GB2340368A - Irradiation chamber comprising a pre-determined reflected radiation pathway - Google Patents

Description

1 2340368 1 HIGH ENERGY CHAMBER 2 3 The invention relates to a method of

distributing by 4 reflection into a chamber at least one high energy 5 electromagnetic radiation beam according to a specific 6 pathway which provides the chamber with'a particularly 7 high density of energy. 8 9 10 Conventional decontamination systems are inefficient at 11 killing or filtering a range of harmful pathogens 12 including, for example: certain strains of influenza, 13 tuberculosis, cryptosporidium, aspergillus niger, 14 legionaires and anthrax. Intense light energy sources 15 have been demonstrated to kill these resistant 16 organisms, and benefit is expected from developing 17 laser technology. More specifically, high average and 18 peak power can create reactions and catalytic effects 19 on a molecular level. This energy can be used to 20 destroy pathogens, create combustion effects or 21 catalyze reactions. The energy can alter or otherwise 22 modify the molecular, biochemical, nuclear or atomic 23 structure of a substance. 24 2 1 Further, the US EPA now sells "rights to pollute" in 2 open markets. Companies that reduce their emissions 3 are able to sell the permits which they do not use 4 while overpolluters must purchase these rights.

6 Laser and incoherent light decontamination of surfaces 7 and liquids has been investigated for a range of lasers 8 and light sources but no technology has been developed 9 that is viable economically or has been optimised for delivery of laser or incoherent sources of light, UV or 11 infra-red, RF or Microwave energy. It is convenient to 12 define these wavelength ranges as light. Lasers have 13 historically been too expensive and their deployment 14 too inefficient to develop into a commercially viable decontamination or combustion processes. Laser sources 16 are becoming cheaper and the development of high power 17 solid state lasers will open new opportunities to 18 exploit laser decontamination and combustion 19 applications. Furthermore, there will be development of laser diodes in the blue end of the spectrum, and 21 there will be continued emphasis on developing shorter 22 wavelength sources to maximise the information storage 23 on CD or other optical based storage systems. High 24 power laser diode sources are available from the red to IR part of the spectrum and the future will see 26 development towards the blue and UV end of the 27 spectrum. These devices can be mass-produced cheaply.

28 Development of optics and active optic systems will 29 lead to efficient collimation of incoherent sources that may make them suitable for implementing in systems 31 like the one of the present invention. The future 32 development of optics technology makes these systems 33 even more viable economically.

34 36 3 1 Therefore there is a need for a method and/or apparatus 2 to distribute and effectively amplify electromagnetic 3 radiation energy for the treatment for example 4 decontamination) of air, gas, water and other fluids with the potential to increase the throughput and make 6 such systems viable. Additionally such systems can be 7 used as the basis for efficient laser combustion 8 systems.

9 11 According to the present invention there is provided 12 apparatus for providing exposure of a fluid to 13 electromagnetic radiation, said apparatus comprising:

14 - a fluid chamber having an inlet and an.

outlet and internal walls; 16 - at least one electromagnetic radiation beam 17 generating means; and 18 - reflection means shaped and positioned on 19 the internal walls of the chamber so as to reflect the electromagnetic radiation beam at 21 least three times within the chamber 22 according to a predetermined pathway which 23 distributes the beam in order to 24 substantially fill the chamber with energy.

26 Typically, the beam is reflected according to a 27 direction substantially perpendicular to the flow of 28 fluid to be treated.

29 Preferably, the electromagnetic radiation is a laser.

31 For example, it may be UV, IR or visible light.

32 33 The present invention will now be described by way of 34 example only with reference to the accompanying drawings, in which:

36 4 2 Fig. la is a representation of a first embodiment 3 of the invention which shows a schematic cross 4 sectioned view of the chamber of the apparatus and the radiation beam reflection pathway.

6 7 8 Fig. lb is a schematic representation of the 9 radiation beam pathway according to the first embodiment of the invention which shows a two 11 dimensional rendition of two sets of twisted 12 helixes.

13 14 Fig. lc is a schematic representation of,another embodiment of the invention which shows a cross 16 sectioned view of the chamber of the apparatus and 17 the radiation beam reflection pathway. For the 18 purpose of illustration, only one reflection from 19 the second strand back to first strand is shown.

21 22 Fig. 2 is a schematic representation of a third 23 embodiment of the invention wherein the radiation 24 beam reflection pathway is shown by transparency.

