH681394A5/de not_active IP Right Cessation
• 1991
  • 1991-11-13 CA CA002075990A patent/CA2075990A1/en not_active Abandoned
  • 1991-11-13 FI FI923632A patent/FI923632L/fi not_active Application Discontinuation
  • 1991-11-13 WO PCT/CH1991/000230 patent/WO1992011548A1/de not_active Application Discontinuation
  • 1991-11-13 JP JP3517634A patent/JPH05504847A/ja active Pending
  • 1991-11-13 EP EP91918584A patent/EP0529006A1/de not_active Withdrawn

Patent Citations (10)

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