APPARATUS FOR LOCATING AN OBJECT, AND LIGHT TRANSMITTER

Abstract: The invention concerns an apparatus for locating an object with the aid of optical radiation. The apparatus comprises a light source (1) comprising a plurality of light elements (2); an optical detector (3); optical means (5, 6) comprising light source optics (5) and detector optics (6); and a control unit (7) which is disposed to activate such light elements (2) as are desired, to locate the light signals incident on the location-sensitive optical detector (3), and on the basis of the location of the active light element and of that of the detection site to calculate the distance of the object's surface by the triangulation principle. As taught by the invention, the light source (1) and the light source optics (5) are integrated to constitute a compact light transmitter unit (10), the light elements (2) belonging to the light source (1) being arranged close to each other and provided with joint light source optics (5). Similarly, the optical detector (3) and the detector optics (6) are integrated to constitute a compact light receiver unit (18). The units (10, 18) are disposed in immediate proximity to each other and, advantageously, to the control unit (7).

Description: APPARATUS FOR LOCATING AN OBJECT, AND LIGHT TRANSMITTER The present invention concerns an apparatus as defined in the preamble to Claim 1, for locating an object with the aid of optical radiation. The invention also concerns a light transmit¬ ter as specified in Claim 10. Fast locating of an object, and contactless distance measurement in particular, range among the commonest needs in the field of machine automation and robotics. Distance is usually measured optically, or with the aid of ultrasonic or microwave techniques. The problem encountered in ultrasonic technique is the high dependency of such measurement on the temperature of the intervening medium material, usually air. Microwave techniques are frequently problematic in view of safety. Optical object-locating apparatus are becoming increasingly common. Optical distance measuring, or range finding, apparatus is usually based on measuring the intensity of reflected light, on triangulations or on determining the travelling time of light. Optical radiation is generally understood to mean radiation of which the wavelength falls, in the first place, in the visible or near infra-red spectral range. An optical apparatus for distance measurement is known in prior art in which a pulsed IR radiation beam from a light-emitting diode, or LED, is directed on the object and the light reflected from the object is detected with the aid of a location-sensitive detec¬ tor. The distance of the object is found by applying the triangulation principle, the distance of the object being thus found on the basis of the location of the reflected light. The drawback embarrassing the apparatus just described is that with its aid the distance from the point of measurement of only one single point of the object can be determined. In applications of robotics and automation, in particular, real-time distance meas¬ urement to a plurality of points of the object is a necessity. In order to outline the objects and to locate various parts thereof, one would have to make several measurements on various points thereof. For this to be successful, the apparatus has to be aimed towards the object several times. Such types of appara¬ tus have been developed in which the radiation beam aimed at the object is mechanically deflected and the beam is made to sweep over the object under measure¬ ment, in one or several planes. Usually this requires a complicated scanner design comprising mechanically moving parts, whereby the cost increases substantially and, frequently, the reliability of the system suffers. In prior art an optical apparatus for locating an object is known in which on the object are directed, from light sources positioned close to each other, sequential light pulses in a given succession and the backward scattering of these light beams from the object is detected with the aid of detectors positioned close to each other and of which the positioning de¬ pends on the object's position in space, and on the basis of the positions of the light sources and detec- tors the scattering points on the object are determined in accordance with the triangulation principle, known in itself in the art, and further the position of the object in space is determined. The drawback embarrassing the above optical apparatus is that in this apparatus light sources are used which are provided with individual lens arrange¬ ments. The light sources are comparatively bulky and, therefore, use up space. The optical apparatus has the further drawback that it is composed of discrete components, and there¬ fore its assembly and commissioning for operation involves major expense. The object of the invention is to eliminate the drawbacks mentioned above. It is a particular object of the invention, to disclose an apparatus for locating an object with good stability, small size and low price, and also a corres¬ ponding light transmitter, particularly for said appa¬ ratus. In addition, it is an object of the invention to disclose an apparatus for locating an object with which determination of distance to a plurality of points on the object, i.e., outlining of the object, can be done quite rapidly. The apparatus of the invention for locating an object is