GB2025724A - An optical scanner with mirror oscillating to triangular wave form - Google Patents
An optical scanner with mirror oscillating to triangular wave form Download PDFInfo
- Publication number
- GB2025724A GB2025724A GB7829813A GB7829813A GB2025724A GB 2025724 A GB2025724 A GB 2025724A GB 7829813 A GB7829813 A GB 7829813A GB 7829813 A GB7829813 A GB 7829813A GB 2025724 A GB2025724 A GB 2025724A
- Authority
- GB
- United Kingdom
- Prior art keywords
- mirror
- magnetic
- magnetic means
- light rays
- triangular wave
- 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
- 230000003287 optical effect Effects 0.000 title claims abstract description 13
- 230000010355 oscillation Effects 0.000 claims description 6
- 239000000872 buffer Substances 0.000 claims description 5
- 230000005405 multipole Effects 0.000 claims description 2
- 239000000725 suspension Substances 0.000 claims description 2
- 230000003534 oscillatory effect Effects 0.000 description 19
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 230000009466 transformation Effects 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
A mirror apparatus (2, 3) is provided for use in generating line image rasters in an optical system comprising a lens (1) to direct light rays to the mirror (2) and a photo-electric receiver (6) to receive light rays from the mirror (2). The mirror arrangement (2, 3) comprises a mirror (2) and magnetic means (3) to so oscillate the mirror (2) about a varying transverse axis thereof that the mirror oscillates with a substantially triangular wave form. This mirror apparatus (2,3) enables optical errors to be reduced. <IMAGE>
Description
SPECIFICATION
Oscillatory mirror apparatus for an optical system
The present invention relates to a mirror apparatus for use in an optical system. Such a system may be used for scanning and reproducing IR-images and may comprise an entry lens, a correcting lens, an oscillatory mirror, a transformer and an IR-detector.
A reproduction unit may be constructed in a similar form.
Scanning and reproduction systems for the linear scanning of an image field are already known. In several of the known systems, the image field scanning is undertaken through an oscillatory mirror. The oscillatory mirror is arranged in a convergent ray path behind the entry lens. This arrangement has the disadvantage in conventional systems that the image plane is displaced, which leads to distortion on movement of the mirror. The image must therefore be corrected by appropriate lens or mirror systems in order to reduce the absorption losses and maintain the quality of resolution. This requires additional optical effort.
In another system, the mirror is so pivoted that it oscillates nearly on a circular path. Although the image quality remains maintained with uniform motion in this case, the time-distance curve is however sinusoidal, thus, thickening of the image point occurs at the start and at the end of the image field, while thinning of the image point occurs in the centre.
According to the present invention there is provided a mirror apparatus for use in generating line image rasters in an optical system comprising means to direct light rays to the mirror and photoelectric receiver means to receive light rays from the mirror, the mirror arrangement comprising a mirror and magnetic means arranged to so oscillate the mirror about a varying transverse axis thereof that the mirror oscillates with a substantially triangular wave form.
The apparatus may comprise suspension means to mount the mirror and drive means to actuate the magnetic means in such a manner that the mirror in use so oscillates that its plane describes a previously determined arcuate path.
The apparatus may comprise guide means disposed at each of respectively opposite sides of the mirror and each provided with an arcuate guide surface.
The apparatus may comprise spring means to support the mirror.
The magnetic means may comprise a single pole magnetic means or multi-pole magnetic means.
The apparatus may comprise electronic drive
means to co-operate with the magnetic means in the generation of a magnetic field for the oscillation of the mirror.
The apparatus may comprise a generally troughshaped member in which the mirror is mounted, the generally trough-shaped member being provided with projection means which engage in guide means.
The apparatus may comprise buffer means adjacent the generally trough shaped member to buffer the oscillation of the mirror.
The triangular wave form comprises equal forward and flyback periods.
In an IR-image scanning system which comprises an entry lens, one or more receiving calls arranged in series or parallel, a transformer system and a planar oscillatory mirror apparatus arranged between the entry lens and the transformer system, bearing and drive of the mirror may be so constructed that a motional course of the scanning beam, which nearly corresponds to a triangular function, is attained through displacement of the rotational centre during the oscillation and appropriate programming of the magnetic means.
The displacement of the rotational centre during the oscillatory motion and the control of the magnetic means may be such that the mirror is moved uniformly and by its image plane oscillates on a previously calculated curved track.
Further, the curved track may be so calculated that its curvature accurately corresponds to the optical error curve.
The mirror apparatus is particularly simple when the oscillatory mirror is guided by lateral projections in two curved tracks and urged by springs against the track.
An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which Figure 1 shows schematically an optical scanning system comprising an oscillatory mirror apparatus,
Figure2 shows in three sections an oscillatory mirror apparatus provided with magnetic drive,
Figure 3 shows a rolling process of the mirror plane of the oscillatory mirror along a notional curve, and
Figure 4 shows the motional characteristic of the oscillatory mirror apparatus nearly attainable by the invention.
