GB2498086A

GB2498086A - Non-destructive detection of defects in fruits and vegetables

Info

Publication number: GB2498086A
Application number: GB201223010A
Authority: GB
Inventors: Philippe Blanc
Original assignee: Maf Agrobotic SAS
Current assignee: Maf Agrobotic SAS
Priority date: 2011-12-23
Filing date: 2012-12-20
Publication date: 2013-07-03
Anticipated expiration: 2032-12-20
Also published as: DE102012024760A1; FR2985025B1; PL402201A1; FR2985025A1; ITMI20122150A1; GB2498086B; GB201223010D0

Abstract

A device, and a method of use, for non-destructive detection of bruises and rotten zones in fruits and vegetables 6 comprises an illuminating device 7 comprising a source 1 of infrared radiation having a low band of wavelengths, and a source 2 of infrared radiation having a high band of wavelengths separated from said low band. The infrared beams are arranged to be collinear and the sources 1 and 2 alternately illuminate the object 6. A radiometric sensor 3 converts a power of radiation transmitted through the object 6 into electronic signals, and a device 5 for processing electronic signals from the radiometric sensor produces an index of defectiveness from the power transmitted through a fruit 6 in the low band and in the high band. A support 8 for the object 6 may be a conveyor.

Description

DEVICE AND METHOD FOR NON-DESTRUCTIVE DETECTION OF

DEFECTS [N FRUITS AND VEGETABLES The invention relates to a device and a method for detection of defects such as bruises, rotten zones and marks left by bruising, etc. in fnnts and vegetables without these being spoiled.

Devices for detection of defects in fruits and vegetables are known. Thus, US 6,847,447 describes a device which allows analysis of the light reflected by or transmitted through fruits under lighting selected according to the fruit. The reflected light is analysed with the aid of a spectrometer.

However, a spectrometer is a particularly costly, sensitive and bulky apparatus. In addition, such devices presuppose that all the spectrogram obtained is then analysed, which requires even more complex data-processing means as the spectrogram obtained depends on the size of the fruit (or vegetable) being analysed.

However, such devices require weighty data-processing means and are difficult to implement on lilies for sorting fauts and vegetables because the time taken for processing is long compared to the time taken for each fruit or vegetable to pass.

In addition, these pieces of apparatus do not allow specific detection of bruises and rotten zones among other defects.

Thus, the aim of the invention is to overcome these drawbacks by proposing a new device and a new method for detection of bruises and rotten zones in fruits and vegetables.

One particular preferred aim of the invention is to propose such a device which is simp'e and compact.

Another preferred aim of the invention is to propose such a device which is inexpensive.

A further preferred aim of the invention is to propose such a device which can be produced with parts which are widely available conimercially.

An additional preferred aim of tile invention is to propose such a device which is sturdy and will withstand very variable temperature and humidity conditions.

Another preferred aim of the invention is to propose such a method which is simple to implement and only requires widely available and inexpensive data-processing means.

An additional preferred aim of the invention is to propose such a method which can be implemented irrespective of the precise dimensions of the fruit or vegetable being analysed.

A further preferred aim of the invention is to propose such a method which produces reliable results so as to allow reliable sorting of the produce being analysed.

An additional preferred aim of the invention is to propose such a method which can be implemented at high frequency for lines for sorting fruits and vegetables operating at a high conveying speed.

Throughout the text, "fruits or vegetables" denotes fresh produce usually consumed as such, including mushrooms.

