SK128294A3 - Method of laser treatment of substrate, device for realization of this method and treated substrate - Google Patents

Abstract

The present invention relates to a method of treating substrates for the purpose of reducing the population of contaminant organisms associated with them; particularly to treatment of foodstuffs, propagative materials and items intended for use in veterinary and medical applications. The method directs laser radiation at the substrate whereby the type and amount of laser radiation are selected such as to render organisms associated with the substrate inviable while leaving the desired properties of the substrate itself substantially unchanged. Apparatus suitable for treating a variety of substrates are disclosed, with a source of laser radiation (9, 28) and means (26, 27, 29) for handling the substrate (24). <IMAGE>

Description

The invention relates to a method of treating substrates with a laser device in order to reduce the population of contaminating organisms associated therewith. In particular, the invention relates to a method of treating foods, promotional materials and elements for veterinary or medical applications. The invention also relates to an apparatus for carrying out the method and the substrates treated in this way.

BACKGROUND OF THE INVENTION

In order to prevent undesirable contamination, fungicidal and pesticidal treatments of plant materials such as fruit, vegetables and cereals are currently carried out to a large extent. Such treatment is often undesirable from an ecological point of view, presents a potential danger to the consumer of the product and is relatively ineffective in smoothing out certain parasitic growth, especially in the case of fungi. Similarly, many animal products need to be treated prior to sale to reduce the number of contaminating microorganisms to a level that is acceptable for the intended end use. For example, eggs and poultry products are often soaked in bactericide solutions to remove bacteria such as salmonella and listeria.

In addition to chemical treatments, physical sterilization procedures are commonly applied to products intended for consumption or veterinary or medical applications. For example, a carton for the packaging of consumable mushrooms is sterilized by microwaves, and high pressure steam treatment in autoclaves is used to treat medical instruments. All of these procedures are potentially dangerous and / or require considerable time to achieve the optimum effect. While the final product is a foodstuff or chemical, the structure of such a substance can be altered to the extent that its desirable properties, such as taste, efficacy and viability (for example in the case of seeds), are impaired by the process used.

In the process of U.S. Pat. No. 3,817,703, high power lasers are used to sterilize laser-permeable liquids. 5 -2 lasers with a specific power of at least 10 W.cm are used and preferably a TO -2 ranging from 10 to 10 W.cm ”. This process can be used for light permeable materials such as wines, but is totally unsuitable for the application of non-light absorbing materials, particularly for materials that are opaque to or partially absorbed by laser light.

SUMMARY OF THE INVENTION

A new process has now been developed in connection with the invention, which can be applied to all of the above and other substrates, whereby contaminating microorganisms are depleted of viability in a short time. This process is not accompanied by the disadvantages of the above processes and does not result in deterioration of the properties of the end product, nor does it leave residues which are harmful from an ecological or physiological point of view. Moreover, in certain applications, such as the inhibition of certain parasites, for example fungal growth, this procedure is more effective than previously used methods.

The method according to the invention differs from the known methods in which the laser is used in that it is based on utilizing a thermal laser effect. In doing so, the temperature of the contaminating organisms is raised to a non-critical level for a time sufficient to kill them. This temperature varies from organism to organism, but for many bacteria and fungi it is approximately 45 ° C. If a heated medium such as steam or an irradiation such as a microwave is used for analog treatment, it also raises the temperature of the substrate to a level incompatible with the intended end use of the product. The process according to the invention does not (with the possible exception of the surface) affect the substrate, while the organisms on the surface heat up ηβ temperature, which deprives them of their viability.

SUMMARY OF THE INVENTION The present invention provides a method of treating substrates which are substantially impermeable to laser radiation, or which are incapable of transmitting laser radiation without absorbing a substantial portion thereof, in order to reduce the level of contaminating organisms attached to the surface of such substrates. consists in targeting laser radiation to the substrate, wherein the type and amount of laser radiation is selected such that organisms on the substrate lose viability and the desired properties of the substrate itself remain substantially unchanged.

