CA2244242A1 - Radiant energy transducing apparatus with constructive occlusion - Google Patents

Abstract

An optical position tracking system that tracks the position of objects, using light intensity and/or frequency with the application of geometry and ratios of detector responses, is provided, having light distributing and light detecting components (59) that employ the concepts of constructive occlusion and diffuse reflection. Diffusely reflective cavities (16), masks (M) and baffles (51) are used to improve certain radiating characteristics of the distributing components (59) and certain response characteristics of the detecting components (59), to tailor the radiation and detection profiles thereof, including them substantially uniform for all angles within a hemispheric area which the distributing and detecting components (59) face. The distributing and/or detecting components (59) are partitioned with specially configured baffles (51). A partitioned distributor has distinct emission sections where the sections can emit spectrally-different or distinguishable radiation. A partitioned detector has distinct detection sections where the sections can detect radiation from different directions.

Description

W O 97/27449 PCT~US97/OlOll RADIANT ENEF'~GY TRANSDUCING APPARATUS WITH CONSTRUCTIVE OCCLUSION

~ J~ of --k~ Tn~ ; i on ~ The present i~n~io~ relates gene-ally ts optical emitt~rs ~d detectors, a~d optical position trac~i~g de~ices, in pa--icular, optical de~ices ha~i"g distinct radiation and detection properties that may ~e u~ed to trac~ position of ob~ects, using a relati~ely 3mall ~ f ~ or optical el~m~ntc.
Position tr~ ns is a growing technology with ever increasing ap~lications. For examDle, in the ente-t~tnm~t arena, position tr~r~ n5 in t~ree ~im~n~ions is used in vi-t~al reality s_mulat~on. Pos-=-on tracking is also used in the in~ustrial are~a, with applic~tions in process control ,~n~ ro~otlcs. The f ield of ~iomedics also 1~ uses position tr~ "g devices for tr~ki ng portions of a h~-m~n body to determine the kody~s motion patter~s.
S;mi 1 ~ly in 7n~m~tion dynamics, the trac~ins o~ m~ltiple body parts is used for controlli~g ~nim~te~ fisures. Many othe- applicatio"s exist, for whic position t-ac.~ns is useful i~ not advantageous.
Con~ent~onal DO5~ t on tr~ ; n5 can be broken down into two ~road eec~nologies, i.e., ac- ve sys.ems and passive systems. Ac_ive sys~ems ~-ti 1; 7e ac~~ve elect=~nic el~nts on the o~jects ~ein tr~c.~ed For ~m~lo, t~e Palh~m~ 3SPACE ISOTRACg II ~ system uses ac ive magnetic el~ml-nrs to create a dy am-c ma5neti~- fiel~ that is r-presentative o~ the ~ody~s ?osi_ion. By se~si.s changes in 'he magnetic rield, _he system de i~re~s a~1 s-x axes o~
the oDject~s spatia~ lccaticn.
~0 Ac_ive sys~ems a_e ge~e_a'ly higr-pe~_c~anc_, hiSh-enc prc~uc-s. Yoweve=, they car. ha~re d-sacva- ages, includ~ng li~i.ec range c~ mo~icr., ~etal --e_~--enc~, com~lex ope-a-icr a c h-5:- c-s.. T, pa~ _a-, =he -~nge SUBSTITUTE SHEET (RULE 26) W O 97127449 PCT~US97/OlOll of the ma~netic ~ield is typically llmited, and tr~;l in~
connection wires are o~ten a n~iC~nt-e Where the area of motion r~nt~i~c su~st~nt;~l metal, mapping o~ the entire field is usually part o~ the system's re~uired S ~ ~t;~ti~n, In contrast, passive systems track obiects w~thout physical lin~s between the object and the system Target pQi~ts such as retro re~lectors may be used, or image processing o~ a video image may be p~rformed While lQ passi~e systems are often }ess complex and less expensi~e ~omr~ed to acti~e systems, they are o~ten l~r~;n~ in resolution Thus, ~or o~iect recognition, passive systems typically re~uire extensive imaye processing, whic~ can increase costs and the prohability o~ e~ The use of reflectors avoids some o~ these problems, ~ut not without introducing othe~ problems, such as the need ~or critical alignm~nt and extensive initialization Aside from the various system limitations ~iscussed above, the sensing ~"~o,lents o~ an optical detector, such as photodiodes or charye-coupled device ~CCD), have their own limitations While these c~ V'~ntC
can be made directionally-sensitive (e s , with the provis~on o~ a slit, or the use ol Gray-co~
mu}ti-element ar_ays), the response is o~ten limite~ For 2~ example, they typically provide direc~ional i~rormation or resolution about one axis only, and the sensor's accuracy is typically limited by the number ol optical el~m~nts provided It should there ore be appreciated tha. there ex~sts a de~inite neec r_r a relatively simple and inexpensi~e positicn trac:~irs system, which can track the ~osition o~ an obje-~ along at least -;nree axes, i_ not all six axes to ir.clude oD,ection rota~ion, using m~n;m~l electrical and/or o~ical ei~m~ntc It is desired that 3s the sys~em has lcw alicnmen- and i~i~ia'ization S~ TESHEET(RULE26) W O 97/27449 PCT~US97/01011 recruirements and low processing ~m~nc~ In that regard, it is desired that the system be structurally and elect-onically simple, while r~m~;ni n~ capable of pro~iding at leas~ directional ind~cative o~ the ~r~ction a~ong which the object is positioned relati~e to the system. It is ~urther desired that the system be a~le to pro~ide locat~on~l data i~clusi~e of range data, along w~th directional data, fcr tr~r~in~ an ob~ect in three ~im~n~ional space. The present in~e~tion addresses all of~0 thcse desires and more.
nna ~ of~ th~ ~n~ n The present in~ention resides generally il an optical position trac~ing sy5tem th~t trac~s the position oi~ OD~ ects, using light intensity and/or frec~uency with the application of geometry and ratios o~ detector responses.
The present in~ention pro~ides for the illumination of ar, area that may be defined by sphe_ical or hemispherical coordinates with a tailored spatial intensity profile, and/or the detection o~ light associated with an ob~ect i~ the area, with the recognition that certain characteristics or proper~ies or the light derected are indicati~e o the rela~ive posi.ion or ~.~o~ ent o- the obiect in the area. Ad~an~ageously, the invention applies the concepts of constructed occlusion and di_ use re~}ec-ion to accomplish its p~pose with ii,~ ~ved e~ciciency.
The positioning trac~ins system in one emDo~im~nt includes a ret-o rerlectcr that is a ~ xe~ to the oDiec~ beins t-acked, and a head module that -c~des a lisht dist--Dut~~ and a light derec.or. Constr_~=ed occlusion as employed by the present inventi~n i~c ldes the use o~ a mas~ that impro~es cer=ain radia~ins characteristics o' the dis-~~~utor and certai~ response ~5 characteristics o. t:ne detec~ ~- example, a mask -n a S~ TESHEET(RULE26) W O 97/27449 PCTrUS97/OlOll predetern~in~} pos~tiQn enables the dist_ ibutor to provide a more un~orm radiation pro~ile, and the detector to pro~ide a more uniform response pro~ile, at least for elevations apprr~ h;ng the horizorL. I~ general, chansi~g S the position and/or size of the mask changes the radiati3g a~d response profiles. The profiles may be further ~ rulated or ~nhan~ with the use o~ a baf~1e, particular for the profile at angles at or near the horizon. The ~affle can ~e conical or an intersecting ~0 stru~Lu~e. Where the elect~o~a~n~tic radiation util~zed by the prese~t in~nt; on in~l t~ visi~le light, components includins the mas~ a~d the baffle are formed o~
a Lambertlan, polymeric mate-ial ha~ing ~ re~ectanc~ or appr~im~tely 9~ for visibl~ wavelengths.
In accordance with a ~eature o~ the present invention, the distribution prof_le o~ a constructively occluded d~stributor can be specifically tailored or made substantially uni~orm ~Sor over most, i~ rlot all, azimuths a~d elevations of a hemispheric area o~er the dist~ butor.
Correspnn~in~ly, the response profile o~ a constr~ctively occluded detector can be specirically tailored or made su~stantially un_for~ ~or mosr, iS not all, azimuths and eleva~ions of a hemispher-c area ove_ the detector. In essence, constructed occlusion can r~nder bot~ the distributor and detec~3r u~i_ormly omnidirect onal in the hemispheric area whic~. the accluded de~ice ~aces.
In order tha~ the system t~ack the posllion o~ a r~lector (or point), or at le~s. prcvide directional inrormation ~or tha~ re~1ector, the head mocule o, the system includes a par~i_ioned occluded device whlch may be either the dist-iDutc~ cr the derector. I~ pa~~i~u~ar, the use o~ a pa~_l~icr.i-.g ba =le i~ a dis_-i~u.or ~-nders a par_ltioned dist--~utor havlns dis.inct emission sect~ons where tne sec- ons can emi: spect_ally-d- erent or dis.ingu_shabl~ ~aa_aticr. ~~--esponc ng y, t:~e ~se c~

S~ TESHEET(RULE26) W O 97/27449 5 PCTrUS97/OlOll a partitioning ba~rle in the detectc- renders a partitioned detector having distinc~ detection sections where the sections can detect radiation ~rom ~~ferent directions.
The system may be variously conrigured, to use di~~erent comb;n~t~o~s o~ partiti~n~ and ~nn~ti~;on~
~ devices, that is, a partitioned dist-ibutor with a ~nnr~titioned detector, or a n~n~ ~ titioned distri~utor with a partitioned detector. A partitioned distri~utor pro~ides a plurality o~ radiation sections and a partit; ~n~ detector pro~ides a piurality o_ detection ~ections. In most con~igurations, a single head m~
provides one ser o~ direc_ional data about two coordinates ~
le.g ., p and e ) f or one reIlector, using one o~ these lS com~inations, wherein one of the de~ces is par.itioned into four sections or quadrants.
An additional head modu~e remotely positioned from the ~irst head module can provide a second set o~
~irectional data for the reflector (e.g., P2 and ~2) . By 20 cross-refer~n~; n5 the second set of dlrectional data with the first set of d~ectional data, the system is able to o~tain positional data in three ~;m~ions o_ the r-flector, tha. is, t~ee coordinates, along t~ree axes for the re~lector.
The system can also track additlonal reflectors, using spectrally-di-Ierent (or at least spectrally distinguishable reflectors) in con~unction with correspon~;ngly spectrally-comDatlble sensors to distinguish between data coliec~ed f~r each re~lec-o-.
~0 Where the system uses a head module having a nonpart t~oned ~is_~~butor and a pa- ~ioned detec--_ to de~ec~ one rer'ectc~, the system car use adc _ional head es, each hous_-g an add-tlonal Set c sensors cor--espon~ in~ to an add _lona' re~1ect3r. Howeve-, the ~5 system can alsc use a s~~.gie head ~cdule tha- is SlJ~a 1 1 1 UTE SHEET (RULE 26) =

W O 97/27449 PCTrUS97/O1011 configured to house all of the addir~nn~l sets OlC sensors.
I~ particular, the single head module can be configured having one parti~;~nr~ detector where each section houses a ~ensor from a set corres~n~;ns to a reflector being tr~ . Accordiugly, a single head ~n~tlle can trac~
multiple reflectors.
As ~ariations on the head module desc-i~ed abo~re, the nr~nr~t~titi t~n~ distr; h~tor and the partit;C n~
detector may use separate ca~ities cr s~are a sinsle ca~ity within the head m~t~1 e. Mo F~v~r, as further ~ariations, the n~nr-~titioned distributor of the head m~tl e may emit cont~nuous ~road bard radiation or pulses of ~road band radiation. Where the radiation is emitted in pulses, the elapsed time for the pulse radiation to reflect off the reflector can be anaiyzed by the system as data pro~iding a range coordinate for the tr~k~
reflector. ~sing both the intensity ~ariation o~ the radiation, and the elapse time of the pulses, the system can deri~e all three coordinates ~for a reflector, without using a separate head mo~
Because the system illuminates the detection zone without discr-m;n~ting between the object 2eing tracked and any othe_ extraneous objects, such as ~urniture or walls, back~round or sel_ illumination can be 2S sisnificant and adversely aCfect the system~s performance. Where sensors of dl~f rent or distin~l;~hle spectral characteristics are used in the system ~Cor detectlng multiple r~flectors, the system pro~ides a separate set Oc sensors dedicated to sensing ~ackground illuminat~on so that the e_ ec~s c_ selC
m; n~tion can be compensated.
The system may also be cor.-i~ured t~ reauce the le~el of bac~ -ound i'lumination. I~ parti-ula-, the system uti'izes a head mcdule having a sr~n~~s beam 3S sou-c~ that i5 S' .~ated be~ween a sp'-- par--~ oned S~ TESHEET(RULE26) W O 97/274d9 PCTrUS97/OlOll detector. The beam is of a predetormined width and sweeps the detection zone in search of re~1ectors. With the beam ~ min~ting on'ly a por'ion of zone at any give time, bachyr~.d illumination i9 substantially reduced a~d the S system is therefore a~ hl e to per~orm a color analysis using a relatively small n~-mh~. o~ filter sensQr comb~ n~ n~ to distirguish hetween a ~ery large numhers of spectrally-disti~;~h~hle re~1ectors. ~ike the previous em~o~im~nts, this em~o~;m~nt uses two head modules to detect all three coordinates of one re~lector.
In an altQrn~tive embodiment also using color analysis, the system uses a head module that includes a n~npartitioned detector with a partitioned distributor.
The pa~titioned distributor houses in e~ch section a lamp o~ a distin~ hle color (~re~uency), such that each section is distinctly associated with a distin~ h~hle color. In accordance with the application o~ color analysis, the detector houses a small combination of ~iltered sensors. The color mix r~flected ~y a re~lector is analyzed by the system to indicate a set o~ direc~ional data for the re~lector relative to the head mn~lle.
The system may also be conrigured as an oprically active system, usir,y active li~ht sources, such as L~nS, that are placed on the object beirg tracked, and a partitioned detector. In this embo~; m~nt, lisht emitted ~rom the LEDs are detected by the partitioned detec~or, and the color or oscillation freouercies or the rFns are used to distinguish between di~rerort r-~nS .
Other optical devices and pos-tion tr~ki~g sys~ems are contemplared by the present invention. For example, an op~ical do~ico cor.-icuro~ as a ring hav-rs two ~ st~uctures which selec_ively oc_ludes t:~e optical s~- ace of t~e othe_ ~or ~- f ~erent el~vation angles is p-ovided.
A~ain, the ~rinciples or const-acted occlusion is applied such that the de~ ce has a tai'o - ~C cr su~stantiall~

SUt~ JTE SHEET (RULE 26) W O 97/27449 . PCT~US97/OlOll uniform prorile whi~h can rende_ the device hemisp~e~ical as a radiator or a detector. To also render the device directional, the structure may be configured such to provl~e distinct a~d separate segments.
other features and ad~antages of the present inventlon should become apparent from the followins descr_ption of the preferred embon; m~ntc, taken in conju~ction with the ~ n~nying drawings, which illus~rate, by way o~ example, the principles o~ the invention.

