The invention will be further elucidated with reference to an exemplary embodiment represented in the drawing. In the drawing:
The Figures are only a schematic representation of a preferred embodiment of the invention. In the figures, equal or corresponding parts are indicated with the same reference numerals.
It is noted that the above-described optical elements merely involve one example of an embodiment of the optical elements. Such a combination of optical elements can naturally be designed differently, for instance without yellow filter or with different numbers of collimating lenses.
Further, it is noted that the numerical aperture (NA) of the optical elements is substantially greater than circa 0.5, for instance in the order of magnitude of 0.6, so that a wider light beam can propagate along the light paths L1, L2. Consequently, the intensity of the light at the connectors 3A, 3B can increase, so that more light becomes available for coupling into light guides. In this way, the intensity of the light can be better tuned to individual light guides. Furthermore, the light exiting from the light source 2 is utilized better, so that, optionally, at a single light source a plurality of separate light paths with associated connectors for light guides may be provided, whereby the light yield, with jointly connected light guides, can simultaneously be at a sufficiently high level. It is also possible to use optical elements that have an NA in the order of magnitude of 0.5, for instance for reducing the cost price of the illumination unit.
The numerical aperture (NA) of an optical element OE is defined with reference to
As described above, the illumination unit comprises, apart from a first connector for light guides with associated optical elements for defining a light path along which light exiting from the light source can travel to the first connector, an additional connector with associated optical elements for defining a separate light path. Accordingly, two light guides can be simultaneously provided with light by the illumination unit. In this way, during an eye surgical intervention, two functioning illumination points can be introduced, so that a good illumination is obtained at the site of the intervention. Also, different instruments that are provided with such a light guide can be used alternately without necessitating exchange of light guides or an extra illumination unit. Naturally, the number of connectors with associated separate light paths can vary, being more than two, for instance three, or fewer than two, i.e. just one connector. Use of a multiple number of connectors is advantageous especially where efficient use is made of the light emitted by the light source, for instance by using optical elements with a relatively high numerical aperture.
The optical elements 4A, 4B comprise furthermore per light path L1, L2 a spherical reflector 13A, 13B for reflecting light exiting from the light source 2. The reflected light propagates along the lamp 2, following the respective light paths L1, L2. Thus, a relatively large amount of light is utilized for coupling into the optical light fibers. Especially for use of a multiple number of connectors with associated light paths, it is of importance, as explained above, to utilize the generated light as efficiently as possible. In principle, however, it is also possible to omit the spherical reflectors 13A, 13B, so that costs for optical elements can be saved on. The geometric center C of the reflector 13A has been placed in the heart of the position in which the light is generated, so that an optically optimal geometry is obtained. In
A reflector surface of the two spherical reflectors 13A, 13B is provided with an infrared filter in one embodiment. Filtering infrared radiation from the light generated by the light source 2 reduces, through prevention of thermal loading, the chance of damage to the light source 2 proper, as well as to optical structures behind it, such as the optical elements 4A, 4B and a connected light guide. The infrared filter comprises a coating which is reflective to visible light but transparent to infrared light and hence hardly, if at all, reflects radiation having a wavelength of infrared light. Alternatively, the infrared filter can comprise material that absorbs infrared radiation, so that the amount of reflected infrared radiation likewise decreases. Thus, light exiting from the illumination unit 1 is better adjusted to light guides connectible to the unit 1. This is then done not by, or not only by, adjustment of the light intensity, but by adjustment of the spectrum of the generated light. It is noted that the infrared filter can also be arranged on a different optical element, or on a multiple number of them. Also, the use of an infrared filter can naturally be omitted, for instance for reasons of cost.
In one embodiment of the eye surgical illumination unit 1 according to the invention, the infrared filter is arranged for absorbing radiation having a wavelength which is substantially greater than circa 0.7 μm, so that also radiation having a wavelength greater than circa 0.7 μm can be absorbed. In this way, possible hazardous energy of specific lamp types, for instance a Xenon lamp, that generate a significant amount of radiation in the region of the spectrum with a wavelength greater than 0.7 μm, can be reduced. The utility of the illumination unit thus increases commensurately. In an alternative embodiment, however, the infrared filter is not designed for absorbing radiation, for instance when using types of lamps that emit only a small amount of radiation having said wavelength.
The light source 2 may be an arc lamp, for instance a Xenon lamp. Consequently, a relatively large amount of light can be generated, which is advantageous in the use of a multiple number of connectors for light guides with associated separate light paths, but also for tuning the light to the light guide to be connected, since the range in light yield is relatively large. In an alternative embodiment, a different type of lamp can be used, for instance a halogen lamp.
