GB2593930A - Method of laser sterilisation - Google Patents
Method of laser sterilisation Download PDFInfo
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- GB2593930A GB2593930A GB2005334.4A GB202005334A GB2593930A GB 2593930 A GB2593930 A GB 2593930A GB 202005334 A GB202005334 A GB 202005334A GB 2593930 A GB2593930 A GB 2593930A
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000004659 sterilization and disinfection Methods 0.000 title claims abstract description 20
- 230000003287 optical effect Effects 0.000 claims abstract description 65
- 244000052769 pathogen Species 0.000 claims abstract description 23
- 239000013078 crystal Substances 0.000 claims abstract description 16
- 238000006243 chemical reaction Methods 0.000 claims abstract description 10
- XBJJRSFLZVLCSE-UHFFFAOYSA-N barium(2+);diborate Chemical compound [Ba+2].[Ba+2].[Ba+2].[O-]B([O-])[O-].[O-]B([O-])[O-] XBJJRSFLZVLCSE-UHFFFAOYSA-N 0.000 claims abstract description 7
- VCZFPTGOQQOZGI-UHFFFAOYSA-N lithium bis(oxoboranyloxy)borinate Chemical compound [Li+].[O-]B(OB=O)OB=O VCZFPTGOQQOZGI-UHFFFAOYSA-N 0.000 claims abstract description 4
- 230000001954 sterilising effect Effects 0.000 claims description 10
- 238000005202 decontamination Methods 0.000 claims description 9
- 230000003588 decontaminative effect Effects 0.000 claims description 7
- 235000013305 food Nutrition 0.000 claims description 6
- 230000001717 pathogenic effect Effects 0.000 claims description 4
- 238000004806 packaging method and process Methods 0.000 claims description 3
- 230000001681 protective effect Effects 0.000 claims description 3
- 230000003750 conditioning effect Effects 0.000 claims description 2
- 239000007792 gaseous phase Substances 0.000 claims description 2
- 239000007791 liquid phase Substances 0.000 claims description 2
- 238000007493 shaping process Methods 0.000 claims description 2
- 239000007790 solid phase Substances 0.000 claims description 2
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 9
- 230000009977 dual effect Effects 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 206010022000 influenza Diseases 0.000 description 3
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 3
- 229910052753 mercury Inorganic materials 0.000 description 3
- 241000588724 Escherichia coli Species 0.000 description 2
- 241000186779 Listeria monocytogenes Species 0.000 description 2
- 241000293869 Salmonella enterica subsp. enterica serovar Typhimurium Species 0.000 description 2
- 235000013351 cheese Nutrition 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002070 germicidal effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 229910052594 sapphire Inorganic materials 0.000 description 2
- 239000010980 sapphire Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 201000008827 tuberculosis Diseases 0.000 description 2
- 241000894006 Bacteria Species 0.000 description 1
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- 241001678559 COVID-19 virus Species 0.000 description 1
- 241000233866 Fungi Species 0.000 description 1
- 102000029797 Prion Human genes 0.000 description 1
- 108091000054 Prion Proteins 0.000 description 1
- 241000726445 Viroids Species 0.000 description 1
- 241000700605 Viruses Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 239000012678 infectious agent Substances 0.000 description 1
- 208000015181 infectious disease Diseases 0.000 description 1
- 230000002458 infectious effect Effects 0.000 description 1
- 208000037797 influenza A Diseases 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000001404 mediated effect Effects 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 230000002906 microbiologic effect Effects 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Classifications
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
- A61P17/00—Drugs for dermatological disorders
- A61P17/02—Drugs for dermatological disorders for treating wounds, ulcers, burns, scars, keloids, or the like
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
- A61L2/02—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using physical phenomena
- A61L2/08—Radiation
- A61L2/10—Ultraviolet radiation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
- A61L2/26—Accessories or devices or components used for biocidal treatment
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L9/00—Disinfection, sterilisation or deodorisation of air
- A61L9/16—Disinfection, sterilisation or deodorisation of air using physical phenomena
- A61L9/18—Radiation
- A61L9/20—Ultraviolet radiation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
- A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
- A61P31/04—Antibacterial agents
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L2202/00—Aspects relating to methods or apparatus for disinfecting or sterilising materials or objects
- A61L2202/10—Apparatus features
- A61L2202/11—Apparatus for generating biocidal substances, e.g. vaporisers, UV lamps
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0092—Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity
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- Health & Medical Sciences (AREA)
- Veterinary Medicine (AREA)
- Public Health (AREA)
- General Health & Medical Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Epidemiology (AREA)
- Nonlinear Science (AREA)
- Organic Chemistry (AREA)
- Medicinal Chemistry (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- General Chemical & Material Sciences (AREA)
- Pharmacology & Pharmacy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Chemical & Material Sciences (AREA)
- Oncology (AREA)
- Communicable Diseases (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Bioinformatics & Cheminformatics (AREA)
- Dermatology (AREA)
- Apparatus For Disinfection Or Sterilisation (AREA)
Abstract
A laser system 1 and method for generating a continuous-wave, tuneable optical output field 25 having a wavelength between 200nm and 300nm which is used for the sterilisation of pathogens or decontaminating objects. The laser system 1 comprises: a continuous-wave, tuneable optical field source 3 employed to generate a first output field; and an optical frequency conversion system through which the first output field propagates through. The optical frequency conversion system may comprise a first enhancement cavity frequency doubler 4, such as an LBO (lithium triborate (LiB3O5)) crystal, and a second enhancement cavity frequency doubler 5, such as a BBO (beta barium borate (BaB2O4)) crystal.