R--;r~ ner-c-~t;on of the r~ ~w; n~rs FIG. 1 is a perspective view o~ a positin~
trac~ing system, in accordance with the present i~vention, ~or determ; n; n~ and displaying the position of game e~uipment;
FIG 2 is a schematic diagram o~ a Lambe~=ian surrace, ~mo~trating the cosine dep~n~ ~,o~crty a~sociated therewith;
FIGS. 3A and 3B are schematic diagrams o~ a mask used to const~uc~ively occlude a Lam~er~i~n su_~ace;
FIG. 4 is a side c~oss-section view or an optical arrangement emDloyi~s the concepts or cons.~uctive occlusion and d -_usive re~;ection, in accordance wi.h the present invention;
2~ FIG. 5 is a graph illustrating the cosi~e dep~n~nre o~ the arrangement or FIG. 4;
FIG. 6 is a side cross-section view o. an optical arrangemen; employing the c-ncepts or c-ns.-_c~ive oc-'usion and ~ usive rellec;ion, and a conical baC-le, in accordance with ~he ~resenr invention;
FIG. 7 is a s-aDh iliust-~ring rhe subs~a-,~lal alleviation or trea~ment or the cosi~e deDendence _ the arrancement or FIG. 6;

S~ UTESHEET(RULE26) W O 97/27449 rCT~US97/~lOll g FTGS. 8A ~d 8B are perspec~ive views of ~n intersecting baffle, in acc~rdance with the present invention;
FIG. 9 is a perspectiYe ~iew of another S intersecting baffle, in accor~a~ce with the present invention;
FIG. 10 is a side cros9-section Yiew of an optical arrangement emDloying the concepts of constructive occl~sion and difru.~e reflection, and the i~tersecting lQ baf~le, with treatment of the Fresnel reflection, in accordance with the present invention;
FIG. 11 is a side cross-section Yiew of an optical arrangement with a specially con_igured mask haYing proper,ies of a ~affle;
lS FIG. 12A is a side cross-section view representative of a partitioned dist_i~utor and a partitioned detector, in accordance with the present in~ention;
FIG. 12B is a cross section view o~ FIG. 12A, 2 0 t ~ k~n along line B-B.
FIG. 13 is a perspective Yiew of a head m~ l e used in association wi.h an oscilloscope, in ac~crdance with the present invention;
FIG. 14 is a concepcual representa~ion oI X-Y
25 coordlnates of a display of the oscilloscope o FIG. 13;
FIG. lS is a s~h~tic diagram oI the electronics for conYer._ng elec~-ical sisnal f_om the head mo~lll e o~ FIG. 13, to the X-Y c~or _nates o~ the oscilloscope of FIG. l~i FIG. 16 is a side c oss-se~-_ion view Q~- an emDo~-m~nt c- the head module, in ac--rdance wi~:. the - present inver.tion;
FIG. 17 is a c-oss-secticr view o- FIG. 15, taken along line X-Xi S~J~ 111 ~JTE SHEET (RULE 26) W O 97/27449 PCTnUS97/OlOll FI&. 18A ls a side cross-sectlon view of another ~mh~i m~nt of the ~ead module, in accordance with the present invention;
FIG. 18B is a cross-section vi~w o~ FIG. 18A
taken along l~e B-B;
FIG. }9A is a side cross-section view of a further ~mh~i m~nt of the head m~ le, in a~ nce with the ~3cnt inv~nt~n;
FIG. l9B is a cros.~-section view of FIG. l9A, taken along line B-~3;
FI&. 20A is a side cross-section view o~ yet another em~o~;m~t o~ the head module, in accordance with the present in~ention;
FIG. 20B is a cross-section view o~ FIG. 20A, taken along line B-B;
FIG. 21 is a perspective view o~ another em~o~; m~nt 0~ the system, in accordance with the present in~ention;
FIG. 22A is a plan view or a platform on which four individual partitioned detectors are mounted;
FIG. 22B is a side view o- the plat_orm oI FIG.
22A;
FIG. 23A is a top plan v~ew or another em~c~-mont or an oc_luded device i~ acc~rdance with the presenl invention;
FIG. 23B is a side view Oc the occluded device o~ FIG. 23A;
FIG. 23C is a side view r~ate 90 degrees ~rom the view OlC FIG. 238;
FIG. 24A is a perspec_ive view o. a ring detecto- in accordance with the p_~se~- invert~on;
FIG. 24B is a tcp plan v-ew o- the rins de--c_or o~ FIG. 24Ai SUBSTITUTESHEET(RULE26) W O 97127449 PCTrUS97/O1011 FIG. 24~ is a cross section ~iew of the r~g detector o~ FIG 24A, ~m~n~trating the SU~st~nt ~ ~1 1 y constant cross ~ection area pro~ided there y;
FIG. 2~A is a perspective view of a sectioned ~ ~ ring detector i~ accordance with the present in~ention;
FIG. 2~B is a top pian view o~ the ring detector of FIG. 25~;
FIG. 25C is a ~ide ~iew of the ring de~ectcr of FIG 2~A, ~m~n~trating the subst~nt; ~1 ly constant cross secticn area pro~ided there~y;
FIG. 26A is a top plan view o~ a multiple ca~itied optical de~ice in accordance with the present invention;
FIG. 25B is a side c-oss-section view or the lS de~ice o~ FIG. 26A, taken along line B-B;
FIG. 27A is a side cross-sec'ion view o~ another em~o~-m~nt o~ an optical a~ r ~ IL~t employing the concepts o~ constructive occlusion and diffusive reflection, and a baf~le, in accordance with the present invention;
FIG. 27B is a view or the o~tical arrangement o~
FIG. 27A 'c~ n along lLne B-B;
FIG. 28 is a side c~oss-section view o~ tWO
partitioned optical arrangements con~isured ~ack-to-back to provide spherical coverage in accor~ance with a f eature o~ the present in~ention;
FIG. 29A is a perspecti~e view o~ two sec~ oned ring detectors configured ~ack-to-~ack to provide spherical co~erage in accordance with the ~resent ~o in~ention;
FIG. 29B is a side c-oss section view c_ t:~e - -~ng detec_ors o~ FIG. 2gA;
FIG. 3OA is a side cross section view o-- one ~ emscnim~t o~ an azimut~al device in accordance wi=:- the ?resen~ i~ention;

SUBSTITUTESHFET(RULE26) W O 97/27449 12 PCT~US97/OlOll FIG . 3 OB is a view o~ the azimu~hal de~rice of FIG. 3OA t~n along line B-3;
FIG. 30C is a view of~ the ~iml~tnal device Of FIG. 3OA taken along line B-B, with a tailored coverage;
FIG. 31A is a side cross section view o~ another ~mht~r~i m~nt o~ the azimuth:~1 device in accordance with the precent inYention;
FIG. 31B is a view of the ~7im~thal device o~
FIG. 31A t~k~n alons line B -Bi and FSG. 3lC is a view o~ the azimuthal device o~
FI~. 31A taken along line B-B, with a tailored coverage.

~c- ~tion o~ the ~-~f~ mko~;m~t~
As shown in the exemDlary drawings, the present invention resides in an opt~cal position tr~; ng system lQ that trac~s the position of an object, witnout recuiring complicated electrical wiring, expensive photodetector arrays, ~ideo cameras, or image processing.
More speci~ically, the system measures optical prope-ties such as light intensity and ~resuency to prov~de at least directional data along two axes, if not positional data along three axes, ~or the object being tracked. If desired, the system may also provide pos~.ional and ~otational ~ata along six axes ~or the ob~ect be~ng tracked.
Referring to FIG. 1, the positlon t~ack~ng system has numerous applications. For example, the system may be used in a viaeo game 11, whe-~ s~gnals repre~entative o~ the position or movement or game equipment within a zone Z are decected and pr~cessed, and conve-ted to ~ideo s~gnals ~ed to a video mor~tor. Though the system and dis~lay '5 a-e sncwn cu~s~de the zore Z, these components may or course be inside tne zone Z.
One emDcdi~ent of the DOS' _ion trac~rg system ~5 10 is shown in F~ , hav~-g a head modul~ ~: trac.~ng a SUBSTITUT~SHEET(RULE26) W O 97/27449 13 PCT~US97/01011 retro reflector RR:L. In accordance with a ~eacure Of the invention, the head m~ e ~ utilizes the concepts of constructed occlusion and di~fuse reflection, both or which are discussed below in _urther detail.
As h~r~ro~d, constr~cted occlusion may ~e used to chanse certain characteristics of a su~s~nri~ly Tamh~tian surface, whether it is an emitter or a detector surface. A sU~st~n~iAlly Lambertian emitter X is shown i~
FIG. 2. While the emitter X is illustrated with a pl~ar surface, an emitter surface with subst~nti ~1 1 y T.~ Lian properties need not be planar.
It is observed that the radiation intensity af the emitter X varies with the angle ~. Thus, the emitter X has a radiat~on i~tensity profile that i5 a fu~c- on o~
the an~le ~. This runction or relati~n Ch ip hetween the radiation intenslty and the angle ~ can ~e seen in the change in the cross sectional area K of the surface A as the an~le ~ changes. In particular, where ~ is defined from the normal of the emitter surface A, the cross sectional area R varies as a coslne function or the an~le FIG 2 is also representative or a su~startially Lam~ertian detector (also designated ~y X). While the detector X is shown with a planar surface, a detec_or surface with su~stantially Lambertian properties need not be planar. As the emitter X, the detector X has a response intensity pro~ile th~t is a ~unction o~ tne angle . Again, this ~unc_ion can ~e seen in the change in the cross section area K, whic~ decreases as the ancle increases ~rom the normal to the hor-zon.
Const-lc~ed oc_lusion aims to reduce, ~~ ~ot el;~-n~te, the cosi~e dep~n~ncy on the angle ~ oth the emitter X and the detector X. As shown i- FL~S. 3A
and 3B, a mask M is employed to const~~c~ively cc_ ude the sur~ace A. Pro~erly sized and pos =ioned --om the su-_ace SU~Ill~TESHEET(RULE26~