26 27 Fig. 3a is a cross-sectioned schematic 28 representation of a fourth embodiment of the 29 invention.

31 Fig 3b is three-dimensional cross-section of the 32 fourth embodiment of the invention showing the 33 repetition of the star-shape pattern throughout 34 the chamber of the apparatus.

36 Fig. 3c is a frontal view of Fig. 3b with the addition of a third and fourth strand being added.

2 3 4 According to a first embodiment of the invention which 6 is shown in Fig. la an apparatus 16 is provided which 7 comprises an enclosed conduit 10 throughout which a 8 fluid (not shown) to be treated flows. The conduit 10 9 is provided with a number of reflectors or mirrored facets 12. Single or multiple lasers or 11 electromagnetic energy sources emit a single or 12 multiple radiation beam 14 that may be either 13 continuous wave or pulsed. In this example, the 14 radiation is 1 ight but this need not always be the case. This light beam 14 is fed into the conduit 10 and 16 reflected by the mirrors 12 throughout the volume. The 17 light beam 14 bounces inside the system, many times in a 18 helical pattern and efficiently fills the conduit 10 19 with the electromagnetic energy (in this example, light energy). The multiple reflections from the mirrors 12 21 have the effect of amplifying the exposure that the 22 contaminants contained in the fluids flowing through 23 the conduit 10 receive. In essence, the apparatus 16 24 of Fig la can create an effect of hundreds of light beams with a single unit. This results in an increase 26 in the peak and main power within the conduit 10.

27 28 The light beam 14 strikes the first mirror 12a of the 29 helix, within the conduit 10, and the light is reflected to the second mirror 12b that is positioned 31 across the diameter or width of the conduit 10, from 32 where it is reflected to the third mirror 12c of the 33 helix, on the other side of the conduit. The light 34 beam 14 makes many reflections as it travels in a helical pathway down the length of the conduit 10, 36 crossing back and forth.

6 1 As shown in Fig. la the helical shape according to 2 which the reflectors 12 are provided allows the maximum 3 number of reflections in a pattern that has the highest 4 probability of interacting with the entire volume of fluid to be treated. Such an amplification method 6 reduces the power and capital equipment requirements 7 and maximises throughput, making decontamination, 8 combustion and catalyzing for example, viable 9 economically.

11 A schematic representation of the first embodiment of 12 the invention can be seen in Fig la where only one 13 reflection from the second strand is shown for clarity.

14 The number of mirrors 12 that can be used and the number of revolutions the light beam 14 makes as it 16 travels down the conduit 10 is determined by the 17 reflectivity of the mirrors 12 and the-&bsorption of 18 the light by the fluid being decontaminated. The total 19 number of reflections that will be possible given for example the wavelength or frequency of the 21 electromagnetic radiation (for example, the laser 22 transition wavelength(s)), absorption properties of the 23 fluid, the reflectivity on the mirrors 12 and the 24 incident intensity of the mirrors can be calculated by any person skilled in the field of optics.

26 27 It is preferred that the helicoidal pattern be repeated 28 at least once so that the electromagnetic beam performs 29 at least one revolution in one direction before reaching the extremity of the conduit 10.

31 32 Once the electromagnetic radiation beam 10 has been 33 reflected along the entire helicoidal pattern of 34 reflectors 12, then the entire conduit 10 will have been filled with the radiation and the contaminant will 36 have been exposed to the electromagnetic radiation.

7 1 The total energy density received can be calculated by 2 any person competent in the area of optics and 3 decontamination. Quite clearly the energy density 4 received will be dependent on the type of electromagnetic radiation used (in the case of laser, 6 laser parameters like pulse energy, pulse width, pulse 7 repetition, frequency, beam size) and velocity at which 8 the contaminant is moving through the system. The 9 applied energy density required to achieve the desired..

process is dependent on the process, the type of 11 electromagnetic radiation beam and the rate of flow of 12 the fluid. The device can be easily optimised for each 13 particular application.