Description
1 Apparatus and Method for Sterilisation of Pathogens 3 The present invention relates to the field of sterilisation of pathogens and other 4 microbiological contaminants. In particular, a spectrally pure, tuneable, high-power laser system is disclosed which finds specific application in the sterilisation of pathogens.
7 A pathogen is the term used to describe an infectious microorganism or agent, such as a 8 virus, bacterium, protozoan, prion, viroid, or fungus. A pathogen is sometimes referred to 9 as an infectious agent.
11 It is known in the art that C-band ultraviolet light (UVC) has very high germicidal effects, 12 see for example the paper by Kim et al. entitled "Using UVC Light-Emitting Diodes at 13 Wavelengths of 266 to 279 Nanometers To Inactivate Foodbome Pathogens and 14 Pasteurize Sliced Cheese'', Applied Environmental Microbiology, 1 January 2016; Volume 82(1), pages 1110 17, (see doi: 10.1128/AEM.02092-15). UVC refers to light in the region 16 of the electromagnetic spectrum between 200 nm and 280 nm. A large body of work exits 17 that demonstrates the sterilisation effects of UVC on a wide range of pathogens such as 18 Influenza, Tuberculosis, E. Coli, S.Typhimurium and L. Monocytogenes, see for example 19 the paper by Welch et al. entitled "Far-UVC fight: A new tool to control the spread of 1 airborne-mediated microbial diseases", Scientific Reports (2018), Volume 8.2752, pages 1 2 to 7, (see https://doi.org/10.1038/541598-018-21058-w).
4 The UVC light sources known in the art primarily rely on the employment of mercury lamps, light emitting diodes (LEDs) or fixed-wavelength, solid-state lasers. All of these 6 UVC light sources have limitations such as low output power, lack of wavelength agility or 7 lack of practicality which make them less than ideal for their use in the sterilisation of 8 pathogens. As a result, light sources known in the art are limited in the speed and efficacy 9 at which they can complete the desired sterilisation process.
11 Summary of Invention
13 It is therefore an object of an embodiment of the present invention to provide an improved 14 UVC light source that obviates or at least mitigate the foregoing disadvantages of the UVC light sources known in the art.
17 According to a first aspect of the present invention there is provided a laser system for the 18 sterilisation of pathogens, the laser system comprising: a continuous-wave, tuneable optical 19 field source, and an optical frequency conversion system wherein a first output field generated by the continuous-wave, tuneable optical field source is 21 arranged to propagate thorough the optical frequency conversion system to provide a 22 continuous-wave, tuneable optical output field of the laser system having a wavelength 23 between 200nm and 300 nm.
The laser system provides a frequency-agile, high-power and spectrally pure light source 26 across the UVC the region of the electromagnetic spectrum which makes it a flexible and 27 efficient source for the sterilisation or decontamination of pathogens. The tunability of the 28 laser system enables an operator to carefully select the operating wavelength of the output 29 field of the laser system thus allowing optimisation of the sterilisation or decontamination process while reducing the risk to humans and other organic organisms.