CA 02244242 l99X-07-22 W O 97/27449 PCT~US97/01011 A, the mask M is rende~ed to selecti~rely n block~' portions o~ the surface A, such that the cross section area K
rDm~n~ consta~t for most angles of ~. Accor~ingly, the mask M offsets the change in cross section area K such that the radiation or respa~se profile o~ the surrace is su~st~nt ~ ~1 1y uni~orm ~or angles o~ ~t those near the horizon. For the co~f iguration shown in FIGS. 3A and 3B, the cross section area ~ r~m~; n ~ constant f or ang~es of ~ between 0 and a~ ;m~tely 80 dL~ _cs. This ~y_ 10 Of angles varies with dif f erent geometry between the mask, aperture a~d cavity. Overall, the radiation or respon~e pro~ile may be distinct~y manipulated as desired with d~erent mas~ and surface geometry.
Whi}e the mask M may be completely opaaue, cons.ruc~i~e occlusion may be achieved without complete opacity in the mask M. So long as the mask M provides a relative reduction in the tr~ncm;ssion o~ radiation ~etween occluded and nonoccluded areas, the cosine dep~n~n~e is altered.
As mentioned, the system also applies the co~cept o~ dif~use reflection. As background, a diffusive re~lec~or can in-rease the erSiciency o~ an optical system by allowing a surrace emi~ter or detector to ~e replaced by a point emitter or detecto-. For ~oth cases, re~erence 2~ is made to FIG. 4.
A su~stantially Lambertian emitting surSace LS
can be created using a point illuminati~g element 12 ~such as a ~iber optic) that illuminates a ca~ity 16 whase inte-ior sur~ace 2Q is di.~usely retlective. The ca~ity 15 di_Susely re~iects radiation _-o~ the point e~ement 12 suc:. tha~ a un SormlY iilum~nated s~~_ace 2~ is c-eaeed at the ape_~u_e 22 o. the ca~ity 15. Cor-espo~ gly, a su~stantially ham~e-tian detec-ion s~- ace LS can be create using a Foi ~ detecti-.g element 12 ~such as a Dhotodicde) that detects lig:-t w~th~- a ca~i,y 15 whose SUt~ UTE SHEET (RULE 26) W O 97/27449 15 PCTnUS97/01011 inrerior sur~ace 20 is di~rusely r~~1ec~ive. The cavity 16 di~Iusely re~iects radiation entering the ca~ity 16 t~rough the aperture 22 such that the point detecti~g element 12 u~i~or~ly detects r~ r; on reachins the aperture 22. It is understood by one or ordinary s~ill in the art that the polnt e}eme~t 12 may he a device localized at the cavity 16, or a light-o~llv~ying de~ice, such as a ~i~er optic 14 or an optical wa~eguide, that e~~iciently tr~n~mits light i~to or away ~rom the ca~ity 16 to a~other area.
With sele~-tive placement ~rd/or sizing oF tb.e mask M above the aperture 22, the occluded arrangeme~t o~
FIG. 4 can either (i~ illuminate an area over the aperture 22 with an intensity proIile that is substantially uni~orm in almost all directions of the area, as an oc-luded dist~i~utor, or (ii) uni~ormly detect radiation over almost all directions of the area, as an occluded distributor, where the area is readily defined in rho and thera directions in sphe--ical Or he~nisphe_ical coordinates. The radiation and detection profiles can r~m~i n substantially unlrorm ror most anyles in ac_~rdance wlth the selected maskJcavi.y/ape-_urQ geometry, except for those angles at or near t:~e ho_izon o~ the oc_'uded a--angement (her-ina~te- re~--red ~ as the hcr~zon district).
The ca~ity 16 of FIG. 4 can be provided i~ a base 18 which also provides a shoulder 28 sur r ol~n~; n~ the aper~ure Z2 o~ the cavity. The base 18 may be ~crmed o~
allsmi n-~m, plastic., or like mate_-als, and coverQd with a c~a.ing or d~r~usel~ re~lective substance, such as barium SU''ate, so that the base 13 as a whole can d _useiy re-lec incide~t lisht. The base 13 may also be _~med o~
a d- _usely re~1e _-ve bulk mate-ial such as Spec=-alon~
sold by Labsphe~e Inc., of Ncr~h Su-_on, New HamDs;~re.
~ 3~ Spec~ralon~ is easi'v mac:-~ed, du-able, and --c~ides a SU~S~ TESHEET~RULE26) WO 97/27449 16 PCT~US97/01011 hlghly e~flcient Lamber~ian sur_ace having a reflectivity o~ over ~9~, in visi~le and near-in,rared wavelengths.
Other suita~le materia~s, tho~gh typically less ef~ective than the diffuse re~lective materials mentioned a~ove, S Llclude ~uasi-di fruse r~ flective materials, such as ~}at white r~in~.
The mas~ M, in particular its underside 24, i5 also constructed of a di~u~ely reflective material, such as Spectralon~, so that any light incident on the ~derside o~ the mask M is not lost but re~lected back i~to the cavity 15. The li~ht redirected ~ack into the cavity 16 is, on average, re~1ected many times within the cavity 16 and ad~acent di~fusely re~lective components.
The cavity 16 is illustrated as a hemisphe-ical }5 cavity; ho~eve-, the cavity may be any shape. Moreover, the size o~ the ape_ture 2Z nee~ not be ~ ~a~le to the ~i~llm cross-sectional area of the cavity; that is, the cavity may be more spherical than hemispnerical.
Furthermore, the aperture Z2 need not be planar. ~owever, the h~m;-~pherical ca~ity with a planar aperture may ~e preferred as it is easie-- to construct and it ai~ords geometric symmetries that allow the use o~ simpli~y~g ca}culations and assum~ ons.
Where the cavi.y 16 is hemispherical ~or spherical) and the aper_ure 22 plana-, as shown in FIG.
4., the aperture 22 o~ the cavity 1~ de~ines a diameter D, and the mask de~ines a diameter DM AS mentioned, the ratio ketween the diameters D, and DM is a paramete~ that can change the prs_ile (-adiation or response) ove_ the ~0 entlre 2~ steraaiar. ~emisphere whic:~ the occluded arrangement aces. In genera', uni_ormlty in the pro~ile is inc-eased i~ t~e mask~ca~ity diamete- rat ~ is close to one; however, this rat o reduces the e~_iciency c the occ~uded arrangemen- by ~im;~shins ~he acce?tanCQ~QScape ~5 area between the mask and t~e a~e-=ure I. is cu-rently SUBSTITUTE SHEET (RULE 2~;) CA 02244242 l99X-07-22 W O 97/27449 PCT~US97/OlOll belie~ed that by decreasing the i~tensity for certain a~gles while i~cre~sing the i~tensity for other angles, the mask su~st~nt~1y a~erages the pro~ile o~er a wide range o~ angles, for a more uni~orm ef~iciency for most a~gles. A mask~ca~ity ~iameter ratio o~ a~out 0. a to 0.9 ss prefe~red. This ratio prov~des a reasona~ly le~el pro~ile, whsle ~;nt~;n;n~ a relati~ely high level of e~ficiency.
The distance or height D ~etween the m~sk M a~d the aperture 22 is another parameter t~at can ch~ge the occluded arrangement's radiation or detection proflle.
Moreo~er, the thickness o~ the mask M ~an ~lso change the prorile.
The graph or FIG. 5 shows the cross-sec ional area K o~ an occluded arrangement with an aperture ~iameter o~ appr~im~tely 2.0", a mask with a ~;~m~ter of approx~m~tely 1.8", and a separation dista~ce Detween the mask and aperture o~ ay~r~imately o 3 n, It can be seen that the pro~ile cf this ocoluded arrangement r~; n~
relati~rely constant until ~ re~-h~e ~ ; m~tely 80 degrees. Thereafter the profile drops ~ramatlcally.
As di_~erent profiles may be o~tained with diC~erent mask/cavity~aperture geometry, it may be userul to construct the ca~ity a~d mask out of a core material that is plia~t, e.g., rubber, so that the ca~ity and/or mas~ may be readily reconrigured to pro~ide d ~f~rent geometries wlth di r~erent radiation cr detection pro~iles.
In order to ~Yp~n~ the un Eorm por~ion of the profile into great~r angles o~ ~, tnat is, into the horizon district, the sys~em lO may either i~crease the energy o~ the illuminatior, radiated or detected, o-pro~ide a de~lec~or or ba-~le 30 as shown in FIG. 6. The ba~_le 30 is con~icured to pro~ide a sur-ace 32 ~elow the mas~ M, that is substantially per~end-cl~ar to the ;~o~ zon distric~. The sur_ace i2 se~ves t- re_lec~ l-g;~ t_ the SU~IllUTES~EET(RULE26) W O 97/27449 la PCT~US97/OlOll horizon distr-ct to sisni~icantly i~crease the ~ llumt nation intensity in that district . Like the mask M
a~d the ba-~e 18, tke baf~1e 30 is constructed OUt O~ a dif fusely re~1ective material such as Spectralon~. The re~lectivity o~ the baf~les can be sraded so that the baffle can ha~e an angle d~y~ reflectivity, i~
desired, for Q~m~l e, to compensate ~n~-n; form e~ects .
~ sed d~ ' iately, the baffle 30, i~
conjunction with the shoulder 28, can extend the pro~ile u~i~ormity into angles of ~ well beyond 90 degrees (see, e.g., FIG. 7). For an occluded emitter arra..~ nt, th~
shoulder 28 redirects toward the up~er hemispheric area that would otherwise be directed below the horizon. For an occluded detector arrangement, tne shou~ de- 28 b}ocks light f rom below the horizon.
As ~entioned, the radiation or detec~ ion prorile o~rer the h~m; ~pneric area may ~e tailored as desired by carefully configurins and ~;m~ncioning the cavity aper~ure 22, the mask M, the baf~1e 30, and/or the shoulder 28.
For example, re~erring to FIG. 7, an occluded distributor R having an aperture wlth a diameter Da 0~ a~ ;m~tely 2.0~', that is constructively occluded by a mask M with a diameter DM 0~ a~L~; m~tely 1. 8~' and ~nh~nced by a ba_ le 30 having a base o~ appro~m~tely 0.27~l in ~i~m~te~ and 2~ appr~Yim~tely 0.21" in length, has a radiation intensiey pro~ile that is relatively consta~t for angles o~ ~ up to 90 degrees.
Other baf~les can be e~ual7y e~rective at increacins the intensity in the horizon dist~ic_. For example, FIG. 11 shows a ba~fle tha_ is inc~r?orated into the mask M by bev~ll;ns edges 48 o~ th~ mask M. Where the mask M has a substa-tia' thickness, the bevelled edges 48 ef~ectively can direc liSht to tne hcr zon dist~ic..

SUBSTITUTESHEET(RULE263 W o 97/27449 19 PCTAUS97101011 Referring ~o FIG. 8A, an alternative embc~im~nt o~ the ba~fle is shown. Also covered with a dif usely-reflecti~e material, a ba~fle 41 is formed o~ multiple ~Yt~n~d members 42 defi~l~g an int-rsection 43 at their S midpoints. The members 42 are preferably planar, but they may be curved or otherwise. The baffle 41 preferably, but not necessarily, de~ines symmetrical sections S in the occluded arra~y~ ~t~
The baffle 41 preferably, but not necessarily, has a length 44 subsr~nti~lly e~al to the ~i~m~ter of the aperture 22. Alternati~ely, the length 44 may be longer to extend beyond than aperture 22, or be shorter and shy of reaching the aper.ure 22. The ba' le 41 preferably, but not necessarily, has a height 46 substantially e~ual to the separation distance D between the mask M and the aperture 22. Alternati~ely, the height 46 may be greater or lesser tha~ the separation dist nce D. Like the ba~fle 30, the ba_~le 41 extends toward the aperture 22 of the ca~ity 16 to create a su~stàntially perpendicular surface 32 relative to the horizon. Consequently, the ba~~1e 41 increases the illumination intensity at the horizor.
district for a mOrQ uniform profile (radiation or response) in the hor~zon district.
The ba~_le 41 may be mod ~~~ed as desired to change the pro~ile. A modified ~a~~1e 41~ is showr. in FIG. 8B. The ~a fle 41~ ~r~ed to the baf~1e 4~ has an en}arged core 4S at the intersection 43. Althousr. the core 4S is illustrated with a c_rcular cross secticr, the core 45 may be d_f_erent sh~pes. The ~a~~1e 41~ may also 3û have greate-- thic ~ ess 47 in rhe memDers 42.
To obta_n a relatively uni-or~ profile, the arrangement of FIG. 10 uses a mask d-amete_ D~ of - approximately 1.8" and an aDer_ure Giamete~ D8 ~~
~pproximately 2.0", whic:- resu7ts in a mask/aper=~~e diamete- ratio or a~prox ~tely 0.9 or 90~. A

SUt~ 1 UTE SHEET (RULE 26) W O 97/2744g 20 PCTrUS97/OlOll mask~aperture diamete ratio of O.9 pro~ides a relatively u~lrorm response over a relatively large range o~ the ansle ~ while mainr~~ n i n~ an accepta~le range o_ operation. Further, the disk- shaped mask M is spaced away _rom the aperture 22 by a~ o~mately o . 3 ~ nt-h~c, resulti~g i~ ~ mask dista~ce to aperture ~;~m~te- ratio o~
~tely 0.2 or 20%.
The arraL~e~ ~t of FIG. 10 may be enclo3ed i~ a cover, e.g., dome 38, to protec- the interior ~ ntc Moreover, the arrangement o_ FIG. 1~ shows the point e}ement 12 being mounted but rather below the mask M and baf_le 41, outside oS the cavity 16. Connection wires 40 from the point element 12 may be inserted t~rough bores provided in the mask and baff 1Q .
With the point eleme~t 12 f acing the aper_ure 22 from the underside of the mask M, "hot spots" that may result from direct angles of radiation or detection into the cavity 16 can be sutstantially a~oided. By "~nverting'~ the point element 12, effects o~ Fresnel reflection, which would other~ise increase the cosine depPn~ce of the arransement profile, may also ~e a~oided. Fresnel reSlec_ion generally occurs whenever light travels throush a sur~ace between two materials having d_~erent ind ces o~ re_rac-ion, Sor example, air and glass or silicon. Much like the cosire dep~n~pnre of the ~amDertian surface on the angle ~ discussed abo~e, Fresnel re~lection i~creases with the ansle ~, which decreases the illumination ntensity o~ lisht in the horizon district.
The arrangement o~ FIG. 10 illus_rates the concepts used by the syscem. The head module H o_ the system 10 in ce_tain emDcdimerts inc~udes an cc-luded and ba~Sled emitter (dis - ~utor R) and in othe- embc~m~nt an occluded and ba _led dete~~or ~de~ectc- L) . OC--' uded - ~S and baSîled dis-- butors and deee-~ors are disc'osed, SU~S~ TESHEET(RULE26) CA 02244242 l998-07-22 W O 97/27449 21 PCT~US97rOlOll respecti~ely, in U.S . ADplication Serial No. 08/590,2~0, filed January 2~, 15g6, and U.S. Application Serial No.
08/58~,105, ~lled ~anuary 23, 1996, both o~ which are incorporated herein by rererence.
S An alternatiYe em~o~m~nt o~ an oc-luded and baf f led emitter is shown in FIGS. 27A and 27B. An elongated lamp L, e.g., a minifluorescent lamp, is located ~ on the underside 24 of the mask M, between two clo~ely ba~flec 41. Electrical power ~or the l;~mp i8 supplied on power leads that ~t~n~ through a passageway ~ormed in the base 18. The _eight of the ba~~1es 41 exceeds that oî the lamD L, such that the lamD L is not visible ~rom the side ol the emitter.
In view o r the f oregoing, i~ can be 5 een that constructive occlusion can rende- the dist-iDutor R and the detector T to provide tailored radiation and detection pro~iles. When desired, constructive occlusion can ~nh~n~e the operation and ~unction o~ the distributor R
and the detector T with respect to radiation in the horizon district, or even ren~e_ the dist-ibutor R and the detector T to be subst~nt;~-ly uni~-rmly omn;~-ectional over a hemis~heric area. The proliles of the distributor R and the detector T can be ~ur~ner ~nh~nred with the aid of the baffle. With determinative siz_nS and positioning o~ the mask and/or ba_fle, the c~st~i~utor R can be occ~uded in a m~nn~ that enab}es it to dist-i~ute u~if~rm intensity in almost all directions and the detector T can be occluded in a m~nn~ - that enables i. to ros~ond uniformly to in~ensity in almos~ al' d_rec ions. The ~0 system advan~ageously a~lies t~ese c~ncepts. ~owever, where the dis=--~u~or R and the detector T ha~e bee~
rendered omrid~-Qc~-onzl, the system uses a head module H
- that is a comDination c an omr~dir~_~ional de~ice wl-h a parti~ioned device tna~ oDerates wl-h axial rescluti2n.