In a preferred embodiment of this first aspect of the invention, the substrate and the laser radiation move relative to each other to ensure that a substantial portion of the substrate surface is exposed to radiation. This relative movement of the substrate is preferably ensured by rotating the substrate, for example food elements, with respect to the direction of laser radiation, preferably by rolling the substrate. Sequential rolling movements of the elements, such as those that can be achieved using a conventional roller type conveyor belt, can be used. Other suitable types of movements are exemplified below in the description of the device of the invention.

The laser device can be supplied from any source capable of causing the organisms to heat to a temperature sufficient to eliminate their viability without permanently altering the desired properties of the substrate. An infrared laser such as a CO2 or YAG laser source is expediently used as the source. In general, any laser that is able to heat the organniy surface of the substrate, including UV lasers, can be used. It can

5-2 3 use a specific power below 10 W.cm, preferably below 10 W.cm and most preferably below 120 W.cm. In the examples given in this description, a specific power of the order of 10 to 120 W.cm, preferably about 30 W.cm &lt; -1 &gt;, is used, which has been found to be most effective in smoothing bacteria while preserving substrate integrity such as eggs or potatoes. and their ability to develop and grow. For this purpose, laser sources capable of producing laser radiation with an output of approximately 10 to 20 V are used. However, a source with a different output can also be used, especially when more flexible substrates are treated. This is apparent to those skilled in the art.

A suitable source of radiation is a YAG laser (units with this source are used in the examples and in the devices described in head j), the tri-doped Ytrium Aluminum Garnet ”(Nd: YAG). CO2 and YAG lasers emit light with different wavelengths; CO ₂ with a wavelength of 10.6 µm and YAG with a wavelength of 1.06 µm. Due to the different levels of absorption of irradiated objects, the type of laser used must be selected individually in each case.

For example, the preferred tuber laser is NE: YAG, while a CO2 laser is best suited for eggs. It has been found that, with the appropriate choice of lasers, these can be expedient

- 5 operate in both CW (Continuous Wave) and Pulse mode. Examples of lasers that are suitable for the CW mode include CO ₂ lasers available from Synrad Inc., Califonia, USA under the designation D48 / 5 (60 W) and Nd: YAG lasers available from Spectron Laser Systems, Rugby, Great Britain, model SL901 (90W). These lasers can be operated at different power, up to maximum power.

The configuration of the laser radiation may vary, but conveniently takes the form of a fan-shaped beam or a fan-shaped beam from one or more sources. These beams are expediently directed across the transport path of the substrate. However, the substrate may also be fixed, whereby irradiation of substantially all of its surface is achieved by using one or more sources without moving the substrate.

The beam of laser beams can be deflected into a fan shape by a variety of methods, in particular using a deflecting mirror, such as the product of General Scanning (USA) designated M3 scanner. Cylindrical optics may also be used. DC deflection mirror used to reflect beams of rays. In the lasers exemplified above, the beam is parallel and has a diameter of approximately 5 to 6 mm while rotating about a central axis. Operation can be controlled by a computer to achieve a predetermined deflection angle of beam throughput on the substrate. When using the cylindrical optic method, the optic is placed in the beam path prior to irradiating the object, thereby deflecting the beam to form a light fan whose angle is determined by the geometry of the optics.

The distance from the substrate at which the laser radiation source can be located can vary considerably. This distance, of course, consists of the following two components:

6) 1) the distance of the laser from the deflection device and 2) the distance of the deflector from the object. In the case of component 1) it is a parallel beam which can be transmitted to the deflector by reflection from a long distance. This distance may range from a few centimeters to tens of meters, but in the examples contained in this specification, the S8 uses a distance of approximately 50 cm. In the case of component 2), the distance from the deflection device 8 and the angle of the fan provided by the device define the area covered by the deflected beam. It is desirable that the substrate elements be completely exposed to laser light. One suitable combination of the distance of the deflection device from the irradiated substrate substrate and the fan substrate angle is 50 cm and 20 °, but a variety of other combinations are also possible.

