System for the Optical Detection of Objects

Abstract

A system for the optical detection of objects includes a first source for generating light, microwaves, or ultrasound of a first wavelength. An object is illuminated by the light, the microwaves, or the ultrasound, wherein the illumination is distorted by the object. The system further includes at least one color light source for the generation of color light of a second wavelength, wherein the same object is illuminated by the color light of the color light source. The first wavelength is different from the second wavelength. Further, a sensor is provided for the detection of the object illuminated by the first source, and a second sensor is provided for the detection of the color light generated by the color light source, which is reflected by the object.

Claims

1. A system for the optical detection of objects, comprising: a first source for generating light, microwaves, or ultrasound of a first wavelength, wherein an object is illuminated by the light, the microwaves, or the ultrasound, and the illumination is distorted by the object; at least one color light source for generating color light of a second wavelength, wherein the object is illuminated by and reflects the color light of the at least one color light source, wherein the first wavelength is different from the second wavelength; a first sensor for detecting the object illuminated by the light, the microwaves, or the ultrasound of the first source; and a second sensor for detecting the color light generated by the at least one color light source and reflected by the object.

2. A system for the optical detection of objects, comprising: a first source for generating light, microwaves, or ultrasound of a first wavelength, wherein an object is illuminated by the light, the microwaves, or the ultrasound, and the illumination is distorted by the object; at least one color light source for generating color light of a second wavelength, wherein the object is illuminated by the color light of the at least one color light source, wherein the first wavelength is different from the second wavelength; a first sensor for detecting the object illuminated by the light, the microwaves, or the ultrasound of the first source and for detecting the color light generated by the at least one color light source and reflected by the object.

3. The system of claim 1, wherein the source is a line laser and the at least one color light source is one or a plurality of LEDs.

4. The system of claim 1, wherein the first wavelength is in a range of a band gap in a solar spectrum.

5. The system of claim 1, wherein the second wavelength is selected from NIR, red, green, and blue.

6. The system of claim 1, wherein the at least one color light source is a plurality of color light sources, and all color light sources have different wavelengths, respectively, and each wavelength of all color light sources is selected from NIR, red, green, and blue.

7. The system of claim 1, wherein the reflected color light is diverted from an optical beam path of the first source by means of a beam splitter or a dichroic mirror to the first sensor or the second sensor.

8. The system of claim 1, wherein the first sensor or the second sensor only detects the reflected color light when a color light source of the at least one color light source is activated, and the first sensor only detects the light, the microwaves, or the ultrasound when the first source is activated.

9. The system of claim 1, wherein the color light of the at least one color light source and the light, the microwaves, or the ultrasound of the first source are directed to the object at least partly along a same optical path.

10. The system of claim 1, wherein the system is moved relative to the object to detect all of the object, wherein the system is movable and/or the object is movable.

11. A method for the optical detection of an object, comprising: a. activating a first source for generating light, microwaves, or ultrasound of a first wavelength to illuminate the object, wherein the illumination is distorted by the object; b. capturing an image and determining elevation information about the object from the distortion; c. deactivating the first source for generating the light, the microwaves, or the ultrasound; d. activating at least one color light source for generating color light of a second wavelength, wherein the object is illuminated by and reflects the color light of the at least one color light source; e. capturing an image of the reflected color light and determining color information about the object from the reflected color light; and f. deactivating the at least one color light source, wherein the first wavelength is different from the second wavelength, and the second wavelength is selected from NIR, red, green, yellow, and blue.

12. The method of claim 11, further comprising capturing a reference image without the first source for generating the light, the microwaves, or the ultrasound and the at least one color light source being activated.

13. The method of claim 11, wherein the at least one color light source is a plurality of color light sources, the method further comprising activating the plurality of color light sources and capturing one image.

14. The method of claim 11, further comprising repeating all steps several times as a cycle for a complete detection of the object, wherein the first source for generating the light, the microwaves, or the ultrasound and/or the at least one color light source are moved relative to the object to detect the object in its entirety.

15. The method of claim 11, wherein an intensity of the color light is variable and, within a cycle, a first image is captured with color light of a defined wavelength and a second image is captured with color light of a same wavelength, wherein the intensity of the color light differs for the first image and the second image.

16. The system of claim 4, wherein the first wavelength is in a range from 900 nm to 1000 nm.

17. The system of claim 16, wherein the first wavelength is in a range from 930 nm to 960 nm.

18. The system of claim 17, wherein the first wavelength is 940 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention will be described hereunder in more detail with reference to a preferred embodiment and to the accompanying drawings.

[0032] In The Figures:

[0033] FIG. 1 shows an embodiment of the system for the optical detection of objects according to the present invention,

[0034] FIG. 2 shows a detail of the system for the optical detection of objects illustrated in FIG. 1,

[0035] FIG. 3 shows an elevation profile captured by the system for the optical detection of objects illustrated in FIG. 1,

[0036] FIG. 4 shows a characteristic reflection spectrum of a plant,

[0037] FIG. 5 shows a flow chart of the method for the detection of an object according to the present invention, and

[0038] FIG. 6 shows a flow chart of another method for the detection of an object according to the present invention.