S~u;, 111 ~JTE SHEET (RULE 26) W O 97/27449 22 PCT~US97/OlOll In order to obtain di~ectional (or angular) data in trackin~ a reflec~or, the system employs a head module that includes at least a part~tioned distributor PR with a tt~nr~titioned detector T, or at least a partitioned detector PT with a nr~n~t_tioned distri~utor R, where the partitioned devices operate with resol~ n about at lea~t one ~x~s. I~ p~rticular, the system e~ables the seneration and~or det~ti~n of ;nt~r~¢ity variations between dif~erent sections that are indicative of a direction along which the reflector RRl is positioned. As a feature o~ the present inv~n~inn, the partit;on~
devices function and operate in a m~nn~ that allows the system to r~m~ t n relatively simple electronically and structurally, and inexpensi~e.
Generally sp~kins~ where a radiation or detection sur~ace ~S as shown in FIGS. 3A ,nd 3B is utilized in the head mo~le ~, without the cavity 16, the baffle 41 effecti~ely divides or partitions the sur~ace ~S
,~nd/or a region between the mask M a~d the sur~ace LS into sections in rende~ing a directional distri~utor or directional detector. In this regard, as expl~in~d below in fu~~her deta~'l, the lish. source providing the radiation surrace LS ( or the derector providing the detect on su-race LS) is ther conrisured to enable distinct radiation ~rom (or distinsuish ~etween distinct incidental radiation on~ each Or t~e sections created by the ba~le 41.
Where the radiation su-~ace or detection surrace is pro~ided ~y the cavity 15 nd the aper~ure 22, such as in the dist-ibutor R and de~ector T descrlbed abo~e, the ba~,le 41 is mod~_ied or exterded a ba_Ile 51 to d-vlde or par-i~ion t~e reslor into t~e sec_~ons that are now inclusive of a volume subs.an~ially between the cavi~y 16 and the mask M. In crde- t~a~ t:~e pa-~-__oned dis.=ibutor (or derecto-) be able to erable dis- -c_ radiation r-~m SIJL.;~ JTE SHEET ~RULE 26) PCTnUS97/01011 (or distinguish between disti~ct in~ tal radiation on) each o~ the sections, the point element 12 is replaced by a plurality of poi~t el~m~nt-c, each of which is associated with a disti~ct ~ection.
As shown in FIG. 9, the baf~1e 51 is sim; 1 ~ tO
t~e ba~fle 41 o~ FIG. 8A, but with the addition of di~iders 53 which are sU~s~nt;~ly ext~n~ port~ons of the pla~ar members 42. The dividers 53 are configured such that when the ba~le 51 is placed between the mask M
and the cavity 16 ~both represented by ~roken lines), the members 42 ~emain abo~e the aperture 22 while the dividers 53 extend below the aper~ure into the cavity 16 a~d O
approac~ or a~ut the interior suriace or the cavity 16.
For example, where the cavity 16 is hemisphe_ical or spherical, the dividers 53 have an curved prorile 55.
Where the radiation or detection sur~ace LS is present, a region G ~etween the st~-Iace LS a~d the mask M
is divided ~y the ba~fle 41 into sections S . Where the cavity 16 with the aperture 2Z are utilized to pro~ide the sur.ace LS, a region or volume G' ~etween the c~vity 16 and the mas~ M is divided by the ba_,~le 51 i~to the sections or subvolumes S .
I~ one embo~im~nt, the ba- le 41 and 51 are substantially opa~ue, having a thic.~ness or z~u ~ r~ m~tely 3.0 mm. In ,an alternative emb~;m~nr, the ba~fles 41 and 51 need not necessarily be opaque, provided that they su~stan~ ly divide the region G into the sec-ions, such that light entering into each section su~stan~ially r~m~in.~ within that sec'ion only.
Where the ba__le 41 or 51 parti_ions or ~ des the ragion into fou_ sections SAt S~, S,. and S" the - par=i--oned aevio-Q has resolution about two axes. Two axes or resoluticn can also be enabied with~- the system lo wnerQ the ba~~le 41 or 51 par~ ons the region into 3S threQ sections; howeve-, it is bel~eve~ tha~ the S~ TESHEET(RULE26) W O 97/27449 24 PCT~US97/01011 calcula~ons used by the system to provide direclion~l in~ormat~on would be more complex. Two axes o~ resol-~ti nn are also enahled where baffle 41 or 51 divides ~he region ~to five or more sections. If only one axis of resol~ nn is desired, the bafrle 41 or 51 is configured to partitson the region i~to ~ewer sections, for ~Y~mrl~, two ~e~tions.
Where the baf~~ e 51 provides four Qections or quadrants (for resolution about two axes), an X~Y
coordi~ate system may be supersmposed on the baffle ~1, as illustrated, such that the ca~ity 16 is quartered in a~ ~,nce with the ~zimuth angle p being measured rom the positive X axis. For purposes of better underst~n~i n5 this discussion, individual sections SA~ SEI, SC and S~, may ~e defined as fQllOWS:
o c p c 90 = sect~on B
~o ~ p c 180 = section A
180 c p c 270 = section ~
270 ~ p c 360 = section C
While the baffles 30, 41 and 51 all serve to increase the illumination intensity at the ~orizon district (i.e., ~ = 90 or so), the ext~n~ ba~fle ~1 divides the cavity 16 and rende_s the distri~utor R and the detector T into partitioned dist_ ibutor and detector PR and PT so that they pro~ide resolution or distingu~sh direction about the X and Y axes. In particular, it is the baf~le 51 which enables the partitioned devices PR and PT to generate intensity variations in a m~nn~ that allows the system to ascertain at least ~irec~ional data, i~ not posit~onal data ~or a re~lector.
FlGS. 12~ an~ 12B illustrate a par~ -ioned device that is representative c_ the parti- oned distributor PR and the part~tioned detector P~, usi~s the ca~ity 16, the mask M and the ~_-le 51. The ~a- 1~ 51 creates the sec-ions, w~ ch -.cluaes lowe~ sec~_ors below S~Jes~ 111 IJTE SHEET ~RULE 26) W O 97127449 25 PCTrUS97/OlOll the aperture 22 within the caYity 16 and u~per sections abo~e the aper.ure 22 and below the mask M. As ~ntioned, ~ plurality o point el~m~nt~ 5~ are used i~stead of the s~nsle point e}ement 12 of FTG. 10 and each po~nt element 59 is associated with a distinct section. Each point ~l~m~nt s~ may ~e mo~nt~ i~ a disti~ct section, in particular, a distinct upper section, on the underside 24 of the mas~ M ~or the reasans preY~ously discussed.
~; n, the point element 5~ may represent li5ht-~L~Veyi~g devices, as descri~ed earlier.
ReferriAg to FIG. 13, the system in one embo~im~nt provides a head module ~ that includes a partitioned detector PT and distri~utor R. The partitioned detector PT may be confisured as illustrated 1~ in FIGS. 12A and 12~, and the dist-ibutor R may be con_igured as illustrated in FIG. 10. As expl~;n~, each point sensor 53 of the partitioned detector PT is configured to generate electrical signa}s based on the light intensity detected in the respectiYe section. Where the point sensor 59 is a photo~;o~, the photodiode has a relatively small responsive area of appro~im~tely O.8 souare m;llim~ter5 and a noise equiva~ent power (~EP) of appro~im~tely 6 x 10-lS Watts/(Hertz~~i. A photodiode with a small responsive area has two siS-i ican~ adYantages:
(i) it generally has low noise characteristics; and (li) the greater e~ficiency of the system (i.e., a decrease in the ratio of sensor size to ca~ity size means greater sensitivity). Using these photodiodes, the ~artitioned light detector~s ef~iciency nears ils asymptotic state with a caYity having ay~ m~ tely a l.0 inch diame~er or width.
As shown in FIG. 13, i~te~si~y varia~ions detected by each of the ~oint sensors in the pa~~i~ioned detec-or PT of the head module H is processed by a processor 49 (a rep~ese~~ative ci~ . 67 thereo~ beins SUI:sa 1 l l UTE SHEET (RULE 26) =

W 097127449 PCT~US97/01011 shown in detail in FIG. lS) for display on an oscilloscope 64. The circuit 67 is ecuivalent to the circ~it suggested by a manufacturer of photodiodes, namely, ~nited ~etector Technologies t'3DT) censors, Inc., of ,~awthorne, Cali_or~ia, for use with its ~uad-cell photodiodes.
Others circuits (;?n~los or digital) may be u~ed.
Referring specl~ically to FIG. 12B, the sectio~
SA S~ SC a~d SD created by the baffle 51 are arranged clockwise, when view~ng down on the partitioned detector PT (see FI&. 13). Note that this arrangeme~t co;~ c with the sections shown in a conceptual representation FIG. 14, in that the normal extends outwardly from the horizon (or XtY) plane into the hemispheric area o~er the partitioned detector T.
lS Re~erring spec_~ically to FIG. 15, the cathodes of the photodiodes are all connected to a ~ l gro~lnd termin~l. The ~n~ of the respective photodiodes are each connected to the re~spective cur~ent-to-voltage ampl~fier 50. The voltages are then 5~?mm~? and~or subtracted by one of three amplifiers S2, 54 and ~7. The first ampli'ier 52 outputs a signal which is the sum o~
the signals ~rom all four sec~ ons SA ~ SB ~ 5,- and SD. The second amplifie~ 54 sums the signals -rom the sections B
and C, and subtr~cts the sum o' the signals 'rom secl ons 2~ A and D. The second ampli~ie-~s out~ut signal is then divided by the first ampl fier~s output signal by a divider sa that pro~ides ,nd X output signal. A third ampli~ier ~7 sums the s-gnals from t:~e sections A and B, and subtracts the sum oî the s_gnais '-om the sec~ions C
and D. The thi_d ampl fi'- - ' S Outpu_ Si gnal is then divided by the _-rs. amp i~ie~r~s OUt - U_ signal by a di~de_ 60 that F-o~ides a Y ou_?ut s~nal. A sui~able divider is the DIVlQ0 manu_ac~ured a.d sold by Bur--~rown~
of Tucson, Arizona.

SlJ~ JTE SHErT (RULE 26 W 097/27449 27 PCT~USg7/01011 The relationship hetween the X and Y OUtPUt signals and the section si5nals is gi~en by the ~ol~owing ~ormulas:
~n. 1 X ~ ttB+C)-(A+D)I/(AlBlC+D) E~n. 2 Y = ~(AIB)-~C+D)]/(A+B+C+D) It is understood by one o~ ordinary skill in the art that ~uations 1 a~d 2 ~ay be varied so long as the configuration o~ the sections S,~, SE~r Sc and SD is consistent therewith.
The X and Y output signals are f ed to the oscilloscope 64 (FIG. 1~). The X output si~nal is connected to the display's horizontal sweep input t_rminal and the Y output signal is con~ected to the oscilloscope's vertical sweep input terminal. It ~s understood ~y one of ordinary skill in the ar. that tne signals X and Y are not necessarlly de~ined with~n a Cartesian coordinate system.
A spot 66 on the oscilloscope 64 indicates the ~7;m--th p and ele~ation ~ position o~ the reflector. For example, the spot 64 indicated on the oscilloscope 64 is representative o~ a retro reIlector positioned rela-ive to the partitioned detector PT at an azimuth o~ about 45 desr~es and an elevation or about 4, degrees. As the refiector changes elevation, the r~ l distance o_ ~he spot 66 from the cente- o- the oscilloscope 64 cnanges.
As the re~1ector moves azimuthally about the head mcdule H, the s?ot 66 will trace a path about the center c_ the oscilloscope 64.
A grid conceptually representative o~ the coor~nate system ~or the X and Y output signals is illustrated in FIG. 14. The azimuth (p) angle, ta.k-ng into account the a?pro?riate sec-io~ (w~,h the apprcpriately de'ined ?os_tive c_ negative va_ues) ~r the ~ reriector ~1 can ~e c-21_ulated Erom the X and Y cu_-ut signals using the ~~llowins ror~ula:
. 35 E~n. 3 p = tan~;(Y/X) S~ TESHEET(RULE26) W O 97/27449 28 PCTrUS97/O1011 The elevation ~ is related to the r~
dis~ance or length L from the cente_ of the oscilloscope 64 to the spot 66 (FIG. 13). This radial distance L is calculated from the X an~ Y output signals using the 5 ~ollowing form~la: -E~n. 4 ~ = (X2+Y2~
The actual elevation associated with the calculated azi~th p and radial lensth L is a complex function o~ the detector geometry. Accordin~ly, a look-up table given in App~i~ A is used to correlate the azimT~th p and the length L, to the elevation, as ~ollows Note, however, that the ta~le pro~ides the elevation angle i~
terms o~ ~ where e = g o - ~ .
E~n. S e = {p,L; Table}
FIG. 14 illustrates conceptually the relatio~h;p set ~orth in Ap~endix A between the ~7~ml1th p, the r~7 ~ length L, and the elevation e 0~ a retro reflector detected at the ~m~th angle p = 30. In particul~r, i~ the reflector is at an ele~ation of e - 10 (i.e., near the horizon~, the spot 64 will be a~,l~; m~ tely 0.89 unit length L ~rom the center o~ the oscilloscope 64. I~ the re~lector moves to an elevation o~ ~ - 80, the spot 64 will ap~ear to closer to the center, with a reduced uni' lensth L o~ appro~m~tely 0.76 ~rom the ce~ter Note that 50 long as the retro r~rlector ram~; n.¢ at an azimuth of p = 30, the spot will also remai~
at an ~7-~m~th of p = 30 on the oscilloscope 64, chansins only the length L ~rom the center to re~lec- the c~ange in ele~ation a~gle I~ the ret~o rerlector moves ~oush di__erent ~7i~ths while r~m~ g at the same eleva.ion, the spot 66 will travel on a somewhat rec~ansula~ path around the cente~ or the osc lloscope 64. Ac~ nsly, the system usins tne eable in Appen~ix A provides a se~ or directional data (~ e , p, ~) ~or a re~lecto- be~g tracked.