14 Referring now to Fig lb, as the first double strand 16 helix 20 comes to the end of its Journey, it is 17 possible for a second helix to be generAted that 18 travels in the opposite direction to the first helix 19 and out of phase therewith. Any number of helixes can be used provided the energy density is sufficient to 21 achieve the required process; this is dependent on the 22 factors described previously. In this way, there will 23 be multiple radiation beams (for example, laser beams) 24 crossing each other many times within the conduit, provided that the pulse length of the laser beam 26 multiplied by the speed of light in the medium is 27 greater than the path length travelled by the beam. In 28 this way, the apparatus according to the invention can 29 be designed so that the contaminant will interact with more than one beam at a time. This results in an 31 additive or amplification effect of the energy. The 32 magnitude of the amplification can be calculated by 33 considering how the beam is attenuated through the 34 system and how many beams intersect at any given point and adding up the resultant spatial energy density 36 profile of the multiple helix system. The beam 8 1 diameter and the phase between the different helixes 2 can be optimised for any particular application.

3 4 To compensate for the loss in energy density as the beam travels down the helix it is possible to make the 6 facets concave, their radius of curvature may be a 7 function of the distance from the first mirror and the 8 number of facets the beam has struck. Additionally 9 this compensates for a diverging electromagnetic radiation beam. If the device creating the beam is a 11 laser then its output mode i.e. its spatial energy 12 distribution has to be considered with the optimisation 13 process for the helix. If the beam has a top-hat 14 distribution then the size of the reflecting facets can be quite close in size to the beam. To reduce 16 diffraction losses and in general optimise the 17 performance of helix the size of the mitrors, their 18 reflectivity profile and radius of curvature can be 19 optimised along its length. These effects can be calculated by any competent person with knowledge of 21 electromagnetic beam propagation and optics.

22 23 24 The electromagnetic radiation projected into the apparatus 10, may come from more than one coherent or 26 incoherent electromagnetic radiation source from any 27 wavelength range. For example, biological and molecular 28 decontamination, require wavelengths of approx 260nm 29 and for thermal effects light at 900 nm - 30 pm is most efficient.

31 32 Laser diode arrays operating at 975 nm are useful in 33 that this corresponds to a peak in the absorption 34 spectrum of water. For incoherent sources normal collimating optics are used to ensure propagation of 36 the light through the system.

9 1 Alternatively a number of sources could be arranged in 2 a helical path down the outside of the conduit with 3 suitable windows on the conduit to allow transmission 4 of the light into the conduit. The windows would be made of material that is appropriate for passing the 6 wavelengths that are most efficient for the process 7 application.

8 9 There may be economic benefit from using 355 nm, in that the efficiency and lifetime of the optics are 11 greater than at 260 nm. The light may be generated 12 from Nd:YAG lasers or KrFl excimer lasers, or laser 13 diodes or laser diode arrays, light emitting diodes or 14 any other light source. The beam may be delivered to the system of mirrors within the system using fibre 16 optics, mirrors, and/or diffractive optics operating in 17 reflection or transmission or using scanning optics.

18 19 There will be economy of scale at which point it is no longer sensible to have further reflective optics when 21 the benefit gained from additional mirrors does not 22 yield any further benefit to the process, be it 23 decontamination or changing the molecular properties of 24 a material, for example Volatile Organic Compounds (VOCs). Furthermore, because of the natural reduction 26 in the energy of the beam as it travels through the 27 system, it will not be necessary to have optics beyond 28 the position at which the energy density is below that 29 required to achieve the process i.e. in the case of decontamination it will be below the threshold energy 31 density to give the required level of sterility 32 assurance for a particular contaminant or the required 33 exposure to reduce the level of VOCs to an acceptable 34 limit. However, the shape of the conduit may be altered to adjust the rate of flow of the medium 36 through it such that it has a longer contact time in 1 the beam where the energy density of the beam has been 2 reduced.

3 4 The last mirror of the system could be partially 6 transmissive, and a detector could be placed behind it 7 to measure the energy transfer through the system and 8 determine whether the system is functioning properly.

9 Other sensor systems can include a detector or series of detectors to measure the scattered light, or 11 conventional particle counters for monitoring the 12 particles. A system could be implemented before, 13 during and/or after the helix. Data collected by the 14 sensors would be used as feed-back to determine, control and op timise the efficiency of the system. For 16 example, error control signals would be generated to 17 control the electromagnetic energy sour - ces for optimum 18 use. If the substrate is relatively clean then a lower 19 power can be used, if the substrate is highly contaminated then a higher power will be needed. The 21 sensor system increases the overall efficiency of the 22 system.

23 24 If the absorption through the fluids is known and the energy loss through the system is measured by one of 26 the monitoring/sensing systems then the quality of the 27 optics can be ascertained and appropriate action taken.

