JPH0248884B2 - - Google Patents

Description

Claim 1: An optical-mechanical scanning mechanism for use in an imaging device that scans a two-dimensional object field, comprising: A. receiving radiant energy originating from the object field and proceeding along a first optical path 28; a vertical scanning plane reflector arrangement 21 arranged to reflect energy along a second optical path 20 separate from said first optical path 28; B a first axis 24 generally perpendicular to said first optical path 28; around the vertical scanning plane reflector device 2
Vertical scanning drive device 4 that changes the angular position of 1
5. C receiving the radiant energy reflected from the vertical scanning reflector device 45 and traveling along the second optical path 20, and transmitting the radiant energy to a third optical path separate from the second optical path 20; 3
8 and above the vertical scanning reflector apparatus, the vertical scanning reflector 21 thereby directing the radiant energy into the first optical path. 2
A fourth optical path 3 different from 8 and reaching the image field
9, and D a second light path substantially orthogonal to the second and third optical paths.
a horizontal scanning drive device 46 for changing the angular position of the horizontal scanning plane reflector device about the axis 25 of the horizontal scanning plane reflector device;
the first, second and third optical paths are not blocked; E a radiant energy detection device 30 for detecting radiant energy disposed in the fourth optical path 39; and F an optical focusing device 3 for imaging an elemental area of the object field onto the radiant energy detection device;
5. An optical mechanical scanning mechanism comprising:

2. The first axis 24 is substantially perpendicular to the first optical path 28, and the second axis 25 is substantially perpendicular to the second optical path 20 and the third optical path 38. The optical mechanical scanning mechanism according to paragraph 1.

3. The optical mechanical scanning mechanism of claim 1, wherein the radiant energy sensing device is an infrared detector.

4 the second axis 2 of the horizontal scanning drive device
3. The optical mechanical scanning mechanism according to claim 2, wherein 5 is substantially parallel to the first optical path 28 and substantially orthogonal to the first axis 24 of the vertical scanning drive.

5. The radiant energy sensing device 30 includes a dual focus radiant energy detector, such that when the horizontal scanning reflector device performs a single horizontal sweep, two horizontal lines within the object field are detected. The optical mechanical scanning mechanism according to item 2.

6. When the vertical scanning reflector device is driven by the vertical scanning drive device to rotate about the first axis in a vibratory manner at the same frequency as the vertical scanning frequency of the deflection circuit of the television; The horizontal scanning reflector device includes a mirror made of beryllium having low inertia and is driven to rotate in an oscillatory manner about the second axis 25 at a frequency that is a submultiple of the horizontal scanning frequency of the television deflection circuit. The horizontal scan drive includes a torsional resonator device, and the vertical scan drive moves the vertical scan reflector in one vertical direction.
3. An optical-mechanical scanning mechanism as claimed in claim 2, including means for linearly sweeping in one direction and then returning said vertical scanning reflector to an initial sweep position.

7. When the vertical scanning reflector device is driven by the vertical scanning drive device to rotate about the first axis in a vibratory manner at the same frequency as the vertical scanning circumferential velocity of the display circuit of the television. comprising a low mass mirror having low inertia, said horizontal scanning reflector device being driven to rotate in an oscillatory manner about said second axis at a frequency that is a submultiple of the horizontal scanning frequency of a television display circuit. 3. The optical mechanical scanning system of claim 2, wherein said vertical scanning drive and said horizontal scanning drive both include torsional resonator devices including a low mass beryllium mirror having low inertia. mechanism.

8. The vertical scanning reflector device has a low inertia when driven by the vertical scanning drive device to rotate in an oscillatory manner about the first axis at a frequency that is the same as the vertical frequency of the deflection circuit of the television. a low mass mirror having a low mass, the horizontal scanning reflector device being adapted to rotate in an oscillatory manner about the second axis at a frequency that is a submultiple of the horizontal scanning frequency of the television display circuit. The vertical scanning drive device and the horizontal scanning drive device each include a mass of beryllium reflectors, and the vertical scanning drive device and the horizontal scanning drive device respectively move the vertical scanning reflector and the horizontal scanning reflector in the vertical direction and the horizontal direction.
3. The optical-mechanical scanning mechanism of claim 2, including means for linearly sweeping in one direction and then returning each vertical and horizontal scanning mirror to its initial sweep position.

