WO2003060376A2

WO2003060376A2 - Lighting device, the corresponding installation and the use of same

Info

Publication number: WO2003060376A2
Application number: PCT/FR2003/000137
Authority: WO
Inventors: Jérôme François Henri MONNOT; Sébastien BOUILHOL
Original assignee: Alm
Priority date: 2002-01-17
Filing date: 2003-01-16
Publication date: 2003-07-24
Also published as: FR2834772A1; WO2003060376A3; FR2834772B1

Abstract

The invention relates to a device that is used to illuminate an object, comprising a light source (12) which is adapted to emit first (F lambda 0) and second (F lambda min, F lambda max) electromagnetic beams. The aforementioned first beams (F lambda 0) have a wavelength that is located in a first domain within the visible spectrum while the second beams (F lambda min, F lambda max) have a wavelength ( lambda min, lambda max) that is located outside of said first domain. The inventive device comprises a flux collector (14) which is designed to direct the beams towards the field to be illuminated (4). Said flux collector (14) comprises a diffractive optical element (16) which is disposed in the course the beams follow from the light source (12) towards the field to be illuminated (4). The invention is suitable for lighting devices used in operating theatres.

Description

LIGHTING DEVICE. CORRESPONDING INSTALLATION AND USE THEREOF

The present invention relates to a device for lighting an object, of the type comprising a light source suitable for emitting first and second electromagnetic beams, said first beams having a wavelength which is situated in a first range included in the visible spectrum, said second beams having a wavelength located in a second domain which is outside said first domain, the object being sensitive to the second beams, and a flux collector having a reference image distance from said first beams, and being adapted to direct the beams towards a field to be illuminated from the object.

It applies in particular to lighting devices in operating rooms. Lighting devices are known that are used in operating rooms. Such devices are used to illuminate the field of intervention of the doctor on the patient.

The light sources used for this purpose emit rays of a spectrum which covers the infrared (IR), the ultraviolet (UV), as well as the visible spectrum. However, the patient's tissues at the intervention site are very sensitive to infrared and ultraviolet rays.

This is why the lighting devices in the field of intervention include IR and UV filters, in order to eliminate these areas of the spectrum. However, these filters are very expensive. The object of the invention is to propose an inexpensive lighting device which makes it possible to illuminate an object sensitive to a domain of the spectrum with a low risk of degradation.

To this end, the subject of the invention is a device of the aforementioned type, characterized in that the flux collector comprises at least one diffractive optical element arranged in the path of the beams from the light source towards the field to be illuminated.

According to particular embodiments, the device according to the invention comprises one or more of the following characteristics: the first domain is delimited by first lower and upper limit wavelengths, these first two wavelengths defining an average wavelength, said second domain is delimited by at least one second limit wavelength, and the image distance of the flux collector of the average wavelength and the image distance of the flux collector of said second limit wavelength differ from each other by at least 10% of the image distance the average wavelength;

- The first lower and upper limit wavelengths are between 400 nm and 650 nm, and in particular between 500 and 600 nm;

- The first domain has a spectrum width of at least 100 nm and preferably at most 400 nm;

- Said second limit wavelength is less than 400 nm or more than 650 nm; the diffractive optical element has a reference wavelength comprised in said first range, in particular between 450 nm and 650 nm, and preferably comprised between 500 nm and 600 nm;

the focal length of the diffractive optical element as a function of the wavelength is inversely proportional to the wavelength; - the focal length of the diffractive optical element as a function of the

wavelength is where fo is the reference focal length and

λo is the reference wavelength of the diffractive optical element;

- the energy radiant of the device is less than 6mW / m ² / Lux, and preferably less than 4mW / m ² / Lux; and the device is a device for lighting a patient, in particular intended to be installed in an operating room.

The invention further relates to an installation comprising a support for an object to be lit, characterized in that it further comprises a lighting device as defined above. According to a particular embodiment, the installation comprises the following characteristic: the lighting device and the support are movable relative to each other so that their mutual distance is adjustable, and it comprises means for limiting the relative displacement between the support and the lighting device, these limitation means being adapted to prevent movement of the support at a distance from the flow collector which is substantially different from the reference image distance from the collec - flow meter.