The parts that are used to secure the substrate elements in the treatment device and all the parts that support the substrate elements that can be impacted by laser energy are made of materials that ensure that no heat buildup will occur. It is therefore advisable to use metals and to attach these parts to suitable heat sink systems in order to avoid indirect heating of the substrate by means of transport and fastening structures. Otherwise, efforts are being made to prevent parts of the surface other than the surface of the substrate or the organisms on the surface from being heated by the beam.

Appropriate temperature control of all surfaces in contact with the substrates makes it possible to deprive organisms of viability, in particular microorganisms having a relatively high surface to volume ratio, while the substrate having a relatively low surface to volume ratio remains at it essentially has no lasting effect on its desired properties. It will be apparent to those skilled in the art of temperature control which cooling mechanisms can be used.

By the method of the invention, it is possible to treat the surface of any substrate, but most preferably substrates that could be adversely affected by other processes. Advantageously, therefore, it is possible to treat plastics and other heat-sensitive materials or chemicals which are required to be sterile in their final use by the method of the invention. The most suitable substrates for treatment with the method of the invention are any consumable or promotional materials in which the taste, texture, viability or other desirable properties may be impaired by known processing methods. For example, crops harvested by the combine (seeds and grains), vegetables, root crops, fruits, feed, ornamental plants, leaves and beans (tea, tobacco and coffee) and dairy products can be treated in this way. The treatment may be carried out before planting or sowing or after harvesting. Substrates such as grasses that transmit laser light, but not without absorbing a substantial amount thereof, can be treated without damage.

Organisms such as bacteria, fungi, algae and viruses are preferably mentioned as viability or destruction organisms. An example of a substrate that is susceptible to salmonella and which can be successfully treated is eggs. Typical fungal parasitic growth that is undesirable on consumer goods is fungal growth on potatoes.

The invention also relates to a device for laser treatment of substrates by the method of the invention, comprising a) a source of laser radiation, b) a means of manipulating the substrate, e.g. in the form of units or elements which ensure that the laser radiation strikes the substrate manipulated by the agent; the radiation is of a type and is applied in such an amount that:

- 8 contaminating organisms are devoid of viability while the desired substrate properties remain unchanged.

Preferably, the device comprises means for providing relative movement of the substrate and laser radiation, with the result that a substantial portion of the surface of each element is irradiated. The above-mentioned means preferably operates by rotating the substrate about one or more of its axes as it passes through the irradiation zone, i. laser irradiation zone.

The substrates are preferably displaced in the form of units, for example plant material elements, by movement along the treatment path, usually on a conveyor belt, for example a roller conveyor belt. This conveyor belt helps to ensure relative movement of the elements and the laser radiation and transports the elements to the following treatment zones. Other treatment paths may also be used, such as liquid pathways, which are partially defined by laser-permeable walls passing through the laser radiation zone. Also contemplated are paths defined by a series of deflectors that ensure reorientation of the substrate in the laser beam path. As a result, a substantial part of their surface is exposed to laser radiation of appropriate intensity, which is a precondition for achieving the desired effect. Individual units can be treated without relative movement when mounted so that one or more beams of laser beams can cover substantially their entire outer surface. Preferably, the series of laser beams is directed to respective receiving sites along the strip. These bundles are usually fan-shaped (as described above). They usually come from one source and are treated in deflection units.

The apparatus according to the invention must therefore be in a form adapted to the treated substrate. Given that treats only the outer surface of the substrates and substrates do not allow the passage of laser radiation, it is clear that using the same equipment can be treated to command a variety of products, and it is only necessary to change the type of laser (C0 ₂ or YAG), exposure time and power to values sufficient to remove contaminating viability organisms while respecting the susceptibility of the substrates for damage. Factory stationary machines may, for example, use a power source with a maximum power of 60 to 250 W. The required specific power will vary and suitable values that may be considered are given in the examples. The choice of surface cooling mechanisms for the individual parts of the device that come into contact with the substrate is within the skill of the art, but these mechanisms should be specifically adapted to suit the end use of the entire device.