9. the first optical path 28 and the third optical path by footprint mapping on the vertical scanning reflector device such that the vertical scanning reflector device and the horizontal scanning reflector device have maximum angular displacement; 7. The surface area of the vertical scanning reflector device is reduced from 38 to the area traversed by reflections incident on the vertical scanning reflector device. The optical mechanical scanning mechanism according to any one of the above.

10. The opto-mechanical scanning mechanism of claim 2, wherein said horizontal scanning plane reflector device is arranged at a nominal angle of inclination of 40° to 60° with respect to said first optical path.

11 a fixed reflector arrangement 2 arranged to receive radiant energy from said fourth optical path 39 and thereby direct said radiant energy to said sensing device;
3. The opto-mechanical scanning mechanism of claim 2, comprising: 3.

12 directing the radiant energy traveling in the fourth optical path 39 back toward the vertical scanning reflector device 58 and along a fifth optical path 70, thereby effecting a third reflection; and mark a third footprint 71 of this reflection on the vertical scanning reflector device, thereby further increasing the vertical sweep range of the object field when the vertical scanning reflector device performs a predetermined vertical sweep. 3. A third reflector arrangement 57 located at the vertical scanning reflector arrangement, wherein said radiant energy is reflected from said vertically scanning reflector arrangement and travels along a sixth optical path 72 to said radiant energy sensing arrangement. optical mechanical scanning mechanism.

13 redirecting the radiant energy traveling along the fourth optical path 39 toward the vertical scanning reflector device 58 and along a fifth optical path 70, thereby causing a third reflection 71 and The radiant energy is reflected from the vertically scanning reflector device to the horizontally scanning reflector device 59, including a third reflector device 57 that marks a third footprint 71 by reflection on the vertical reflector device. The radiant energy travels along a directed sixth optical path 72, thereby making a second reflection 80 and leaving a second footprint 80 of the reflection on the horizontal scanning reflector arrangement, wherein the radiant energy is 3. The optical-mechanical scanning mechanism of claim 2, wherein the radiant radiation is reflected from a horizontal scanning reflector device and travels along a seventh optical path 81 to said radiant radiant energy detector.

14 A scanning reflector device for transmitting radiant energy between an object space and an image space, comprising: A receiving radiant energy originating from the object space and proceeding along a first optical path 28; A second optical path 20 separate from
a vertical scanning reflector device 21 arranged to transmit along B a first axis 2 generally perpendicular to the first optical path;
a vertical scanning drive device 45 for changing the angular position of the vertical scanning reflector device about 4; C receiving the radiant energy reflected from the vertical scanning reflector device and traveling along the second optical path 20; the radiant energy to the second
a horizontal scanning reflector device 22 arranged to reflect back onto the vertical scanning reflector device along a third optical path 38 separate from the optical path 20 of the
the vertical scanning reflector thereby reflects the radiant energy along a fourth optical path 39 in communication with the image space that is included in a plane different from the plane in which the first optical path 28 is included; A second optical path substantially orthogonal to the second and third optical paths.
a horizontal scanning drive device 46 for changing the angular position of the horizontal scanning reflector device about the axis 25 of the scanning device, characterized in that the first, second and third optical paths are unobstructed; Reflector device.

15. A scanning reflector apparatus according to claim 14, including means for focusing elemental areas of said object space into said image space.

16 The second axis 25 is the first optical path 28
15. The scanning reflector device according to claim 14, which is substantially parallel to and substantially perpendicular to said first axis 24.

17. The scanning reflector device of claim 14, wherein said vertical scanning plane reflector is disposed at a nominal angle of inclination of 40° to 60° with respect to said first optical path.

18 a fixed reflector arrangement 23 arranged to receive radiant energy from said fourth optical path 39 and thereby direct said radiant energy into said image space;
15. The scanning reflector device according to claim 14, comprising:

19 directing the radiant energy traveling in the fourth optical path 39 to travel back toward the vertical scanning reflector device 58 and along a fifth optical path 70, thereby effecting a third reflection; and a third footprint 71 due to this reflection is marked on the vertical reflector device, thereby further increasing the vertical sweep range of the object space when the vertical scanning reflector device performs a predetermined vertical sweep. Said third
a reflection device 57 is arranged, the radiant energy being reflected from the vertical scanning reflector device into a sixth optical path 7.
19. A scanning reflector system as claimed in claim 18, in which the scanning reflector device travels along the radiant energy sensing device.