characterized by that which is stated in Claim 1. The apparatus of the invention for locating an object with the aid of optical radiation comprises a light source, an optical detector, optical means and a control unit. The light source comprises a plurality of light elements which are disposed with a spacing from each other. The optical detector is a location-sensi¬ tive detector. With the aid of such a detector the incident light beam can be observed at different points of the detector surface. With the aid of the detector those light beams are observed and located which are scattered from the object insofar as they are within the observation range of the detector. The optical means comprise light source optics and detector optics, the first-mentioned being disposed in conjunction with the light source and the latter, in conjunction with the detector. The light source optics enable a plurality of light beams with small aperture angle to be produced from the radiation emitted by the light elements, these beams being directed into a given solid angle, towards the object which shall be located. With the aid of the detector optics, light beams scat- tered by the object are collected and focussed on the light-sensitive surface of the detector. The control unit has been arranged to activate those light elements which are desired in each in- stance, to locate the light signal entering the loca¬ tion-sensitive detector, and to calculate the distance of the point on the surface of the object by triangula¬ tion on the basis of the location of the active light element and the location of the detection point. As taught by the invention, the light source and the light source optics are integrated to consti¬ tute a compact light transmitter unit in which the light elements belonging to the light source are ar¬ ranged close together and are provided with common light source optics; and the optical detector and the detector optics are integrated to constitute a compact light receiver unit in which the detector elements are provided with common detector optics; said units being disposed in immediate proximity to each other and, ad- vantageously, to the control unit. A compact unit is here understood to mean a partial entity resembling an electronic component, which is coherent and has been accommodated in a comparatively small volume. In an embodiment of the apparatus, the light source unit and the light receiver unit are disposed in separate packages, such as housings. Thus each inte¬ grated unit constitutes a unitary and compact electron¬ ic component. The light elements comprised in the in¬ tegrated light transmitter unit are arranged to lie close together and they are disposed in a small and unitary housing which has been fitted with light source optics. In like manner, the location-sensitive detector serving as optical detector which is comprised in the integrated light receiver unit, and which comprises a plurality of detector elements, is disposed in another small and unitary housing which has been fitted with detector optics. The housing of each unit just mentioned is, to greatest advantage, a standard housing comprising a bottom part, a cover part provided with a window, and a mantle part to which the bottom part and cover part are attached, and which housing is hermetically sealed. Housings of this kind are commonly used in packaging electronic components. In an embodiment of the apparatus, the light source optics and the detector optics both comprise similar lens arrangements. The focal planes of these lens arrangements are substantially coplanar with the light elements of the light source, respectively the detector elements of the optical detector. Both sets of optics have thus substantially identical characteris- tics. Therefore the light transmitter unit and the light receiver unit match each other, and their appli¬ cation in various environments is facilitated. In an embodiment of the apparatus, the light source unit and the light receiver unit are disposed in a single, compact, that is small and unitary, package, said units being separated by a suitable shield which is impermeable to light. In this apparatus the units can be disposed in a joint housing or frame to consti¬ tute a unitary electro-optical component in which the light source and detector optics are located in each other's immediate proximity, either abutting on each other or spaced by a small distance. In that case the optical systems must be shielded from each other by means of a shield plate, or interface, so that the radiation from the light source cannot affect the de¬ tector directly, through the optical systems. The disposition of the light source unit as well as the light receiver unit in one compact package affords the advantage that practical applications of a locating apparatus like this are facilitated. The apparatus is compact and requires minimal space. More¬ over, the units can be matched and fitted together so that they will operate reliably, and with the accuracy agreed upon, in given predetermined conditions. In an embodiment of the apparatus, the light source optics and the detector optics comprise a holo- graphic element, for improving the optical performance. This element may be a holographic grating or lens. The element may be useful in correcting the lens errors of the optics and in improving the characteristics of the optics proper in order to optimize the dimensions thereof, such as shortening