Furthermore, the subject of the invention is the use of a device as defined above for illuminating a field to be illuminated, characterized in that:

- the object to be lit is arranged with its field to be lit at a distance which is substantially equal to the reference image distance from the flow collector; and

- the lighting field is illuminated by the lighting device. The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which: - Figure 1 is a schematic view of a lighting installation according to the invention;

- Figure 2 is a graph showing the focal distance and the efficiency of the diffractive lens of the installation of Figure 1 as a function of the wavelength; - Figure 3 is a graph showing the spectrum of an example of a halogen bulb used for the installation of Figure 1; and

- Figures 4 to 6 are graphs showing the relationships between different parameters of the device according to the invention.

In FIG. 1 is shown an installation according to the invention, designated by the general reference 2.

This installation 2 is used in the medical field to allow a surgeon to intervene on a patient 3, in particular in a field of intervention 4 lit by the installation.

The installation 2 comprises a lighting device 8 and an operating table 10. The lighting device 8 consists of a light source 12 and a diffractive flow collector 14.

The patient 3 is lying on the operating table 10. The intervention field 4 is defined approximately by the plane P ₀ . The light source 12 is considered to be extended and is placed above the patient 3. It emits beams of electromagnetic rays towards the patient.

The light source 12 is a bulb which emits rays whose wavelength is located in the visible range, in the ultraviolet (UV) range and in the infrared (IR) range.

An example of such a light source 12 is a tungsten-halogen bulb of the HLX 64638 type from the company OSRAM. The spectrum of such a bulb is shown in Figure 3. The maximum intensity of the light flux from the bulb is 900 nm. As shown in Figure 3, about 20% of the electromagnetic energy emitted by this bulb is contained in the visible spectrum (400 nm to 800 nm). The rest of the energy emitted is found in the ultraviolet and infrared spectra.

Only the rays included in the visible spectrum are effectively used for lighting the field of intervention 4, while the infrared and ultraviolet rays are harmful to the latter because of the heating of the tissues.

The flux collector 14 is arranged between the light source 12 and the patient 3, at a distance X from the light source 12. The optical plane P of the flux collector 14 extends parallel to the plane Po. The flux collector 14 allows, on the one hand, to guide and focus the visible beams on the intervention field 4, and, on the other hand, to attenuate in the intervention field the harmful UV / IR beams.

For reasons of simplicity, in the present case, the flow collector 14 consists of a diffractive lens 16 whose optical plane is co-planar with the plane P. As a variant, the flow collector 14 also comprises other known optical elements, for example parabolic mirrors, which collect the flux of beams from the light source 12, or else a lens or any other optical component. The diffractive lens 16 has a reference wavelength λ ₀ , located in the visible spectrum, for example λ ₀ = 550 nm. The reference wavelength is the wavelength for which the efficiency of the lens is maximum. This reference wavelength is preferably situated between 450 nm and 650 nm, in particular between 550 nm and 650 nm.

The reference focal distance of this lens, that is to say the distance for the radiation whose wavelength is the reference wavelength, is noted f (λo) = fo-

The focal length of the diffractive lens 16 is inversely proportional to the wavelength. In this case, the focal length f of the len¬

tille as a function of the wavelength λ is - This relation is

represented by the curve C1 in FIG. 2 for a diffractive lens with a reference wavelength λ ₀ equal to 550 nm.

The ideal yield η (λ) of the lens 16 as a function of the length

wave λ is given by the formula The actual yield is represented by the curve C2 in FIG. 2. For the reference wavelength λo, the real efficiency η of the lens 16 is 0.94. As shown in Figure 1, the intervention field 4 is located at a distance do from the plane P of the diffractive lens 16. This distance do is chosen to be identical to, or at the very least very close to the reference image distance X o flow collector 14 defined by the formula -

In the following, the paces of three beams F _λ0 , F _λm j _n and F _λ m _ax of different wavelengths λ ₀ , λ _mi n = 0.5 x λ ₀ , and λ _max = 2 x λ ₀ will be described. Generally, the beam F _λ0 has a wavelength which is located in a first spectral range included in the visible spectrum, while the beams F _λm j _n and F _λma χ have wavelengths which are located in outside this first spectral domain. The first domain is, for example, between the lower wavelength limits Ai = 400 nm and upper λ - 800 nm, and in particular between 500 nm and 600 nm. The first domain has a spectrum width between 100 nm and 400 nm. Limit wavelengths also define an average wavelength! = • & -. In the latter case, λ ^~ ^600nm ^00nm + = 55Q _nm. Preferably, the average wavelength λ is chosen to be substantially identical to the reference wavelength λ ₀ For the example given λo =

550 nm (visible), λ _m i _n = 275 nm (ultraviolet), and λ _ma χ = 1100 nm (infrared).