20 the radiant energy traveling in the fourth optical path 39 is directed back toward the vertical scanning reflector 58 and directed along a fifth optical path 70, thereby causing a third reflection 71 and The third reflector 57 is arranged to leave a third reflective footprint 71 on the vertically scanning reflector device, and the radiant energy is reflected from the vertically scanning reflector device to the horizontally scanning reflector device. Mirror device 59
Proceeding along a sixth optical path 72 directed at
Thereby effecting a second reflection 80 and leaving a second footprint 80 of this reflection on the horizontal scanning reflector arrangement, the radiant energy is reflected from the horizontal scanning reflector arrangement into a seventh optical path 81. 19. The scanning reflector device of claim 18, which travels along the radiant energy sensing device to reach said radiant energy sensing device.

BACKGROUND OF THE INVENTION The present invention relates to an optical-mechanical scanning device for use in two-dimensional imaging devices, and more particularly to an optical-mechanical scanning device for use in two-dimensional imaging devices, and more particularly to at least two scanning devices driven to pivot on mutually orthogonal axes to scan an elemental area of a field of view. The present invention relates to a raster scanning reflector device of the type that includes a reflector.

In imaging devices that receive or project radiant energy, the radiant energy emanating from successive element areas in the background is directed to a suitable detector, or the radiant energy emanating from a radiant energy source is projected to successive locations in space. For this purpose, a device consisting of a reflector and a lens is used. Some devices additionally use a reflector device that projects radiant energy onto the target to illuminate the target, thereby increasing the brightness of the received image of the object.

Typical image brightness enhancement radiation sources that can be used in the types of imagers described above include coherent laser radiation sources, incoherent visible light sources, and thermal radiation sources (e.g., ranging from the ultraviolet to the infrared range). .
Detectors usable in such devices must naturally have optical response characteristics that match the wavelength range of the radiant energy to be detected. Some of these detectors consist of a vertically aligned linear array of optically sensitive elements which determine the successive vertical positions of a real image imaged on the element relative to the background of the object corresponding to said real image. Detected by horizontal sweep. Such a detector can be used in a scanning mirror system having a single horizontal sweeping mirror instead of both horizontal and vertical sweeping mirrors. The vertical field of view of this type of device is limited by the number of optically sensitive elements arranged in a vertical array of detectors.
There are other devices that use a single focusing detector in which the horizontal scanning reflector and the vertical scanning reflector are movable to pass successive elemental portions of the real image across the detector element. It is. Both mirrors are actuated electromagnetically so that the real image, which is focused on the plane in which the detector is located, moves from one end of the detector element to the other in raster fashion.
In this device, the vertical as well as the horizontal field of view is limited by the maximum angular displacement of the reflector.

For movable reflector mechanisms that use a single focused detector element to sweep the real image, a single reflector gimbaled to obtain the desired field of view in both vertical and horizontal directions may be sufficient. Available for use.
However, as the scan frequency increases, the reflector actuation mechanism begins to experience mechanical failure because it is difficult to vibrate the relatively large mass of the inner gimbal assembly at high frequencies in response to the scan frequency. This is due to the fact that it becomes difficult. Therefore, two mirrors are commonly used, each mirror being independently driven to oscillate about its orthogonal axis.

Imaging of the object background onto the detector is accomplished by placing an objective lens assembly in the optical path of the device. In that case, a plane reflector is usually used. It is also possible to provide a curvature on one or both of the pivoting mirrors, thereby obviating the use of an objective lens assembly for image focusing. One of the disadvantages of using a focusing mirror is that it introduces a focal plane error, which increases as the scan angle increases. In particular, when a concave mirror is used to perform both focusing and scanning functions, each point included in an elemental area in the object background is rotated about one axis (as the concave mirror scans). Become. Therefore, when using a focused detector to detect reflected energy emanating from successive points on a planar image, such a detector will not be properly positioned on the focal plane except at a single angular position of the reflector. become. That is, for all other angles the detector is not in the focal plane and the distance of the detector from the focal plane increases as the mirror aperture angle increases. On the other hand, if a plane reflector is used to scan the object background, the points on the object background will be imaged onto one plane. A detector placed in such a plane therefore retains its correct position with respect to the image even if the angular position of the lens changes.