the focal distance so that a smaller package becomes feasible. In an embodiment of the apparatus, the appara¬ tus comprises a plurality of light source units. The apparatus thus comprises e.g. two light source units and one light receiver unit. The light source units are so adjusted that one of them directs the light beams into the proximity region in a given sector, for exam¬ ining this region, and the other directs them to the remote region in another sector, for examining that region. The proximity region is located e.g. about 0.5 m from the apparatus, while the remote region is a region several metres distant. The advantage with an apparatus like this is that it is possible with its aid to examine efficiently and reliably a rather extensive region, where the light source units are optimated to operate within their specific sectors and/or at their specific distances from the apparatus. The sectors of the light source units may overlap partially or com¬ pletely.. In an embodiment of the apparatus there has been provided, in the light source unit and in the light receiver unit, an optically transparent inter¬ mediate component serving to match refractive indexes, between the light source and the light source optics, respectively between the optical detector and the de¬ tector optics. In the light source unit this intermedi¬ ate component is disposed tight against the light source as well as the light source optics and in the light receiver unit it is similarly disposed tight against the detector elements of the optical detector as well as the detector optics. The purpose with said intermediate component is to match with each other the refractive indexes of the different components, i.e., of the light elements and the light source optics, respectively of the detec¬ tor elements and the detector optics. The advantage gained by this arrangement is that the losses are re¬ duced, there are fewer interfaces which may get soiled, and water cannot condense inside the unit. Furthermore, the cooling of the light elements in the light source unit improves. In an embodiment of the apparatus, the inter¬ mediate components in the light source unit and in the light receiver unit are produced of poured material, advantageously of an epoxy. In view of manufacturing techniques, it is advantageous to produce the intermed- iate components by casting them of a material which is well permeable to light and convenient to handle. Epoxy is one such material known in the art. In an embodiment of the apparatus, the light source optics, and similarly the detector optics, with intermediate component are implemented without joints of one single, solid optical material, such as epoxy for instance. This structure is advantageous as regards manufacturing techniques because the optics and the intermediate components are not made separately but they will rather be formed in one single work step. In an embodiment of the apparatus, the control unit is functionally divided into two distinctly sepa¬ rate units: a light source control unit and a light signal processing unit. The light source control unit is connected to the light transmitter unit and the light signal processing unit is similarly connected to the light receiver unit. In an embodiment of the apparatus, the light source control unit comprises controllers for the light elements of the light source, for activating and deac¬ tivating the light elements, a modulator for control- ling the active light elements as desired, and a data processing unit, such as a microprocessor with suitable auxiliary circuits for controlling and supervising the functions of controllers and modulator. The numbers and sequencing of the light beams transmitted with the aid of the light source control unit can be varied, depend¬ ing on the object under examination, etc. It is further possible to modulate the transmitted light beams e.g. in order to eliminate any background illumination. It is for instance possible to transmit light signals in pulses with different timing from different light ele¬ ments, or to modulate them with different repetition frequencies, and to transmit for instance simultaneous¬ ly from different light elements. It is advantageous to synchronize the light elements of the light transmitter unit and the optical detector of the light receiver unit to operate simul¬ taneously. The sensitivity of the detector in receiving light signals emitted by the light elements can hereby be significantly improved. This can be implemented in that the light source control unit and the light signal processing units are interconnected and synchronizing of their operation is effected on the basis of the con¬ trol function of the light elements of the light source, by transferring information on the operating or modulating frequency and on the phase, to the light signal processing unit. In an embodiment of the apparatus, the light signal processing unit comprises a plurality of pre¬ amplifiers for amplifying the signals from the loca- tion-sensitive detector, and a signal processing unit for processing the amplified signals. The signal pro¬ cessing unit comprises, to greatest advantage, a data processing unit, such as a microprocessor with appro¬ priate auxiliary circuits. In an embodiment of the apparatus, the light source control unit and the light signal processing unit are configurated to constitute integrated units. Each unit thus constitutes a unitary and compact elec¬ tronic component. The light transmitter of the invention is characterized by that which is stated in Claim 10. The light transmitter of the invention comprises: a light source, comprising a plurality of light elements; light source optics, with the aid of which from the radiation emitted by the light elements is produced a plurality of light beams having a small aperture angle and which are directed into a given solid angle, outward from the light transmitter. As taught by the invention, the light source and light source optics of the light transmitter are integrated to constitute a compact light transmitter unit in which the light elements belonging to the light source are arranged close to each other and disposed in a compact, that is small-sized and unitary, package, such as a housing, which is provided with light source optics. The integrated unit thus constitutes a unitary, and compact, electronic component. The housing most advantageously comprises a bottom part, a mantle part and a cover part. The light elements of the light sour¬ ce are arranged close to each other in the bottom part of the housing, and the cover part of the housing is provided with a window and with light source optics. The light source of the invention is most ad¬ vantageously employed as a component of an object-lo¬ cating apparatus. It is obvious, however, that the applications are not exclusively confined to locating apparatus; numerous other applications are equally feasible, such as optical switches and monitoring apparatus, for instance. In an embodiment of the apparatus, the housing of the light transmitter unit is most advantageously a hermetically enclosed standard housing, as was noted in the foregoing already in context of the light transmit- ter unit for locating an object of the invention. In an embodiment of the apparatus, the light source optics comprise a lens arrangement having its focal plane substantially coplanar with the light ele¬ ments of the light source. The light beams obtained from the light source unit with an arrangement like this are maximally dense beams with minimal dispersion angle. In an embodiment of the apparatus, the light source optics comprise, as their lens arrangement, a planoconvex lens. The fixing of such a lens on the cover part of the housing, and preferentially on the window in the cover part, is comparatively simply ac¬ complished. It ix obvious that many kinds of lens arrangements are feasible, but it is desirable in view of manufacturing and costs that the lens arrangements be comparatively simple ones. In an embodiment of the apparatus, the light source optics comprise a holographic element, such as a transmission grating or a lens element, as was already observed in the foregoing in context of the object- locating apparatus.lt is possible with such a holo¬ graphic element to correct the principal errors of the lens arrangement and to optimize the dimensions of the optics. Connecting the holographic element to the light source optics is accomplished simply e.g. between the lens and the cover part of the housing. In an embodiment of the apparatus, an optical¬ ly transparent intermediate component matching with each other the refractive indexes of the optics and the light elements has been provided, between the light source and the light source optics, This intermediate component is disposed tight against the light source as well as the light source optics. The intermediate com¬ ponent is a component of the kind disclosed in the foregoing in context of the object-locating apparatus. In an embodiment of the apparatus, the light element is a light-emitting diode, and the light source is composed of a plurality of light-emitting diodes, or LEDs. These LED components may, for instance, be effi¬ cient GaAs and GaAlAs LEDs, which operate in the near infra-red range. LEDs, especially so-called LED chips, can be integrated in minimal space in a highly compact configuration, with a view to increasing the angular resolution of the apparatus. In an embodiment of the apparatus, the light element is a semiconductor laser, and the light source is composed of a plurality of semiconductor lasers. In an embodiment of the apparatus, the light source is composed of light elements to which have been connected light conductors, such as optic fibres, for conducting the light from a suitable, defined place towards the light source optics. The light elements of the light source of the invention can be implemented in numerous ways. The light elements presented in the foregoing are primarily meant to serve as examples, and the alternatives of the light elements shall not be confined in accordance with them. In an embodiment of the apparatus, the light elements are arranged in a suitable geometric configu¬ ration, such as one or more straight or curved lines, a ring or a matrix array. Considered generally, the light elements may be placed with suitable spacing on a straight or curved base in any expedient geometrical configuration, which depends on the application and particularly on the shape of the surface to be observ- ed, in order to achieve a reception signal as reliable as possible. In an embodiment of the apparatus, the detec- tor is a one-dimensional or two-dimensional, location- sensitive light detector. The optical detector compris¬ es a plurality of detector elements arranged close to each other and disposed in a tightly sealed housing provided with detector optics. The