It should be noted that a device in which substrates on a conveyor belt come into contact with laser radiation is known, for example from EP 0 231 027 and GB 2 195 438. However, these devices are used for detection purposes only and are not suitable. for the purposes of the present invention. In particular, the lasers in this case are not configured to produce a thermal effect and the substrate does not rotate.

The method and apparatus of the present invention are illustrated in more detail in the following examples and in the accompanying drawings. The examples and figures are illustrative only and do not limit the scope of the invention in any way.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1 shows a plan view of a device according to the invention which is suitable for treating relatively large substrate units, such as potatoes or eggs.

In FIG. 2 is a perspective view of the inside of the laser treatment unit of the apparatus of FIG. 1. FIG. 2 shows the arrangement of the laser sources and shows the longitudinally arranged rollers as well as the substrate units. In FIG. 2A is a cross-sectional view of the ends of the rollers and substrate units resting on the rollers.

In FIG. 3 shows an alternative arrangement of the interior of the laser unit (with respect to FIG. 2). In this case, the rollers are positioned transversely to the direction of travel of the substrate units. In FIG. 3A is a cross-sectional view of the ends of the rollers and substrate units resting on the rollers.

In FIG. 4 is a plan view of the device of the invention (representing an alternative to the device of FIG. 1). The device shown is specially adapted for the treatment of potatoes. In FIG. 4A is a perspective view of the interior of the laser treatment unit of the device.

In FIG. 5 shows a cross-section of a device according to the invention which is suitable for the treatment of loose substrates such as granular materials, for example whole cereal grains.

Examples of embodiments of the invention

Example 1

Hen eggs artificially contaminated with Salmonella enteritidis and Aspergillus fumigatus spores are exposed to laser light from two separate sources at different energy levels. The disinfecting effect of lasers is determined by determining the residual contamination level after treatment.

The 4 cm area at the blunt end of 700 hen eggs is contaminated with Salmonella enteritidis suspension and Aspegillus fumigatus spores. A night culture is prepared

S. enteritidis in Buffered Peptone Water. A. iumigetus is grown on malt agar plates until significant sporulation. The spore suspension is prepared by washing the plates with Maximum Recovery Liluent (MRL). A volume of 10 µL / 2 of each suspension is spread over an area of 4 cm at the blunt end of each egg using an inoculation loop and a 2 x 2 cm template and stored overnight at room temperature.

batches of eggs of 100 pieces each are subjected to disinfection treatment by scattering the beam of laser rays onto the contaminated area, each egg being manually placed in a suitable position before treatment. Treatment is performed at 3 levels of energy using each laser (COg and YAG source). The level of energy delivered to the egg surface is controlled by adjusting the laser power and the rate at which the deflected beam passes through the substrate surface (scan speed). The number of S. enteritidis. .

Bacteria and fungal spores are removed from the egg surface by placing each egg in a sterile plastic bag with 10 ml MRM and wiping the contaminated surface through the wall of the bag for 2 minutes. The washing liquid is subjected to a 10-fold serial dilution and the samples are plated on XLL agar plate (Oxoid CM469) for counting S.enteritidis bacteria and OAES agar plate for counting A. fumigatus fungal spores. The XLL agar plates are incubated for 4 days at 37 ° C, the visible colonies of both organisms are counted, and the number of viable organisms per egg is calculated. Mean values are calculated and the results analyzed using the MINITAB statistical software package 'These results are shown in Tables 1 and 2.

After treatment with C3, no salmonium bacteria were detected in 57 out of 100 eggs treated. At a similar level of energy, the laser COg source appears to be more efficient than the Yttrium Aluminum Gernet (YAG) source. At the highest energy setting, the COg laser reduces the mean number of contaminating salmonella by 99.72% and the mean value of A. fumigatus resistant spores by 86.9 Analysis of variation data shows that the mean value differences are significant to 5% for each treatment level, and do not result from variation in each sample, indicating that laser light can be effectively used to reduce both bacteria and fungal spores on substrates, particularly eggshells.

- 13 Table 1

treatment Specific performance (W cm ^ ^) Power (W) / Speed Passing Parameters (Mm / s) Medium number / egg S. ent A f um. yl 0.4 1.85 / 193.5 16000 3400 Y2 2.7 12.5 / 193.5 26000 4300 Y3 27.0 23/60 11000 2200 « C1 0.2 1.6 / 193.5 29000 5400 C2 1.65 10.5 / 162.5 8600 6700 • C3 30.0 11/34 81 640 inspection 29000 540

Table 2

Treatment Reduction in% of viable organisms (rounded to the nearest whole number)

S. enteritidis A. fumigatus

yl 44.82 30.61 Y2 62,02 55,10 C1 0 0 C2 70.34 0 C3 99.72 86.9

- 14 Example 2

Effect of different levels of laser light used for disinfection on the inside of eggs

The suitability of using laser light to disinfect the surface of eggs shall be examined, paying particular attention to the effect of the treatment on the interior of the eggs. This effect is monitored by the early development of chicken embryos. In this test, a rotating plate, placed in the beam path of a 5 mm wide C0 laser source, is used to fix the individual eggs at the butt end.

Eggs come from 450 laying hens, which are used in broiler production. The disinfection procedure, which involves passing the surface of the eggs through a deflected beam of laser rays, treats two doses of 150 eggs each. The 5µm bundle proceeds one step at a time so that after each complete turn of the egg, the bundle moves downward, resulting in gradual treatment of the individual peripheral portions of the egg shell. The level of laser energy applied to the egg surface corresponds to levels C2 and C3 in the above examples. Table 3 lists the parameters used in this procedure.

Table 3

Egg speed (min Laser power (W)

C2 78 10.6

C3 16 30

Treated eggs and 150 untreated control eggs are placed overnight and placed in hatcheries the following day.

- 15 Western. Not each of the five hatcheries is randomly placed with the same number of untreated control eggs and eggs from the two treated batches. After five days of incubation, all eggs are opened and embryo development status is determined by expert expertise. The results of this test are shown in Table 4.

Table 4

treatment hatchery Number of eggs without fetus dead germ alive Zarodov C2 1 90 12 4 73 2 60 11 3 46 overall 150 23 7 119 C3 1 90 18 4 68 2 60 5 8 47 overall 150 23 12 115 inspection 1 90 15 3 72 2 60 11 2 47 overall 150 26 5 119

Thus, it is clear that treatment with C2 and C3 has no significant adverse effect on the number of viable embryos produced in the treated eggs.

Example 3

Device for sterilizing egg surfaces

The device shown in FIG. 1, it comprises a plurality of conveyor rollers 1, which are arranged parallel to each other along the direction of displacement in the device. Gripping elements 2 are arranged on the surface of the conveyor rollers 7 so that during rotation they move the substrate units 2 located in the upper depressions 6 between adjacent conveyor rollers 1. The folds 6 arranged in the tracks are disposed longitudinally in the direction of movement of the device. These paths pass through the inlet station by the laser treatment unit 6 and the output to the sorting and packaging station J. The rollers 1 or at least the gripping elements 2 are made of a resilient material such as rubber and cause the substrate units 2 to rotate about their axis during their movement. which is transverse to the direction of displacement. In operation, the substrate units are, for example, eggs placed in the tracks, and the conveyor rollers 1 are driven to rotate about their longitudinal axis so that the substrate units 2 are advanced while rotating while passing through the laser treatment unit 6 and progressing to the sorting and packaging position 7. The forward speed and the egg speed are adjusted to achieve a slight performance relative to the surface equivalent to grade C3.