Some scanning mechanisms require simultaneous use with television. Without the use of expensive inter-scan converters, simultaneous use of the scanning device and the television is possible only if the scanning waveform of the opto-mechanical scanning device is the same as that of the deflection circuit of the television image monitor. Must be consistent. In typical television equipment, the horizontal scanning of the intensity-modulated electron beam is usually accomplished with a sawtooth sweep waveform at a relatively high frequency, typically around 15,750 cycles per second. Vertical scanning of the intensity modulated electron beam is usually accomplished with a sawtooth sweep waveform at a low frequency, typically about 30 cycles per second. Therefore, in order for simultaneous use to be possible, the vertical and horizontal mirrors of the mechanical scanning mechanism must match the vertical and horizontal scanning cycles of the television set in terms of both frequency and scanning wave. An example of a scanning device that can be used with a television is described in commonly assigned US Pat. No. 3,978,281. To achieve high mechanical scanning speeds, optical mechanical scanning devices compatible with television must utilize relatively low mass reflectors. For some high-speed scanning devices, high-speed scanning requires severe structural (e.g., stress, strain, and fatigue tolerances) and material (e.g., mass, size, and strength) constraints. ) constraints will be placed on the reflector components and their cooperating drive mechanisms.

Image distortion is yet another problem associated with opto-mechanical scanning mechanisms used in conjunction with television image monitors. Image distortion results from the difference between the scanning waveform of the mirror and the scanning waveform of the television monitor's electron beam. A typical television video monitor is produced by scanning a raster in the xy plane, even though x and y are perpendicular. To eliminate image distortion, the scanning waveforms of the mirrors of an opto-mechanical scanning mechanism must also be perpendicular to each other, as in a television image monitor. The conditions for such mechanical scanning require that the central vibration axes of the two reflecting mirrors be orthogonal to each other. The optical throughput, i.e. the amount of radiant energy transmitted through the reflector device, can be reduced to reduce the required sensitivity of the radiant energy detector or, in the case of projection devices, to reduce the attenuation of the projected energy source. It's better than as high as possible. Optical throughput can be increased by using larger mirrors and lenses or by reducing obstacles in the optical path.

From the above, it is clear that a trade-off between several factors must be considered when designing and manufacturing a two-dimensional raster scanning reflector. These include scan angle (field of view), sensitivity, scan rate or frame frequency, image distortion, optical throughput, mirror dimensions, and lens assembly. Other design considerations associated with prior art scanning devices will become apparent upon reading this specification.

US Pat. No. 3,704,342 to Stoddard ed al., dated November 28, 1972, describes a high speed infrared scanning mechanism incorporating a two-dimensional raster scanning mirror arrangement. The mechanism includes an objective lens assembly that images an elemental area of the object background onto an infrared sensing element. A planar vertical scan mirror pivots on a first horizontal axis and a planar horizontal scan mirror pivots on a second vertical axis, the second vertical axis being perpendicular to the first horizontal axis. The torsional resonator drives the vertical scanning mirror approximately 5% from its nominal position to produce an image frame with a 10% vertical sweep at 30Hz, while the horizontal scanning mirror is driven approximately 5% from its nominal position to produce each frame. Perform a 10% horizontal sweep at 3000 Hz to generate a scan line within the range.

In the device of Stoddard et al., the beam of light emanating from each successive elemental area of the field of the object to be scanned first impinges on a vertical scanning mirror, then on a horizontal scanning mirror, and finally is detected by a lens assembly. The image is formed on the device. In another embodiment, the light beam is directed to the detector by a folding mirror.

Another scanning device is disclosed in Streifer, US Pat. No. 3,997,721, issued Dec. 14, 1976. This patent describes a method for reducing the effective scan angle of a beam projection scanning device. A unique advantage provided by the Streifer patent is that focal plane errors are reduced when scanning a proximal planar object surface. Although the proximal field of view scan angle increases, the actual field of view or scan angle for the distal field decreases. Streifer's split-spectral field scanning device requires several additional reflectors, which improves the accuracy of the device but reduces the overall cost of device construction and maintenance costs. It will increase.

Macall U.S. Patent No. 3816741
Still another infrared scanning mechanism is described in that patent, which includes a focusing concave vertical scanning mirror and a planar horizontal scanning mirror pivoting on mutually orthogonal axes of rotation. Multiple reflections of the radiant energy occur on the plane scanning mirror, which includes in the path of the radiant energy bundle an evanescent reflector of smaller size than the plane scanning mirror. Due to multiple reflections, the effective sweep angle becomes large when the plane horizontal scanning mirror is swept by a predetermined angle. Therefore, a plane scan mirror with a smaller scan angle can be used, which allows the plane scan mirror to swing faster for a given scan angle. However, the optical throughput of the device is reduced by the presence of a small eclipse reflector in the path, thus requiring the use of a more sensitive detector or a larger reflector. For reasons previously pointed out, large reflectors cannot be used simultaneously with televisions. In addition, since an elongated reflector smaller than these mirrors is placed between the vertical scanning reflector and the horizontal scanning reflector, it is no longer possible to place both scanning mirrors closest to each other. Therefore, the scanning angle obtained when the sizes of both scanning mirrors are determined becomes small.

