Illumination system

Abstract

The present invention provides a lighting device, comprising a beam combiner, the beam combiner comprising two dichroic reflective surfaces and configured to combine a first light, a second light, and a third light into a combined light, wherein the first light is obtained from a first light source, the second light is obtained from a second light source, and the third light is obtained from a third light source; the combination of the second light passing through the combiner and the third light passing through the combiner is closer to the white point than each of the second light and the first light passing through the combined portion; or the third light passing through the combiner is closer to the white point than each of the second light and the first light passing through the combined portion.

Description

Technical Field

[0001] The present application relates to an illumination system. In particular, the present application relates to an illumination system for an endoscope that allows for enhanced illumination, such as vascular patterns, by both white light illumination of two different colors and narrow-band (colored) illumination.

[0002] abbreviation:

[0003] B blue

[0004] CIE International Commission on Illumination

[0005] G Green

[0006] Gw green wide

[0007] Hb hemoglobin

[0008] HbO2 oxygenated hemoglobin

[0009] LED light emitting diode

[0010] R Red

[0011] V Purple

[0012] WL white light

[0013] WLI White Light Illumination Background of the Invention

[0015] White light (WL) and vascular pattern enhanced illumination (so-called narrow-band illumination, which has an illumination spectrum synchronized with the hemoglobin absorption spectrum) are becoming increasingly popular for endoscopic imaging. Figure 1 The absorption spectra of Hb (hemoglobin, i.e., deoxyhemoglobin) and HbO2 (oxyhemoglobin, i.e., oxyhemoglobin) are shown, taken from JP 2016-022043 A. E1 to E8 are the isosbestic points of Hb and HbO2, i.e., the wavelengths at which Hb absorption is the same as HbO2 absorption (E8 is a quasi-isosbestic point). In other words, absorption at the isosbestic points is independent of the oxygenation level of hemoglobin. W0 to W7 and WR represent the wavelength ranges between two adjacent isosbestic points and beyond the isosbestic point E8, respectively.

[0016] Therefore, in conventional vascular imaging, tissue is illuminated with a spectrum, e.g. Figure 2As shown schematically, the spectrum includes violet light V and / or green broadband light Gw. The green broadband light includes wavelengths ranging from blue-green to red. These lights generally include at least one of the wavelength ranges W0, W1 (for V light), and W5 (for Gw light). In these wavelength ranges, there is a large absorption difference between Hb and HbO2. Therefore, the intensity of the absorbed light differs significantly between tissue containing Hb and tissue containing HbO2. The green broadband light Gw is also used for optically observing tissue. Because it can have a wide spectral distribution, the Gw light has a green hue. Typically, the emission spectra of the V light and the Gw light do not overlap.

[0017] In endoscopy, to simplify the system and to allow compatibility with many different types of endoscopes, the light source can be arranged in an external box (light source box or processor system). The light from the external box can be guided from the proximal end of the endoscope to the distal end of the endoscope through one or more optical fibers to illuminate the object space of the objective lens arranged at the distal end of the endoscope.

[0018] CIE 1931 relates the distribution of wavelengths in the electromagnetic visible spectrum to the physiologically perceived colors in human color vision. Figure 3 The color gamut according to CIE 1931 (xy plane, taken from people.cs.clemson.edu) is shown. The center area (without color annotation) represents white light. The numbers at the gamut boundaries indicate the wavelength (in nm) of the corresponding spectral clean light. White light has coordinates x = 1 / 3, y = 1 / 3, and z = 1 / 3. Summary of the Invention

[0019] The present invention provides an improved lighting system that allows greater flexibility between WLI and narrowband lighting.

[0020] The present invention provides a lighting device, the lighting device comprising a beam combiner, the beam combiner comprising first, second and third input ends, a combining portion, and an output end; wherein

[0021] The combining portion is configured to combine the first light, the second light, and the third light into a combined light output from the output end, the first light being input into the combining portion from the first input end, the second light being input into the combining portion from the second input end, and the third light being input into the combining portion from the third input end; the combining portion includes two dichroic reflecting surfaces; the combining portion is configured to transmit a first transmission wavelength band of the first light and block the first light in a wavelength range outside the first transmission wavelength band; the combining portion is configured to transmit a second transmission wavelength band of the second light and block the second light in a wavelength range outside the second transmission wavelength band; the combining portion is configured to block the first transmission wavelength band of the third light, block the second transmission wavelength band of the third light, and transmit the third light in a wavelength range outside the first and second transmission wavelength bands; the first transmission wavelength band does not overlap with the second transmission wavelength band; and the lighting device further comprises:

[0022] A first light source is arranged to input a first light into a first input end of a beam combiner; a second light source is arranged to input a second light into a second input end of the beam combiner; and a third light source is arranged to input a third light into a third input end of the beam combiner; wherein the first light includes at least a portion of a first transmission wavelength band; the second light includes at least a portion of a second transmission wavelength band; and at least one of the following conditions is satisfied: the combination of the second light transmitted through the combination part and the third light transmitted through the combination part is closer to a white point according to CIE 1931 than each of the second light transmitted through the combination part and the first light transmitted through the combination part; and the third light transmitted through the combination part is closer to a white point according to CIE 1931 than each of the second light transmitted through the combination part and the first light transmitted through the combination part.

[0023] This allows for greater flexibility in vascular imaging. Specifically, it allows for true RGB illumination with white light, which is closer to white than the standard green, broad-band illumination used for vascular enhancement imaging. Thus, tissue can be observed in more natural colors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The absorption spectra of Hb and HbO2 with isosbestic points are shown;

[0025] Figure 2 Schematic illustration of conventional illumination spectra used for vascular imaging;

[0026] Figure 3 The color gamut according to CIE 1931 is shown;

[0027] Figure 4 Some embodiments of the present invention schematically illustrate a plan view of a lighting device;

[0028] Figure 5 shows a three-dimensional view of an orthogonal block used in some embodiments of the present invention;

[0029] Figure 6 (top) schematically illustrates the reflectance spectra of an orthogonal block used in some embodiments of the present invention, and Figure 6 The rest of FIG shows light emission spectra and white output light spectra of example LEDs that can be used as the first to third light sources;

[0030] Figure 7 Some embodiments of the present invention schematically illustrate a reflection spectrum of an orthogonal block, emission spectra of first to third lights, and a spectrum of combined light;

[0031] Figure 8 shows the emission spectrum of a yellow phosphor covered LED that may be deployed as a Gw light source in some embodiments of the present invention;

[0032] Figure 9 Shown is a yellow phosphor covered Figure 8 an emission spectrum of an LED having an emission spectrum of , a dome reflective lens applied to the yellow phosphor, the LED being deployed as a Gw light source in some embodiments of the present invention;

[0033] Figure 10 Shown is the emission spectrum of an LED that may be deployed as a white light source in some embodiments of the present invention. DETAILED DESCRIPTION

[0034] According to some embodiments of the present invention, Figure 4 As shown in a plan view of FIG, the illumination device includes three light sources 1, 2, and 3, and the light from the three light sources is combined by a dichroic combiner, such as an orthogonal block 8. Light sources 1 and 2 may correspond to narrowband light sources for conventional vascular imaging (i.e., a violet or ultraviolet light source emitting V light, and a broad-band green light source Gw). A third light source 3 emits light such that, if the combiner combines light from the Gw light source and the third light source, the combined light is closer to the CIE 1931 white point (x=y=z=1 / 3) than light from only the Gw light or light from only the V light transmitted through the dichroic combiner. For example, the third light source may emit red light; or blue light; or red and blue light; or red, green, and blue light. In some embodiments, light from only the third light source (when transmitted through the dichroic combiner) may be closer to the white point than light from only the Gw light source or light from only the V light source transmitted through the dichroic combiner.

[0035] An example of the combined light (illumination spectrum) emitted by the lighting device for the case where the three light sources 1, 2 and 3 are turned on is shown in Figure 6(the last spectrum from the bottom). Figure 6 As shown, the V light and the Gw light can be identical according to existing techniques. A third light source 3 provides additional blue and / or red (amber) light to the combined light. Thus, the visible spectrum includes RGB light (or BG light), which is generally closer to the white point than the broad green Gw light alone. This allows doctors to observe tissue in more natural colors compared to conventional lighting systems.