SUBSTITUTESHEET(RULE26) It bears ~mrh~ ~is that the algorithm used in App~n~i~ A is merely one o~ numerous algorithms that may ~e used ~y the sy~tem. The ~lgorithm o~ App~n~i~ A is also one Of many algor~thms that allows the spot 66 to r~m~; n on the display regardless o~ the position o~ the o~ect in the detection zone ~ r ~vv~r, it is understood by one o~ ordinary s~ill in the art that directional data may provided ~y the system 10 t}~ ~U~l the use o~ analytic relatinn-~hir~ (e.g., polyn~m~l e~uations), as opposed to the described ~mho~m~nt using the look-up table of App~ ~ A.
In view o~ the ~oregoing, it can be seen that the parti.ioned light detector PT o~ the present inv~nt; ~n provides at least directional i~ormation ir the ~orm oI a 1~ set o~ azimuth and elevation coordinates (p, e) for a given retro reflector. A partitioned detector embodylng features o~ the present invention is disclosed in ~.S.
Application Serial No. 08/589,104, ~iled Janua~ 23, 1~96, which is 2~ incorporated herein by re~erence.
As an alternative embodiment o~ the parti_ioned de~ices in general, two partitioned devices PDl and PD2 ~eithe- both discributors or boti detectors) may be placed back-to-back as shown in FIG. 28, to provide sphe~ical coverage that results ~rom the two opposing hemispheric area of the two devices.
While the ~mho~i; m~nt desc--ibed above uses a head module having a partitioned detector with a nonpartitioned, omn-~ir~ctional ~ist-_~utor, the system ~O may also use a par~_tioned detector with other conventional ligh~ sources under ~- eren. conditions.
For exampl~, an ordinary broad band light bulb can be used where the detec-ion zone is ~ree ~~cm other types o~
illt~min~tion. Fluoresc~nt lisht soU~Ce'5 that ~lic.~e- can ~lso be used A suitabie _lucrescen_ lignt bulb is the SlJ~ 111 ~JTE SHEET (RULE 26) W O g7/27449 pcTrus97lololl ~Mini Fluorescent~' ~TM), Model ~F659 in white color, made by Jgl Components Corp. of Pacoima, Cali~ornia. Alt~ough c~v~LLtional light sources will likely provide a ~n--n; rOrm radiation profile in the detection zone Z (the p~ofile being particularly deficient at a~gles o~ ~ at or near the horizon relative to the light source), the system will _u~ction ade~uately for those areas su~sr~nr;~lly normal to and outside the horizon district o~ the light source. The use o~ the distributor R instead o~ an ordinary light source ~Yr~n~ the oDerati~e zone o~ the system i~to a hemispheric area o~er the distributor R, including the horizon district o~ the distributor R.
In order to track multiple retro re~lectors R~l simultaneously with the roregoing Qmh~;m~nt ~see FIG. 1), that is, to provide additional cets c~ directional d~ta ~Pi, e. ) ~or additional retro re~lec.ors (whether a~.ixed to additional objects, or to di~rerent locations on the same object), the system necessarily distin~;~h~s between signals att-i~utable to distir,ct retro re~lectors. In this regard, it is noted that the term l~simultaneously" is used flguratively, and not necessa_ily literally, ir that processing o~ data ~or multiple rer~ectors by the system may occur serially and not in parallel Parallel processing may ke accomplisned with additiona} processors.
The system 10 distinguisnes betweer multiple re~lectors by usirg spectrally-selec~ive sensors. In particular, where the lis~t emitte~ ~rom the distributor R
is broad band lighr~ re-lec~ors o~ di~te-ert spec_ral characte istics are provided, alor,g with a co_-esponding set of spectrally-_esponsive pQin. s~nsors (e.g., photodiodes equlpped wi.h spec~-a'ly-selectlve - lt-rs) ~or each add--ional reflectcr ~elrs tracked. With the cor-es~ondlng set or poi.t sersors ~-ac.~ing i~s ~assigned~' retro re~lecto-, the system is capanle o~ trac~ing S~ TESHEET~RULE26~

W O 97127449 31 PCTrUS97/OlOll mul~iple retro re~lectors and dist~ng~ chtn5 between the intensities variations collected _or different reflec_ors.
Referring to FIG. 17, multiple sets of spec~rally-selective point sensors 71 and 72 ~with _re~uencies responses o~ A~ and A2, respectively) may all ~e housed in a s~ngle partitioned detector PT. In particular, the sets 71 and 7~ may ~e arranged such that each section below the mas~ M is occupied by cne sensor from a given ~et. T~e partitione~ detector PT o~ FIG. 17 can therefore detect at least two reflectors with fre~uency spectrums Sim; 1~ to A~ and Az. The reflectors may each be a~fixed to different objects, or the reflectors may all be a~fixed to a single ~su~stantially rigid) object to trac~ its orien~ation.
In general, it is noted that the ~-e~uencies or spec~ral characteristics of the electronics desc-ibed herein are not s~eciEic wavelengths, but rather denote ranges o wavelensths. The responses from the sensor sets 71 and 72 are used in Equations herein to determine the position of the correspon~i n~ refle~tors. In general, the spec~ral characteristics o~ the reflectors need not be ~dentical to the response characreristic o~ rS "assisned"
sensors, thouyh perrormance o'~ the system 10 is improved i they have simila- charact--istics.
2~ ~f a third reIlect~r is to be trac~ed, a third set o~ corresp~n~ins spectrally-responsive sensors with fre~uency spectrum A~ may be added to the par~itioned detector ~T o~ the head modul~ Y. In the alternarive~ an add-tional head module u with simply a pa~ -_ioned detector PTn may ~e added and used in con~unc-ion with the head module }~ w~thout rec~i-ing ~eccn-igurat cn c the latter. It can be seen in gene_~' that add-~iona~ sets of sensors f or detecti~g ad~-~iona reflectors may re housed in the par~i~oned detec-cr - an e~is~ins head modu~e, or ~ 35 ~n separate and dis~inc~ pa-- - ored detec,crs T . As S~IllUTFSHEET~RULE2~) W O 97/27449 32 PCTrUS97/01011 shown in FIGS. 22A and Z2B, four separate and distinct parti~ir n~ detectors PT,~, PT~" PTC and PTD are ~ L~Ve::.Ll,i ently ~ ~ounted on a single plat~orm P, where each partitioned detector houses one set of sensor sets SA~ S9, SC and SD.
It has been noted that a single par_itioned detector PT Of the .~o~re description can pro~ride one set Of directional data ~Pl, el3 for a given reflector.
Refe~--ins bac~ to FIG. 1, where it is desiral:le to ascertain the position Of a reflector in three ~;m~on~ior2s (along three axes), the system uses at least o~e additional partitioned light detector PT2 to provide a s~n~ set o~ directional coordinates P2 and 62, which when processed with the f~rst direc~ional coord~nates P2 and e~, provides all three coordinates ~or the reflector. The relative positions of the part-tioned detec~ors PT and PT2 to each othe- is made known to the system so that it can cross-ref~rence the sisnals from both partitioned detectors to ascertain all thre~ coordinates for a ref lector f rom two sets o~ directional data.
In view of the foregoing, it can be seen that to ascertain all six coordinates _or an object (that is, position .nd rotational orientation), the system uses at least three reflectors and two par~itioned detectors.
However, detec-ion o~ all six degrees or ,..~v~--,ent or an o~ject is not always desirable cr re~uired, and the system 10 can ~e con~igured ~oyriately~
Refe-ring to FIG. 1, where a second partitioned detector PT2 is u~ed, i, is par~ of a second nead module H2 providing a second distr_~utor R2. The second dis~ utor ~0 R2 provides the light that is detected by the secor,d partitioned detecto~. With ;he two head modules u~ and H2 and thei- relative pos~tions ~owr" the syst-~ c-~n c-oss-rererence the respec=i~e sets oI directional data ~or any one re~1ector track-,.g the movemert o.~ tha; reflec-or in - ~5 three coordinates. ~ divide- or a ~eparatir.g wa ~ ~not SIJ~S 111 ~ITE SHEFT (RULE 26) W O 97127449 33 PCTrUS97/O1011 shown) may be situared between the head modules ~ and H2 to y~cv~l~t interrerence by the respecti~e lif~ht distr~butors. Alternatively, the radiation ~rom the respective distributors may be pul~ed or ~lickered at 5 different fref~f~n~;f~, e.g., lOOH~ ~nd 130Hz.
As shown in FIG. 1, broad band light is emitted throughout the de~ection zone Z. Where the detection zone Z cont~tnC f~xtraneous objects such as _urniture or walls w~th extensive reflective surfaces, lisht is reflected not only off the reflectors, but off these surfaces as well.
Any light detected by the head module not attributa~le to the re~lector contriDutes to the bac~y r o~u~d energy which may signi_icantly limit the perIo~mance o~ the system lO.
However, because this bachy~ d ene-yy ~a}so known as bac~ground or self ill~min~tion) is not a noise source, but a background source, its e rects can be compensated.
Where multiple sensors or different spectral responsiveness are used, this bac~yround source can be r~Al-cf -fi i~ not ~limin~ted~
Referring back to the em~n~imf~nt shown in FIG.
11A and 17B, multiple sensors of dif_erent spec;ral responsiveness are used, that is, sensor sets 71 an~ 72 responsive to freJuencies A1 and Az are used to trac.~ two correspnnfii ng r~lector5, as previo~sly desc_iDed. To compensate ~or bac~ground illumination, a third set oI
sensors 73 is provided. The ~requency response o_ the third set 73 is selected to be responsive to all wavelengths in the area or tne spect-um near the fre~uencies A. and A2 50 -hat i- can act as a bac~s-ou~d 3 0 n~l 1 i ny detector. To f~f~on~trate the eErects o~
backyround illumina.ior., res~onses _ and r2 o_ the _irs.
- and second sets of sensors, arter s~ ac. on c_ t~e bac~g-ound eneryy, are S~ven by:
Ef~n. 6 r = X~ LR
Where:

SlJt~ 111 ~JTE SHEET (RULE 26) - =

PCT~US97101011 ~1 K ~ R._~ ~ R
I r2 1 ~C21 1 1 ; R ~ I R2 R~ I ~;K~ 1.
lrn ) ~ lJ ~ Rn ) And Rl is the se~sor respance be~ore back~
ction a~d ~il are co~stants of correction.
As the h~k~ r ~d level increaQes, the dynamic range re~uir~nt~ of the e7ectronics increase. ~o calculate the m~n~tude o~ the sel~ ill7~min~t;nn~
~tegrat~g sphere ~ c are used. The h~sround light B re~lecti~g a~ the walls of a room back to t~e partitioned deeector PT is gi~en by:

Ecn. 7 ~ * Wr B = ~4 tl--Wr I 1~

Where Ac is the acceptance area or aperture of the partitioned detector PT, A4 is the area of the room walls, and Wr is the room wall reflectance.
The signal from the retro reflector is g~ven by:
E~n. 8 S = Lr * Pr Where:
A
Ls = 2~Dr ; Pr = ~Tr T_ = Dr tan ~ 2 and e ~ is the d~ ~ergent angle of the retro reflector, as pre~iously defined, A_ is t~e area or the retro reflector, and D_ is the distance to ~he retro 3û ref 7 ector.
Table 1 ~elow lists signal to bac~grsund and A~D
requirements for selected conc--ions using a l" dlame~er r-tro re~lector, wnere Rs is the room size in reet, D_ is distance to the retro reflec~or in ~eer, and W_ is the-wall 3S rerlectance. A smaller si~r.al '_ bac.~ground resuired a SUBSTITUT~5HEET(RULE26) PCTnUS97/OlOll larger Analos to Digital ~A~D) converter. For a system re~ul-ing a 1 reso}ution, a 20 bit A/D is sufficient or a signal to h~ ~d of 0 ~013- 20 bit A~Ds are readily available and inexpensi~e.
Condi~ion Sis~al Backy~ou~d SfB Ratio AID
Rs D~ Wr in Watts in Watts Re~uired 12'12' 75% 2.9E-6 2~2~-4 l.~E-2 20 bit 12~6~ 75* 4~6E-5 2~2E-4 2.1E-1 14 b~t 12~61 95~ 4.6E-5 1~ 4~-3 3.3E-2 18 bit 12'10' 10% 2.0E-6 8.1E-6 3.5E-1 14 ~it 24~24~ 75~ 1.8~-7 5.5E-5 ~. 3~-3 24 bit 24112' 75~ 2.~E-6 5.5E-5 S. 3E-2 18 bit 24112' 95% 2.gE-6 3 .SE-4 8 7r-3 18 bit 24~24' 10~ 1. 8E-7 2.OE-6 8.~E-2 16 bit A head module H including a partitioned detector PT
and a nonp~ ~titioned distributor R is shown in F~G. 16. The parti-ioned detector PT and the distributcr R o~ this head module each has its own ca~ity. A ca~i-y 10~R~ mask M~ and ba~Cle 41 are prcvided ~or the dist~~butor R, and a separate cavity 16X, mas~ M~ and baf.le ~1 are pro~ided ~or the partitioned detector PT, albeit the ca~ity 16~ is actually configured ln the mask M~ of the partitioned detectc- PT.
Confisured in this m~ ~, the partitio~ed detector PT and the dist-ibutor R ~unction without signi~icant dist~h~nre to the other. The distributor R dist~ibutes light into the ~5 hemisphe_~c area o~er the head module ~, including the horizon dist-ic1 arourd tne dist-_Dutor R land the head modu~e ~). Any ligh~ re~'~ected by a re~1ector in the hemisphe~~c a-ea is detected by the par,-_ioned detect-- PT, even i r~ lected ~rom the horizon diseric_. E~uipped wi~h the extended ba ~le 5 the ~ar~ oned detec~c~ ~T is able tO detec_ _~te~.s- ty SUBSTITUTE SHEET (RULE 26) W O 97/27449 ~ P~/u~97lololl variations between the sections to enahle the system to pro~ide a set o~ directi~n~ 1 data o~ p a~d e ~or eacn re~lector.
The head module with separate cavities may be the s~mplest and least costly to manufacture. The separate ca~ity S ~eature enables the use o~ cnn~in~ us or 510wly osrillating illt~m~n~tion and relatively larger light sources. This embo~im~nt is adv ntageous i~ thzt it a~oids the use of mo~ing ~ .. ",~nt.c a~d imposes relatively s~ow response re~ui~ c on the electronics of the system.
As a v~riation on the head mo~ e, reference is made to FIGS. 18A and 18B. A single ca~ity 16 is pro~ided and sh2red by a distri~utor R and a partltioned detector PT. One mask M and one extended ba~fle 51 ~re used in this ~ho~im~nt~
The partitioned detector ~T uses three sets o~ sensors 71, 72 and 73 to detect two reflectors (the third set 73 for bac~ground illumination). Since the dist-ibutor R shares a ca~ity 16 that has been dl~ided by the ba~fle 51, the distri~utor R uses a plurality o_ emitters 74, one for each section under the mask M. As a ~urther variatlon on the head m~ 1 e, the emitters 74 can ~e broad band pulse emitters. By measuring the time elapsed for the pulses to retur~ to the head module H, the system can obtain a range R o_ the reIlector from the head module ~, by:
E~n. 9 Range = ~; m~