Referring to the accompanying drawings, an optical scanning system shown in Figure 1 comprises an entry lens 1 which receives parallel light rays and converts them into a convergent ray bundle, an oscillatory mirror 2 arranged in the convergent ray path with a magnetic drive 3, a deflecting mirror4, a transformation optical system 5 and a receiving cell 6. The deflecting mirror 4 can be constructed as a tilting mirror and then takes over the line shift, while the oscillatory mirror scans the individual lines. Only one receiving cell is shown in Figure 1, but several receiving cells may be arranged above or beside one another. If the receiving cells are arranged above one another, several lines are written simultaneously during one oscillation.
The oscillatory mirror apparatus is shown to a somewhat larger scale in Figure 2 in which:
(a) shows a view taken along a line A - A of (c),
(b) shows a view taken along a line B - B of (c), and
(c) shows a view taken along a line C - C of (b).
The oscillatory mirror 2 sits in a generally troughshaped member 12 having two walls which are opposite each other and which by spigots engage in guide slots of a lateral guide 8. Two helical springs 9 and 19 urge the trough-shaped member upwardly.
The mirror 2 is exited into oscillatory motion by magnets 13 and 23 which are driven by an electronic system (not shown).
The control of the oscillatory motion is so programmed that the oscillatory motion of the mirror corresponds to a rolling motion ofthe mirror plane on an accurately calculated curve 7 (Figure 3), in which case approximately the motional characteristic shown in Figure 4 occurs.
The accuracy of the oscillatory motion can be improved if small buffers 10 and 20 are mounted below the oscillating ends of the trough-shaped member 12 to absorb the thrust shortly before the end ofthe motion an a given direction and return it resiliently.
It is an advantage of the embodiment of the present invention described above that optical errors are reduced to a minimum and oscillating parts can be kept small and light and furthermore that the characteristic (time-distance curve) is nearlytriangular.
Claims (10)
1. A mirror apparatus for use in generating line image rasters in an optical system comprising means to direct light rays to the mirror and photoelectric receiver means to receive light rays from the mirror, the mirror arrangement comprising a mirror and magnetic means arranged to so oscillate the mirror about a varying transverse axis thereof that the mirror oscillates with a substantially triangular wave form.
2. An apparatus as claimed in claim 1, comprising suspension means to mount the mirror and drive means to actuate the magnetic means in such a manner that the mirror in use so oscillates that its plane describes a previously determined arcuate path.
3. An apparatus as claimed in either claim 1 or claim 2, comprising guide means disposed at each of respectively opposite sides of the mirror and each provided with an arcuate guide surface.
4. An apparatus as claimed in any one of the preceding claims, comprising spring means to support the mirror.
5. An apparatus as claimed in any one of the preceding claims, wherein the magnetic means comprises a single pole magnetic means.
6. An apparatus as claimed in any one of claims 1 to 4, wherein the magnetic means comprises a multi-pole magnetic means.
7. An apparatus as claimed in any one of the preceding claims, comprising electronic drive means to co-operate with the magnetic means in the generation of a magnetic field for the oscillation of the mirror.
8. An apparatus as claimed in any one of the preceding claims, comprising a generally troughshaped member in which the mirror is mounted, the generally trough-shaped member being provided with projection means which engage in guide means.
9. An apparatus as claimed in claim 8, comprising buffer means adjacent the generally troughshaped member to buffer the oscillation of the mirror.
10. A mirror apparatus substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7829813A GB2025724B (en) | 1978-07-13 | 1978-07-13 | Optical scanner with mirror oscillating to trangular waveform |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7829813A GB2025724B (en) | 1978-07-13 | 1978-07-13 | Optical scanner with mirror oscillating to trangular waveform |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2025724A true GB2025724A (en) | 1980-01-23 |
| GB2025724B GB2025724B (en) | 1982-09-29 |
Family
ID=10498428
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7829813A Expired GB2025724B (en) | 1978-07-13 | 1978-07-13 | Optical scanner with mirror oscillating to trangular waveform |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2025724B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5313137A (en) * | 1989-11-30 | 1994-05-17 | Wittey Malcolm G | Display devices |
| EP0614103A1 (en) * | 1993-03-03 | 1994-09-07 | Thomson-Csf | Infrared telescope with oscillating mirrors |
-
1978
- 1978-07-13 GB GB7829813A patent/GB2025724B/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5313137A (en) * | 1989-11-30 | 1994-05-17 | Wittey Malcolm G | Display devices |
| EP0614103A1 (en) * | 1993-03-03 | 1994-09-07 | Thomson-Csf | Infrared telescope with oscillating mirrors |
| FR2702283A1 (en) * | 1993-03-03 | 1994-09-09 | Thomson Csf | Oscillating mirror bezel for infrared vision. |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2025724B (en) | 1982-09-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |