GB2110897A - Imaging systems - Google Patents
Imaging systems Download PDFInfo
- Publication number
- GB2110897A GB2110897A GB07835096A GB7835096A GB2110897A GB 2110897 A GB2110897 A GB 2110897A GB 07835096 A GB07835096 A GB 07835096A GB 7835096 A GB7835096 A GB 7835096A GB 2110897 A GB2110897 A GB 2110897A
- Authority
- GB
- United Kingdom
- Prior art keywords
- rotor
- rotors
- mirrors
- imaging system
- scene
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000003384 imaging method Methods 0.000 title claims abstract description 14
- 230000005855 radiation Effects 0.000 claims abstract description 10
- CCOXWRVWKFVFDG-UHFFFAOYSA-N pyrimidine-2-carbaldehyde Chemical compound O=CC1=NC=CC=N1 CCOXWRVWKFVFDG-UHFFFAOYSA-N 0.000 claims 1
- 229910000661 Mercury cadmium telluride Inorganic materials 0.000 abstract description 2
- MCMSPRNYOJJPIZ-UHFFFAOYSA-N cadmium;mercury;tellurium Chemical compound [Cd]=[Te]=[Hg] MCMSPRNYOJJPIZ-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
- H04N3/02—Scanning details of television systems; Combination thereof with generation of supply voltages by optical-mechanical means only
- H04N3/08—Scanning details of television systems; Combination thereof with generation of supply voltages by optical-mechanical means only having a moving reflector
- H04N3/09—Scanning details of television systems; Combination thereof with generation of supply voltages by optical-mechanical means only having a moving reflector for electromagnetic radiation in the invisible region, e.g. infrared
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Electromagnetism (AREA)
- Toxicology (AREA)
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Mechanical Optical Scanning Systems (AREA)
Abstract
An imaging system includes first and second scanning rotors 1, 2 having sets of (n1+n2) and n1 plane mirrors, respectively, (where n1=5 and n2=1, for example), the sets of mirrors extending around the rotor axes W1, W2, the adjacent mirrors in each set being inclined at different angles to the rotor axis and the rotors being arranged such that radiation from a scene may be reflected from one set to the other and thence to a detector, and means for driving the first rotor 1 at <IMAGE> x the speed of the second rotor 2. Where the system is used with infrared radiation, the detector is composed of cadmium mercury telluride and its output is connected to a cathode ray tube to form a display of the scene being scanned. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to imaging systems
The present invention relates to imaging systems and particularly, though not exclusively, to imaging systems which collect infra-red radiation from a scene and produce an image of the scene by means of a rotating scanner.
A known imaging system employs a rotating prism which has reflecting facets and a flapping mirrorfor sweeping a scanned image of a scene onto a detector which is responsive to the radiation from the scene. Such a system requires accurate synchronisation between the rotating prism and the flapping mirror.
Another known system employs a rotor with facets which are inclined so as to produce a banded scan. In this system it is necessary to have a large number of plane surfaces and consequently a large rotor to produce a satisfactory image.
According to the present invention an imaging system includes first and second scanning rotors having sets of n, and (n, + n2) plane mirrors, respectively, (where n, and n2 are integers) the sets of mirrors extending around the rotor axes, wherein the adjacent mirrors in each set are inclined at different angles to the rotor axis and wherein the rotors are arranged such that radiation from a scene may be reflected from one set to the other and thence to a detector, and means for driving the first rotor at
(n, + n2) -----x the speed of the second rotor.
n,
In a preferred form of the invention, the rotors are of truncated pyramidal configuration, the one facing the other.
The rotors may be driven at constant speeds or one or both rotors driven intermittently to achieve a particular scanning pattern.
The system may include means for producing an afocal image of the scene at one of the rotors.
The mirrors of each set may be attached to a rotor bodyorthe mirrors may be integrally formed with the rotor body by, for example, polishing plane faces of the rotor.
The invention will now be described by way of example only, with reference to the accompanying drawings of which:
Figure lisa schematic plan view of an imaging system
Figure 2 is a perspective view of a pyramidal rotor
pair of the system shown in Figure 1.
The imaging system shown in Figure 1 includes an afocal lens system L, which focuses infra red radiation from a source Son a six sided scanning rotor 1 which reflects the radition from its sides which con
stitute plane mirrors onto a scanning rotor, 2, having five sides which also constitute plane mirrors and
which then reflects the radiation from its sides onto a
single detector, D, composed of cadmium mercury telluride whose output is connected to a cathode ray
tube C to from a display of the source in a conventional manner.
The scanning rotors 1,2 are driven by an-electric motor via a gearbox (not shown) and are rotated in the same direction at constant speeds W1 and W2, respectively, where the speed ratio
W, equals the ratio N2 = 5 (where N, and N2 are 6
W2 N1 the number of sides of the rotors 1 and 2 respectively). The rotors are machined from aluminium bar and the sides are highly polish planar reflectors.
Successive sides of each rotor are inclined at progressively increasing angles to the rotor axis as shown in Table 1 below. The total angle that the incident radiation is reflected through is 2#( 1 + 1 )whereN,and N,arethenumberof N1 N2 sides on the rotors 1 and 2.
(i) Rotor 1 2.5 5 7.5 10 12.5 15 2.5 5 7.5 10 12.5 15 2.5 5 7.5 (ii) Rotor 2 0.5 1.0 1.5 2.0 2.5 0.5 1.0 1.5 2.0 2.5 0.5 1.0 1.5 2.0 2.5 (iii) Angular Difference 2.0 4.0 6.0 8.0 10.0 14.5 1.5 3.5 5.5 7.5 12.0 14.0 1.0 3.0 5.0 (degree) (iv) Coinoiding-pair 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 number (i) Rotor 1 10 12.5 15 2.5 5 7.5 10 12.5 15 2.5 5.0 7.5 10.0 12.5 15 (ii) Rotor 2 0.5 1.0 1.5 2.0 2.5 0.5 1.0 1.5 2.0 2.5 0.5 1.0 1.5 2.0 2.5 (iii) Angular Difference 9.5 11.5 13.5 0.5 2.5 7.0 9.0 11.0 13.0 0 4.5 6.5 8.5 10.5 12.5 (degree) (iv) Coinoiding-pair 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 number In Table I lines (i) and (ii) give the angles of each mirror with respect to a fixed datum for the rotors 1 and 2, each column containing the angles for an aligned pair of mirrors.Line (iii) gives the difference between the angles in (i) and (ii) for the aligned pairs and line (iv) gives reference numbers fo the aligned pairs in order of coincidence as rotors 1 and 2 rotate.
As the rotors rotate, radiation is reflected from a first pair of sides which are aligned and then by subsequent aligned pairs until the fifth pair has come into alignment. The next reflection in the sequence is from the sixth side of rotor 1 to the first side on rotor 2. The sequence continues for alignment of 30 pairs of sides, which constitutes one cycle (and therefore a single scan of the source, S) which is then repeated.
Table 1 above shows alignments of rotor sides over one cycle. The display produced by the system shown in Figures 1 and 2 has 30 bands, each band corresponding to an aligned pair of sides. The relative position of each band within a final display of the source S, created by the collection of bands over a cycle is indicated by the value of the angular difference given in line (iii) of Table 1. The scanning pattern (ie the manner in which the bands go together to form a complete display) of the imaging system is therefore illustrated by Table 2 below which correlates the coinciding pair numbers of line (iv) in Table 1 with the angular differences of line (iii).
2
ANGULAR DlmRENcE (DEGREES) COINCIDING PAIR NUMBER
The sides of the rotor are only exactly aligned at the centre of each line scan and they are in error by #[(1/N1) - (1/N2)] at the extremities of the scan, where ss is the scan efficiency. The result of this alignment error is antisymmetric distortion in the display. Hence it is important that [(11N1) - (11N2)] is minimised.
Claims (5)
1. An imaging system including first and second scanning rotors having sets of n1 and (nt + n2) plane mirrors, respectively, (where n1 and n2 are integers), the sets of mirrors extending around the rotor axes, wherein the adjacent mirrors in each set are inclined at different angles to the rotor axis and wherein the rotors are arranged such that radiation from a scene
many be reflected from one set to the other and thence to a detector, and means for driving the first
rotor at
(n, + n2) - x the speed ofthe second rotor.
n,
2. An imaging system as claimed in claim 1 wherein the rotors have a common rotational axis.
3. An imgaging system as claimed in claim 1 or
claim 2 wherein each set of rotors is of truncated
pyrimidal configuration.
4. An imaging system as claimed any previous
claim including means for producing an afocal
image of a scene on one of said rotors.
5. An imaging system as described herein with reference to the accompanying drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB07835096A GB2110897B (en) | 1977-09-13 | 1978-08-31 | Imaging systems |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3815877 | 1977-09-13 | ||
GB07835096A GB2110897B (en) | 1977-09-13 | 1978-08-31 | Imaging systems |
Publications (2)
Publication Number | Publication Date |
---|---|
GB2110897A true GB2110897A (en) | 1983-06-22 |
GB2110897B GB2110897B (en) | 1983-11-30 |
Family
ID=26263710
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB07835096A Expired GB2110897B (en) | 1977-09-13 | 1978-08-31 | Imaging systems |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2110897B (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0213866A2 (en) * | 1985-08-22 | 1987-03-11 | Rank Pullin Controls Limited | Imaging apparatus |
EP0226273A1 (en) | 1985-09-27 | 1987-06-24 | The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and | Improvements in or relating to rangefinders for imaging systems |
GB2196441A (en) * | 1983-02-11 | 1988-04-27 | British Aerospace | Optical-mechanical scanning apparatus |
US5574592A (en) * | 1992-12-24 | 1996-11-12 | Fuji Electric Co., Ltd. | Rotatable polygon mirror |
-
1978
- 1978-08-31 GB GB07835096A patent/GB2110897B/en not_active Expired
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2196441A (en) * | 1983-02-11 | 1988-04-27 | British Aerospace | Optical-mechanical scanning apparatus |
EP0213866A2 (en) * | 1985-08-22 | 1987-03-11 | Rank Pullin Controls Limited | Imaging apparatus |
US4763192A (en) * | 1985-08-22 | 1988-08-09 | Rank Pullin Controls Limited | Imaging apparatus |
EP0213866A3 (en) * | 1985-08-22 | 1988-09-14 | Rank Pullin Controls Ltd | Imaging apparatus |
EP0226273A1 (en) | 1985-09-27 | 1987-06-24 | The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and | Improvements in or relating to rangefinders for imaging systems |
US4733072A (en) * | 1985-09-27 | 1988-03-22 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Rangefinder for imaging system eliminating effect of rotor rotation |
US5574592A (en) * | 1992-12-24 | 1996-11-12 | Fuji Electric Co., Ltd. | Rotatable polygon mirror |
Also Published As
Publication number | Publication date |
---|---|
GB2110897B (en) | 1983-11-30 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PE20 | Patent expired after termination of 20 years |
Effective date: 19980830 |