detector elements are integrated in a small space in configuration of a dense, and advantageously straight, line or matrix. The optical detector may for instance be a location-sensi¬ tive photodiode, a CCD detector, or any other equival- ent detector known in itself in the art. In an embodiment of the apparatus, the detec¬ tor optics comprise light conductors, such as optic fibres, on their first ends being focussed radiation scattered from the object, with the aid of the detector optics, and the second ends of said fibres being con¬ nected to the optical detector. The invention affords the advantage that the locating apparatus as well as the light transmitter can be implemented in the form of a small-sized, easy to handle and reliable mass production instrument which is applicable in many different branches of technology, particularly in robotics. The invention affords the advantage that the light transmitter and detector units can be implemented in the form of component series with variable but closely specified characteristics. Apparatus according to the invention further affords the advantages of clear-cut design, small size and low manufacturing cost. Thanks to apparatus according to the inven¬ tion, the locating apparatus can be implemented with the aid of just a few components, and of components best suited in each particular application. Further, thanks to the invention, there will be more opportunities and applications of location measurement than before. The invention, and in particular the location measuring apparatus of the invention, affords the ad¬ vantage that a plurality of light sources can be com¬ bined therein which are directed to cover a sector each of its own. These sectors may overlap partially or com- pletely. The invention, and in particular the location measuring apparatus of the invention, affords the ad¬ vantage that the light source, or the plurality of light sources, can be modulated with any desired fre- quency and in correspondence with the operation of the optical detector, and thus the sensitivity of the loca¬ tion measuring apparatus can be improved, among other things. The invention affords the advantage that loca¬ tion measurements can be performed most rapidly. In the following the invention is described in detail, with reference to the attached drawing, wherein Fig. 1 presents the block diagram of a locat¬ ing apparatus according to the invention; Fig. 2 presents schematically, and sectioned, an embodiment of the light transmitter; Fig. 3 shows the section A-A of the light transmitter of Fig. 1; Fig. 4 presents schematically, and sectioned, an embodiment of the optical detector; Fig. 5 shows the section B-B of the detector of Fig. 2; Fig. 6 presents schematically, and sectioned, an embodiment of the apparatus for locating an object; Fig. 7 presents, as viewed from above, the apparatus of Fig. 6; Fig. 8 presents schematically, and sectioned, another embodiment of the light transmitter; Fig. 9 presents schematically, and sectioned, another embodiment of the apparatus for locating an object; and Fig. 10 presents schematically an embodiment of the locating apparatus of the invention. Fig. 1 depicts, in block diagram form, an ap¬ paratus for locating an object in space. The apparatus comprises a light source 1. The light source 1 compris- es a plurality of separate light elements 2, mutually spaced in a given direction and which can be activated to operate in pulses. The apparatus further comprises an optical detector 3, which is a location-sensitive detector, for detecting, and locating with said detec- tor, the beamed light pulses scattered from the object. The apparatus also comprises optical means, i.e., light source optics 5, for directing the light pulses from the light elements 2 in the form of light beams toward the object, and detector optics 6 for collecting the light beams reflected by the object and focussing them on the detector 3. The apparatus furthermore comprises a control unit 7. The control unit 7 is composed of a light source control unit 8 and a signal processing unit 9, these being connected to the light source 1 and the detector 3, respectively. The light source control unit 8 activates the desired number of light elements 2, for instance one by one in desired succession, it locates the light pulses incident on the location-sensitive detector 3 and calculates, from the location of the active light element 2 and from that of the detection site in the detector 3, the distance of the point of the object, using the principle of triangulation, known in itself in the art. In the triangulation principle, a light beam is directed from the base plane towards the object under a given angle θ against the base plane. The de¬ tector is located at distance b from said light source. The optic axis of the detector is at right angles against the base plane. The distance of the point from the base plane, 1 , is then obtained by the formula 1 = b • tanθ . The light source 1 and the light source optics 5 have been integrated to constitute the light trans¬ mitter unit 10, or a transmitter component, as shown in Figs 2 and 3. In the light transmitter unit 10, the light source 1 and the light source optics 5 are so disposed in the housing 11 that the light elements 2 are arranged in a straight line 2a, with regular spac¬ ing. Alternatively there may be provided light elements in two straight lines 2a,2b (indicated with dotted lines in Fig. 