32 Preferably, the first output field has a narrow-linewidth, i.e. a linewidth of 1 GHz or less.
34 Most preferably the optical frequency conversion system comprises a first frequency doubler wherein the first output field is arranged to propagate through the first frequency doubler.
2 Most preferably the optical frequency conversion system further comprises a second 3 frequency doubler wherein a first frequency-doubled output field generated by the first 4 frequency doubler is arranged to propagate thorough the second frequency doubler.
6 Optionally, the first frequency doubler comprises a first enhancement cavity frequency 7 doubler. Optionally, the second frequency doubler comprises a second enhancement 8 cavity frequency doubler.
Most preferably the first continuous-wave, tuneable optical field source is tuneable 11 between 800 nm and 1200 nm. Preferably the first continuous-wave, tuneable optical field 12 source comprises a Ti:Sapphire laser.
14 Preferably the frequency doubler comprises an LBO (Lithium Triborate (LiB305)) crystal.
Most preferably the first frequency doubler generates the first frequency doubled output 16 field having a wavelength between 400 nm and 600 nm.
18 Preferably the second frequency doubler comprises a BBO (Beta Barium Borate (BaB204)) 19 crystal.
21 Preferably the optical output field of the laser system has a linewidth of less than 500 kHz.
22 Optionally the optical output field of the laser system has a linewidth of less than 100 kHz.
23 In a further alternative the optical output field of the laser system has a linewidth of less 24 than 10 kHz.
26 Most preferably the optical output field of the laser system has a power between an 0.05 27 and 0.5 Watts.
29 According to a second aspect of the present invention there is provided a method for generating a continuous-wave, tuneable optical output field having a wavelength between 31 200 nm and 300 nm for the sterilisation or decontamination of a pathogen, the method 32 comprising: 33 -generating a first continuous-wave, tuneable optical field; and
34 -frequency converting the first output field.
1 Preferably frequency converting the first output field comprises frequency doubling the first 2 output field to generate a first frequency-doubled output field.
4 Preferably frequency converting the first output field further comprises frequency doubling
the first frequency-doubled output field.
7 Most preferably the first generated continuous-wave, tuneable optical field is tuneable 8 between 800 nm and 1200 nm.
Most preferably the frequency doubling the first output field comprises generating the first 11 frequency-doubled output field having a wavelength between 400 nm and 600 nm.
13 Preferably the generated continuous-wave, tuneable optical output field has a linewidth of 14 less than 500 kHz. Optionally the generated continuous-wave, narrow-linewidth, tuneable optical output field has a linewidth of less than 100 kHz. In a further alternative the 16 generated continuous-wave, narrow-linewidth, tuneable optical output field has a linewidth 17 of less than 10 kHz.
19 Most preferably the generated continuous-wave, tuneable optical output field has a power between an 0.05 and 0.5 Watts.
22 Embodiments of the second aspect of the present invention may comprise features to 23 implement the preferred or optional features of the first aspects of the invention or vice 24 versa.
26 According to a third aspect of the present invention there is provide a method of sterilising 27 or decontaminating an object contaminated by one or more pathogens the method 28 comprising generating a continuous-wave, tuneable optical output field having a wavelength 29 between 200nm and 300 nm in accordance with the second aspect of the present invention.
31 Most preferably the method of sterilising or decontaminating an object comprises selecting 32 the operating wavelength of the continuous-wave, tuneable optical output field.
34 The method of sterilising or decontaminating an object may comprise shaping the
continuous-wave, tuneable optical output field.
2 The object may comprise an object in a solid, gaseous or liquid phase. The object may 3 comprise a surface, a volume of air, a food product, food packaging, clothing or personal 4 protective equipment (PPE). The volume or air may be contained with an air conditioning system.
7 Embodiments of the third aspect of the present invention may comprise features to 8 implement the preferred or optional features of the first or second aspects of the invention 9 or vice versa.
11 Brief Description of Drawings
13 Aspects and advantages of the present invention will become apparent upon reading the 14 following detailed description and upon reference to the following drawings in which: 16 Figure 1 presents a schematic representation of a laser system in accordance with an 17 embodiment of the present invention.
19 Figure 2 presents schematic diagram of a narrow-linewidth laser employed within the laser system of Figure 1; 22 Figure 3 presents schematic diagram of a frequency doubling cavity employed within the 23 laser system of Figure 1; and Figure 4 presents a tuning curve of the output field of the laser system of Figure 1.