28 The sensor system allows for quality control measures 29 to ensure that complete destruction or reaction has been achieved.

31 32 The flow of the contaminated fluid through the system 33 has to be optimised. Aerofoils placed strategically 34 through any of the systems will help the flow stability and uniformity. For some turbid fluids there may be an 36 advantage in deliberately introducing turbulence into 1 the system. Additionally, some of the fluid treated by 2 the system could be fed back into the system again to 3 help control the flow dynamics. Furthermore, by 4 looping the fluid around the system the purity of the decontaminated fluid can be improved even further.

6 7 According to the first embodiment of the invention the 8 apparatus 16 includes a number of reflective facets 12 9 arranged in a helical shape down the conduit 14. The -conduit may be any shape, for example cylindrical as 11 shown in Figs la and lb, square in cross-section as 12 shown in Figs. lc or rectangular, oval or conical.

13 14 Even though one helix may be sufficient it is preferred 16 to improve the system performance by providing the 17 conduit 10 with more than one helix. This second helix 18 is not shown in Figs. la and lc for clarity purposes.

19 The second helix 20 which is best shown in Fig lb may be generated from the last mirror of the first helix 18 21 and returns in the opposite direction to which the 22 first was travelling and either in phase or out of 23 phase (rotated by a certain amount) with the first 24 helix 18.

26 In one example, when the energy reached the end of the 27 conduit it would be aimed at a primary point on a third 28 and fourth strand whereby the energy would return to 29 the opening of the conduit near the point of origination.

31 32 A single helix offers the advantage of having a good 33 fill factor for the conduit, and multiple helixes offer 34 an amplification effect and higher fill factors over the use of a single electromagnetic radiation beam. If 36 the absorption is very low, then the losses of the 12 1 system will be dominated by the losses associated with the mirrors. If the initial energy density is many times higher than the killing threshold then the beam 4 can make many reflections before the energy density is below the threshold to give the desired level of 6 decontamination or sterility.

7 8 As with the multiple helix design with the 9 electromagnetic radiation bouncing up and down the conduit, it is possible to have multiple helixes 11 originating from the same end of the conduit with or 12 without the return helixes incorporated into the 13 system. Here there may be multiple sources hitting the 14 first mirror of each helix or a single source and mirror system designed to strike each first mirror of 16 several helixes in turn or in any desired combination.

17 It is possible to have the source or sotrces at one or 18 either end of the conduit, or to use mirrors to input 19 the radiation to each helix from either end of the system. The helix itself may rotate and one or 21 multiple sources be used. In these cases the firing of 22 the electromagnetic radiation source and alignment of 23 the mirrors can be done by using optical sensors or 24 otherwise to detect when the optics are in the correct position and triggering the electromagnetic radiation 26 sources as appropriate.

27 28 The conduit could contain two or more distinct sets of 29 helixes that are used to distribute two or more different wavelengths. For example one helix may be 31 utilised to produce a photochemical effect associated 32 with a UV laser while simultaneously a second laser 33 energy is reflected off a secondary grouping of helixes 34 which produce a photothermal effect associated with IR lasers.

36 13 1 Fig 2 is an example of a tapered helix for a 2 conical-based conduit. At the narrow part of the tube 3 the medium will be travelling faster and will spend 4 less time in the beam than at the wider part of the tube. Hence the energy density at the thinner end will 6 have to be greater and this will be the position where 7 the electromagnetic radiation is injected into the 8 helix. At the wider part of the conduit, the flow will 9 be slower and the energy density will be lower, so this.

is suitable for the beam after it has experienced some 11 attenuation. Alternatively, if the radiation is 12 injected into the wider end first, then a higher energy 13 density will be given to the material as it flows 14 through the system.

16 17 An alternative to the double strand of-keflectors that 18 has been described hereinabove in the first, second 19 other embodiments is to reflect the electromagnetic radiation beam according to a plane perpendicular to 21 the flow of fluid. This is achieved with the 22 embodiment of the invention which is shown in Fig. 3a 23 where the beam is reflected in a plane according to a 24 star shape pattern.