Other shortcomings and disadvantages of prior art devices, other than those described above, will become apparent upon consideration of the disclosure of the invention set forth below.

SUMMARY In view of the above description, it is an object of the present invention to provide an opto-mechanical scanning mechanism and dimensions for improving the scanning performance of a two-dimensional raster scan imaging device.

Another object of the invention is to provide an optical mechanical scanning mechanism that has maximum optical throughput and can scan a relatively large angular range for a given mirror size.

Another object of the invention is that by using two plane reflectors arranged very close to each other and pivoted about an axis perpendicular to the principal axis of the incident light beam of each reflector, Two-dimensional raster without image distortion, capable of scanning object space at larger scanning angles with high optical throughput and a number of pixels per frame comparable to conventional television raster-forming deflection devices. An object of the present invention is to provide a scanning mirror device.

It is another object of the present invention to construct an imaging device having improved sensing capabilities, frame field of view dimensions, frame scanning efficiency at high frame frequencies, greater optical throughput, and less image distortion and occultation, and The aim is to gain greater flexibility in designing.

To summarize, the first invention of the present application is an optical-mechanical scanning mechanism used in an imaging device for scanning a two-dimensional object field, comprising: A. radiation originating from the object field and traveling along a first optical path 28; a vertical scanning plane reflector device 21 arranged to receive energy and reflect said radiant energy along a second optical path 20 separate from said first optical path 28; B generally perpendicular to said first optical path 28; The vertical scanning plane reflector device 2 is rotated around the first axis 24 to
Vertical scanning drive device 4 that changes the angular position of 1
5. C receiving the radiant energy reflected from the vertical scanning reflector device 45 and traveling along the second optical path 20, and transmitting the radiant energy to a third optical path separate from the second optical path 20; 3
8 and above the vertical scanning reflector apparatus, the vertical scanning reflector 21 thereby directing the radiant energy into the first optical path. 2
A fourth optical path 3 different from 8 and reaching the image field
9, and D a second light path substantially orthogonal to the second and third optical paths.
a horizontal scanning drive device 46 for changing the angular position of the horizontal scanning plane reflector device about the axis 25 of the horizontal scanning plane reflector device;
the first, second and third optical paths are not blocked; E a radiant energy detection device 30 for detecting radiant energy disposed in the fourth optical path 39; and F an optical focusing device 3 for imaging an elemental area of the object field onto the radiant energy detection device;
5, 36, and 37.

Further, in a second invention, the first axis 24 is substantially perpendicular to the first optical path 28, and the second
2. The optical mechanical scanning mechanism according to claim 1, wherein an axis 25 of the optical axis 25 is substantially perpendicular to the second optical path 20 and the third optical path 38.

Other advantages, features and aspects of the present invention will become apparent from the following description of the invention disclosed in conjunction with the accompanying drawings.

[Brief explanation of drawings]

FIG. 1 shows a two-dimensional high speed raster scanning mirror apparatus according to the prior art. FIG. 2 is a perspective view illustrating one embodiment of the two-dimensional scanning reflector mechanism according to the present invention. FIG. 3 is a front view of FIG. 2, showing the optical path of the scanning mechanism as seen from the perspective of the object. FIG. 4 is a side view of the scanning mechanism of FIG. 2. FIG. 5 is a plan view of the scanning mechanism of FIG. 2. FIG. 6 shows a curved horizontal scanning waveform traced by a prior art optical-mechanical scanning mechanism with non-orthogonal pivot axes. FIG. 7 shows an undistorted horizontal scan waveform having essentially straight horizontal scan lines drawn by a scanning device incorporating the scanning mirror device of the present invention. FIG. 8 shows another embodiment of the invention in which one of the mirrors performs three reflections. FIG. 9 shows yet another embodiment of the invention in which multiple reflections are performed with both horizontal and vertical scanning mirrors.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS For ease of explanation, the operation of the scanning mechanism of the present invention will be described with respect to the scanning infrared sensing device for two-dimensional image formation illustrated in FIGS. 2-5. However, such a device can also be used in a variety of other imaging devices, such as those that project coherent radiation onto an image-bearing medium. A specific imaging device that can be used simultaneously with a television and that incorporates the mechanism of the present invention is disclosed in US Patent No.
Described in No. 3978281. US Patent No. 3978281
No. 1 of the present specification for comparison.
As shown, the optical mechanical scanning mechanism of the present invention is used in place of the scanning mechanism disclosed in this patent.