27 In the description which follows, like parts are marked throughout the specification and 28 drawings with the same reference numerals. The drawings are not necessarily to scale and 29 the proportions of certain parts have been exaggerated to better illustrate details and features of embodiments of the invention.
1 Detailed Description
3 A laser system 1, in accordance with an embodiment of the present invention will now be 4 described with reference to Figure 1. In particular, Figure 1 presents a schematic representation of the laser system 1 that can be seen to comprise an optical pump source 6 2, a continuous-wave, narrow-linewidth, tuneable optical field source 3, a first frequency 7 doubler in the form of a first enhancement cavity frequency doubler 4 and a second 8 frequency doubler in the form of a second enhancement cavity frequency doubler 5.
In the presently described embodiment the continuous-wave, narrow-linewidth, tuneable 11 optical field source 3 is the applicant's proprietary SolsTiS® laser platform which is a 12 Ti:Sapphire laser, a schematic representation of which is presented in Figure 2. The 13 continuous-wave, narrow-linewidth tuneable source 3 can be seen to comprise a laser cavity 14 6 that exhibits a bow-tie ring cavity geometry defined by a first mirror 7, a second mirror 8, a dual piezo-actuated mirror 9 (of the type described within UK patent number 16 GB 2,499,471 B) and an output coupler 10 all of which are located within a mechanically 17 stable housing 11. Located within the cavity 6 is a Ti:Sapphire gain medium 12 (between 18 the first 7 and second 8 mirrors); an optical diode 13 (between the first 7 and the dual piezo- 19 actuated 9 mirrors); a birefringent filter (BRF) 14 (between the second mirror 8 and the output coupler 10); and an air-spaced etalon 15 (between the piezo-actuated mirror 9 and 21 the output coupler 10). It is a combination of the ring cavity geometry and the optical diode 22 13 that forces the laser cavity 6 to operate in a unidirectional manner, resulting in a travelling 23 intracavity optical field 16 that removes the detrimental effects of spatial-hole burning within 24 the gain medium 12.
26 Given that the optical absorption within Ti:Sapphire occurs over a broad wavelength range 27 from -400nm to -600nm, the gain medium 12 can be optically pumped by a pump field 17 28 generated by any commercially available continuous-wave "green' laser 2 e.g. a 532 nm 29 diode pumped solid-state laser source. Pumping of the gain medium 12 preferably takes place through the second mirror 8. In the presently described embodiment the pump field 31 17 has a power of 20 Watts.
33 In order to tune the wavelength of a laser output field 18, the intracavity BRF 14 is 34 employed. The BRF 14 introduces a wavelength-dependent loss into the cavity 6, and wavelength tuning is accomplished by rotation of the BRF 14. The BRF 14 provides a 1 relatively rapid but coarse wavelength adjustment. In the absence of any further linewidth 2 narrowing techniques the laser output 18 exhibits a linewidth of -8 GHz.
4 The introduction of the air-spaced etalon 15 to the laser cavity 6 acts to further narrow the linewidth operation of the laser 3. This is because the air-spaced etalon 15 introduces a 6 spectral loss into the cavity 6 that has a narrower transmission bandwidth than that 7 exhibited by the BRF 14. By electronically adjusting the spacing of the air-spaced etalon 8 15 the laser output field 18 can also be finely tuned. Long-term single mode operation for 9 the laser cavity 6 can also be achieved through the electronic servo locking of the intracavity air-spaced etalon 15, a technique known to those skilled in the art. This 11 technique involves locking the peak of the air-spaced etalon's 15 transmission function to 12 the nearest cavity 6 longitudinal mode (within the capture range of the servo loop) by 13 dithering the spacing of the air-spaced etalon 15. In the absence of any further linewidth 14 narrowing techniques, the laser output field 18 exhibits a linewidth of -5 MHz.