[0036] In this application, the term "closer to the white point" means a shorter Euclidean distance from the white point x=y=1 / 3 (neglecting the z direction) in the xy plane of the color gamut of CIE1931. i 、y i The Euclidean distance of the illumination light from the white point in the xy plane is (x i -1 / 3) 2 +(y i -1 / 3) 2 .

[0037] Hereinafter, embodiments of the lighting device will be described in more detail.

[0038] Figure 4 An overview of the lighting apparatus is shown in plan view. Three light sources 1, 2, and 3 are arranged so that they illuminate the first, second, and third input faces of the orthogonal block 8 with first light L1, second light L2, and third light L3, respectively. Each of the light sources 1, 2, and 3 may comprise a respective LED, laser, or another light-emitting device. Each of the light sources 1, 2, and 3 may or may not comprise one or more lenses, mirrors, or other optical components to direct the respective light to the respective input face of the orthogonal block 8. Each of the light sources 1, 2, and 3 may be controllable independently of the other light sources 1, 2, and 3. For example, each of the light sources 1, 2, and 3 may be turned on and off independently of the other light sources. In some embodiments, the intensity of some of the light sources may also be individually controllable.

[0039] Figure 5 3D view of the orthogonal block 8 is shown. Small letters a to h represent the corners of the orthogonal block. The orthogonal block includes a first two-color reflective surface acge and a second two-color reflective surface bfhd. Figure 4 In the plan view of the orthogonal block 8 shown, sections ac and bd of the dichroic reflective surfaces form the diagonals of a square, thereby forming the upper surface of the orthogonal block. In some embodiments, the combined portion of the orthogonal block includes the first and second dichroic reflective surfaces.

[0040] The input surfaces are the three outer side surfaces of the orthogonal block. That is, the first input surface is side surface abef, the second input surface is side surface cghd, and the third input surface is side surface aehd. The first input surface is opposite the second input surface, and the third input surface connects the first and second input surfaces.

[0041] Combined light L4 is emitted from output surface bfgc, which is opposite to the third input surface and connects the first and second input surfaces.

[0042] Each of the first and second dichroic reflective surfaces reflects a corresponding wavelength band and transmits light of a wavelength band outside the reflected wavelength band. Preferably, one or both of the dichroic reflective surfaces transmits all visible wavelengths outside the corresponding reflected wavelength band.

[0043] Figure 6 (Top) Schematic representation of the reflection spectrum of the orthogonal block X. The first dichroic reflective surface reflects V light, and the second dichroic reflective surface reflects Gw light. The reflectivities of the dichroic reflective surfaces can be the same or different from each other, as shown in FIG. Figure 6 shown.

[0044] Figure 6 The rest of FIG schematically illustrates the corresponding light intensity of the light source according to one embodiment of the present invention. The light source may be, for example:

[0045] Light source 1 (L1, purple): second chart from the top (e.g., NVSU233B-U405 from Nichia Corporation);

[0046] Light source 2 (L2, green): third chart from the top (e.g., Nichia Corporation NCSGE17AT); and

[0047] Light source 3 (L3, other): bottom diagram (e.g., Nichia NF2L757GRT-V1.

[0048] When both L2 and L3 are open, Figure 6 The spectrum of the second graph at the bottom of FIG shows the output light. As can be seen, the combined light includes R, G and B light, making it closer to the white point of CIE 1931 than the spectrum of only L2.

[0049] Figure 7 The wavelength ranges of the first to third emitted lights L1, L2 and L3 and the resulting combined light L4 are additionally schematically shown for the reflection spectrum of the orthogonal block. Figure 7 The edges of the reflectance spectrum are sharp and are considered to be 100% or 0% reflectance. Figure 7Only the wavelength range in which the first light L1 to the third light L3 are emitted is indicated, thereby ignoring any intensity dependence of the wavelength. If these simplifications are invalid, the resulting combined light L4 is obtained by convolution of the reflection spectrum (first light L1 and second light L2) or the transmission spectrum (third light L3) and the light intensity.