As is clear, horizontal and vertical directions are relative. As used herein, "vertical scan reflector"
The term ``vertical'' as used in ``vertical'' refers to the angular movement of a vertical scanning reflector about a horizontal axis, thereby effecting vertical scanning of an elemental area of the object landscape. In the raster forming operation, one frame screen is created each time a vertical scan is completed. The term "horizontal" refers to moving a horizontal reflector about a horizontal axis, thereby scanning an elemental area of the object landscape horizontally. in general,
To enable the mechanism of the present invention to be used simultaneously with a television, the horizontal scanning reflector vibrates at a significantly higher frequency than the vertical scanning reflector. Further, as used herein, the term "field" refers to a distal or proximal two-dimensional or three-dimensional object view scanned by a scanning mechanism, or to a distal or proximal two-dimensional or three-dimensional object view scanned by a scanning mechanism, or A distal or proximal surface or medium that bears a two-dimensional or three-dimensional image projected by radiant energy.

In the prior art scanning mechanism shown in FIG. 1, reflector 10 is carried on shaft 11 and vibrates to perform frame scanning, whereas reflector 12 oscillates about axis 13 to perform linear scanning. . axis 11 and axis 1
3 are orthogonal to each other. The radiant energy flux 14 emitted from the object background first enters the vertical reflector 10, where this radiant energy flux 14 becomes the radiant energy flux 1
5 and directed toward the horizontal reflector 12. Mirror 12 then directs the received radiation bundle 15 along the optical path of radiant energy bundle 16 through objective lens assembly 18 . This energy flux 16 is transmitted to the infrared detector 1 by the objective lens assembly 18.
7 and then focused onto a suitable sensing element such as 7. As the object background is scanned, successive portions of the real image of the object background imaged onto the detector are swept across the detector. This sweep causes the detector to generate electrical signals responsive to the instantaneous intensity of the radiant energy in successive portions of the real image. This electrical signal is fed to and processed by a signal processing circuit such as that described in US Pat. No. 3,978,281. To summarize what is described in this US patent, a normal signal processing circuit is used to convert a horizontal sweep and a vertical sweep of a video signal into horizontal sweeps and vertical sweeps of a sinusoidal waveform of a reflector built into a scanning mechanism. A luminance modulated video signal is generated by synchronizing with the vertical sweep of the sawtooth waveform. The intensity of this brightness modulation signal is proportional to the output electrical signal of the detector 17. This makes it possible to display a visible image corresponding to the infrared radiation of the scanned image on the surface of the cathode ray tube. The cathode ray tube, in the exemplary embodiment, may take the form of a conventional television video monitor.

FIG. 1 shows how a horizontally scanned waveform moving across detector element 17 is generated. Vertical scan axis 11 of mirror 10 is perpendicular to the path of radiant energy flux 14, whereas horizontal scan axis 13 of mirror 12 is not perpendicular to the path of radiant energy flux 15. Therefore, a distorted horizontal scanning waveform approximately as shown in FIG. 6 is generated. When the television equipment is synchronized with a linear sweep waveform over time, the distorted or curved scan waveform of FIG. 6 produces an undesirably distorted image on the television video monitor.
As the sweep angle increases, the image distortion also increases.

Moreover, the time required to complete a raster image is determined by the vibration frequency of the vertical sweep mirror 10. The size of the vertical field of view is determined by the displacement angle of the vertical sweep mirror 10. The vertical resolution of the imaging device depends in part on the number of scans performed before the next vertical sweep. The size of the horizontal field of view is determined by the maximum displacement angle of the horizontal sweep mirror 12. In keeping with one object of the present invention, it is possible to increase the vertical angle by having multiple reflections occur on a vertically swept reflector so as to produce a larger vertical angular sweep in the object field at a smaller deflection angle of the reflector. It is desirable to maximize the area included in the directional object field of view. To achieve this objective, the two scanning reflectors are placed close together by placing the light beam perpendicular to the horizontal scanning axis;
At the same time, it was found that double reflection could be performed on the vertical scanning reflector. To do this, the nominal oscillation angle of one of the scanning reflectors is changed so that the radiant energy flux moves along the object's background in a plane that is contained in a plane different from the plane containing the optical path that it travels while reaching the detector. The radiant energy flux emitted from the was made to advance. This arrangement is the optical path of the radiant energy flux 14 emitted from the object background, and the reflectors 10 and 12.
This is in marked contrast to the scanning arrangement shown in FIG. 1, in which the optical path of the reflected energy bundle 15 to and from the detector 17 and the optical path of the energy bundle 16 extending to the detector 17 are all contained in the same plane. ing. In the present invention, the path of the radiant energy flux travels within a three-dimensional space, and is incident on the scanning reflector and is reflected from the scanning reflector. In this way,
Two separate and non-interfering optical paths are formed, one for receiving energy from the background of the object and one for transmitting the energy flux to the detector. The beam bundle 16 is conveyed to the detector 17 by a third fixed reflector 19, which may be arranged in the optical path 16.