16 The dual piezo-actuated mirror 9 comprises first and second piezoelectric crystals. The 17 thickness of the second piezoelectric crystal is less than the thickness of the first 18 piezoelectric crystal. With this arrangement the dual piezo-actuated mirror 9 provides a 19 means for maintaining a single longitudinal mode operation as the laser frequency is tuned since accurate control of the first, thicker piezoelectric crystal of the duel piezo-actuated 21 mirror 9 allows the cavity length to be changed precisely, and to match the single 22 oscillating longitudinal cavity mode frequency as the cavity length is tuned. With the air- 23 spaced etalon 15 peak lock circuit engaged, the peak transmission of the air-spaced 24 etalon 15 is then kept locked to this oscillating longitudinal mode frequency (to within the capture range of the locking circuit), even as this frequency is tuned by the dual piezo- 26 actuated mirror 9. The combination of the first and second piezoelectric crystals of the 27 dual piezo-actuated mirror 9 can also be employed to lock the laser cavity to an external 28 reference cavity (not shown) which reduces the laser line width further. In the presently 29 described embodiment, the narrow-linewidth tuneable laser 3 is arranged to generate a laser output field 18 at wavelength of 910 nm having a linewidth around -5 kHz and a 31 power of 5.7 Watts.
33 As can be seen from Figure 1, laser output field 18 is arranged to propagate thorough the 34 first enhancement cavity frequency doubler 4, a schematic representation of which is 1 presented in Figure 3. The applicant's proprietary SolsTis® ECD-X is a suitable example 2 of such an enhancement cavity frequency doubler 4.
4 The first enhancement cavity frequency doubler 4 can be seen to comprise a Brewster-angle cut crystal 19 formed from LBO (Lithium Triborate (LiB305)) located within a ring 6 cavity defined by a first mirror 20, an output coupler 21, an input coupler 22 and a second 7 mirror 23. The first enhancement cavity frequency doubler 4 employs resonant 8 enhancement to convert the output frequency of the laser output field 18 to produce a first 9 frequency-doubled output field 24. In the presently described embodiment, the first frequency doubled output field 24 has a wavelength of 455 nm and a power of 2.4 Watts.
12 As can be seen from Figure 1, the first frequency doubled output field 24 is then arranged 13 to propagate thorough the second enhancement cavity frequency doubler 5. The 14 applicant's proprietary SolsTis® ECD-Q is a suitable example of such an enhancement cavity frequency doubler 5, a schematic representation of which is again provided by 16 Figure 3.
18 The second enhancement cavity frequency doubler 5 is identical to the first enhancement 19 cavity frequency doubler 4 except for the fact that in the second enhancement cavity frequency doubler 5 the Brewster-angle cut crystal 19 is formed from BBO (Beta Barium 21 Borate (BaB204)). The second enhancement cavity frequency doubler 5 therefore 22 employs resonant enhancement to convert the output frequency of the first frequency 23 doubled output field 24 to produce a second frequency doubled output field 25. In the 24 presently described embodiment, the second frequency doubled output field 25, which acts as the output field for the laser system 1, has a wavelength of 227.5 nm and a power 26 of 0.5 Watts.
28 Frequency tuning of the output field 25 generated by second enhancement cavity 29 frequency doubler 5 can be achieved by tuning the wavelength of laser output field 18 and by simultaneously rotating the Brewster-angle cut crystals 19 of the first frequency doubler 31 4 and the second frequency doubler 5 about their respective axis 26. This rotation of the 32 Brewster-angle cut crystals 19 allows for maintenance of the required phase-matching 33 conditions required for the second harmonic generation processes to take place within the 34 first enhancement cavity frequency doubler 4 and the second enhancement cavity frequency doubler 5.
2 Figure 4 presents a tuning curve of the output field 25 of the laser system 1 when the 3 narrow-linewidth tuneable laser 3 is scanned between 820 nm and 1000 nm and the 4 Brewster-angle cut crystals 19 of the first frequency doubler 4 and the second frequency doubler 5 are appropriately rotated about their respective axis 26. As can be seen from 6 Figure 4 the laser system 1 produces an output field 25 of several hundred milliwatts of 7 power across the UVC the region of the electromagnetic spectrum. The linewidth of the 8 output field 25 matches that of the narrow-linewidth tuneable laser 3, in the presently 9 described embodiment this linewidth is around -5 kHz.
11 As a result of the laser systems 1 superior performance, when compared with those 12 system known in the art based on the employment of mercury lamps, light emitting diodes 13 (LEDs) or fixed-wavelength solid-state lasers, the laser system provides sterilisation 14 efficacy that are orders of magnitude greater than the known prior art systems.