[0050] The first dichroic reflective surface acge reflects light of a first transmission wavelength band (eg, violet and / or ultraviolet light; Figure 6 Indicated as first), the light is input to the first input surface, so that it exits from the output surface, and it transmits other visible wavelengths. The first light source 1 emits violet and / or ultraviolet light L1. The emission spectrum of the first light source 1 and the reflection spectrum of the first dichroic reflective surface acge overlap. Therefore, if the first light source 1 emits the first light L1 to the first input surface abef, the combined light L4 includes violet and / or ultraviolet light of overlapping wavelength ranges. For example, the light may be V light for conventional vascular imaging, or light different therefrom. The first light L1 of the first light source 1, which has a wavelength different from the reflection spectrum of the first dichroic reflective surface (first transmission wavelength band), is transmitted through the first dichroic reflective surface, making it useless for the output light L4.

[0051] The second two-color reflective surface bfhd reflects light of a second transmission wavelength band (eg, green light; Figure 6 Indicated as the second in FIG, the light is input to the second input surface so that it exits from the output surface and transmits other visible wavelengths. The second light source 2 emits green light or green wide-band light L2. The emission spectrum of the second light source 2 overlaps with the reflection spectrum of the second dichroic reflective surface bfhd. Therefore, if the second light source 2 emits the second light L2 to the second input surface cghd, the combined light L4 includes green or green wide-band light of an overlapping wavelength range. For example, the light may be Gw light for conventional vascular imaging, or light different therefrom. The second light L2 of the second light source 2 having a wavelength different from the reflection spectrum of the second dichroic reflective surface (the second transmission wavelength band) is transmitted through the second dichroic reflective surface, making it useless for the output light L4. The first transmission wavelength band and the second transmission wavelength band do not overlap.

[0052] The third light L3 emitted by the third light source 3 is transmitted through both the first dichromatic reflective surface acge and the second dichromatic reflective surface bfhd to contribute to the combined light L4. Therefore, the third light L3 emitted by the third light source 3 contributes to the combined light L4, and the light of the first transmission wavelength band and the light of the second transmission wavelength band are thereby blocked.

[0053] exist Figure 7In the example shown in FIG, the wavelength range of first light L1 is greater than the first transmission wavelength band (first reflection wavelength band) of the first dichroic reflective surface. Combined light L4 includes only the contribution of first light L1 within the transmission wavelength band. Because other light L2 and L3 are not emitted within the wavelength range that exceeds the first transmission wavelength band, combined light L4 has a gap 12 within this wavelength range.

[0054] Compared to the emission spectrum of second light L2, the second transmission wavelength band (second reflection wavelength band) of the second dichroic reflective surface extends further toward the long wavelength side. The orthogonal block prevents third light L3 from transmitting through the reflection wavelength band of the second dichroic reflective surface. Therefore, combined light L4 has a gap 13 in this wavelength range.

[0055] In wavelength range 15, second light L2 is transmitted through the second dichroic reflective surface. Therefore, second light L2 does not contribute to combined light L4 in this wavelength range 15. On the other hand, third light L3 also includes wavelength range 15. The third light is transmitted through both the first and second dichroic reflective surfaces, so that it contributes to combined light L4 in wavelength range 15.

[0056] On the other hand, in the wavelength range 16, only the second light L2 contributes to the combined light L4 because, in the wavelength range 16, the third light L3 is reflected by the second dichroic reflective surface so that it does not exit from the output face.

[0057] Figure 7 Examples of reflection wavelength bands and corresponding emission wavelength bands are shown. This example is non-limiting. For example, one or more of the emission wavelength ranges may be smaller than the corresponding reflection wavelength band. The third light may have a gap in its emission spectrum (preferably, the second reflection wavelength band). The third light has an emission spectrum on only one side of the second reflection wavelength band. The reflection wavelength bands and the corresponding emission wavelength bands may be arranged so that the wavelength range of the combined light L4 does not have any gaps or any number of gaps.

[0058] Typically, the first and second light sources 1 and 2 include two narrowband light sources, such as a violet light source (LED or laser) and a green (or broad green) light source (LED or laser). The third light source 3 is typically a broadband light source, such as a white (or broad green) light source. The white light source can be a phosphor-coated LED (or laser), where the phosphor converts a portion of the blue / violet / ultraviolet light emitted by the LED (laser) into light of a longer wavelength.