26 As can be seen in Fig 3a, the apparatus is provided 27 with a chamber or conduit 110 throughout which a fluid 28 to be purified or catalyzed is passed. The apparatus 29 is provided with means to introduce a electromagnetic radiation beam 114 into it which is directed to a first 31 reflector or mirror 112a which directs it to a second 32 reflector 112b and then to a third reflector 112c and 33 so on in order to accomplish a revolution. 34 35 A star shaped pattern is formed whereby the 36 electromagnetic radiation (eg. light) would first 14 1 bounce within a plane several or many times before 2 being reflected down the conduit to a primary point on 3 a secondary star shape, this process continues down 4 the length of the conduit.

6 In this way, any contaminant that crosses the 7 irradiated planes will effectively encounter a 8 superpositioning of many radiation beams. The 9 amplification can be calculated in a similar way as before by any competent person knowledgeable in the 11 field. The electromagnetic radiation beam can be made

12 to pass through the plane in any number of 13 configurations. As an example, the first beam can pass 14 through the centre of the conduit, strike the-first mirror on the far wall of the conduit, from where it is 16 reflected to a second mirror positioned close to the 17 entry point of the first beam, it is then reflected 18 through the middle of the conduit, such that it passes 19 through the position where the first beam went, it strikes the third mirror positioned close to the first 21 mirror, from where it is reflected towards a mirror 22 positioned close to the second mirror. The beam 23 reflected from this mirror passes through the centre of 24 the conduit and strikes a mirror positioned close to the third mirror. In this way, the beam is passed many 26 times through the centre of conduit forming a multiple 27 star pattern, a substance passing through this plane 28 experiences an amplified effect of the radiation beam.

29 The last optic in the plane reflects the radiation towards the first mirror of the next star pattern 31 further down the conduit slightly out of phase with the 32 first star pattern. The radiation bounces around this 33 star pattern and is finally reflected to the next set 34 of mirrors on the third plane, again out of phase with the second star. The first mirror of each plane may 36 form a helix shape through the length of the conduit, 1 so that the radiation completely fills the conduit.

2 Spinning optics and/or multiple sources can be used to 3 fire the electromagnetic radiation beam into different 4 planes. The planes may be separate or overlap so as to completely fill the conduit.

6 7 This system could be incorporated with the helix or 8 multiple helixes described above, where many 9 electromagnetic radiation beams interact with each other. These systems could be designed so that 11 interference and diffraction patterns are deliberately 12 generated increasing the maximum intensity available 13 from the systems. The interference patterns could be 14 stepped through the conduit in a helical pattern giving a good fill geometry to the system.

16 17 18 Referring now to Fig 3b, after completion of the first 19 perpendicular star shape, the last reflector 120 on the first star would be aimed at the first point 122 on 21 a secondary star slightly further down the length of 22 the conduit and slightly out of phase with the original 23 star. These would be arranged in a helical pattern 24 whereby each star would be slightly out of alignment with the previous star shaped pattern whereby the stars 26 would descend down the length of the conduit in a 27 helical shape.

28 29 If one more than one wavelength source is used then multi-photon ionization processes may occur that result 31 in transformation of harmful pathogens or high levels 32 thereof into safe or safer ones or more efficient 33 combustion processes.

34 Systems could be attached to smokestacks and other 36 pollution producing or gas expulsion or bi-product 16 1 diffusion systems to reduce the negative environmental 2 impact of the off gases. Similarly, polluted water or 3 other liquid agents could be treated to reduce the 4 environmental impact.

6 A secondary catalytic effect could be created whereby 7 the initial stage of decontamination may use a coherent 8 light source or other electromagnetic energy source 9 then followed by the use of an incoherent light source,, such as a xenon flashlamp or other electromagnetic 11 energy source or vice versa. During one or both of 12 these processes a gas stream could be introduced to 13 further facilitate a beneficial catalytic effect.

14 In some cases the photochemical effect will produce 16 ozone which could further aid in a catalytic effect 17 whereby a molecular "scrubbing" would'occur.

18 19 In some cases a secondary gas or liquid could be introduced into the helix chamber. This could produce 21 several desirable effects including osmosis, reaction 22 or bonding. For example one could introduce a 23 hydrocarbon based fuel into a chamber and 24 simultaneously introduce pure oxygen. The effect of for example, an IR laser, would be to create a more 26 complete combustion of the material.

27 28 One could also create compounds whereby two elements or 29 compounds would be introduced into the chamber and either a photochemical or photothermal or other 31 electromagnetic energy effect would occur to create a 32 different molecule or compound. Additionally, other 33 reactions could be created by the same principal 34 including atomic and or nuclear reastions.