16 The tunability of the laser system 1 also enables an operator to carefully select the 17 operating wavelength of the output field 25 thus allowing optimisation of the sterilisation or 18 decontamination process while reducing the risk to humans and other organic organisms.
The physical nature of the laser system 1 means that it can easily be employed to sterilise 21 or decontaminate objects contaminated with a wide range of pathogens such as Influenza, 22 Tuberculosis, E. Coli, S.Typhimurium and L. Monocytogenes in the solid, gaseous or liquid 23 phase. A particular application of the laser system1 is in the sterilisation or 24 decontamination of objects, including surfaces and a volume of air, contaminated with the Covid-19 virus.
27 The high-quality of the output field 25 emitted by the laser system 1 can easily be shaped 28 and thus allows configurations of large spot size or line scan decontamination. As known 29 in the art, low doses of UVC radiation of only 2 mJ/cm2 are enough to eradicate influenza A. At this dose, the present laser system 1 can be employed to decontaminate an area of 31 5 square meters in less than 1 minute. The high power of the output field 25 thus enables 32 the sterilisation or decontamination of significantly larger surface areas, at greater speeds 33 and efficacy, compared to traditional prior art solutions. The laser system 1 has been 34 demonstrated to exhibit an increase in germicidal efficacy of 150,000 times when compared to other light sources such as mercury lamps and LEDs.
2 In addition to the removal of surface contamination, the illumination of air by the output 3 field 25 can be employed to kill Influenza when airborne. It has previously been shown 4 that at deep UVC the radiation is safe for humans. The laser system 1, can therefore be employed to create 'light curtains' that generate germ free zones in hospitals and isolation 6 areas to increase overall safety.
8 Alternative ways of deployment could be in the use of sterilising circulating air in air- 9 conditioning units. Similarly, the laser system 1 could be employed for the sterilisation of food products e.g. cheese, food packaging, clothing, including personal protective 11 equipment (PPE).
13 The above embodiments have been described with a Ti:Sapphire laser being employed as 14 the a continuous-wave, narrow-linewidth, tuneable optical field source 3. It will however be appreciated by those skilled in the art that alternative continuous-wave, narrow-linewidth, 16 optical field sources may be employed as the continuous-wave, narrow-linewidth tuneable 17 source 3, e.g. other solid state lasers or optical parametric oscillators (0P0s) as long as 18 they are tuneable between 800 nm and 1200 nm so as to allow the output field 25 to be 19 tuned between 200 nm and 300 nm.
21 As will also be appreciated by the skilled reader, the combined effects of the first 22 enhancement cavity frequency doubler 4 and the second enhancement cavity frequency 23 doublet 5 is to provide an optical system that frequency quadruples the laser output field 24 18. Other optical systems which frequency quadruple the laser output field 18 may be employed in alternative embodiments.
27 A laser system and method for generating a continuous-wave, tuneable optical output field 28 having a wavelength between 200nm and 300 nm is disclosed. The laser system 29 comprising: a continuous-wave, narrow-linewidth, tuneable optical field source employed to generate a first output field. The first output field is arranged to propagate thorough the 31 first enhancement cavity frequency double to generate a first frequency doubled output 32 field. The first frequency doubled output field is then arranged to propagate thorough a 33 second enhancement cavity frequency double to generate a second frequency doubled 34 output field which acts as an output field for the laser system. The laser system thus provides a frequency-agile, high power and spectrally pure light source across the UVC 1 the region of the electromagnetic spectrum which makes it a flexible and efficient source 2 for the sterilisation or decontamination of pathogens.
4 Throughout the specification, unless the context demands otherwise, the terms "comprise" or "include", or variations such as "comprises" or "comprising", "includes" or "including' will 6 be understood to imply the inclusion of a stated integer or group of integers, but not the 7 exclusion of any other integer or group of integers.
9 Furthermore, reference to any prior art in the description should not be taken as an indication that the prior art forms part of the common general knowledge.
12 The foregoing description of the invention has been presented for purposes of illustration 13 and description and is not intended to be exhaustive or to limit the invention to the precise 14 form disclosed. The described embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others 16 skilled in the art to best utilise the invention in various embodiments and with various 17 modifications as are suited to the particular use contemplated. Therefore, further 18 modifications or improvements may be incorporated without departing from the scope of 19 the invention as defined by the appended claims.