In one embodiment of the invention, two focusing detectors are placed very close together so that a single horizontal sweep of the horizontal scanning reflector simultaneously scans two lines of the object background. be done.

The information collected during the mechanical scan is large enough to rival the information receiving capacity of a typical television video monitor, so that a higher resolution image of the object field is obtained, in other words a larger number of pixels. This embodiment is particularly advantageous when used in optical-mechanical scanning devices that can be used simultaneously with television video monitors. It is also possible to use additional focusing detectors to obtain even greater resolution, ie to obtain a larger number of pixels.

An exemplary embodiment of an opto-mechanical scanning device incorporating features of the present invention, having a single focusing detector, is depicted in FIGS. 2-5. In the figure, reflecting mirrors 21 and 2
2 pivot about orthogonal axes 24 and 25, respectively, while the third non-scanning reflector 23 is arranged in a fixed position. Electromechanical actuators 45 and 46 engage axes 26 and 27 of reflectors 21 and 22, respectively, to align the respective reflectors with their axes 24 and 22.
Scan the field of view by moving around 5 to change the angle so as to draw a two-dimensional raster. The scanning operation will be detailed later. Reflector 21 and 22
The activation of the action can be effected electromechanically, for example by means of a torsional vibrator, in which case the reflector consists of a lightweight beryllium mirror. Reflector 21
and 22 may be replaced with a reflecting prism.

In a preferred embodiment, vertical scan actuator 45 moves vertical scan reflector 21 through a nominal angle in a serrated manner. That is, a vertical sweep of the field of view of the object is performed in one direction. At the end of each vertical sweep, reflector 21 quickly returns to the angular displacement position at the start of the sweep during the retrace period of the sweep, after which actuator 45 drives the reflector to complete the next vertical sweep cycle. Typical waveforms in the vertical sweep circuit diagram are pictorially illustrated in FIG.
This waveform consists of both a sweep period and a retrace period.
The ratio of the duration of the sweep to the total duration of the sweep and retrace in the vertical sweep provides one evaluation criterion of the scanning efficiency of the vertical scanning reflector 21. The applicant was able to achieve a scanning efficiency of more than 80% for vertical scanning. Of course, since vertical scanning can be done in both directions, increasing the sweep time and increasing the retrace time, an efficiency of 100° can be obtained. In this case, actuator 45
consists of a torsional oscillator.

In contrast, the preferred horizontal scanning actuator is a torsional resonator that scans in both left-to-right and right-to-left directions to generate information signals with 100% efficiency. do. The information obtained by odd interlaced scanning is stored, and even interlaced scanning is performed in the opposite direction, and the information obtained by these interlaced scanning is transferred to a television circuit that scans horizontally only once. Prior to providing the information, the information obtained from the even interlaced scan is combined with the information obtained from the odd interlaced scan.
Such scanning and signal processing methods are described in the aforementioned U.S. Pat.
It is described in detail in No. 3978281.

Other variations on the scanning method include using resonators for both vertical and horizontal scanning, and using sweeps for both vertical and horizontal scanning.
There is a method using a flyback actuator. The selection of the scanning method will depend on the nature of the application of the opto-mechanical scanning mechanism; for example, the image projector of a flying spot scanner need not be able to be used simultaneously with a television.