where c is t~e speed o~ light 5 3.998 x 10~ m/sec.
A pulse le~c~ing edge width or rise time o~
apprnxim~tely 1 nanosec~nd would sive a reso'ution or a~,~,~im~tely o.~5 m or 5.8~'. As opposed to recu -i-.g ~n electronics response time of approximat~ly mil'_se-onas ~10-3 sec) as in the separate cavi~y emDonim~nt discussed akove, this embo~im~nt typically r~qu~ _es an elec---~nics --esponse.ime o:~
approximately nanoseconds (10-9 sec). Wi,h the elapsed time me~surement providing ac~ual ran~e data ~as opFosed -o the ~5 representat-.ve leng~ L discussed above), the system using this SUtf~ JTE SHEET (RULE 26) W O 97127449 37 PCT~US97/OlOll variation o~ the head module is able to pro~ide all three coordinates o~ a re~lector w~out using a second head m~ e.
In order to tracX rotational l~lov~ ~L, the system 10 needs only two additional retro reflectors, both of which are a}so tr~rk~
S by the head ~0~ e H. It is unders~ood by one o~ ordinary ~kill in the art that the n time of ~light" ~ariation is not limited to the single-ca~ity em~odiment~ but may also be used in the separate-ca~rity ~mh~im~nt, described earlier.
While h~rkLj~u~d illumination can be cont~n~;ns ~actor in the ~mho~i m~ntS described above, the system can be ccnfigured to generate minim~l background illuminaticn, as discussed below.
Referring to FIGS. l9A and l~B, the light distributor R of the head module ~ is replaced ~y a s~nning light me~h~ni~ 76. The s~nning light me~ni~m 76 includes a plurality o~ 5~nn i n5 mirrors 78 whose ..,~ve.,._nt are guided by galvanometers 80. Light from a point light source 82 is redirected by the mirrors 78 to ~orm a scan ~eam 84 that sweeps the zone Z. Other types 20 of optical Sr~nn~5 exist, such as rotati~g wedges ~d rotatiny re~lectors, and may be u-~ed in the system.
The s~nni n5 beam 84 may ~e approximately l0 desrees wide. The beam or i1s sweeping actlon is not timed or se~uenced, but simply serves tO i~ lumi~a~e a iimited section or portion or the detection zone Z at a g~ven time. The part tioned detector PT is set with a detection threshold such that no position tracking is attempted by the system 10 i~ the beam striXes no reflector. When the beam ~4 does illnmin~t~ a rerlector, the optical intensity s.riking the par~i.ioned de~ec~or PT
exceeds the threshold anc the system l~ processes the intensity ~aria~ions detected ky the sets c~ sensors.
The par=i=ioned detec-~r PT cr t~is emDC i~nt is split into symme-~ cal components As shown in FIG.
l9B, the par=i~ioned light detec_2r P~ is di~ded in~o two StJ~ JTE SHEET (RULE 26) W O 97/Z7449 38 PCTAUS97/OlOll portions pr~ and PTb, betweer~ which the Sr-C7,nntn~ me~-h,~nie:m 76 is positioned. By splitting the partitioned detector PT, shadowing by the 5~nn; ng me~-h~ni.~m 76 is ~i 5n; f ica~tly reduced and the partitioned detector PT
5 r ~ ~-; n~ r~p~hl e of detecting radiaticn about two axes o~
resolution. The head module H of this ~mho!7;m~7t pro~ides only a one set of directional dat~ (~7~imtt~h and elevation) for a re~lector.
Because the scan beam 84 ill~min~tes only a section of the zon~ Z at a given time, this ~mh~;m~nt has a distinct advantage of lower h~k~ound i~ min~tion and may thus be preferred for applications with a large n~-mh~
o~ reflectors. Without the need to perform back g ound subtrac~ion, the system o~ this embo~im~nt can readily track multiple retro reflectors using a small num~er of filte- sensor combinations which cooperati~ely pe-~orm a "color~ analysis on the 5~gnals detected. In fact, the system can be con~igured to distinguish between a very large number (i.e. tho~c~"Aq) of spectrally-distin~,sk~hle re~lectors, using as little as two orthree sets of sensors. 0~ course, it is understood by one of ordina y skill in the art that a large- number or sets can be used.
The color analysis per-ormed by the system is much like that used by the i7--m~n eye to detect color. The eye using only three detectors (or "cones") is able to distinguish between a va~iety of colors. Correspo~;n~
the system using only three sets o~ spectrally-selecl~ Ye sensors 91, g2 and 93 as shown in FI~. lgB, can 3 0 dis~inguish between a va_iety o~ spec~rally-dis.inguishable ref' ectors.
I_ the scan beam 84 happens to s._ike mul: pie rerlec-ors simul,aneously, the system can pr~cess the sisnals in a m~nn~ - much like that used for compensating bac.~ground 3~ -min~~ or., desc~~bed above.

S113t~ JTE SHEET (RUEE 26) W O 97/27449 39 PCT~US97/OlOll The system also uses color analysis in another em~o~im~nt. Re~erring to F}GS. 20A and 2~B, the system 10 i~cludes a head mo~ule H ha~i~g a n~nn~rtitioned detector T and a partitioned distri~utor P~, with separate ca~ities 5 16~ and 16PR, separate mas~s M~ and M~, a baffle 41 and a cavity di~id~ng baf~le ~1. The part~tioned distributor PR
i~ e~uipped with different color lamps C~, C~, CD a~d C~ to radiate a different colo~ (i.e., radiation of a difrere~t wavelength) from each section. The result~ ng color msx reflected by a ~eflector is detected by the detector T
using three si~gle point sensors 95. The system analyzes the color mix detected by the detector T to obtain a set of directional data (a2imuth and ele~at~on) for that re~lector.
t5 Additional re~lectors may be tracked where the reflectors are e~uipped with shutters, such as LCD
shutters. This allows this embo~ nt o~ the system 10 to distinguish between multiple points, e.g., by timing the shutters so that the light data transmitted by each ref~ector is transmitted as pulse ~ata at di~rerent pulse rates.
Still re~erring to FIGS. 20A and 2~B, the partitioned distributor P~ i~ an alternative embc~i m~nt may be esuipped with emitters or ~ erent tem~oral frequency. That is, each section of the par~_-ioned distributor PR may house a lamp or emitter that f lickers at a distinct frequency so that the nonpart~tioned detector T is able to distinuish ~etween light from each lamp cr emitter.
While the abo~e em.~o~;m~ts of the ?resent invention are configured as optically-passive sys~ems, the invention may also be con.igured as an op~ically-ac-i~e sys~em. Refe-ring .o FIG~R~ 21, active light sou~ces 88L
and a 82r such as LEDs, replace the o~tically-~assi~e re~lectors (thereby ob~iati~.g the use of a lish~ sou-ce or SUBSTITUTESHEET(RULE26) , =~

W O 971274~9 4~ PCTAUS97/01011 li~ht dist~iDutors). With one par-itioned detector PTL, directional data for each o~ the sources 38~,~nd 882 is ob~ ~;n~A, With two parti~ion~ detec~ors PTl and PT2, positi ~n~l data in all three coordi~ates for Doth of S ~o~ ~as 88~ d 882 o~r~in~ The active lisht sources are d~sting~7i~h~hle from each other by emitti~g distins~eh~hle colors, or os~;'l~ting at disti~s~;~h~hle ~re~ s.
As another optically-active ~h~; m~nt 0~ the prese~t i~t; ~71l~ the system lQ includes the partit;~
d~stributor PR of FIG. 2OB, a~d the partitioned detector PT o~ FIG. 17. The partitioned dist_i~utor PR with the co}or lamps CAt C~, CD and CDr or em eters of d~i~ferent temporal ~reauencies, as descr~bed a~ove, may itsel~ be mounted an or otherwise atr~h~ to the object being tracked. The resulting color mix rrom the partitioned distributor PR is detected ~y the sets cf sensors 71, 72 and 73 of the partitioned detec_or PT oI FIG. 17, wh-ch now perform a color analysis on the color mix to provide a set of directional data ~or the ob;ect relati~e to t~e par;itioned detector PT.
It is noced that the acc~racy Q~ the directional per-ormance o~ the liSht dlstr_Dutor and~or light detector can ~e e~p~rically optimized usir.g a variety o~
parameters. For example, the heisht, rela,ive diameter, thic~ness, and reflectivity o~ the mas~, the width and reflectivity of the shoulders, the height and re~lectivity of the baf~le assembly, the shaDe ~nd reflecrivity or the cavity, and the phctodiode~s ~i~mQte-, all a_-ec' the light deteccor~s dirQctional rQsponse. Conversely, the dis.~iDutor~s and/or the detec_-r~s direc,~o~al per-ormance can ~e tailorQd to he ~os~7ni-or~r i. aesired, Dy varying s ecl -c parameters. Fc example, dec-~asing the dis.ance Decwee~. the mask and the ape~~u_e will 3~ dec-ease the sphe_ cal pro_ile c_ t'ae decec-~r~s r~sponse, SUBSTITUTESHErT(RULE26) W O 97/27~49 41 PCTAUS97/OlOll whil~ lncreasing the detector's ~on-axis~ ef_~clency.
When the mask is placed in the plane of the aper~-~e, the detector's "on-axis" e~ficiency i~ L~v~s to about gO~, comDared to about 40~ w~th a mask above the apertuse, but S its response prof~le is ~a~ r~d, rendering a less uci_orm detection profile. The light detecror~s spectral respcnse can also be t~ i 1 ored by using spectrally selec~ive pa~nt or. the di~usely -e lec.1ve cur~aces or a Iiitered dome or c~er.
Referriny bac~ to FIG. 1, ~or all the ~ im~rs discussed abo~e, the signals representative cf the position o_ the ob~ect tracked can be con~e~ted into video signals to drive a video mon~ror display~ns the posi_ion or ,-,~v~-,ent of the object. The reflect~rs may be i5 L~r.,ovdbly a~_ixed to the objec~, such that they can be readily tra~s~~rred between d~_ erent same e~u~pment, such as game swords or game boxing gloves.
As ~ur_her em~o~im~nts of the system, an occluded distributor or detector g8 may be con_isured to provide to a radiation or detection pro_ile that is substantially uniCorm o~er a sphe~ica} area. As illustrated in FIGS. 23A, 2~B, 23C, the occ1lded de~ice includes a tubula- memDe_ lOo havins a dlCIusely reflective inrerior su~_ace 102 def ning an interior volume or ca~ity 104. The t~bular member 100 is illustrated with a cylincrical co~~iguration; however, the member 100 need not have a ci~cular cross sect~on. The tubular mem~er 100 has open ends lQ6 pro~idin two ~per_ures 108 from which radiation may ente- nto c- exi~
from the cavi~y 104. The aper-ures 108 are const- c~i~ely occluded wi h masks M and the cavl.J 104 is d-v-de~ by a plana~ ba~~le 110 ts ~orm t~lO ha7- ~roiumes V and V. ir.side the tubula_ memDe_ 100. A ~oint element 112 is housed in each hal ~olume, at a m-dlocation aiong the lens_h c. the Sl~ LITE SHEET (RULE 26~

CA 02244242 l99X-07-22 W O 97127449 42 PCTnUS97/OlO11 ~.r .~ ~ 100. Accordi~gly, the device 98 is operational wsth respect to one axis of resolution.
Where the point element 112 is an emitter, radiation is emitted from each end 106 of the occluded de~ice 98 with a tailored distri~ution profile o~er the aperture 108. ~orres~nn~in~ly, where the poi~t eleme~t 112 is a detector, the occluded de~ice 98 detects radiation with a tailored detection profile o~er the aperture 108.
~0 For su~sr~n~ y spherical co~erage, a second occluded tubular de~ice 114 is pro~ided. The second device 114 is structured s;mil~rly to the first de~ice ~8 and thus like numerals rerer to like el~m~n~. The second de~rice 114 is positioned orthogonally tO the de~rice such that its apertures 108 are o~set substantially 90 degrees from the a~ertures 108 of the first de~ice. As the device 114 is also dlvided by the planar baffle 110, the two de~ices together are operat; on~ 1 with respect to two axes of resolution.
Additionally, the concept o~ constructed occlusion can be accompl; '~ A by reconfiguring the su~stantially ~amDertian surface int~ mulllpl~ dist~nct surfaces which can alter~atively occlude each other. As illustrated in FIGS 24A-24D, an ~nnl-l Al- or rirg structure 120 is illustrated, having an opening or otherwise nonoptical area 122 through which an axis or boresight 124 can be drawn. It is understood by one o~ ordinary skill in the art that the area 122 may alrernatlvely be non-reflecti~e and/or nontr~issi~e~ The axis 124 is ~O substantially normal to a plane with n wnicn the ring structure 120 is con-ined. The elevation ansle ~ is defined as the angle ~rom the koresight 124.
The -ing structure 120 pro~ides two distinct surfaces that can eithe~ radiate or àetec~ ht. In 3~ part cula-, the rirg str-c ure 120 i cludes a ~ rst SU~IlIUTE SHEET(RULE 26~