Claims (2)
1 Claims 3 1) A laser system for the sterilisation of pathogens, the laser system comprising: a 4 continuous-wave, tuneable optical field source, and an optical frequency conversion system wherein a first output field generated by the continuous-wave, tuneable optical 6 field source is arranged to propagate thorough the optical frequency conversion 7 system to provide a continuous-wave, tuneable optical output field of the laser system 8 having a wavelength between 200 nm and 300 nm.
2) A laser system as claimed in claim 1 wherein the first output field has a linewidth of 1 ii GHz or less.13 3) A laser system as claimed in either claim 1 or 2 wherein the optical frequency 14 conversion system comprises a first frequency doubler and the first output field is arranged to propagate through the first frequency doubler.17 4) A laser system as claimed in claim 3 wherein the optical frequency conversion system 18 further comprises a second frequency doubler and a first frequency-doubled output 19 field generated by the first frequency doubler is arranged to propagate thorough the second frequency doubler.22 5) A laser system as claimed in either of claims 3 or 4 wherein the first frequency doubler 23 comprises a first enhancement cavity frequency doubler.6) A laser system as claimed in either of claims 4 or 5 wherein the second frequency 26 doubler comprises a second enhancement cavity frequency doubler.28 7) A laser system as claimed in any of the preceding claims wherein the first continuous- 29 wave, tuneable optical field source is tuneable between 800 nm and 1200 nm.31 8) A laser system as claimed in any of the preceding claims wherein the first continuous- 32 wave, tuneable optical field source comprises a Ti:Sapphire laser.34 9) A laser system as claimed in any of claims 3 to 8 wherein the first frequency doubler comprises an LBO (Lithium Triborate (LiB305)) crystal.2 10) A laser system as claimed in any of claims 3 to 9 wherein the first frequency doubler 3 generates the first frequency doubled output field having a wavelength between 400 4 nm and 600 nm.6 11) A laser system as claimed in any of claims 4 to 10 wherein the second frequency 7 doubler comprises a BBO (Beta Barium Borate (BaB204)) crystal.9 12) A laser system as claimed in any of the preceding claims wherein the optical output field of the laser system has a linewidth of less than 10 kHz.12 13) A laser system as claimed in any of the preceding claims wherein the optical output 13 field of the laser system has a power between an 0.05W and 0.5 Watts.14) A method for generating a continuous-wave, tuneable optical output field having a 16 wavelength between 200 nm and 300 nm suitable for sterilisation or decontamination 17 of a pathogen, the method comprising: 18 -generating a first continuous-wave, tuneable optical field; and19 -frequency converting the first output field.21 15) A method for generating a continuous-wave, tuneable optical output field as claimed 22 in claim 14 wherein frequency converting the first output field comprises frequency 23 doubling the first output field to generate a first frequency-doubled output field.16) A method for generating a continuous-wave, tuneable optical output field as claimed 26 in claim 15 wherein frequency converting the first output field further comprises 27 frequency doubling the first frequency-doubled output field.29 17) A method for generating a continuous-wave, tuneable optical output field as claimed in any of claims 14 to 17 wherein the first generated continuous-wave, tuneable optical31 field is tuneable between 800 nm and 1200 nm.33 18) A method for generating a continuous-wave, tuneable optical output field as claimed 34 in any of claims 15 to 17 wherein frequency doubling the first output field comprises 1 generating the first frequency-doubled output field having a wavelength between 400 2 nm and 600 nm.4 19) A method for generating a continuous-wave, tuneable optical output field as claimed in any of claims 14 to 18 wherein the generated continuous-wave, narrow-linewidth, 6 tuneable optical output field has a linewidth of less than 10 kHz.8 20) A method for generating a continuous-wave, tuneable optical output field as claimed 9 in any of claims 14 to 19 wherein the generated continuous-wave, narrow-linewidth, tuneable optical output field has a power between an 0.05W and 0.5 Watts. ii12 21) A method of sterilising or decontaminating an object contaminated by one or more 13 pathogens the method comprising generating a continuous-wave, tuneable optical 14 output field having a wavelength between 200nm and 300 nm in accordance with the method of any of claims 14 to 20.17 22) A method of sterilising or decontaminating an object contaminated by one or more 18 pathogens as claimed in claim 21 wherein the method comprises selecting the 19 operating wavelength of the continuous-wave, tuneable optical output field.21 23) A method of sterilising or decontaminating an object contaminated by one or more 22 pathogens as claimed in either of claims 21 or 22 wherein the method comprises 23 shaping the continuous-wave, tuneable optical output field.24) A method of sterilising or decontaminating an object contaminated by one or more 26 pathogens as claimed any of claims 21 to 23 wherein the object may comprise an 27 object in a solid, gaseous or liquid phase.29 25) A method of sterilising or decontaminating an object contaminated by one or more pathogens as claimed in any of claims 21 to 24 wherein the object comprises a 31 surface, a volume of air, a food product, food packaging, clothing or personal 32 protective equipment (PPE).1 26) A method of sterilising or decontaminating an object contaminated by one or more 2 pathogens as claimed in claim 22 wherein the volume or air is contained with an air 3 conditioning system.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2005334.4A GB2593930A (en) | 2020-04-09 | 2020-04-09 | Method of laser sterilisation |
| PCT/GB2021/050867 WO2021205177A1 (en) | 2020-04-09 | 2021-04-08 | Apparatus and method for sterilisation of pathogens |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2005334.4A GB2593930A (en) | 2020-04-09 | 2020-04-09 | Method of laser sterilisation |
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| GB202005334D0 GB202005334D0 (en) | 2020-05-27 |
| GB2593930A true GB2593930A (en) | 2021-10-13 |
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| GB2005334.4A Pending GB2593930A (en) | 2020-04-09 | 2020-04-09 | Method of laser sterilisation |
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| WO (1) | WO2021205177A1 (en) |
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|---|---|---|---|---|
| US6088379A (en) * | 1997-06-10 | 2000-07-11 | Nikon Corporation | Ultraviolet laser apparatus and semiconductor exposure apparatus |
| US20020034198A1 (en) * | 2000-09-21 | 2002-03-21 | Hisashi Masuda | Laser light generating apparatus and optical apparatus using the same |
| US20050079096A1 (en) * | 1999-03-01 | 2005-04-14 | Brown-Skrobot Susan K. | Method and apparatus of sterilization using monochromatic UV radiation source |
| US20140105784A1 (en) * | 2012-10-15 | 2014-04-17 | Sharp Kabushiki Kaisha | Ultraviolet treatment device |
| US20160088804A1 (en) * | 2014-09-29 | 2016-03-31 | King Abdullah University Of Science And Technology | Laser-based agriculture system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU3691500A (en) * | 1998-11-25 | 2000-07-03 | University Of New Mexico | Precisely wavelength-tunable and wavelength-switchable narrow linewidth lasers |
| GB2499471B (en) | 2012-06-01 | 2014-09-10 | M Squared Lasers Ltd | Method and apparatus for locking and scanning the output frequency from a laser cavity |
| WO2015024094A1 (en) * | 2013-08-20 | 2015-02-26 | Khalid Ashraf Najeeb | Uv apparatus and method for air disinfection |
| US10682525B2 (en) * | 2015-05-15 | 2020-06-16 | Emil I. COHEN | Systems, apparatuses, and methods for ultraviolet (UV) treatment |
| GB2563005B (en) * | 2017-05-23 | 2021-04-21 | M Squared Lasers Ltd | Nonlinear crystal |
-
2020
- 2020-04-09 GB GB2005334.4A patent/GB2593930A/en active Pending
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2021
- 2021-04-08 WO PCT/GB2021/050867 patent/WO2021205177A1/en active Application Filing
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6088379A (en) * | 1997-06-10 | 2000-07-11 | Nikon Corporation | Ultraviolet laser apparatus and semiconductor exposure apparatus |
| US20050079096A1 (en) * | 1999-03-01 | 2005-04-14 | Brown-Skrobot Susan K. | Method and apparatus of sterilization using monochromatic UV radiation source |
| US20020034198A1 (en) * | 2000-09-21 | 2002-03-21 | Hisashi Masuda | Laser light generating apparatus and optical apparatus using the same |
| US20140105784A1 (en) * | 2012-10-15 | 2014-04-17 | Sharp Kabushiki Kaisha | Ultraviolet treatment device |
| US20160088804A1 (en) * | 2014-09-29 | 2016-03-31 | King Abdullah University Of Science And Technology | Laser-based agriculture system |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2021205177A1 (en) | 2021-10-14 |
| GB202005334D0 (en) | 2020-05-27 |
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