Thus, the invention relates to a device for detection of defects in objects chosen from fruits and vegetables without these objects being spoiled, comprising: (a) a first source of electromagnetic radiation in a first band, designated a low band, of wavelengths in the infrared range; (b) a second source of electromagnetic radiation in a second band, designated a high band, of wavelengths in the infrared range, said high band being separated (disjointed) from said low band; (c) a radiometric sensor adapted to convert a power of electromagnetic radiation received from any one of the first and second sources of radiation into electronic signals representative of that power, said sources of radiation being: (i) capable of each producing a beam of electromagnetic radiation which is substaitiaIly colinear with the beam of electromagnetic radiation from the oilier source of radiation, (ii) disposed in the directioll of said radiometric sensor, such that said beams are directed in the direction of said radiometric sensor, (iii) disposed with respect to the radiometric sensor to permit an object to be passed therebetween or disposed a distance from the radiornetric sensor at least equal to the maximum size of an object, and (iv) adapted so that at least a portion of the electromagnetic radiation emitted passes through an object disposed between said sources of radiation and the radiornetric sensor said device further comprising: (d) at least one device for control of said sources of radiation adapted so as to be able to switch on the first source of radiation and the second source of radiation in alternation; and (e) at least one device for processing of electronic signals, the device for processing being: (i) linked to the radiometric sensor so as to be able to receive the electronic signals supplied by the latter, and (ii) adapted so as to be able to produce an index of defectiveness of an object from the power of electromagnetic radiation transmitted through said object in the low band and from the power of electromagnetic radiation transmitted through said object in the high band.

The invention thus makes it possible to obtain a device which is inexpensive and compact.

Advantageously, the radionietric sensor may be an infrared sensor.

In fact, two sources of electromagnetic radiation, one emitting in the low band and the other in the high band, are sufficient. Thus, inexpensive sources of infrared light such as light-emitting diodes (LEDs) can be Lised.

LEDs have the advantage of emitting narrow bands of wavelengths.

In addition, a radiometric sensor according to the invention can be chosen from any type of technology, as long as it is adapted so as to be able to measure a power of electromagnetic radiation at least in the low band and in the high band. In particular, a single sensor can be used in place of a sensor array because a device according to the invention does not need to obtain an image of the object.

The device for control is adapted so as to be able to switch on one then the other of the two sources of electromagnetic radiation iii alternation.

Thus, the two sources of radiation are never switched on simultaneously.

In fact, in a device according to the invention, the measurements of transnñssivity of an electromagnetic radiation through a fruit/vegetable are carried out in alternation in each band of wavelengths, and not simultaneously.

This is why a device according to the invention does not require a spectroscope or a spectrometer, which significantly reduces the bulk, the complexity and the cost of manufacturing and maintaining such a device, hi the absence of a spectrometer, a device according to the invention also withstands the conditions of temperature (very hot in summer, very cold in winter) and high humidity which are normal in zones in which fruits and vegetables are sorted.

The device for processing &ectronic signals can take different forum: for example a data-processing unit dedicated to one or more devices according to the invention, or a data-processing unit controlling other automatic systems in addition to one or more devices according to the invention, for example automatic systems for a line for conveying and sorting fruits/vegetables. Equally, one or more remote data-processing units can perform this task.

The device for processing electronic signals may operate on the basis of a data-processing program recorded in a memory.

The processing device may advantageously perforni the task of control device for the sources of radiation. Thus, when it is also in charge of thc automatic systems of a sorting line, it synchronises the frequency with which the sources of radiation are switched on with the conveying speed of the objects.

The inventors have found that calculation of a simple index of defectiveness from the powers of electromagnetic radiation transmitted through a fruit (or a vegetable) in a first band and a second band sufficiently separated from the first band, makes it possible to obtain a very accurate result regarding the presence of a defect or defects in the fruit (or vegetable).

Thus, by choosing the low and high bands appropriately for each type of fruit/vegetable, the inventors have found that calculation of a ratio of the powers transmitted through the fruit/vegetable makes it possible to determine the presence of internal defects sLtch as over-ripe or rotten zones.

In particular, the ratio of the powers transmitted in the low band and the high band makes it possible to operate irrespective of the differences in the size of a series of frLtits/vegetables of the same type.

The ratio of the powers is established using corrected powers, i.e. a difference between the power (passing through the object) measured by the radiometric sensor while one source of radiation is switched on and the power measured by the radiometric sensor when neither source of radiation of the device is switched on: this means the background radiation for example such as the lighting hi the building in which a device according to the invention is installed.

Numerous defects are present inside fruits/vegetables (close to the seeds or pips for example) and are not detected by the devices for measuring reflected radiation or photographic devices. The invention, by implementing a measurement of defectiveness of a fruit/vegetable by virtue of a power of electromagnetic radiation transmitted, makes it possible to check the heart of the fruit/vegetable and thus ensure reliable detection of even the innermost defects.

This is why, advantageously and according to the invention, the device for processing may also be adapted so as to be able to compare the index of defectiveness of an object with at least one predetermined value, so as to be able to sort the said object according to its index of defectiveness.

In particular, tile processing device may comprise one or more predetermined values recorded in a memory corresponding to quality thresholds for the objects being analysed. The sets of predetermined values are advantageously peculiar to each type of fruit or vegetable and depend on the sorting it is desired to carry out, which can vary according to the culture of each company, the demands of the traders, etc. Advantageously and according to the invention, the sources of electromagnetic radiation may be adapted so that at least a portion of the electromagnetic radiation emitted passes through an object disposed between said sources of electromagnetic radiation and the radiometric sensor.

In particular, the power of the sources of radiation may be chosen so that at least a portion of the electromagnetic radiation emitted passes through an object.

In particular, advantageously and according to the invention, the mean wavelength of the low band and the high band may be adapted so that at least a portion of the electromagnetic radiation emitted by each of the two sources of radiation passes through an object.

In particular, advantageously and according to the invention, the sources of radiation may be adapted to emit an electromagnetic radiation in the infrared range.

More particularly, the sources of radiation may advantageously emit in the near infrared range. According to the type of fruit or vegetable to be analysed, the wavelengths of the sources of radiation can also be chosen in other electromagnetic ranges, as long as the ratio between the two powers transmitted is different depending on whether the fruit/vegetable is sound or not.

Moreover, advantageously and according to the invention, the mean wavelength of the high band and the mean wavelength of the low band may be separated by at least 80 nanometres (nm).

The separation of the bands is chosen in order to obtain a reliable index of defectiveness. In particular, for a type of fruit/vegetable, it is possible to rely on two spectrograms produced on a sound fruit and on a fruit having a defect. Advantageously, a first band may be chosen which presents a particularly marked change in amplitude of the spectrogram between sound fruit and damaged fruit, and a second band in which the amplitude of the spectrogram is little changed between the two states of the fruit, such that the ratio between the two values is changed according to the defectiveness of the fruit.

Advantageously and according to the invention, the thw band and the high band may be separated by about 1 00 nanometres (nm).

Moreover, advantageously and according to the invention, the device for control and the sources of radiation may be adapted so that the power of the electromagnetic radiation emitted by each of the sources of radiation, in the absence of an object, produces a same measurement for the power of the electromagnetic radiation by the radiometric sensor.

In fact, like the human eye, the majority of radiornetric sensors exhibit a sensitivity which differs according to the wavelength. It is therefore necessary to compensate for this variation by choosing sources of radiation of suitable power and adapting their electrical power supply so that the radiometric sensor supplies a same power measurement to the device for processing when each source is switched on individually without any interposed

fruit/vegetable.

Advantageously and according to the invention, each source of radiation may comprise at least one light-emitting diode (LED) emitting respectively in the low band and in the high band.

Light-emitting diodes (LEDs) have a number of advantages, induding among others a low cost and emission in a narrow band of wavelengths.

They also withstand extreme environmental conditions (e.g. temperature, humidity, vibration) very well.

Moreover, advantageously and according to the invention, when each source of radiation comprises a plurality of light-emitting diodes (LEDs), an array of LEDs may be mounted substantially in one and the same plane, the LEDs emitting in the low band being mixed in the plane with the LEDs emitting in the high band so as to form substantially identical beams.

S

In this way, sources of radiation are obtained which emit beams which are substantially identical in direction and in shape and would coincide if they were switched on sinmitaneously. They are notably substantially colinear. The optical path of the radiation in the low band and the radiation in the high band in each fruit/vegetable is thus the same overall. The difference in power measured by the radiometric sensor between the low band and the high band is therefore not due to any difference in lighting or optical path through the object.

In addition, as a result a single source of light is formed which can emit radiation in the low band and in the high band in alternation. The power supply is controlled by the device for control, notably if it is necessary to supply the LEDs emitting in the low band with a different electrical power to the L.EDs emitting in tile high band (to obtain the same electromagnetic power value measurement when switched off from the radiornetric sensor). A source formed in this way is also particularly compact.

Moreover, advantageously and according to the invention, the LEDs may be disposed in an oval configuration.

This form is particularly advantageous when fruits/vegetables are passing successively between the sources of radiation and the radionietric sensor to undergo checking for defects. In fact, in this case, the LEDs are disposed in an oval configuration perpendicularly to the direction in which the fruits/vegetables are passing, so as to avoid distorted measurements on the front and rear flanks of the fruit/vegetable in the direction in which it is moving.

In fact, advantageously and according to the invention, the radiometric sensor and the sources of electromagnetic radiation may be disposed respectively on either side of a conveyor for objects.

A device according to the invention when mounted on a conveyor makes it possible to carry out a sorting operation on fruits/vegetables passing on it according to their index of defectiveness.

Advantageously and according to the invention, each source of radiation may comprise a convergent optical device adapted to focus the electromagnetic radiation from said source on an object.

In particular, advantageously, a single convergent optical device may be disposed between the two sources of electromagnetic radiation on the one hand and the object on the other hand. Thus, a same optical device (for example a convergent lens) focusses the electromagnetic radiation from the first source and the electromagnetic radiation from the second source such that the optical paths followed by the radiation coming from tile first source and the radiation coming from the second source, between each source and the radiometric sensor, are substantially identical.

Moreover, advantageously and according to the invention, the device for processing the device for control and the sources of radiation may be adapted so that a plurality of measurements of transniissivity of electromagnetic radiation can be carried out for each object in each of the low band and the high band.

Measuring the radiation transmitted through a same object several times successiv&y in each band of wavelengths makes it possible to improve the defect detection. In fact, each series of measurements can inckjde aberrant values which can be eliminated when a plurality of measurements are carried out (for example by calculating variance). The correct values can be averaged and the index of defectiveness calculated from these mean values in each band of wavelengths.

The invention also extends to a method for detection of bnuses and rotten zones in objects chosen from fruits and vegetables without these objects being spoiled, comprising: (a) sequentially in either order, and at least once (i) making a first measurement of a power of electromagnetic radiation transmitted through an object, by a radiation of wavelengths in the infrared range emitted in a first band and designated a low band, and (ii) making a second measurement of a power of electromagnetic radiation transn1itted through said object, by a radiation of wavelengths in the infrared range emitted in a second band and designated a high band, wherein the second band is separated from the low band; and (b) producing an index of defectiveness for the object from said first and second measurements of power.

Advantageously and according to the invention, the index of defectiveness may be a ratio of a function, designated the low function, of the first power of radiation in relation to a function, designated the high function, of the second power of radiation.

In particular, advantageously and according to the invention, the low function and the high function may be of the same type.

Notably, advantageously and according to the invention, the low function and the high function may be closely related with the same coefficients.

The controlling coefficient is advantageously equal to one, and the ordinate at the origin is a value measured for the background radiation when switched off, i.e. when the sources of radiation are not switched on, in the presence of a typical object.

Moreover, advantageously and according to the invention, the index of defectiveness of an object may be compared with at least one predetermined value, so as to be able to sort said object according to its index of defectiveness.

Thus, the ftuits!vegetables which undergo a method according to the invention can be sorted according to different categories of quality.

In particular, advantageously and according to the invention, each predetermined value may be established empirically from measurements carried out on typic& objects.

The predetermined values corresponding to each evel of defectiveness of the objects can be established empirically with the aid of typical objects, i.e. sound fruits/vegetables and fruits/vegetables which have been deliberately damaged to certain degrees to serve as references. A device according to the invention is calibrated with the aid of these typical objects.

In a method according to the invention, advantageously sources of electromagnetic radiation emitting in the infrared range are chosen.

Also, advantageously and according to the invention, tile low and high bands may be chosen such that their mean wavelengths are separated by at least 80 11111.

Moreover, advantageously, the power supplied to each source of electromagnetic radiation may be chosen so that, in the absence of an object, the radionietric sensor measures a same power of electromagnetic radiation for each of the two sources of electromagnetic radiation. Thus, the difference in sensitivity of the sensor according to the wavelength is corrected.

Advantageously and according to the invention, the detection of defects may be carried out on objects passing one after another on a conveyor.

Thus, a method according to the invention makes it possible to sort fruits/vegetables passing at high speed on a conveyor according to their level of defectiveness: notably according to their level of ripeness or their proportion of internal or externa' defects, said defects being defects peculiar to the fruit/vegetable -notably bruises or rotten zones.

In particular, in a method according to the invention, each source of electromagnetic radiation niay be switched on then switched off several times during the passing of an individual object so as to obtain a plurality of measurements of the power of electromagnetic radiation transmitted in each band of wavelengths. Tile extreme measurements (regarded as aberrant) are eliminated, then the mean of the values in each band is established. The calculation of the index of defectiveness is carried out using these mean values in each band ofwav&engths.

The time for which each source of radiation is switched on and the dark" time between successive actuations of the two types of source are chosen so as to be a lot less than the time taken for each object to pass between the radiometric sensor and the sources of radiation. Thus, the optical path taken by the radiation in the low band is substantially identical to the optical path taken by the radiation iii the high band, because the object only moves a very small amount between the successive actuations of the two sources of radiation.

Moreover, advantageously, in a method according to the invention, the power of the background radiation -i.e. the radiation received by the radiometric sensor while the sources of radiation are switched off (and advantageously in the presence of an object) -may be also measured and subtracted from tile measurements of the power of radiation received while each of the sources of radiation is switched on.

The invention may also relate to a device mid a method which are characterised in combination by all or part of the characteristics mentioned above or below.

Further aims, characteristics mid advantages of the invention will become apparent from a reading of the following description which is given by way of non-limiting description and refers to the attached figures in which: Figure 1 is a diagrammatic illustration of a device for detection of defects in objects chosen from fruits and vegetabies without these objects being spoiled according to one mode of embodiment in accordance with the invention, Figure 2 is a diagrammatic illustration from the front of sources of electromagnetic radiation of a device according to the invention, and Figure 3 is a block diagram of one mode of embodiment of a method according to the invention.

A device according to the invention is shown in Figure 1. An object 6, which is an apple, is disposed on a support 8, laterally between an illuminating device 7 and a radiometric sensor 3.

The ifluniinating device 7 comprises a plurality of light-emitting diodes (LEDs) i emitting in a first band, designated a low band, of wavelengths having a mean wavelength of 780 nm and a width of approximately 25 nm (at 50% of the maximum intensity) for an LED of type SMB78O-l 100-02-I from the manufacturer Epitex Inc. The iUuminating device 7 also comprises a plurality of LEDs 2 emitting in a second band, designated a high band, of wavelengths having a mean wavelength of 880 nm and a width of approximately 50 nm (at 50% of the maximum intensity) for an LED of type SMB88O-ll00-0l-I from the manufacturer MarLibeni America Corporation.

The low band LiDs 1 and the high band LEDs 2 are arranged in alternation with one another iii the plane of the support 9 of the illuminating device so as to form substantially colinear beams of electromagnetic radiation so that the optical path taken in the fruit is substantially identical for the radiation of each band of wavelengths.

Advantageously, as shown in Figure 2, the low band LEDs 1 and the high band LEDs 2 are distributed over a single support 9 in patterns which are oval overafl and stretched in a direction perpendicular to the direction of passage of the fruits 6. The LEDs 1, 2 are in particular distributed in two concentric ovals.

In this pattern the LEDs 1 emitting in the low band and the LEDs 2 emitting in the high band are mixed spatially in the plane of the support 9, in such a way as to create substantially colinear beams. In Figure 2 the low band LEDs 1 are shown in white and the high band LEDs 2 are shown in black.

It is particularly advantageous in a device according to the invention to have numerous LEDs of small dimensions, the different types of LEDs being mixed to obtain beams with the greatest possiHe similarity in the ow band and in the high band.

The illuminating device 7 advantageously has dimensions in a front view of 50 mm x 50 mm to analyse apples whose dimensions are generally in the region of 75 mm in diameter. Thus, by choosing an illLtminating device 7 with dimensions slightly smaller than those of the objects being analysed, one can be sure that the radiation detected by the radiometric sensor 3 is indecd radiation passing through the object. The LEDs 1, 2 of the illuminating device 7 are operated by an electrical power supply controlled by a switch 4 controlled by a processor 5.

The processor 5 and the switch 4 serve as control unit for the LEDs.

The radiometric sensor 3 is disposed facing the fruit 6 so that it only receives the electromagnetic radiation from the illuminating device 7 that has been transmitted through the fruit. The radiometric sensor 3 also receives background radiation which is measured while the sources of radiation are switched off, and subtracted from the measurements made while the LEDs 1, 2 are switched on.

The radiometric sensor 3 is of type 82387-101 OR from the manufacturer Hamamatsu, and its sensitivity is greater than 1O.4% in the high band (880 nm) iii relation to the thw band (780 nm). Consequently, the high band LEDs 2 and the low band LEDs 1 are provided with a power supply which can be adjusted to correct this difference in the sensitivity of the radiometric sensor. Thus, the low band LEDs I are supplied with a current of between 0.8 and 1.6 amps, and the high band LEDs 2 are also supplied with a current of between 0.8 and 1.6 amps, but the current supplied to each group of LEDs is adjustable.

The processor 5 serves as the processing unit for the data received from the radiometric sensor 3.

Thus, as shown in the block diagram in Figure 3, while a fruit 6 is passing between the illuminating device 7 and the radiometric sensor 3, a plurality of steps 11 in which the low band LEDs 1 are switched on and the measurement of the power received by the radiometric sensor 3 is acquired are carried out in alternation with a plurality of steps 12 in which the high band LEDs 2 are switched on and the measurement of the power received by the radiometric sensor 3 is acquired.

Every time the LEDs are switched off, a measurement of the background power received by the radionietric sensor 3 is acquired.

In the following step 13, the set of values acquired in the low band are analysed, and the aberrant values are eliminated. The inventors have estabhshed that the analysis is particularly reliable when the lowest value in the series is chosen.

In the step 14, the same selection is made with the values acquired in the high band.

In the step 1 5, the value measured for the background power is subtracted from the value calculated or adopted in step 13 in the low band.

In the step 16, the value measured for the background power is subtracted from the value calculated or adopted in step 14 in the high band.

In the step 17. the ratio of the result of step 16 is divided by the result of step 15. Thus, an index of defectiveness is obtained which in the step 18 is compared with predetermined threshold values recorded in a memory.

The threshold values were established previously from empirical measurements carried out on sound fruits and on sound fruits which were deliberately damaged in a controlled mamier (for example with microwaves).

The support 8 for the fruit 6 is advantageously a conveyor support 8 conveying a large quantity of fruits 6 one after another. Advantageously, the frequency with which the LEDs 1, 2 are switched on is adapted according to the speed at which the fruits 6 are passing. To do this, the processing unit 5 for the signals from the radiornetric sensor 3 can also be used to control the conveying operation of the conveyor, and to sort the fruits on the basis of the index of defectiveness calculated using the measurements of transmissivity. For example, for a conveying speed of approximately I metre per second for the fruits 6, the choice of frequency with which each source of radiation is switched on is approximately 640 Hertz. Consequently, approximately 64 measurements can be carried out in each band of wavelengths for each fruit 6.

The invention can cover numerous other variants which are not illustrated.

For example, the sources of light can be other than LEDs as long as they each emit in a narrow band of the electromagnetic spectrum.