3), these lines crossing at right angles. The light element 2 is a light-emitting diode, or LED, and the light source 1 is composed of a plurality of LEDs. The housing 11 is a standard housing, e.g. type TO-8, comprising a bottom part 12, a cover part 13 and a cylindrical mantle part 14. The cover part 13 is provided with a window 13a. The bottom part 12 and cover part 13 are tightly joined to the mantle part 14. The housing 11 is hermetically sealed. The light ele- ments 2 of the light source 1 are mounted in the bottom part 12 of the housing 11, the light source leads 15 being carried through the bottom part. The cover part 13 is fitted with a set of light source optics 5. The light elements 2 are disposed at a distance a from the light source optics 5 which is consistent with the focal distance of said light source optics. In the light transmitter component of Figs 2 and 3, the light source optics 5 comprise, as their lens arrangement, a planoconvex lens 16 and a holo- graphic transmission grating 17 for correcting the principal errors of the lens system. The lens 16 and the transmission grating are affixed to the window 13a of the housing 11, e.g. by cementing. The optical detector 3 and the detector optics 6 are integrated to constitute the light receiver unit 18, or a receiver component, as shown in Figs 4 and 5. In the light receiver unit 18, the location-sensitive detector serving as optical detector 3 and the detector optics 6 are so disposed in the housing 19 that the detector elements 4 of the optical detector 3 are ar¬ ranged in a straight line 4a with regular spacing. The detector elements 4 of the detector 3 are photodiodes which have been integrated to form a straight line 4a. The detector 3 can equally be implemented in the form of a one-dimensional or two-dimensional location-sensi¬ tive light detector, such as a CCD line or matrix de- tector. The housing 18 is a standard housing, and it is advantageously consistent with the housing 11 of the light transmitter unit 10. In Figs 4 and 5 the same reference numerals as in Figs 2 and 3 have been used for equivalent parts. In this case, too, the housing 19 comprises a bottom part 12, a cover part 13 and a cyl¬ indrical mantle part 14. The cover part 13 is provided with a window 13a, to which is affixed in a suitable way the detector optics 6, such as a planoconvex lens 20. The housing 18 is hermetically sealed. The detector elements 4 are mounted in the bottom part 12 of the housing 18, the leads 21 of the detector 3 being car¬ ried through said bottom part. The detector elements 4 are disposed at a distance b from the detector optics 6 which is consistent with the focal distance of the detector optics. The control unit 7 is functionally divided into two separate units, that is, a light source con¬ trol unit 8 and a light signal processing unit 9, as was observed in the foregoing in context of Fig. 1. Physically, the units 8,9 may for instance constitute a single, unitary integrated circuit. The light source control unit 8 comprises con¬ trollers 22 for the light elements 2 of the light source 1, for activating and deactivating the light elements, a modulator 23 for modulating, e.g. pulsing, in desired manner those light elements which are active, and a data processing unit 24, such as a micro¬ processor with appropriate auxiliary circuits, for con¬ trolling and supervising the functions of the control¬ lers 22 and the modulator 23. It is possible with the aid of the light source control unit 8, to change the numbers and se¬ quencing of the light beams transmitted from the light source 1, depending on the object or equivalent to be examined. Furthermore, the transmitted light beams can be modulated e.g. in order to enhance detection and to eliminate background illumination. The inputs 25 of the control unit 9 of the light source 1 are used to supply to the apparatus those data, such as desired direction¬ al angle of the light beam, on the basis of which the light element 2 of the light source 1 is selected and activated with the aid of current signals supplied through the first inputs 26. The light signal processing unit 9 comprises a plurality of preamplifiers 28 for amplifying the sig- nals obtained from the optical detector 3 through in¬ puts 29, and a signals processing unit 30 for proces¬ sing the amplified light signals. The signals proces¬ sing unit 30 comprises a data processing unit 31, such as a microprocessor with appropriate auxiliary cir- cuits. The distance from the starting point of the light beam of each light element 2 to the object is obtained at the output 33 of the light signal proces¬ sing unit 9. The light source control unit 8 is by its sec- ond outputs 27 connected to the second inputs 32 of the light signal processing unit 9. From the light source control unit 8 information associated with modulation frequency and phasing is transmitted to the light sig¬ nal processing unit 9 in order to accomplish synchroni- zation. The light source control unit 8 and the light signal processing unit 9 are formed to be integrated units. Each unit thus constitutes a unitary, and com¬ pact,, electronic component. In Figs 6 and 7 is depicted an apparatus for locating an object according to the invention, in this apparatus the light source unit 10 and the light re¬ ceiver unit 18 being accommodated in one single, tightly sealed housing 35. In this connection the same reference numerals as in Figs 2 to 5 are used for