36 The helix could be used as a preheater of materials to 17 1 be burned or otherwise heated.

2 3 Economic benefits would include a reduction in the 4 volume of waste being generated. This would equate to a direct economic benefit in that fines can be imposed 6 to companies that over pollute.

7 8 Formulas will be created to weigh the overall cost per 9 unit of energy, the specific application, throughput, reaction to peak vs mean power, molecular effects, 11 coupling and economic factors.

12 13 Certain processes and effects are dependant on high 14 peak power but are not cessarily reliant on high mean power. This can aid in reducing the costs by looking 16 at the specific effects created by these factors and 17 matching them to their application.

18 19 In some cases the catalytic effect could be used to produce a more complete disintegration of the material 21 being treated. This could include liquid gas and gas 22 compounds. This effect could be utilised to, for 23 example, create the complete combustion of a 24 hydrocarbon based fuel whereby the fuel would be exposed to large amounts of electromagnetic energy.

26 Such applications could include for example a laser 27 combustion engine, a laser turbo booster, or laser jet 28 engine. In this case an IR laser may be more 29 effective. one could ignite, for example, hydrogen using apparatus in accordance with the present 31 invention.

32 33 The shape of the helix could be advantageous from a 34 aero/fluid dynamic standpoint in that the helix could be abutted by a fin in order to keep debris away from 36 the reflective facets.This would also keep the gas or 18 1 liquid moving in a desirable direction from a control 2 standpoint. The fins would act to create venturi, 3 vortexes or screw shapes and could be modified and 4 adapted to create desirable effects.

6 on the last mirror could be a sensor to monitor the 7 level of electromagnetic energy being produced. This 8 would allow for quality control measures to ensure that 9 complete destruction was being achieved.

11 Modifications and improvements may be made to the 12 foregoing without departing from the scope of the 13 invention. 14 References 16 17 18 1. Ward, G., Watson, I.A., Stewart-Tull, D.,

Wardlaw, 19 A., Chatwin, C.R. 'Inactivation of bacteria and yeasts on agar surfaces with high power Nd:YAG 21 laser light', Letters in Applied Bacteriology, 23, 22 136-140. ISSN 0266 8254.

23 2. Photonics Spectra, Lasers aid in bacteria.

24 destruction, February 1998, 32(2), 45. Laurin Publishing Company, Inc., Berkshire Common, PO Box 26 2037, Pittsfield MA, 01202-2037, USA.

27 3. Ward, G., Watson, I.A., Stewart-Tull, D., Wardlaw, 28 A.'Inactivation of E.coli. in liquid suspension 29 with Nd:YAG laser light', Seventh International Congress on Engineering and Food, Brighton April, 31 1997.

32 4. Wang, R. K., Ward, G., Watson, I.A., Stewart-Tull, 33 D., Wardlaw, A. 'Temperature distribution of 34 Escherichia coli. liquid suspensions during irradiation by a high power Nd:YAG laser 36 irradiation for sterilization applications', 19 1 Journal of Biomedical Optics, 2/3, 295-303, may 2 1997. ISSN 1083-3668/97 3 5. Watson, I., A., Ward, G., Wang, R., Sharp, J., 4 Budgett, D., Stewart-Tull, D., Wardlaw, A., Chatwin, C. (1996) Comparative bactericidal 6 activities of lasers operating at seven different 7 wavelengths. Journal of Biomedical Optics, 1(4), 8 pp 1-7. ISSN 0140-018/97.

9

Claims (3)

1 CLAIMS

2 3 1. Apparatus for providing exposure of a fluid to 4 electromagnetic radiation, said apparatus comprising:

6 7 - a fluid chamber having an inlet and an outlet 8 and internal walls; 9 at least one electromagnetic radiation beam 11 generating means; and 12 13 - reflection means shaped and positioned on the 14 internal walls of the chamber so as to reflect the electromagnetic radiation beam at least three 16 times within the chamber according to a 17 predetermined pathway which distributes the beam 18 in order to substantially fill the chamber with 19 energy.

21

2. Apparatus as claimed in Claim 1 wherein the beam 22 is reflected according to a direction 23 substantially perpendicular to the flow of fluid 24 to be treated.

26

3. Apparatus as claimed in Claim 1 or 2 wherein the 27 electromagnetic radiation is a laser.

28 29 31 32 33 34