Claims

<claim-text>CLAIMS1. A device for detection of bruises and rotten zones in objects (6) chosen from fruits and vegetaHes without these objects (6) being spoiled, comprising: (a) a first source (1) of electromagnetic radiation in a first band, designated a low band, of wavelengths in the infrared range; (B) a second source (2) of electromagnetic radiation in a second band, designated a high band, of wavelengths in the infrared range, said high band being separated from said low band; (c) a radiometric sensor (3) adapted to convert a power of electromagnetic radiation received from any one of the first and second sources (1, 2) of radiation into electronic signals representative of that power, said sources (1, 2) of radiation being: (i) capable of each producing a beam of electromagnetic radiation which is substantially colinear with the beam of electromagnetic radiation from the other source of radiation, (ii) disposed in the direction of said radiometric sensor (3) such that said beams are directed in the direction of said radiometric sensor (3), (iii) disposed with respect to the radiometric sensor (3) to permit an object (6) to be passed therebetween, and (iv) adapted so that at least a portion of the electromagnetic radiation emitted passes through an object (6) disposed between said sources (1, 2) of radiation and the radiometric sensor (3); said device türther comprising: (d) at least one device for control (4) of said sources (1, 2) of radiation, adapted so as to be able to switch on the first source (1) of radiation and the second source (2) of radiation in alternation; and (e) at least one device for processing (5) of electronic signals, the device for processing being: (i) linked to the radiometric sensor (3) so as to be able to receive the electronic signals supplied by the latter, and (ii) adapted so as to be able to produce an index of defectiveness of an object (6) from the power of the electromagnetic radiation transmitted through said object (6) in the low band and from the power of tile electromagnetic radiation transmitted through said object (6) in tile high band.</claim-text> <claim-text>2. The device according to claim I, wherein the device for processing (5) is also adapted so as to be able to compare the index of defectiveness of an object (6) with at least one predetermined value in such a way as to be able to sort said object according to its index of defectiveness.</claim-text> <claim-text>3. The device according to claim 1 or 2, wherein the mean wavelength of the high band and the mean wavelength of the low band are separated by at least 80 nm.</claim-text> <claim-text>4. The device according to claim 1, 2 or 3, wherein the at least one device for control (4) and the sources (1, 2) of radiation are adapted so that in the absence of an object (6) the power of the electromagnetic radiation sensed by the radiometric sensor (3) is the same for the first source and the second source.</claim-text> <claim-text>5. The device according to any preceding claim, wherein each source (1, 2) of radiation comprises at least one light-emitting diode (LED) emitting respectively in the low band and in the high band.</claim-text> <claim-text>6. The device according to any preceding claim, wherein each source (1, 2) of radiation comprises a plurality of light-emitting diodes (LEDs), and the LEDs are mounted in an array substantially in one and the same plane, the LEDs emitting in the low band being mixed in the plane with the LEDs emitting in the high band so as to form substantially identical beams.</claim-text> <claim-text>7. The device according to claim S or 6, wherein the LEDs are disposed in an oval configuration.</claim-text> <claim-text>8. The device according to any preceding claim, wherein the radiometric sensor (3) and the sources (1, 2) of electromagnetic radiation are disposed respectively on either side of a conveyor (8) for objects (6).</claim-text> <claim-text>9. The device according to any preceding claim, wherein the device for processing (5), the device for control (4), and the sources (1, 2) of radiation are adapted so that a plurality of measurements of transmissivity of electromagnetic radiation can be carried out for each object (6) in each of the low band and the high band.</claim-text> <claim-text>10. A method for detection of bruises and rotten zones in objects (6) chosen from fruits and vegetables without these objects (6) being spoiled, comprising: (a) sequentially, in either order, and at least once (I) making a first measurement of a power of electromagnetic radiation transmitted through an object (6) by a radiation of wavelengths in the infrared range emitted in a first band and designated a low band, and (ii) making a second measurement of a power of electromagnetic radiation transmitted through said object (6) by a radiation of wav&engths in the infrared range emitted in a second band and designated a high band wherein the second band is separated from the low band; and (b) producing an index of defectiveness for the object (6) from said first and second measurements of power.</claim-text> <claim-text>11. The method according to claim 10, wherein the index of defectiveness is a ratio of a function, designated the low function, of the first measurement or measurements of power of radiation in relation to a function, designated the high function, of the second measurement or measurements of power of radiation.</claim-text> <claim-text>12. The method according to claim 10 or 11, including comparing the index of defectiveness of an object (6) with at least one predetermined v&ue, so as to be able to sort said object according to its index of defectiveness.</claim-text> <claim-text>13. The method according to daim 10, 11 or 12, incktding choosing the thw and high bands such that their mean wavelengths are separated by at least 80 lint 14. The method according to any one of claims 10 to 13, including passing said objects (6) one after another on a conveyor (8) to detect defects on said objects (6).</claim-text>