equivalent parts of the units. The units 10,18 are separated by a suitable shield 36, impermeable to light. In the light source unit 10 and in the light receiver unit 18 has further¬ more been provided an optically transparent intermedi¬ ate component 37,38 between the light source 1 and the light source optics 5, respectively between the optical detector 3 and the detector optics 6. The intermediate components 37,38 are cast of epoxy, tightly in place. The light source optics 5 and the detector optics 6 comprise holographic elements 39,40, such as holograph- ic transmission gratings, for correcting optical errors. The light source 1, optical detector 3 and control unit 7 of the units 10,18 are disposed on a circuit board 41. The components on the circuit board may advantageously be protected with a housing 42 of their own, which may be filled with a protective sub¬ stance, e.g. with epoxy. From the units 10,18 departs outward one single connecting cord 41, containing the requisite number of conductors and channels for commu- nication with external apparatus and for power supply to the units. In Fig. 8 is depicted an embodiment of the light transmitter. This light transmitter is in its essential parts equivalent to the light transmitter of Figs 2 and 3, and the same reference numerals are therefore used to indicate equivalent parts. The light transmitter comprises an optically transparent inter- mediate component 44, most advantageously cast of epoxy to fill the space between the light source 1 and the light source optics 5. The light source control unit 46 has been disposed in conjunction with the bottom part 45, on the opposite side with reference to the light source 1. The bottom part 45 is provided with an addi¬ tional housing 47 (or the light transmitter in its en¬ tirety is enclosed in a suitable manner) and it is filled with protective substance 48, such as epoxy, in order to protect the control unit 46. In Fig. 9 is depicted an apparatus for locat¬ ing an object according to the invention, in this ap¬ paratus the light source unit 10 and the light receiver unit 18 being disposed in one single, sealed package. In this embodiment the light source optics 5, and simi¬ larly the detector optics 6, with their intermediate components 37,38 have been implemented without joints of one single, solid optical material, such as epoxy. This apparatus is otherwise in its essential parts equivalent to the apparatus of Figs 6 and 7, and the same reference numerals have here been used for equiva¬ lent parts. The optics 5,6 and the intermediate compo¬ nents 37,38 may be coated with a film 49 impermeable to light, in order to eliminate any luminous effects from the ambience. With a view to elucidating the operation of the locating apparatus of the invention, we refer to Fig. 10. In the line of light elements 2a of the light source 1, one LED 2 , LED 2 , ... is activated and its radiation is collineated by means of the light source optics 5 to have the shape of a narrow beam, and di¬ rected on the object K. The location of the LED light element 2 1 , 2 2 , ... relative to the optic axis 00 of the light source optics 5 determines the starting angle, or the starting direction of the radiation beam 01, 02, ... The light signal reflected from the object is col¬ lected with the detector optics & onto the location- sensitive detector 3, which is used to determine the angle of incidence between the optic axis II of the detector optics 5 and the angle under which the illumi¬ nated point of light P on the surface of the object K is being viewed, i.e., the direction of incidence of the reflected radiation beam II, 12, ... The distance to the object in this particular direction can then be determined by triangulation. By activating another LED in the line of light elements 2a, one is enabled to change the direction of measurement. For instance, a distance image of line or matrix type can be formed of the object by measuring the distance to the object in a plurality of measuring directions. The numbers of light signals and the suc- cession in which the light signals or beams are trans¬ mitted are changed in dependence of the object under examination, etc., and the light signals are modulated in order to eliminate background illumination, in con¬ nection with transmitting as well as detection, in step and synchronously. The LED components serving as light elements 2 in the light source 1 may be, for instance, efficient GsAs and GsAlAs light-emitting diodes, which emit radi¬ ation having a wavelength which falls into the near infra-red range. The LEDs may be integrated in the shape of a very dense line or matrix array, in order to enhance the angular resolution. The LEDs may be inte¬ grated on one semiconductor chip or on a suitable sub¬ strate, using separate LED chips. In this way a struc- ture integrated so as to require minimal space is ob¬ tained for light source. The LEDs may be pulsed or mul¬ tiplexed with high frequency in order to minimize the interference of background light. Laser diodes may equally be used for light sources, but the component costs will be lower if LEDs are used. The light source components may equally be e.g. a line or matrix of optic fibres connected to LED light sources. The invention is not exclusively confined to read on the embodiment examples presented in the fore¬ going: numerous modifications are feasible within the scope of the inventive idea defined by the claims.