As shown in Figure 1, the beam F _λ0 is focused on the lighting field 4 which is in the plane Po. Consequently, the spectral illumination (^) of the beam F _λ o of wavelength λo is maximum in the plane P ₀ , which leads to good lighting of the field of intervention 4 to be lit. In addition, the efficiency η of the diffractive lens 16 for the beam F _λ o is close to 0.94 (see curve C2 in Fig. 2). Thus, this beam F _λ0 is only very slightly attenuated.

The focal length f _λm j _n of the diffractive lens 16 is 2 xf ₀ for the beam F _λm i _n of wavelength λ _m i _n . This beam F _λmin is therefore focused on a plane P _m j _n , which is seen, seen from the light source 12, behind the plane Po, at a distance of X _λm j _n from the plane P. This distance X _λrrι j _n is the image distance of the flux collector for the rays of wavelength λmin. At the location of the plane Po, the beam F _λrrι jn is distributed over a spot of diameter d _λrτ , i _n , which makes the spectral illumination § - (^) of the beam

f _λ min weak at this location. In addition, as shown in Figure 2, the efficiency η (λ _m i _n = 275 nm) of the diffractive lens for these beams F _λ min is of the order of 1%. 99% of the intensity of this beam is therefore partly reflected by the diffractive lens 16 towards the interior of the lighting device.

The beam F _λma χ of wavelength λ _max is focused on a plane P _max , located at a distance X _λ m _a x from the diffractive lens 16, which is half the distance X _λ0 between the diffractive lens 16 and the plane P ₀ . When the beam F _λ m _a x meets the plane P ₀ , it is distributed over a spot of diameter λmax- The spectral illumination of the beam F _λmax inciding on the plane P ₀ is then low for a given intensity of the light source 12 in this spectrum area. In addition, as shown in Figure 2, the diffractive lens has an efficiency η (λ _max = 1100 nm) of around 40%. The limit wavelengths of the first and second domains are chosen such that the image distance of the limit wavelength of the second domain differs by at least 10% from the image distance of the average wavelength λ.

The energy radiant RE is the ratio of the energy illumination to the visual illumination of the field to be illuminated 4. This radiant is defined by the formula:

and V _λ = reference curve of the eye given by Cl.

In the medical field, the energy radiant RΕ of a lighting device must be as low as possible. In any event, it must be less than 6 mW / m ² / lux, and preferably less than 4 mW / m ² / lux.

In FIG. 4, the energy radiant RE of the installation 2 is represented, as a function of the reference wavelength λ ₀ of the diffractive lens 16. The abscissa indicates the reference wavelength λo, while that the ordinate indicates the energy radiant RE. As shown in Figure 4, for a reference wavelength of 550 nm, the energy radiant is 1.75. It remains less than 6 for reference wavelengths between 400 nm and 620 nm.

In addition, for lighting devices in the medical field, the average transmission must be greater than 50%. Transmission is the ratio of the flux at the input of the diffractive lens 16 to the flux at the output of this lens.

The input flow is, and the output flow is

, TΛo _P is the transmission of the material of the diffractive lens [in%],

. "_Surfacedelasourcedelumière (12) xSurfacedelalentillediffractive (16)

(Distanceentresourcedelumièreetlentillediffractive (X) f

(the geometric extent of the optical system [in m ² ])

In Figure 5, the transmission of the lens is plotted on the ordinate, while the abscissa indicates the reference wavelength λ ₀ . Transmission reaches a maximum of 63% with a diffractive lens of λ ₀ = 650 nm.

In Figure 6, the energy radiant RE is represented as a function of the reference focal length. The distance do between the intervention field 4 and the diffractive lens is kept constant at 1000 mm and therefore x ~ 111 mm for focal length f ₀ of 100 mm. Likewise, the reference wavelength λo of the diffractive lens 16 is kept constant.

