RU236703U1 - Multispectral Light Source - Google Patents

Abstract

The utility model relates to biomedical equipment, namely to software-controlled multispectral illumination sources, which are in demand, for example, in microsurgical visualization systems. The technical result is to ensure uniform illumination of the surgical microscope operating field with the required intensity sequentially in several spectral channels. In order to achieve the technical result, it is proposed to use a multispectral illumination source consisting of light-emitting diodes emitting in different spectral ranges, focusing optical systems for introducing light-emitting diode radiation into light guides, polymer optical fibers optically coupled with light-emitting diodes, a homogenizer of the light flux based on total internal reflection, a diaphragm limiting the light spot, and a projection optical system forming a light spot of a given area at the required distance. The source can be used to solve the problem of improving tissue differentiation during microsurgical operations based on the difference in their spectral characteristics.

Description

The utility model relates to biomedical equipment, namely to software-controlled multispectral illumination sources, which are in demand, for example, in microsurgical visualization systems, where it can be used to improve tissue differentiation during surgical operations by analyzing their spectral characteristics. An actively developing direction in minimally invasive surgery - surgery under visual control - determines the need for multispectral illumination sources that provide the formation of directional optical radiation with specified spectral, spatial and temporal characteristics. The main requirements for such systems are the ability, with a standard magnification of a surgical microscope (5-25 times), to provide uniform illumination of an area of at least 25 cm ² in each spectral channel at a distance of at least 20 cm from the system, i.e. sufficient for performing surgical manipulations in sterile conditions, and the ability to programmatically control switching between spectral channels.

At the current level of technological development, the following technical solutions are known for creating multispectral light sources:

1. Combination of a broadband radiation source, an optical system that forms the light flux, and color optical filters placed in a filter wheel and used to isolate narrow spectral lines [1]. The limitation of this approach is the complexity of controlling the sequence and duration of radiation for each individual channel, low speed, and insufficient reliability of such systems.

2. Combination of a broadband radiation source, an optical system that forms the light flux, and optical elements for bandwidth tuning (diffraction gratings, acousto-optic filters, liquid crystal filters, etc.). [2, 3]. These systems have a large number of spectral channels, but do not provide sufficient output power due to its decrease in proportion to the bandwidth of the allocated spectral subrange.

3. Combining individual spectral channels into a single array in the form of independent light sources and optical systems that form the light flux [4]. Separating optical systems provides sufficient light flux, but leads to differences in the angles of illumination of the object in different spectral channels and can create artifacts due to differences in the angle of view, which complicates digital image processing. Creating "shadowless" lighting for such a scheme requires a significant increase in light sources, which is not always acceptable.

4. Combination of light fluxes of individual spectral channels in the form of independent light sources and optical systems that form the light flux by using optical prisms and translucent mirrors, or by using a diffusing filter. A projection lens can be installed at the output of the system [5, 6, 7, 8]. Such systems ensure the coaxiality of the output light fluxes of individual channels and eliminate "shadow" artifacts, but the design features of such sources limit the number of possible spectral channels and, as a consequence, lighting modes.

5. The prototype of the proposed utility model is a light source circuit in which the combination of light fluxes from individual LED light sources is achieved by using light guides in the form of optical glass fibers [9]. The fibers are installed with their input end in close proximity to the emitting surface of the LEDs and are connected into a single bundle that transfers radiation to the output end and forms a light spot after it. To equalize the intensity of the light beam, it is proposed to install one of the versions of the integrating optical rod behind the output end of the fiber bundle.

The main advantage of the prototype is the ability to use a large number of independent spectral channels. At the same time, the small aperture of optical fibers causes large energy losses when introducing light into the fiber, making the use of powerful LEDs with a large emitting surface area and wide aperture ineffective.

The technical challenge is to create a multispectral light source that simultaneously satisfies the following requirements:

- the required number of time-independent spectral channels to provide various visualization modes;

- ensuring in each spectral channel sufficient illumination of an object with an area of at least 25 ^cm2 , located at a distance of at least 20 cm from the lens;

- uniform illumination of the object, free of “shadow” artifacts, in all spectral channels.

The technical result of the utility model is to ensure uniform illumination of the surgical microscope operating field with the required intensity sequentially in several spectral channels.

In order to solve the stated technical problem with the achievement of the specified technical result, it is proposed to use a multispectral lighting source with several spectral channels and the possibility of software control, consisting of light-emitting diodes emitting in different spectral ranges, polymer optical fibers optically coupled with the light-emitting diodes using focusing optical systems, based on the total internal reflection of a homogenizer of the luminous flux, a diaphragm limiting the light spot, and a projection optical system installed after the homogenizer, forming a light spot of a given area at the required distance.

The essential features that coincide with the prototype include:

- the use of LEDs as light sources, emitting in different spectral ranges, which allows for independent control of the temporal and energy characteristics of spectral channels;

- the use of optical fibers, assembled at the output into a bundle, to transmit light energy from the LEDs to the optical circuit, which ensures the alignment of light flows while maintaining the compactness of the device;

- the presence of a homogenizer - an optical element that ensures uniformity of the light flux at the output of the system.

The essential features that differ from the prototype include:

- the use of LEDs as light sources, which are characterized by an increased emitting surface area and, as a consequence, increased power;

- use of multi-chip LEDs to increase the number of spectral channels without increasing the size of the device;

- the use of polymer optical fibers as light guides, the diameter of which is comparable to the area of the emitting surface of the LED, which, together with the increased optical aperture, significantly reduces energy losses when introducing light into the fiber;

- use of a focusing optical system to further increase the efficiency of radiation input into the fiber;

- use of at least two LEDs per channel instead of one, which ensures increased power and uniformity of output radiation;

- use of a projection optical system to form a light spot of a given area at the required distance.

The proposed design is illustrated by drawings.

Fig. 1. Schematic diagram of the main units of the multispectral lighting source: 1 - LED, 2 - focusing system, 3 - polymer optical fiber, 4 - hexagonal homogenizer of the light flux, 5 - diaphragm, 6 - projection optical system.

Fig. 2. The result of the operation of the sample multispectral light source.

Implementation of the utility model:

When several LEDs corresponding to one spectral channel (Fig. 1, pos. 1) are switched on, the light from each of them is collimated and focused by the optical system (Fig. 1, pos. 2) into the end of the polymer optical fiber (Fig. 1, pos. 3). Then the light radiation is transmitted via the optical fiber into the light flux homogenizer common for all channels (Fig. 1, pos. 4), where multiple total internal reflection of the light beams occurs, leading to alignment of the light flux at the output of the light flux homogenizer. The shape of the light beam is determined by the diaphragm (Fig. 1, pos. 5). Then the light beam from the end of the light flux homogenizer is collected and focused by the optical system consisting of two spherical lenses (Fig. 1, pos. 6), at a distance of 200 mm.

Possible implementation option of the system.

To confirm the possibility of solving the technical problem using the proposed utility model, a sample of a multispectral lighting source was assembled (Fig. 2).

High-power SMD LEDs were used as light sources: 12 monochrome and 1 white with a power consumption of 1 W for the IR range and 5 W for the visible and UV ranges (Fig. 1, pos. 1). In order to reduce the number of LEDs, two of them were multi-chip LEDs providing 5 spectral channels. Thus, the assembled sample had 10 spectral channels located in the spectral range of 415-880 nm and one white light LED for general illumination of the surgical field. Polymer optical fibers with a diameter of 3 mm with a PMMA core and a fluorinated polymer sheath were used as light guides (Fig. 1 pos. 3). An optical system consisting of two lenses made of N-BK-7 glass (Fig. 1, callout A, pos. 2) was used to introduce light into the fiber. A hexagonal homogenizer made of N-BK-7 glass (Schott), 150 mm long and 12.5 mm in diameter (Fig. 1, pos. 4) was chosen as a homogenizer of the luminous flux. Polymer fibers from each light-emitting diode were combined into a bundle at a short distance, the cut of which was pressed to the end of the hexagonal homogenizer of the luminous flux (Fig. 1, reference B). A diaphragm with a round hole of 12.5 mm in diameter is adjacent to the other end of the homogenizer of the luminous flux (Fig. 1, pos. 5). At the output of the optical circuit there were two spherical lenses with a diameter of 40 mm made of N-BK-7 glass (Schott) with focal lengths of 60 and 200 mm (Fig. 1, pos. 6), focusing the light beam at a distance of 200 mm.

The proposed technical solution can be used as part of microsurgical visualization systems to improve tissue differentiation, in particular, in oncological operations in neurosurgery, otolaryngology, ophthalmology, dentistry, as well as in assisted reproductive technology programs to improve the results of microdissection sperm extraction from testicles in severe forms of male infertility.

Bibliography:

1. Fei Hu, Yi Li, Yi Yang. Light Source System Employing Wavelength Conversion Materials And Color Filters. Patent US 009631792 B2. Apr. 25, 2017.

2. Digital Light Processing Hyperspectral Imaging Apparatus And Method Zuzak et al. US Patent 009 1985.78 B2 Dec. 1, 2015.

3. Eliot S. Wachman; Daniel L. Farkas:Wen-Hua. Niu. Subicron Imaging System Having An Acousto-Optic Tunable Filter. Patent US 00579652 A. Aug. 18, 1998.

4. Gultyaev Yu.P., Klyukin A.V., Kovalchuk V.S., Pismenny E.V. LED illuminator with a combined emission spectrum. Patent RU 187121 U1. 2018.10.22.

5. Multispectral illumination device Westphal et al. US Patent 009239293 B2 Jan. 19, 2016

6. Source of polychromatic radiation with a controlled spectrum. Rospatent.2478871 from 10.06.2011.

7. Multi-Color Led Light Source For Macroscope Illumination/Ravkin. US Patent 20070211460 A1 Ravkin Pub. Date: Sep.13, 2007.

8. Yagudin I.T., Zhukov N.D. Multispectral controlled LED radiation source. RU 2766307 C1. 2020.11.28.

9. Fournier R., Pawluczyk R. Bioimaging/Light Sources: Flexible LED light sources for scientific applications. https://www.laserfocusworld.com/lasers-sources/article/14074077/flexible-led-light-sources-for-scientific-applications.

Claims (1)

A multispectral illumination source with spectral channels for use in microsurgical visualization systems, including light-emitting diodes emitting in different spectral ranges, optical light guides optically coupled with them, the output end of which is pressed against the end of a light flux homogenizer, a diaphragm, wherein light-emitting diodes with a power of 1 W for the infrared range (IR) and 5 W for the visible and ultraviolet (UV) ranges and multi-chip light-emitting diodes are used, polymer optical fibers are used as light guides, wherein said source includes a focusing optical system for inputting light-emitting diode radiation into said polymer optical fibers and has a projection optical system for forming a light spot of a given area at a required distance, installed after the homogenizer along the beam path.