[0059] Figure 8 and Figure 9 Some emission spectra of example LEDs are shown, which can be used as green (green broad) light sources ( Figure 4 and Figure 6 L2 in ). Figure 8 Figure 2 shows the emission spectrum of a phosphor covered white LED which can be used as a GW light source. However, it is preferred to use this LED with a dome reflective lens, such as Figure 9 As shown and explained in DE 11 2018 003134 T5 (Figures 11 and 12), the white LED light that does not directly pass through the opening of the dome reflective lens is reflected several times between the dome reflective lens and the LED, each time passing through the phosphor, and finally passing through the opening of the dome reflective lens to the outside. As a result, the proportion of green fluorescence is increased in the output light.

[0060] Figure 10 The emission spectrum of another example LED is shown, which can be used as a white light source ( Figure 4 and Figure 6 In this case, the LED is covered with a mixture of red and green phosphors.

[0061] In some embodiments, one of the narrowband light sources (e.g., the second light source 2 emitting green light) emits such a broad spectrum of green light that it appears white with a green tint. On the other hand, the third light source 3 can emit complementary colors to the second light source, namely red and blue light. Thus, the combined light comprises RGB.

[0062] Table 1 shows some examples of reflection bands for dichroic reflective surfaces. Figure 1 The isosbestic points of Hb and HbO2 are selected. W1 to W6 represent Figure 1 The wavelength range shown. A third light outside the shown spectral band can be transmitted through the orthogonal block to benefit the combined light.

[0063]

[0064] Table 1: Preferred reflectivity bands for first and second dichroic reflective surfaces for vascular imaging

[0065] The wavelength ranges of the colors described above are examples within the following ranges:

[0066] Violet or ultraviolet 380–450nm.

[0067] Blue: 450-495nm.

[0068] Green: 495-570nm.

[0069] Yellow: 570-590nm.

[0070] Orange: 590-620nm (sometimes also called amber).

[0071] Red: 620-750nm.

[0072] Visible light is considered to cover the wavelength range of 400-750 nm.

[0073] It is sufficient that a major part of the light intensity is emitted / reflected / transmitted in the wavelength range shown. The light may or may not include other components outside the wavelength range shown.

[0074] Some embodiments of the present invention are described as follows: a dichroic reflective surface completely reflects the corresponding transmission wavelength band (reflectivity = 100%) and completely transmits wavelengths outside the corresponding transmission wavelength band (transmittance = 0%).

[0075] =100%). However, in some embodiments, the reflectivity may be less than 100%. For example, the reflectivity may be greater than 60%, preferably greater than 80%. Correspondingly, in some embodiments, the transmittance may be less than 100%. For example, the transmittance may be greater than 60%, preferably greater than 80%.

[0076] Some embodiments of the present invention have been described in which light is combined using an orthogonal block. However, the present invention is not limited to using an orthogonal block for combining light. Alternatively, two dichroic mirrors may be used, each having a spectral reflectance corresponding to the dichroic reflective surface of the orthogonal block. The two dichroic mirrors are arranged sequentially. In the first dichroic mirror, both of the first to third lights are combined, and in the second dichroic mirror, the combined light from the first dichroic mirror is combined with the remaining light from the first to third lights.

[0077] In some embodiments, even more than three lights are combined. For example, the combined light of the orthogonal block (or two dichroic mirrors) is combined with the fourth light via (another) dichroic mirror, or it is combined with the fourth and fifth lights via (another) orthogonal block, etc. In addition, the orthogonal block may include one or two additional dichroic reflective surfaces. Figure 5 In the perspective view of FIG, these additional dichroic reflective surfaces can be arranged so that they reflect light entering the top and bottom faces of the orthogonal block to the output faces (surfaces afgd and hebc). The reflection bands of these additional dichroic reflective surfaces do not overlap with each other and do not overlap with the reflection bands of other dichroic reflective surfaces.

[0078] Instead of an orthogonal block, an orthogonal prism may be used, wherein at least one of the side lengths is different from the other side lengths, and / or wherein at least one of the edges does not form a right angle.

[0079] According to some embodiments of the present invention, the lighting device may not include any movable parts. In particular, the reflective dichroic surfaces may be immovable relative to each other, relative to the input surface, or relative to the light source, which facilitates setup and reduces maintenance work.

[0080] According to some embodiments of the present invention, the lighting system may be arranged in an external box (light source box or processor system). Light from the external box may be guided from the proximal end of the endoscope to the distal end of the endoscope via one or more optical fibers to illuminate the object space of the objective lens arranged at the distal end of the endoscope. However, the light source may be arranged in the control body, the endoscope connector, or even alternatively, in the distal tip of the endoscope.