W O 97/27449 43 PCTnUS97/01011 ~r~n~ ~ struc'ure 126 that pro~rides a ~irst sur_ace 128 that ~aces inwardly toward the area 122. The ring structure 120 also i~cludes a second ~nn~ ~ struc;ure 130 tshown in exploded view in broken lines in FIG. Z4A) tha~
pro~ides ~ second surface 132. The second structure 130 ~ fits within the ~irst structure 126 and may reside at any predeterm~ n~ depth within the first structure 126 ~s shown by the arrow 123. Ft~ted ; nC; ~ the first structu~e 16, the second structure 130 ef~ecti~ely proiects 1~ a~gularly from the first structure 126 with the surfaces 128 and 132 ~eing angularly offset ~rom each other. I~
one embo~i m~n t, the first and second sur~aces are normal to each other, with the second surface 1~2 being substantially p~rallel with the plane or the area 122 and thus su~stantially normal to the boresight 124. While this may offer the simplest configuration, the ~irst and Qecond surfaces 128 and 132 need not be normal to each other so long as they can occlude each other as desired and any angle therebetween is known. Typically mutual selective occlusion is a~rorded if the structures 126 and 130 are nonparallel. Moreover, the second surface 132 need not be normal to the ~oresight 124 so long as any ang~e therebetween is ~nown~
Re~erring to FIG. 24C, the second s~ruc-ure 130 is situated at a lower depth within the ~irst str~c~ure 12~. Howe~er, as mentioned, the second structure 130 can also be situated at a midline o~ the ~irst stn~cture 126, as shown in FIGS. 25A-25C. Depending on ~;m~ions 134 o~
the ~irst st~c-ure 126 and 136 of the second st-~cture 130, and a spacing 137 the ~irst and second s~r~c-ures, the c-oss sec~ion K can be kept suDstantially constan, ~or most angies o~ ~. It can be seen that ~or th~ angle cr approaching the hori2cn as shown in FIG. 24C, the rst and second le~~ sur~aces 128. and 130. are unc~~luded, whereas the firs_ and second -isht sur aces are oc-luded, SlJtsS ~ JTE SHFET (RULE 26) W O 97127449 44 PCTrUSg7/01011 to pro~ide the total cross sect on K. Where the angle o~
is su~stantially zero, only the second surraces 130R ~d 130L are unoccluded, whereas hoth the flrst surfaces 128R
and 128L are effectively occluded to pro~ride the total cross section R.
Accordingly, the first and .~rn~ s~ructures 126 and 130 each constructively ~çr7~ C the surfaces of the other for different angles o~ ~, keeping the cross ~ection aroa ~ relatively constant to provide a relatively uniform radiation or detection profile. Like the occluded devices described earlier, the ring structure 120 ~s subs~nti~lly omnidirectional ~or either radiation purposes or detection purDoses.
Where the second st~ crure 1~0 is at a mid-depth in the ~irst struCturQ 126, the cross sect~on K also r~m~i nC relatively constant ~or dif~erent angles o~ ~. As shown in FIG. 25C, the left second structure 130~
constructively occludes or mas~s a portion 138 o~ the left first sur~ace 128L, while the risht ~irst structure 126R
completely occludes the right second surface 13Z~.
Accordingly, the ~irs~ and second structures. 126 and 130 each cons~ructively occludes the sur'aces or the other ~or di$feront angles of ~, keepins the c_oss sec~ion area K
relatively constant to pro~ide a relatively uni~orm radiation or detection pro~ile. In FlGS 24A-24C and 2~A-25C, the struc ure 120 is configured as a circul,r rinS; however, it c~n be conrisured in any shape, provided the opening or nonopt cal area 122 is present.
Re$erring to FIGS. 25A-25C only, to provlde at least one axis o~ reso~ution i~ rendering the s.-lc~ure 120 ~_rectional in one coorcina~Q, tne st-~ctu-e 120 is di~ided into at leas~ two discrere- pcr~ions c- segments 150. The disclosed st~uc~ure 120 o~ is di~ide~ int~- ~our segments 150a, 150~, lSOc and lSOd, as bes~ shown in-F~G.
.~5 24B, to provide two axes o_ ~esoiution rende-i3s the SU~STITUTESHEET(RULE26) -W O 97t27449 45 PCTAUS97/OlOlI
structure 120 directional in two coordin~tes, ~n the m-nn~ described earlier.
In FIG. 2~A, the sesment 150d is shown partially bro~en away to reveal the cross section view c~ segment ~SOa whic~ is representative of all the se3~nt-~ lSOa-t50d. The division in the st~ucture 120 is preferably, ~ut not necessarily, made SQ that each segme~t provides - su~st~nt;~1y symmetrical aud equal surfaces 128 and 132.
~ t}~ embo~im~n~ the 3~y~ tS l~Oa-150d are insulated ~rom each other by gaps 152 ~ lled with air or insulati~g material such t~at each sc~-.._~L is u~af~ected by the radiation or detection fu~ction o~ the others.
With the struc~ure 120 as a radiator or emitter, each or the seyments can radiate distin~;~h~hle radiation. With the structure 120 as a detec~or, the structure 120 is electrically conrigured such that each ~ ,t lSOa-150d can generate signals re~resentati~e of th~ radiation incident on the respective segment.
As a further variation, the structure 120 can be constructed out o~ silica, or a calorimetric substance that is sensiti~e to in~rared radia~ion. In that regard, the ~irst and second sur~aces 128 and 1~ 2 may De rendered a dar~ shade or co~or such that in~rared radia.ion in~ nt on the structure 120 is readily detec'~d.
Where sphe-ical coverage is desired or iate, two ring structures 120~ and 120" may be used in a back-to-back configuration as shown ~n FIGS. 29A and 2g~. In the illustrated embodiment, a sinsle non-reflectiYe and non-tr~n~ ssive memDe- 122~ is pro~ided ~etween the two struc~ures 120~ and 120~ and each or the structures 120~ and 120~ is d_~ided into the segments 15Qal-lSOd~ a~d 150a"-150~, r~spec~ively, to pro~ride r~solution about two axes (the segmenrs lSod~ and 15Qd~' are not shown and the seomen~s lSoc~ and 150c" are showr partially broken away).

SUBSTITUTE SHEET (RULE 26) W O 97/27449 46 PCT~US97/OlO
In the orientation oI FIGS. 29A and 2~B, i~ can be seen that the r~g struc~-~e 120' provides "top"
hcmispherical coverage ~d the ring structure 120"
provides ~ottom" hemispherical coverage, which together provide the spherical coverage.
Referring to FIGS. Z6A and 26B, another ~mh~; m~nt 0~ a constructively occluded, direction~l optical device 160 is illustrated. The device 160 includes a ba~e 162 constructed mueh li~e t~e ba~e 18 ~0 earlier descri~ed, except that the base 162 contalns fo~
~pherical ca~ities 164a, 164b, 164c ~nd 164d, all of which are constructively occluded by a mas~ 166 confisured from an upper portion 168 o~ the base 162. Each or the spherical cavities has a surface or aperture 167 that is 1~ occluded by the mask 166 so that the cross section area K
re~i nc substantially constant ~or most ansles o~ ~. A
plurality oî optical point el~m~ntc 1~0, either emitters or detectors, are provided, with each beiny associated with a distinct cavity.
Z0 Described another way, it can ~e seen that the four spherical cavities 164~-164d ~ointly form a larger cavity (~l;n~ted in FIG. 26B by broken line segments 169) which has been parti_ioned ~y a core section 170 o~
the base situated be~ween the Iour s~herical c~vities, on which the mask M is supported. The core section 170 acts much like the ba~fle 51 desc-ibed earlier in ena~ling the radiation in each cavity 164a-164d to r~m~i n therei~.
With the f our spherical cavities, the device oC~-rs two axes of resolution, as descriDed ea-lier.
As mentloned, tne radlaticn or detec~ion pro_ile of an occluded device in accordance with a f ea~ure o~ .he present invention can be tailore~ as desired c- needed.
As an example of an occluded device providing a nonn-ifor~, tailore~- rad~at~n or detect~on pr~_ile, rer~erencQ is made to FIGS. 33A-30C. An oc-lude dev_ce SU~Ill~TESHEET(RULE26) W O 9~127449 47 PCTrUS97/~1011 200 is shown, having a diffusely re~lective cavity 202, which in the illustrated ~mhoni m~nt, is cylinc~ical with a constant circular cross-~ection area 204. An aperture 2~6 of the cavity 202 provides a radiation or detection surface 208. The cccluded device 200 includes a di-_usely ~ re~lective mas~ M.
In this embo~imonr~ the mask M has a width WM
~ tha~ is greater than a wic~th WA Of the aperture 206 and is positioned a distance D from the surface 208 or aperture 206. For ~ mrle, the width WM may be ~,,~im~tely 0.26~", the width WA may be ,~yl,~,Limately 0.250", and the distance D may be 0.075n. In this ~mh~;m~nt, the mas~ M
overreaches and extends beyond the aperture 206. With the mas~ M so conrigured, it can be seen that a c_oss section l~ area K~ for angles of ~ i~ the horizon distr~c~ is substantially at a m~X;ml~m, a~d is r~ e~ to a cross ~ection area KF as the angle ~ is reduced. In fact, for ang}es of ~ approaching zero (i.e., normal to the aDertu-e 2Q6), the cross section K is zero, as the mask M
ZO completely occludes the aperture 206. ~ccor~ingly, the device 200 has r~ function in the elevation angles over the hemispheric area or sector which the àevice 200 faces. But ~ecause the c~oss section area g~ is substantially at a m~i m~lm and r-mzi n.~ su~stantially at the m~ximllm for all azimuth ~ngles ~i.e., 0 c p~ 360), ~he device 200 is rendered an ~imllthal device havi~g a radiation or detection pro~ile that is su~stantially u~irorm in the azimuth direc_ion at or near the hor zon district o~ the device 200.
To pro~ide resolution a~cut at leas. one axis in the azimuth directior., the device inciudes a d-~_usely rerlec~ive ba._le 214 that par~itions or divi~es t:~e cavity 202 into the sections S. Rere--ins speci_ically to ~m~o~ ment o_ FIG. 30B, the ba-~e 214 pre~era~ly, but not necessarily, div~des the cav~y 202 into fou~ sec~ SA~

S~Ill~TESHEET(RULE26) W O 97/27449 4a PCTnUS97/01011 S~, S_ and SD. AS an emitte~, the de~ e ZOO may then ~clude four emitters 220A - 220D, each o~ which is housed i~ a disti~ct ~ectio~. Much like the hemispherical partitioned distributor PT of FIGS. 20A a~d 20B, described earlier, the emi~ters 22Q can be lamps of di~erent colors or di~erent t~ ~l fre~ , except that the device 200 operates ~ t~ally, as opposed to hemispherically.
As a detector, the ~ rh~ device 200 may include a p~urality o~ detectors (al80 represented by ~0 reference n~m~als 2Z0) in a~so~i~t; ~n with the sectors.
For the device 200 to locate the azimuthal angle of ;n~ n~ light over 360 degrees in its horizon ~istrict, the ba~le 214 is con~iyured to part~tion the ca~ity 202 into at least the rour sections SA~ 59, S~ and S~, each of l~ which houses a disti~ct emitter 220.
Fcr the azimuthal device 200 to locate the azimuth angle o~ in~o~i n~ light o~er 180 degrees in its horizon district, the baffle 214 is con~igured to partition the cavity 202 i~to at least three sections that span pre~er~ly, ~ut not necessarily, 270 degrees. As shown in FIG. 3~C, the three sections may }:e sectlo~ls SA~
SD and Sc, each with its respectlve detector 220. As a fourth detector 220 is not used l~ th-s em~on;m~t for detection coverage o 180 degrees, the "nonac_i~e" section S~ is shown without a detector.
It is understood by one or o~dinary skill in the art that the plurality oI sections and/or the plurality o~
optical elements 220 associated with the sec~ions S may be tailored or changed to meet the desired ~unc-ion and op~ration or the devlce 200 as eiehe_ a par~-tioned ~zim~thal dis~- butor or a par--tioned azimu~hal detector.
As a fu_~he_ example or tailoring th~ radia~ion or detection prorile o_ the az-muthal de~ice 200, the device 200 is shown ~a FIGS ~lA~ whe_e the wld_h w~ of - 35 thé mask M is su~s.~ntia''v eaual t~ the w-~h WA C~ the SUt~5 ~ TE SHEET (RULE 26) W O 97/27449 49 PCTAUS97/~1011 a~_~ L ~ 206. It can be see~ that the t~ross section area R~ has r~m~in~ s~hstantially t~nrh~nged from that Of FIGS.
30A-30C; h~,.._v~=r, cross section area KE' Of FIG. 3iA has ~ ~creased o~er the area ~ Of FIG. 3OA.
It is noted that the optical el~m~nt.~ 220 of FIGS. 30A-30C are posi~;~n~ i~ the "bottom" of the ca~ity 202, whereas the optical el~m~n~c 220 of FIGS. 31A-31C are po8i~i~n~ on the nsides" o~ the ca~ity 202. In either ~nst~ce, the sites of the ~l~m~nts 220 within the ca~ity 202 are selected so as to avoid nhot spots," as descriDed earlier, if "hct spots" are undesira~le or disruptive.
~he ~mhO~;m~nt Of FIGS. 30A-3aC may be preferred for a ~oor-mounted ~7tm-trh~1 device and the ~mho~;m~nt o~ FIGS.
3~A-31C may be preferred for a wall-mounted ~m~thal device.
Like the ~h~ i m~nt c descrihed above, the cavity ~C2, the mask M, and/or the ba~le 214 may be dif~usely reflecti~e, and the ca~ity 202 may be any shape, although the cylindrical shape is preferred in most inst~n~c~ A
protecti~e cover 224 may also be provided.
It can be seen that the present invention provides a relatively simple and cost ef~ective system that can track the position of objec.s moving in a three-~im~ncional zone, without a large number o~ optical elQm~nt.c or complex processing electronics. Although the ~oregoing discloses the presently preferred emDo~;m~ntC of the present inv~nt; ~n, it is understood t~at the those s~illed in the art may ma~e various changes eo the pre_erred emDo~im~nts snown and descri~ed without departing _rom the scope of the i~venrion.
Accordingly, the invention is de~i~ed only by the following cl~; mc SU~ ~ JTE SHEET (RULE 26 W O 97/27449 50 PCT~US97101011 Arr:~u LCOK~r~ Ta~le fcr a~D A~; ",~ ATAN(y~x~'t80~PI() l~xd~,t 80.0)+1F~AND(x~,y~),36~.0 Azsmuth E ~n~h E~va~on o t.ocao o l~-~h,_SQRT~x'~2+y~2 0 a.g640t 0 a Q.~3452Q YVh~
a 0.88C330 X~(b+c)-(a~d)Jf(a+~c+d) 0 0.83~a4 40 y~(a~ c~d~/(a I b~c+d) 0 0.794550 - -a a.J36460 an~ ah.c.~ ale ~ ~rt r~
~ ~.685470 o Q.35t380 o a.oGaaso tO ~.at54 Q
I O O.g61:~3t O
t0 0~q3r31 Z0 Q.gts~ t0 tQ 0.1~71 40 tO 0.8701 50 t 0 0.8458 6 ~
a.77~2 70 tO 0.4tYt 80 tO o.oaao so ZQ t.0642 1~
0.~32a 10 2Q Q.~017 20 0.87~2 30 2Q 0.862Q 4a 2Q 0.82g0 ~ 0 0.J~i ~ Q ô 0 a.72s3 70 2Q 0.4B~6 ~ a Q.OQQo ga t.l547 0 Q~ay83 10 ~0 0.8408 Z Q
0.8306 30 Q.BC23 4 0 0.7543 ~ 0 0.,5~6 ôO
0.7a~?170 0.53__ 80 a.oaoo ~ a t.~aC~ O
~0 0.8 / 8 l 1 (:i Q.8t~6 sU~ ~ TE SHEET (RULE 26) CA 02244242 l998-07-22 W O 97/27449 5~ PCT~US97/OlOll Ar~ L~ A