The inside of the laser treatment unit shown in FIG. 2, comprises two means 8 for fan-shaped deflection of a laser light, preferably a light coming from a COg laser, which are fixed so as to direct the laser light to the respective paths. The laser light has a configuration of two fan-shaped beams 2 ^and 10 'and their plane is parallel to the conveyor rollers 10 so that light falls on the untreated substrate units 3 as they rotate and move forward through this part of the device without substantially impinging on any part conveyor rollers 1. The entire machine which passes through the tracks is neutralized by a thermal trap under the conveyor rollers L This thermal trap can be designed as a bundle stop made of material

- 17 absorbing light, the stop being positioned against the point from which the beam protrudes. The purpose of the thermal trap is to absorb all laser light.

In FIG. 3 shows another alternative conveyor mechanism in which a plurality of driven rollers 11 are arranged transversely to the conveying direction of the substrate units, for example eggs, which are located in recesses formed by the spaces between the surfaces of adjacent driven rollers 11. As the driven rollers 11 rotate, , exposing previously hidden surface portions to the fan beams 9 and 10 of the laser light. The driven rollers themselves are forced to travel through the laser treatment unit while carrying the substrate units. In this case, the driven rollers 11 do not remain in the unit and there is no danger of overheating. In both alternatives described above, a fan with an angle of approximately 20 ° is used, with a distance from the substrate units of 50 cm.

Example 4

Suppression of pathogens on potatoes using leser light

Seed potato tubers are the source of inoculum of several important diseases including potato tuber flake (Rhizoctonia soleni), anthracnose of potato roots (Colletotrichum coccodes), silver scab (Helminthosporium solani), subsp. Phoma foveata), dry rot (Fusarium caeruleum) and rustling nets (Erwinia carotovora ssp atroseptica).

The control of these diseases in cultivated tuber crops is strongly dependent on the suppression or killing of pathogens settled in seedlings. The range of fungicidal seed treatment products for healthier crops is constantly expanding, but most of these products do not have a broad spectrum of efficacy. It is therefore necessary to apply a greater number of formulations. In addition, fugicide resistance is an ever-worsening problem, so new and new fungicides need to be developed, registered, and approved for use. In addition, there is an increasing pressure to reduce the doses and the number of agrochemicals applied to potatoes and attempts to use alternative methods to control these diseases.

For laser treatment tests, tubers with the natural development of the skin disease are selected, the viability of the organisms being determined in various ways suited to the particular disease being studied; these vary according to what is shown by inspection of the tuber, transferred lesions or transferred organisms after exposure to laser light.

The tests are performed in such a way that the rate of advancement of the leser bundle along the tuber surface varies over a wide range in order to identify energies that could cause damage to the skin or which might be ineffective. Using three power levels (W) within a narrower defined laser beam speed range, the interactions between these parameters are determined. A suitable output is 30 W.

In the initial tests, C. coccodes is used as an indicator pathogen, and at a relative rate of progression of potato tuber and bundle of 612 at 30 W, nearly 50% of the lesion pieces separated from the peel are unable to cause fungal growth after transfer to agar plates. At a relative speed of 214 mm.s-1, the suppression is 100%, while the relative speed is above 612 mm ^- 1.

- 19 (for example 1100 mm.s · ^ and above) give poor suppression results.

When tested using different power levels, no difference in viability of B. solani as an indicator pathogen was found. Suppression of this pathogen is successful with prolonged irradiation. A considerable degree of inhibition of the development of penicillium fungus after incubation is also found. To move the laser beam in the vertical direction along the potato tuber, a stool with a different rotation frequency is used, which is located 50 cm from the deflecting mirror at the center of the center of the potato tuber side. The traverse speed is defined as the traverse speed and corresponds to the time in the table. The stain has a diameter of 5 to 6 mm.

Table 5

Power time restoration Relative recovery laser 0-5 (see behind) R. solani Penicillium 30 0 100 49 30 1 79 46 30 2 32 13 30 3 11 0 30 4 5 5 30 5 0 0 45 0 95 44 45 1 19 17 45 2 46 6 45 3 3 7 45 4 3 3 45 5 0 0

Table 5 (continued)

Performance Recovery Time Relative Laser Recovery 0-5 (see note) R. solani (%) Penicillium

60 0 93 47 60 1 46 17 60 2 33 20 60 3 26 18 60 4 8 14 60 5 5 8

notes:

Shift time / speed 0 = zero, 5 = maximum, 1 = shortest, = 106.7 mm.s \ 4 = 133.3 mm.s ' ¹ ', 3 = 160.0 mm.s ”^, = 186, 7 mm.s-1, 1 = above 186.7 mm.s-1.

The results of the application of laser energy to different organisms are shown in Table 6. The laser power is 30 W.

Table 6

Speed Relative shift recovery

C. coccodes H. solani P. pustuleňs P. foveata F. caeruleum 0 95 100 22 80 56 1 76 90 6 62 0 2 51 38 0 20 0 3 9 6 0 0 0 4 6 0 0 0 0

This treatment has also been shown to be effective in suppressing E. c. spp. atroseptica, in addition to the aforementioned pathogens. The test conditions used tend to cause necrosis of the treated skin area, but there is no secondary rot. From this it is clear that the graying properties in terms of tracing and use for consumption are maintained. The experiments also show that, at least by using YAG, the parameters can be adjusted to avoid the effect, even though the organism is still suppressed. The pale pink break of the tuber ends and the growth rate of the stems remain the same as the number of folded leaves relative to the stem.

Example 5

Leser treatment equipment suitable for approximately spherical products such as potatoes

Νθ obr. 4 shows a treatment device that is suitable for approximately spherical substrate units such as tuber potatoes. This device comprises a roller conveyor 12 passing through the laser treatment unit 13 between the inlet hopper 14, the screen 15 and the collecting plate 16 and further into the chamber filler 17. In FIG.

4A shows an arrangement of an inward laser treatment unit 13 having a 30 W YAG laser light source located 50 cm from the substrate units on the roller conveyor 12. The laser beam is deflected into a fan shape by a deflecting mirror or optic to form fan bundles 9 and 10 with an angle of 20 °. The fan bundles 9 and 10 impinge on the rollers as well as on the substrate elements 18 disposed thereon. The rollers 19 are positioned transverse to the direction of movement and rotate as they pass through the unit, imparting rotation to the substrate element 18 and exposing substantially their entire surface to a beam of laser beams. The rotating rollers 19 are metal, allowing rapid heat dissipation from the substrate elements 18 applied at the 22 recesses between the upper surfaces of the adjacent rotating rollers 19. The rotation of the rotating rollers 19 may be passive, in which case active, ie. the drive means acts on each roller individually.

Example 6

A laser treatment device suitable for bulk materials such as cereal

A treatment device which is suitable for irradiating bulk materials, such as whole grains, with laser light to suppress the viability of organisms deposited on these grains is shown in FIG. The grains are fed into a vertically arranged housing 25 by an inlet belt conveyor 26. wherein the dust and husks are separated upwardly by means of a separator, while the grains fall under gravity into a laser treatment area which is arranged below the inlet belt conveyor 26. which is made of a material which can act as a body trap, causes the grains to gradually roll and turn, impacted by the fan bundles 6 and 10 of the laser beams of the type described above from several locations at different heights of the cylinder housing

25. Fan bundles 9 and 10 enter the cylindrical housing through slots 28 and come from clearing devices located 50 cm from the grain path. As with all these devices, the source itself may be located within a centimeter to meter distance from the deflection device, but this distance is preferably 50 cm. All other parameters can be the same eye parameters listed above.

In this case, it is possible to move the fan bundles 9 and 10 on a predetermined area to cover

- 23 largest quantity of grains. To ensure effective treatment time and coverage of substantially the entire grain surface, several fan bundles 8 and 10 are used through which the grains must pass before they reach the exit conveyor 29.

Claims (26)

PATENT CLAIMS A method of treating substrates which are substantially opaque to laser radiation, or which are incapable of transmitting laser radiation, without absorbing a substantial portion thereof, in order to reduce the level of contaminating organisms attached to the surface of said substrates, characterized by: The method of claim 3, wherein the type and amount of laser radiation is selected such that organisms on the substrate lose viability and the desired properties of the substrate itself remain substantially unchanged. Method according to claim 1, characterized in that consumable and / or propagation material is used as the substrate, the contaminating organisms being microorganisms. Method according to claim 1 or 2, characterized in that the substrate and the laser radiation have been given relative motion relative to each other to ensure that a substantial part of the surface of the substrate is exposed to radiation. 4. The method of claim 3, wherein the relative movement of the substrate comprises rotating the substrate relative to laser radiation. Method according to any one of claims 1 to 4, characterized in that an infrared laser source is used for laser radiation. 6. The method of claim 5, wherein a laser source capable of emitting laser radiation having a power of about 10 to 250 watts is used. - 25 Method according to any one of the preceding claims, characterized in that the laser source operates in a continuous wave CW mode. 8. The method according to any one of the preceding claims, characterized in that the power density of the laser on the substrate is from about 10 to about 120 W.cm ^- ^. Method according to claim 8, characterized in that the specific laser power relative to the substrate surface 2 is in the range of 20 to 50 W.cm Method according to any one of the preceding claims, characterized in that the laser radiation is in the form of a divergent fan beam or beams which originate from one or more sources. Method according to claim 9 or 10, characterized in that, before deflection, the bundle is parallel and has a diameter of about 5 to 6 mm. Method according to any one of claims 9 to 11, characterized in that the distance from the point where the laser beam is deflected to the substrate to be treated is approximately 50 cm. 13. Apparatus for treating substrates which are substantially opaque to laser radiation or which are incapable of transmitting laser radiation without absorbing a substantial part thereof, in order to reduce the level of contaminating organisms attached to the surface of these substrates, characterized by: (a) a source of laser radiation; and (b) a substrate manipulation means which ensures that the laser radiation hits the substrate handled by the device, being of a type and applied in such a quantity that the contaminating organisms are devoid of viability; while the desired substrate properties remain unchanged. 14. The apparatus of claim 13, comprising means for imparting relative movement of the substrate and laser radiation to irradiate a substantial portion of the surface of each substrate element. Device according to claim 13 or 14, characterized in that it comprises a treatment path that passes in successive treatment zones. 16. The apparatus of claim 15, wherein the substrate is guided along a treatment path on a roller conveyor belt that imparts relative movement of the substrate relative to laser radiation. 17. The apparatus of claim 15, wherein the treatment path is defined by a series of deflectors urging the substrate to reorient in the laser radiation zone. Apparatus according to any one of claims 13 to 17, characterized in that the laser radiation originates from a 10 to 250 W heat laser source. Device according to one of claims 13 to 19, characterized in that the laser source emits infrared laser radiation. 20. The apparatus according to claim 19, characterized in characterized in that the eco obsnhuje laser YAG laser or C0 ₂ 27 The apparatus of claim 19 or 20, wherein the specific power of the laser relative to the substrate area is in the range of about 10 to about 120 W.cm ² . 22. The apparatus of claim 21, wherein the specific power of the laser relative to the substrate area is in the range of about 20 to about 50 watts. Device according to one of Claims 13 to 22, characterized in that the substrate is forced to rotate about one of its axes when conveyed by a station where it is incident by laser light. Substrate which is substantially opaque to laser radiation, characterized in that the surface-associated organisms have been rendered inoperable according to any one of claims 1 to 12. A substrate that does not transmit laser radiation without absorbing a substantial amount of laser energy, characterized in that the organisms associated with its surface have been rendered inoperable by the method of any one of claims 1 to 12. 26. A substrate as claimed in claim 24 or 25, characterized in that it is a consumable product, seed or planting material or an object intended for veterinary or medical use.