As shown in
The position of the light source 2 relative to the optical elements 4A, 4B is settable, in particular in the height direction H. In this way, the position of the light source 2, for instance after replacement, can be optimized relative to the optical elements in order to obtain optimum coupling of the generated light. The positioning of the light source 2 can for instance be realized using a stepper motor.
In addition, the illumination device has a sensor 14 for a position measurement of the position P where during operation the light is generated in the light source 2.
Each of the intensity filters 9A, 9B comprises a displaceable, substantially optically transparent carrier 17 which is provided with a substantially optically impermeable layer 18 with a coverage varying as a function of the location, as shown in
The intensity filter 9 is arranged in the illumination unit 1 so as to be rotatable about a central midpoint 20, such that in each position of the disc 17 an area from a ring-shaped segment 21 of the disc 17 is in the optical light path L. The ring-shaped segment 21 is bounded by an outer radius 22 and an inner radius 23 relative to the central midpoint 20 of the filter 9. An area that is in the optical light path L has such dimensions that it fits into the opening 19.
The optically impermeable layer 18 is formed by absorbing material that has been applied to the substantially optically transparent disc 17, so that incident light is partly absorbed. The coverage of the optically impermeable layer is a measure for the percentage of light that is allowed to pass. The coverage is locally substantially uniform and increases in a counterclockwise direction, so that by swiveling the filter 9 in a swiveling direction the intensity increases or decreases uniformly, that is, without intermediate respective decrease or increase. A locally substantially uniform coverage has been obtained by applying the material in a more or less balanced manner as relatively small or large areas 24 on the disc 17, so that a kind of matrix structure is formed. In this way, an even attenuation of the light beam can be realized, whereby the numerical aperture (NA) is not, or virtually not, affected.
After introducing the end 27 into a connector 3A, 3B of the illumination unit 1, identification of the light guide 25 is done by means of an optical measurement. The optical measurement can be performed with readily obtainable scan equipment. Furthermore, on the basis of information stored in a memory element of the illumination unit, such as setting characteristics of the light guide 25, information is generated for direct tuning of light exiting from the light source. This generated information contains for instance data about a maximum light yield of the light guide, such as an ISO value and/or an illumination value (lumen value). Such information is shown via a display panel 34 on the housing of the illumination unit. Thus, a user can observe directly, without use of additional documentation, what the optical performance of the connected light guide is and determine how long and with what intensity the light guide can be employed in a specific eye surgical treatment.
Various operations, such as executing the identification and generating information for direct tuning of the amount of light exiting from the illumination unit to an identified light guide, can optionally be carried out by dedicated program loaded into a computer system 30, comprising a processor 31 which is connected via data links to an optical measuring device 32 for performing the optical measurement, a memory element 33 for storing setting characteristics of light guides, and a display panel 34 for displaying the generated information of an identified light guide.
In a special setting of the illumination unit 1, the intensity of the light exiting from the unit is automatically tuned to the identified light guide, based on the generated information on the light guide. Thus, the use of the illumination unit 1 is simplified still further and its utility is augmented still further. The user of the unit can set the spectral character of the exiting light with the aid of spectral filter settings. Furthermore, the user can determine the maximum duration for the use of the light source on the basis of the generated information on the light guide, especially on the basis of the so-called ISO values. The calculated ISO values can depend on the type of connected light guide, the intensity of the light that is coupled into the light guide, and spectral fiber settings. As described hereinabove, the intensity of the coupled light depends on the setting of the intensity filter. Furthermore, the illumination unit 1 may be so arranged that, notwithstanding manual setting possibilities, the amount of exiting light is actively limited to a maximum value at which the identified light guide can still be used without sustaining permanent damage. This prevents possible injury to the eye of a patient and damage to the light guide as a result of too high a light intensity.
The invention is not limited to the exemplary embodiments described here. Many variants are possible.
Thus, the illumination unit may be arranged for displaying the number of operating hours of the light source, so that the light source can be timely replaced so as to prevent untimely failure. Optionally, the number of operating hours displayed may be reset after replacement of the lamp. Also, the illumination unit may be arranged for displaying the number of operating hours still to be traversed until a pre-set replacement period has been completed.
Furthermore, identification of the light guide, instead of taking place in the illumination unit proper, can take place in a separate unit which is connected to the illumination unit via a data communication link.
In addition, when using a multiple number of connectors with associated separate light paths, a first connector may be arranged for connection to a first type of light guide and a second connector for connection to a second type of light guide, so that different types of light guides, for instance with different types of fastening elements, can be connected to the illumination unit.
Such variants will be clear to those skilled in the art and are understood to fall within the scope of the invention, as set forth in the following claims and the various embodiments disclosed herein are not intended to act as limitations on the scope of the claims.
Number | Date | Country | Kind |
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1032559 | Sep 2006 | NL | national |