[0081] In some embodiments, the optical fiber and optical components can be considered as belonging to the output end of the lighting device, and the optical components are used to introduce light from the orthogonal block into the optical fiber. In these embodiments, when designing the light source and the dichroic reflective interface, their impact on the light output from the orthogonal block can be considered.

[0082] The endoscope including the lighting device may be a capsule endoscope without a shaft (eg, a flexible tube), or may be an endoscope including a rigid end portion and a shaft (eg, a rigid or flexible tube). The rigid end portion may be connected to the shaft directly or indirectly via an angled section.

[0083] If at least two colored illumination lights and white (or substantially white) illumination light are needed or desired, illumination devices according to some embodiments of the present invention can be used externally on the endoscope. Depending on the substance to be observed, the colored light source can emit colors other than violet (or ultraviolet) light and green (or broad green) light. For example, some fluorescent imaging agents, such as 5-ALA, can be used, which have a peak absorption wavelength of 405 nm, and the reflection band of the dichroic mirror can be adjusted accordingly.

Claims

1. A lighting device comprising A beam combiner comprising a first input, a second input, and a third input, a combining portion, and an output; wherein The combining portion is configured to combine first light, second light, and third light into combined light output from the output end, wherein the first light is input into the combining portion from the first input end, the second light is input into the combining portion from the second input end, and the third light is input into the combining portion from the third input end; The combined portion includes two dichroic reflective surfaces; the combining portion being configured to transmit a first transmission wavelength band of the first light and to block the first light in a wavelength range outside the first transmission wavelength band; the combining portion being configured to transmit a second transmission wavelength band of the second light and to block the second light in a wavelength range outside the second transmission wavelength band; the combining portion is configured to block the first transmission wavelength band of the third light, block the second transmission wavelength band of the third light, and transmit the third light in a wavelength range other than the first transmission wavelength band and the second transmission wavelength band; The first transmission wavelength band does not overlap with the second transmission wavelength band; And the lighting device further includes: a first light source arranged to input the first light into the first input end of the beam combiner; a second light source arranged to input the second light into the second input of the beam combiner; a third light source arranged to input the third light into the third input end of the beam combiner; The first light includes at least a portion of the first transmission wavelength band; The second light includes at least a portion of the second transmission wavelength band; and satisfies at least one of the following conditions: a combination of the second light transmitted through the combined portion and the third light transmitted through the combined portion being closer to a white point according to CIE 1931 than each of the second light transmitted through the combined portion and the first light transmitted through the combined portion; and The third light transmitted through the combined portion is closer to the white point according to CIE 1931 than each of the second light transmitted through the combined portion and the first light transmitted through the combined portion.

2. The lighting device according to claim 1, wherein at least one of the following applies: The first transmission wavelength band includes at least one of violet light and ultraviolet light; ・The second transmission wavelength band includes green light; The third light includes at least one of red light and blue light. 3 . The lighting apparatus according to claim 2 , wherein at least one of the second light and the third light comprises red light, green light, and blue light. 4 . The lighting device according to claim 1 , wherein each of the first to third light sources is individually controllable.

5. The lighting device according to any one of claims 1 to 3, wherein the combined part is one of the following: ・A pair of dichroic mirrors; and ・Orthogonal prism with two dichroic interfaces. 6 . The lighting device according to claim 1 , wherein at least one of the first to third light sources is a light emitting diode or a laser diode.

7. The lighting device according to any one of claims 1 to 3, wherein at least one of the following: The two dichroic reflective surfaces are not mechanically movable relative to each other, and The two dichroic reflective surfaces are non-mechanically movable relative to the first to third input ends and the output end.

8. A rigid end portion of an endoscope or a capsule endoscope, the rigid end portion being for insertion into a lumen of a human body, the rigid end portion comprising an objective lens and an illumination device according to any one of claims 1 to 7, the illumination device being arranged to illuminate at least a portion of an object space imaged by the objective lens with the combined light.

9. An endoscope comprising a shaft and a rigid tip portion according to claim 8, the shaft being for insertion into the lumen of the human body, wherein the rigid tip portion is directly or indirectly connected to the shaft.

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