40a.stzz ~o 4C~sQsQ 4a 4aQ~74s2 s o 4C~.730.7 6 0 400.~78 70 40o~5go4 8 0 40a.saoa ~o col~3Qs4 o .8784 ~o Q~st36 20 soo.s~2z 30 ao.scs~ 40 c~a.74s~ g o saa.73a~7 60 saa.~, 8 7a soa.~qo4 sa ~Ca.aaco ~o 6~ 47 o 6~t~.8g83 10 6QQ~s4os 2a 60Q~s3Q6 ~ o 6~~.8028 40 60Q~7s43 g o 600.7~ 6 0 6QQ.JG'21 70 liQa.';3=a 8 0 600.0000 ~a 7~t.0642 Cl 70o~g3zo tO
70~.~ot~ 20 7~0.87~ 2 30 70a.s~o 4a 70a~82~0 sa 7~ Q.. 7~7~ ~ o 7Q0.7Z~3 ~o 70C.48~ 8 a 7~o.oaoo ~a 8QI .0 t 54 0 ~00.~3 t a Q ~8 1 Z5 aoa ~l51 3a - 8Q0.88~ 1 4Q
8Qa.8~ 01 !;0 8~0.345~3 6 5 80a.~,62 ,a 8QC.41 ql 8 ~

SUBSTITUTE SHEET (RULE 26) PCTrUS97101011 W O 97/27~49 52 O.OQaO S0 g~ t.oaoo O
S0 O.g64a t Q
~0 0.~345 20 ~Q Q.8853 3 0 9~ ~.8304 4 ~0 ~J,7945 c Q
!aO a.7364 60 gQ o~Bsy4 7Q
!~0 03gt3 80 0.~000 5~ Q
t50 t.t~t~i4 0 tO0 Q.g~~3 t 0 tO0 O.g38~ Z0 tCG Q.gl~;l 30 tC0 a.8871 40 1~0 ~.8701 S0 laO Q.84S8 60 laO 0.T762 ;'0 laO 0.4tSt ~lO
~ao o.oaoo s o ltO t.0642 0 ttO C.g320 1 a tlO 0.301~ 20 l'tO Q.~7'12 30 llC ~.8020 4a tll~ 0.82~Q ~Q
llQ a.7S~Q eiO
tta 0.7Z~~ 70 tlQ a.4896 ~}0 ltO a.oooo 5~Q
120 t.l54~ 0 12Q ~.8Y83 1 0 120 a.34as 20 t20 a.8306 0 tZ0 a.8QZ~3 4a lzQ 0.7S43 5Q
t25 Q.;'~6 6 0 ~ZQ Q.;'031 ~0 t2S~ a.53~-- 8 0 tZ0 a aaoo aQ
t 30 t .~Q5~ Q
t30 a.8784 t 0 ~30 O.~l~ô 2a ~30 a.3~2z 30 1 3C a. ~ac ~ Q

SlL~ JTE SHEET (RULE 26) W O 97/27449 53 PCTAUS97/OlOll 130 0.74g2 0 t3~ a.73G7 60 ~30 ~.6~78 70 ua Q.~a4 80 t30 o.aooa ~Q
140 1.30~4 0 ~40 Q.a784 t a 140 Q 8t36 20 140 ~.8tZZ ~ O
140 Q.80~ 4~
14Q Q.74g2 50 140 0.73~7 t 0 140 0.~78 70 t40 Q.~504 80 t4~ 2.Q~Q0 ~ 0 t co 1.1 ~47 0 150 0.~83 10 150 G.8408 20 Q 0.8306 30 ~50 O.aOZ8 40 co 0,~4~3 50 tSQ 0.7-76 6Q
t50 0.703~ 70 leO 0.5~aa 80 t~0 o.oaao ~Q
t6~ t.064Z Q
t6~ O.q3Z0 10 t6Q a.q,ot~ 20 16~ Q.87t~ 30 160 Q.8620 40 16~ Q.8~qO S 0 160 a 7~Jo 6Q
~60 Q.7Z~ 7~
t 60 Q.48~6 8 Q
t6Q O.QQaO ~0 t 70 t .Ql -~4 0 t70 0.~66~ 10 t70 Q.-q381 20 t70 Q.~t-~t 30 170 0.887t 1 4a 170 0.8701 ~0 t70 Q.84g8 60 ~70 a.7~62 70 t70 a.4tq~ 80 t70 o.oaoo ~ 3 t ~0 t .oaao SUBSTITUTE SHEET (RULE 26) W o 97127449 54 PCTAUS97/OlO
A~r~L~

18~ Q.964~ t 0 t80 O.g345 20 t80 a.8~3 3a t~0 a.83a4 40 t80 Q.7~45 ~ Q
180 ~.7364 50 ~80 0.58~4 7Q
180 Q03~13 aQ
t8Q 0~00~0 gO
t~0 ~.0~54 0 1~0 a g663 t o t~0 ~.g381 2Q
t~0 O.gl51 3Q
tgO ~.8871 40 tgO a.8701 50 t ~0 0.8458 60 t~0 0.77~Z 70 t$Q Q.4~ 51 8 Q
~gO Q.OOOQ ~0 2ao t.0642 a 2~0 Q.g320 t 0 200 O.gOt7 20 2Q0 ~.8712 30 200 0.862D 40 2~0 Q.82~0 SQ
2~0 0.757~ 60 200 0.72e3 70 2~0 0.48g6 8 Q
2ao a.QaaO ~ 0 2~0 1.1547 0 2~0 0.8583 I Q
210 Q.8408 20 2~Q Q.8306 30 2tO Q.8C28 40 2~0 Q.7~43 so 2tO Q.7 76 60 210 Q.~03~ ~0 Z~ Q Q.~3_3 ~ 0 z~o o.oaoo so ZD t.3a~4 0 2~0 Q.878¢ t 0 Z20 0.8t~6 20 Z20 0.~1z 3~
~a a.8a~0 4a ZQ a ~ Z --~
Q ~3~

S~ TE SHEET (RULE 26) PCTAUS97/OlOll Arr~

22~ Q~6~7s ~ o 2~0 Q~5~04 80 22~ o.oaoo - ~o 23C 1.3QS4 o 230 0.8784 t~
2~a Ol~t~6 20 ~30 ~.8t2 ~o - 2~0 a.8ago 4a 23a 0.74s~2 ~o 2~0 a.7307 ~
230 O.Eg78 7 0 2~a Q~iQa4 80 230 o~ooco ~o 240 l.t547 o 24a a.s~s3 t 0 240 0.840~ 20 2~0 a.s306 3Q
Z40 a.8a28 40 240 a.7~4~ 50 240 0.7~ 6a 240 0.7~3t 70 z~ Q~3s- 80 24~ O.Qt~00 5 0 2s~ t.0642 0 2SI~ Q,C3Z0 t 0 o.sc~7 20 a.s7t 23 0 z~ a.86zQ 40 z ~ Q~sz~o ~o 2 o Q~7s7a 50 2CO a~?~s3 70 2~ 0.4qS6 8Q
2C0 a.oGQo ~a 1.0154 0 2sQ Q~36s~ l ~
25~ Q~s3sl ZQ
2~a O.gt-l 30 2~:1 Q~s~7~ 40 Z~~ a.8~01 ~iO
2~i0 0.84!~36 a 260 Q.7~Z ~a 2f;0 0.41 ill 8G
26Q o.aaao ~a 2~0 t oaaa a 2~ ~ Q ~a t a Z~O O.33t3 20 SUBSTITUTE SHEET (RULE 26) W O 97/27449 PCT~US97/OlOll ~r~

Z~~ 0.88~3 3a 2J0 0.83a4 40 Z70 a.7~45 5~
ZJ~ 0.7364 6 0 2~0 O. 8g4 70 ~70 0.3913 80 Z7O ~.ooao ~Q
280 t .Q1 ~4 2~0 ~.9663 1 0 2110 ~381 Z0 280 O.91!il3 Q
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280 0.4~- sa 28Q O.Q000 g 0 2gC 1.06~2 0 2!~0 O.g3ZD t Q
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SUt~ JTE SHEET (RULE 26) WO 97/27~49 57 A~r~ ~ 'L~ A

3~0 a.ac~o ~a 320 t.30~4 a 3~a 0.8784 ~ 0 3Z~ Q.8t3~ 2~
~ 320 a.8~zz 30 320 a.so 0 43 320 0.749Z ~ Q
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330 0.8~08 2Q
330 Q.8306 3a 33~ 0.8028 40 ~'30 0.7~43 50 330 ~.7~7~ 60 330 a.7a3t 7Q
330 a~ 80 330 O.OQ00 gO
340 1.5642 0 340 0~3Z~ 10 340 O.qO~7 Z0 340 0.87t 2 30 340 0.8E20 40 340 0.82g~ 5 Q
340 0.7~7Q 6 Q
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350 G.7~2 70 3~0 a4tg~ ao 3~0 a oa~o gQ

SUBSTITUTE SHEET ~RULE 26)

Claims (25)

We claim:

1. A radiant energy transducing apparatus comprising:
a base having a diffusely reflective surface and an optical area defining a horizon district with respect to the transducing apparatus;
a mask spaced from the base and positioned to occlude a portion of the optical area so as to present a substantially constant portion of the optical area over a range of angles above the horizon district; and an electromagnetic transducer transducing between radiation associated with the optical area and corresponding signals.

2. An apparatus as in claim 1, wherein the base comprises a diffusely reflective cavity, and the optical area is an aperture of the cavity.

3. An apparatus as in claim 2, wherein the cavity is substantially hemispherical.

4. An apparatus as in claim 2, wherein the cavity is substantially cylindrical.

5. An apparatus as in claim 1 or claim 2, further comprising a baffle dividing the region between the mask and the optical area into a plurality of sections, wherein the electromagnetic transducer comprises a plurality of electromagnetic sensors each responsive to radiation in a distinct one of the sections.

6 An apparatus as in claim 5, further comprising a second plurality of sensors each responsive to radiation in a distinct one of the sections, wherein each plurality of sensors is responsive to a different type of radiation.

7. An apparatus as in claim 6, wherein the different types of radiation differ in wavelength.

8. An apparatus as in claim 6, wherein the different types of radiation comprise radiation pulsing at different rates.

9. An apparatus as in claim 1 or claim 2, further comprising a baffle dividing the region between the mask and the optical area into a plurality of sections, wherein the electromagnetic transducer comprises a plurality emitters each emitting radiation through a distinct one of the sections.

10. An apparatus as in claim 9, further comprising a second plurality of emitters each emitting radiation through a distinct one of the sections, wherein each plurality of emitters emits a different type of radiation.

11. An apparatus as in claim 10, wherein the different types of radiation differ in wavelength.

12. An apparatus as in claim 10, wherein the different types of radiation comprise radiation pulsing at different rates.

13. An apparatus as in claim 1 or claim 2, further comprising a light deflector positioned between the mask and the optical area.

14. An apparatus as in claim 13, wherein the light deflector comprises a diffusely reflective cone.

15. An apparatus as in claim 13, wherein the light deflector comprises a baffle.

16. An apparatus as in claims 2, 3, or 4, wherein the electromagnetic transducer emits light into the cavity.

17. An apparatus as in claim 16, wherein the electromagnetic transducer emits light into the cavity from a location on a surface of the mask facing the aperture of the cavity.

18. An apparatus as in claim 16, wherein the electromagnetic transducer emits light into the cavity from a point on a wall of the cavity.

19. An apparatus as in claims 2, 3, or 4, wherein the electromagnetic transducer detects light in the cavity.

20. An apparatus as in claim 19, wherein the electromagnetic transducer detects light reflected from the cavity to a location on a surface of the mask facing the aperture of the cavity.

21. An apparatus as in claim 19, wherein the electromagnetic transducer detects light incident on a point on a wall of the cavity.

22. An apparatus as in claim 1 or claim 2, wherein a surface of the mask facing the optical area is diffusely reflective.

23. An apparatus as in claim 1 or claim 2, wherein:

the electromagnetic transducer comprises an optical emitter for radiating light in response to the electrical signals; and the mask intercepts a portion of the light radiating from the emitter, such that the apparatus substantially uniformly illuminates a range of azimuths and elevations of a hemispherical region above the horizon district.

24. An apparatus as in claim 23, wherein a surface of the mask facing the optical area is diffusely reflective.

25. An apparatus as in claim 1 or claim 2, wherein:
the electromagnetic transducer comprises an optical sensor for generating the electrical signals in response to incident light detected by the optical sensor; and the mask intercepts a portion of incident light from the optical area and the sensor, such that the apparatus has a substantially uniform sensitivity to light incident from a range of azimuths and elevations of a hemispherical region above the horizon district.

25. An apparatus as in claim 25, wherein a surface of the mask facing the optical area is diffusely reflective.