DESCRIPTION OF THE INVENTION

[0039] The laser triangulation system of the present invention for the optical detection of objects as illustrated in FIG. 1 comprises a housing 10. A source 12 for generating light is arranged inside the housing 10, which source may be e.g. a line laser. The light of the line laser 12 illuminates an object 16, illustrated as a plant, via a mirror 14. The topology of the plant 16 causes a distortion of the line-shaped illumination of the line laser 12. The object 16, and in particular the distorted line-shaped illumination of the object 16, is detected by a first sensor 18 via a mirror 22, wherein the sensor is also arranged inside the housing 10. The first sensor 18 is connected to an evaluation unit 20, wherein elevation information about the object along the line-shaped illumination can be determined by the evaluation means based on the distortion of the line-shaped illumination caused by the object 16. A typical elevation profile is shown in FIG. 3. A plurality of data points 24 are determined along the line of the line laser 12, which together form an elevation profile 26. Here, the entire housing 10 of the system can be moved along the arrows 28 in the y-direction so that the entire topology of the object 16 can be captured successively by means of a plurality of elevation profiles 26.

[0040] In addition the system comprises a plurality of color light sources 30 configured as LEDs and adapted to generate red, green, blue and near infrared light. The object 16 is illuminated by the color light sources 30. Here, the illumination by the color light sources 30 occurs in a plane identical to the illumination by the line laser 12. In FIG. 1 the common plane is perpendicular to the y/z-plane. The color light reflected by the object 16 reaches a second sensor 34 via the mirror 14 and a dichroic mirror 32. The dichroic mirror 32 transmits light of the wavelength of the line laser 12 and reflects all other wavelengths. The second sensor 34 captures the reflected color light, and the evaluation unit 20 calculates color information about the object.

[0041] The first sensor 18 and the second sensor 34 are designed as CCD cameras, for example in order to acquire the light intensity in particular independently of the respective wavelength.

[0042] For preventing the first sensor 18 from being affected by sunlight, the housing 10 comprises a filter input 36 configured as a bandpass and exclusively transmitting light of the wavelength of the line laser 12. The wavelength of the line laser 12 is selected in particular to correspond to a band gap in the solar spectrum so that there is only little or no influence by sunlight.

[0043] The color light sources 30 are arranged on both sides next to the mirror 14 (as illustrated in FIG. 2). A first color light source formed by three red light LEDs 38 on the one side and another three red light LEDs on the other side are arranged alternating with green light LEDs 40, blue light LEDs 42 and LEDs 44 for generating near-infrared light. Here, the arrangement on the left and on the right of the mirror 14 is in particular symmetric.

[0044] Based on the color information obtained by means of the color light source 30 and the second sensor 34, it is possible to perform an exact characterization of the object 16 and to differentiate similar, yet not exactly identical objects 16 from each other. If the object is e.g. a plant, it is possible to determine the nutritional condition of the plant based on the color information and/or to determine diseases or the disease condition the plant. Further, the ripeness of a plant's fruits can be determined based on the color information. In particular, the color information provides a possibility to differentiate, whether the object is actually a plant. In this regard, FIG. 4 illustrates a characteristic reflection spectrum of a plant having a low proportion of blue 46, a high proportion of green 48, a low proportion of red 50 and a characteristic steep rise in the near infrared 52. It is possible to determine from the color information, in particular from the difference between the red range 50 and the near infrared range 52, whether the object is actually a plant or another not vegetal object.

[0045] FIG. 5 illustrates a cycle of the method according to the invention for the optical detection of objects. The cycle comprises six pulses. Each pulse has a length of 0.05 to 1 s. The frequency of the cycles is 10 to 500 Hz. The first line 54 illustrates the clock of a cycle generated by a pulse generator. The second line 56 illustrates the activation of the line laser 12. The same is activated at the first pulse. At the same time, according to the second line 56, an image is captured by the first sensor 18. The second sensor 34 does not capture an image at the first pulse. The color light sources 30 remain deactivated as well. From the second to the fifth pulse all color light sources are activated one after the other and, at the same time, an image is captured by the second sensor 34, as indicated in the third and the fourth line 58, 62 in FIG. 5. For example, the red light LED 38 is activated at the second pulse, the green light LED 40 is activated at the third pulse, the blue light LED 42 is activated at the fourth pulse and the near infrared LED 44 is activated at the fifth pulse. The color information can be determined from these images by the evaluation unit 20. At the sixth pulse, neither the color light source nor the line laser 12 is activated, and the first sensor 18 and the second sensor 34 capture an image as a reference image.

[0046] The system is displaced relative to the object 16 as indicated by the arrows 28, either after a full cycle has been passed or continuously. In this manner the system is captured in its entirety. In particular, the complete color information about the object 16 is obtained to enable an exact characterization of the object 16.

[0047] FIG. 6 illustrates a cycle of another method of the present invention for the optical detection of objects. Here, two images are captured for each color, i.e. each color light source 38, 40, 42, 44 is activated twice in one cycle. The second sensor 34 is activated accordingly. Here, first, an image is captured for each color with the full intensity of the color light, and thereafter, by a shortened activation, an image with a lower intensity of the color light is captured upon the second activation of the color light source 38, 40, 42, 44. This is illustrated in the corresponding lines in FIG. 6. The further proceeding of the method corresponds to the method in FIG. 5.