Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
APPARATUS FOR LOCATING AN OBJECT, AND LIGHT T~ANSMITTER
The present invention concerns an apparatus as
defined in the preamble to Claim 1, for locating an
object with the aid of op~ical 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 techniquea. 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
increasin~ly common~ Optical dis~ance measuring, or
range finding, apparatus is usually based on measuring
the intensity of reflected light, on triangulations or
on determining the travelling time of lightO 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 dis~ance measurement
is known in prior art in which a pulsed IR radiation
beam from a light-emit~ing 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 o the
reflected light.
The drawback embarrassing ~he 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 roboticsand 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 de~lected 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 sub~tantially
and, frequently, the reliability of the system suffers.
In prior art an op~ical apparatus for locating
an object is known in which on the object are directed,
from liyht sources positioned close to each othex,
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 okher and of which the positioning de-
pends on the object's position in space/ and on the
basi~ of the positions of the light sources and detec-
tors the scattering points on the object are determinedin accordance with the triangulation principle, known
in itself in the art, and further the position of the
object in space is detarmined.
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 fuxther drawback
that it is composed of discrete components, and there-
fore its assembly and commissioning for operation
involves major expense.
The object o~ 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 de~ector 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 ob~ect insofar as they are within
the observation range of the detector.
The opti al means comprise light source optics
and detector optics, th~ 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 tha 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-
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tered by the object are collected and focus~ed on the
light-~ensitive 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 li~ht signal entering the loca-
tion-sensitive detector, and to calculate the distance
of the point on the surface of ~he object by ~riangula
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 in~egrated to consti-
tute a compact light transmit~er 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 uni~s being
disposed in immediate proximity to each other and, ad-
vantageously, to the control unit. A compact unit i~here understood to mean a partial antity resembling an
electronic component, which is coheren~ 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. ~hus ~ach in~e-
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 hsusing which has been fit~ed with light source
optics. In like manner, the loca.ion-sensitive detector
serving as optical detector which is comprised in the
integxated 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.
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The housing of each unit just mentioned is, to
greatest advantage, a standard housincJ 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 h~rmetically sealed.
Housings of this kind are commonly used in packaging
electronic components.
In an embodiment of thle apparatus, the light
source op~ics 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 th~
detector elements of the optical detector. Both sets of
optics have thus substantially identical characteris-
tics. Therefore the light transmitter unit and theli~ht receiver unit match each other, and their appli-
cation in various environments is facilitated.
In an emboclimPnt of the apparatus t the light
source unit and the light receiver uni~ are disposed in
a single, compact, that is small and unitary, package,
said units bein~ separated by a suitable shield which
is impermeable to lightO 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 immedi~e 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 canno~- 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 aclvantage that practical applications of a
locating apparatus like this are facilita ed. The
apparatus is c:ompact and requires minimal space. More-
over, the uni1:s can be matched and fitted together so
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tha~ they will operate reliably, and with the accuracy
agreed upon, in given predetermined condition~.
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 impro~ing the characteristics o~ the
optics proper in order to opt:imiz the dimensions
thereof, such as shortening the focal dis~ance 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. ~wo light source un~ts
and one light receiver unit. The light source units are
so ad~usted that one o~ them directs the light beams
into the proximity region in a given sector, for exam-
ining this region, and the other direc~s 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 distan~. The advantage with an
apparatus like this is that it is possible with its aid
to examine eficiently 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 uni~s 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,
3~ respectively between the optical detector and the de-
tector optics. In the light source unit this intermedi-
ate component is disposed tight agains~ the light
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source as well as the light source optics and in ~he
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 ~y 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 co~ponents 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 op~ics, 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 ~wo 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 transmit~0r unit and the
light signal processing unit is similarly connected to
the light receiver unit.
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In an embodiment of the apparatus, the light
source con~rol unit comprises controllers ~or 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 dataprocessing unit, such as a microprocessor with suitable
auxiliary circuits for con~rolling and supervising the
functions of controllers and modulator. ~he 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 pos~ible to transmit light signals in
lS pulses with different timing from different light ele-
ments, or to modulate them with different repetition
frequencies, and to transmit for instance simul~aneous-
ly from different light elements.
It is advantageous to synchronize the li~ht
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 uni~s 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-s~nsitive detector, and a signal processin~ unit
for processinc; 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.
~ he 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 plurali~y 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 constitu~e a compact light transmitter
unit in which the light elements belcnging to the light
source are arranged close to each other and dlsposed in
a compact, that is small-sized and unitary, package,
such as a housing, which is provided with light æource
optics. The integrated uni~ thus constitutes a unitary,
and compact, electronic component. The housing most
advantageously comprises a bottom par~, 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 li~ht source of the lnvention is most ad-
vantageously employed as a component of an object-lo-
catin~ 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 embodimen~ o~ the apparatus, the housing
of t.he 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 o~ 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 par~/ is comparatively simply ac-
complished. It ix obvious that many kinds of lens
arrangemen~s 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.It 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 ~he 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 ma ching with
each other the refractive indexes of the optics and the
light elements has been provided, between khe 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 i5 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 ai optic fibres, for
conducting the light from a sui~able, defined place
towards the light source optics.