Claims: CLAIMS 1. An apparatus for locating an object with the aid of optical radiation, comprising - a light source (1) comprising a plurality of light elements (2); - a location-sensitive optical detector (3); - optical means (5,6) comprising light source optics (5) with the aid of which from the radiation emitted by the light elements (2) is produced a plurality of light beams having a small aperture angle and which are di¬ rected into a given solid angle towards the object to be located (K); and detector optics (6) for collecting the light scattered from the object (K) and directing it on the location-sensitive detector (3); and - a control unit (7) which is disposed to activate such light elements (2) as are desired, to locate the light signal incident on the location-sensitive detector and on the basis of the location of the active light ele- ent and of that of the detection site to calculate the distance of the object's surface by the triangulation principle, characterized in that - the light source (1) and the light source optics (5) are integrated to constitute a compact light transmit- ter unit (10) in which the light elements (2) belonging to the light source (1) are arranged close to each other and provided with joint light source optics (5); and - the optical detector (3) and the detector optics (6) are integrated to constitute a compact light receiver unit (18); said units (10,18) being disposed in immedi¬ ate proximity to each other and, advantageously, to the control unit (7) . 2. Apparatus according to claim 1, character- ized in that the light source unit (10) and the light receiver unit (18) are disposed in separate packages, such as housings (11,19). 3. Apparatus according to claim 1, character¬ ized in that the light source unit (10) and the light receiver unit (18) are disposed in one single, small- sized and unitary package, said units being separated by means of a suitable shield impermeable to light. 4. Apparatus according to claim 1, character¬ ized in that the light source optics (5) and the detec¬ tor optics (6) comprise a holographic element for improving the optical performance. 5. Apparatus according to claim 1, 2, 3 or 4, characterized in that the apparatus comprises a plural¬ ity of light source units (10). 6. Apparatus according to any one of the pre¬ ceding claims, characterized in that in the light source unit (10) and in the light receiver unit (18) has been provided an optically transparent intermediate component matching the refractive indexes, between the light source (1) and the light source optics (5), re¬ spectively between the optical detector (3) and the detector optics (6). 7. Apparatus according to claim 6, character¬ ized in that the intermediate components of the light source unit (10) and of the light receiver unit (18) are formed of poured material, advantageously of epoxy. 8. Apparatus according to claim 6 or 7, char¬ acterized in that the light source optics (5), and sim¬ ilarly the detector optics (6), and the respective in¬ termediate components are implemented without joints using one solid optical material, such as epoxy. 9. Apparatus according to any one of the pre¬ ceding claims, characterized in that the control unit (7) is functionally divided into two separate units: a light source control unit (8) and a light signal pro¬ cessing unit (9), and the light source control unit (8) is connected to the light signal processing unit (9) for transferring the modulation frequency and phase information required in synchronous detection of the light source. 10. A light transmitter comprising - a light source (1) comprising a plurality of light elements (2); - light source optics (5) with the aid of which from the radiation emitted by the light elements is accom¬ plished a plurality of light beams having small aper¬ ture angle and which are directed into a given solid angle outward from the light transmitter, characterized in that the light source (1) of the light transmitter and the light source optics (5) are integrated to con¬ stitute a compact light transmitter unit (10), the light elements (2) comprised in said light source (1) being arranged to lie close together and disposed in a small-sized and unitary package, such as a housing (11) which is provided with light source optics (5). 11. Apparatus according to claim 10, charac¬ terized in that the light source Optics (5) comprise a holographic element, such as a transmission grating (17). 12. Apparatus according to claim 10 or 11, characterized in that the light transmitter comprises an optically transparent intermediate component match¬ ing the refractive indexes of the optics and of the light elements, between the light source (1) and the light source optics (5) . 13. Apparatus according to any one of the preceding claims, characterized in that the light ele¬ ment (2) is a light-emitting diode, and the light source (1) is composed of a plurality of light-emitting diodes (2a) which are most advantageously integrated to constitute a monolithic structure. 14. Apparatus according to any one of the preceding claims, characterized in that the light ele- ments (2) are arranged in a suitable geometrical con¬ figuration, such as one or several straight or curved lines (2a), a ring or a matrix array. 15. Apparatus according to claim 2 or 10, characterized in that the housing (11; 19) is a stan¬ dard housing comprising a bottom part (12), a cover part (13) provided with a window (13a) and a mantle part (14) to which the bottom part and cover part are attached, and which housing is hermetically sealed.

Inventors: KERAENEN HEIMO, MARSZALEC JANUSZ, KERAENEN, HEIMO, MARSZALEC, JANUSZ
Applicants: VALTION TEKNILLINEN, VALTION TEKNILLINEN TUTKIMUSKESKUS
Application year: 1992
Main classification: G01C3
IPC codes: G01S7, G01S17