The energy radiant RE increases with the reference focal distance f ₀ for an object plane P ₀ located at 1 m. It should be noted that the device according to the invention can be applied to fields other than the lighting of a field of operation, for example the lighting of works of art in a museum.

The installation also includes a safety device which ensures that the patient 3, or more precisely the lighting field 4, cannot be placed in the focal plane P _m i _n / Pmax of the UV / IR beams. In this case, this safety device consists of two stops 20, 22 which limit the movement of the lighting device 8 so that the patient cannot be placed in the focal planes Pmin Pm _a x-

The stops 20, 22 prevent movement of the support 10 and therefore of the lighting field 4 at a distance from the flow collector 14 which is clearly different from the reference image distance. Thus, the stops 20, 22 ensure that the distance between the flow collector 14 and the patient 3 remains substantially equal to the reference image distance X _λ o.

Claims

1. Device for lighting an object (3), of the type comprising

- a light source (12) adapted to emit first and second electromagnetic beams, said first beams (F _λ o) having a wavelength which is located in a first range included in the visible spectrum, said second beams (F _λm j _n , F _λmax ) having a wavelength (λ _m j _n , λ _max ) located in a second domain which is outside said first domain, the object (3) being sensitive to second beams (X _λmi n Xλmin); and - a flow collector (14) having a reference image distance

(X o) of said first beams, and being adapted to direct the beams (F _λ o, F _λmin , F _λmax ) towards a field to be illuminated (4) of the object (3), characterized in that the flux collector (14) comprises at least one diffractive optical element (16) arranged in the path of the beams from the light source (12) towards the field to be illuminated (4).

2. Device according to claim 1, characterized in that the first domain is delimited by first lower (λi) and upper (λ _s ) limit wavelengths, these two first wavelengths defining an average wavelength (λ), in that said second domain is delimited by at least a second limit wavelength, and in that the image distance of the flux collector (14) of the average wavelength and the image distance of the collector flux (14) of said second limit wavelength differ from each other by at least 10% of the image distance of the average wavelength.

3. Device according to claim 2, characterized in that the first lower (λj) and upper (λ _s ) limit wavelengths are between 400 nm and 800 nm, and in particular between 500 and 600 nm.

4. Device according to claim 2 or 3, characterized in that the first domain has a spectrum width of at least 100 nm and preferably of at most 400 nm.

5. Device according to any one of claims 2 to 4, characterized in that said second limit wavelength is less than 400 nm or greater than 650 nm.

6. Device according to any one of the preceding claims, characterized in that the diffractive optical element (16) has a reference wavelength (λ ₀ ) included in said first range, in particular between 450 nm and 650 nm, and preferably between 500 nm and 600 nm.

7. Device according to any one of the preceding claims, characterized in that the focal distance of the diffractive optical element (16) as a function of the wavelength is inversely proportional to the wavelength.

8. Device according to any one of the preceding claims, characterized in that the focal distance f of the diffractive optical element (16)

as a function of the wavelength (λ) is f (λ) = f 2p, where fo is the distance

reference focal length and λo is the reference wavelength of the diffractive optical element (16).

9. Device according to any one of the preceding claims, characterized in that the energy radiant (RE) of the device is less than 6mW / m ² / Lux, and preferably less than 4mW / m ² / Lux.

10. Device according to any one of the preceding claims, characterized in that it is a device for lighting a patient, in particular intended to be installed in an operating room.

11. Installation comprising a support (10) for an object (3) to be lit, characterized in that it further comprises a lighting device (8) according to any one of claims 1 to 10.

12. Installation according to claim 11, characterized in that the lighting device (8) and the support (10) are movable relative to each other so that their mutual distance is adjustable, and in that that it includes means for limiting (20, 22) the relative movement between the support (10) and the lighting device (8), these means for limiting (20, 22) being adapted to prevent movement of the support ( 10) at a tance of the flow collector (8) which is significantly different from the reference image distance (X _λ o) of the flow collector (14).

13. Use of a device according to any one of claims 1 to 10 for lighting a field to be lit (4), characterized in that: - the object to be lit (3) is arranged with its field to be lit (4 ) at a distance which is substantially equal to the reference image distance (X _λ0 ) of the flow collector (14); and

- the field to be lit is illuminated by the lighting device.