The light elements of the light source of the
in~ention 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 confi~u-
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 an~
particularly on the shape of the surface to be observ-
ed, in order to achieve a reception signal as reliableas possible.
In an embodiment of the apparatus, the detec-
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tor is a one-dimensional or two-dimensional, location-
sen~itive 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 okher equival-
ent detector known in itself in the art.
In an embodiment of the apparatus, the detec-
tor optics comprise light conductors, such a~ 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 i~plemen~ed in th~ form of a small-sized, easy to
handle and reliable mass production instrument which is
applicable in many different branches of ~echnology,
particularly in robotics.
The invention affords the advantage tha~ 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-~ut 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
bP more opportunities and applications of location
measurement than before.
The invention, and in particular the location
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13
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 modula~ed with any desired fre-
quency and in correspondence with the operation of theoptical 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 followin~ the invention is de cribed in
detail, with reference to the attached drawing, wherein
Fig. 1 presents the block diagram of a locat-
ing apparatus according to ~he invention;
20Fig. 2 present~ schematically, and sectioned,
an embodiment of the light transmitter;
Fig. 3 shows the section ~-A o~ the light
transmitter of Fig. l;
Fig. 4 presents schematically, and sectioned,
an embodiment of the optical detector;
Fig. 5 shows the section B-B of the detector
of Fi~. 2;
Fig. 6 presents schematically, and sectioned,
an embodiment of the apparatus for loca ing an object;
30Fig. 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
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14
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, mutuallyspaced in a given direction and which can be activated
to operate in pulses. The apparatus further comprises
an optical detector 3, which i9 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 llght 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 ~ource 1 and the
detector 3, respectively. The ligh~ 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 objec~, 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 ~ against the base plane. The de-
tector is located at distance b ~rom said light
source. The optic axis of the detector i5 at right
an~les against the base plane. The distance of the
point from the base plane, l , is then obtained by the
formula l = b-tan0 .
The light source 1 and the light source optics
5 have been integrated to cons~itute the light trans-
mitter unit 10, or a transmitter component, as shown in
Figs 2 and 3. In the light tran~mitter unit 10, the
li~ht 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 Gi is a light-emitting diode, or LED,
and the light source 1 is composed of a plurality of
L2Ds.
The housing 11 is a standard housing, e.g.
type TO-8, compri~ing 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 bo~tom part 12 and
cover part 13 are ~ightly 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 bottompart 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 o~ 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 theprincipal errors of the lens sy~tem. 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 integral:ed 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
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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
S detector elements 4 of the de~ector 3 are photod~odes
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 standaxd housing, and itis 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 i5 affixed in a suitable
way the detector optics 6, such as a planoconvex lens
20. The housing 18 is hermetically sealed. The detectsr
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 optic~
2S 6 which is consistent wi~h ~he focal distance of the
de~ector optics.
The control unit 7 is functionally divided
into two separate units, ~hat is, a ligh~ source con-
trol uni~ 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 fox 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-
quQncing 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 o~ the
control unit 9 of the light source 1 are used to æupply
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 selec~ed and
activated with the aid of current signals supplied
through the first inputs 26.
The light signal processing unit 9 comprises a
plurality of preampliPiers 28 for ampllfying 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 thelight 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 thelight 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 ordQr to accomplish synchroni-
zation.
The light source control unit 8 and the lightsignal proc*ssing unit 9 are formed to be integrated
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18
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 ln one single,
tightly sealed housing 35. In ~his 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
dekector 3 and ~he 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 opticalerrors.
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 advantayeously 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 supplyto 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 ~ransmitter of
Figs 2 and 3, and the same reference numerals are
therefore used to indicate e~uivalent parts. The light
transmikter comprises an optically transparent inter-
:
19
mediate component 44, most advantageously cast of epoxyto fill the space between the light source l 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 ligh~
source 1. ~he bottom part 45 is provided with an addi-
tional housing 47 tor the light transmitter in its en-
tirety is enclosed in a ~uitable manner) and it is
filled with protective substance 48, such as epoxy, in
order to protect the control unit 46.
In Fig. 9 i5 depicted an apparatus for locat-
ing an object according to the invention, in thls 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 refexence numerals have here been used for aquiva-
lent parts. The optics 5, b and the intermediate co~po-
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 21, 22, ... relative to the optic axis 00 o~ the
light source optics 5 determines the starting angle, or
the starting direction of the radiation beam Ql, 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 theangle 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 I1, I2, ... 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 slgnals are modulated
in order to elimlnate background illumination, in con-
nection with transmitting as well as detection, in step
and synchronously.
The LED components ~erving as light elements 2
in the light source 1 may be, for instance, efficient
GsAs and GsAlAs light-emittlng diodes/ which emit radi-
ation h ving 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. ~he 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-
tain~d 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 ~he componen~
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 ~he embodiment examples presented in the fore
going: numerous modifications are feasible within the
scope of the inventive idea defi.ned by the claims.
; , , ";