The radiant energy flux 28 emitted from the object view is the first
The light travels along the optical path 28 and hits the vertical scanning reflector 21. When the reflector 21 oscillates (FIG. 2), the axis 28A of the radiation bundle 28 scans the element area of the object view, but as long as the reflector 22 is in a fixed angular position, the axis 28A of the radiation bundle 28 is a vertical reflector. maintain a constant angle with respect to the axis 24 of 21. The aperture 51 provided in the housing 50 of the scanning mechanism and the lens or window that may be fitted into the aperture are areas that limit the range of movement of the radiant energy bundle 28 in a raster fashion. The profile of the circular energy flux traveling along axis 28A forms what can be characterized as a "footprint" 31 on the surface of reflector 21. This circular energy flux is then axis 2
0 (FIG. 4) toward the horizontal scanning reflector 22 to form a second footprint 32 on the surface of the horizontal scanning reflector. The axis 20 of the radiant energy beam is always perpendicular to the axis 25 of the horizontal scanning reflector 22 when the horizontal scanning reflector 22 oscillates. The energy flux reflected at footprint 32 is along axis 38
(FIG. 3) and reaches above the surface of the reflector 21, forming a third inclined footprint 33 on the same surface. In the illustrated embodiment,
The energy flux is then transferred from the reflector 21 to the fixed reflector.
That is, the energy flux is directed onto a folding reflector 23 which is arranged at an angular position such that it ultimately directs this energy flux towards the sensing element 30 . The footprint 34 marks the footprint of the circular energy flux onto the folding reflector 23, which in turn directs the energy flux onto a path different from that of the energy flux traveling along the first optical path 28. along a second optical path 29 included in the optical path. Optical path 29 includes an objective lens assembly, depicted in FIG. The detector may be an array of sensing elements arranged in the optical path 29.

The operation will be explained. As the horizontal scanning reflector 22 pivots about its axis 25, the footprint 31 on the vertical scanning reflector 24 aligns with the axis 24 of the vertical scanning reflector 21.
The minimum horizontal scan width necessary in relation to forming an essentially stable footprint 33 on the surface of the mirror 21 in a direction parallel to the Secured by turning. As shown in FIGS. 2-5, the optical path 28
and the main axis of the optical path 29 are arranged along different paths, so that when the vertical scanning reflector 21 rotates around its axis 24, the incident light beam 28
This axis 25 must be arranged so that it is not obstructed by the axis 25 of the horizontal scanning reflector 22. To better meet this requirement, the nominal angle at which the vertical scanning reflector 21 is placed should be such that the angle it makes with the optical axis 28a is between 45° and 60°. In this way, reflector 2
1 and 22 can be placed close to each other. Moreover, axis 25 is perpendicular to axis 24 so as to provide a scanning waveform that can be used as a scanning waveform in a conventional television image monitor. The scanning waveform of an exemplary opto-mechanical scanning device is shown in FIG. 7, which shows an undistorted horizontal scanning pattern.
The improved undistorted waveform is created when the principal axis 28a of the incident radiant energy flux 28 is reflected by the vertical scanning reflector 21 and the axis 2 of the horizontal scanning reflector 22.
This can be obtained by arranging this vertical scanning reflector 21 so as to be perpendicular to 5.

Moreover, according to the embodiments shown in FIGS. 2 to 5, it is also possible to achieve a smaller reflector mass and therefore a smaller inter-reflector minimum distance and a larger scanning angle. is possible, but
It reflects footprints in a predetermined scanning area through mirrors 21 and 22.
In addition, by truncating the external dimensions of the vertical scanning mirror 21 to a size sufficient to include the mapping area of the footprint, that is, by shaping the vertical scanning mirror 21. It is done. In particular, the corner 43 (Fig. 2) of the reflecting mirror 21, where no footprint mapping is recorded, is cut off, and the reflecting surface of the reflecting mirror 21 is placed as close as possible to the reflecting surface of the reflecting mirror 22, thereby creating optical interference. or mechanical interference. Reflector 2
In order to make the mass of 1 as small as possible, reflector 2
1 other truncated corners 40, 41 and 42
Other parts of the reflector 21 can also be cut off, depending on the footprint pattern, as shown by (FIG. 2).

The instantaneous intensity of the radiant energy detected by the detector 30 is determined by the instantaneous vertical position of the reflector 21 and the reflector 2.
represents the radiant intensity at a position within the field of view of the object determined by the instantaneous horizontal position of 2. In certain exemplary embodiments of the scanning mechanism of FIGS. 2-5, the reflector 2
1, when actuated, moves up and down approximately ± about the nominal angle “A” (Fig. 4), which forms an angle of 45° with the horizontal line.
It oscillates over an angular range of 2.6° to produce a 21° vertical field of view. When actuated, the reflector 22 oscillates from side to side over an angular range of approximately ±7° about the nominal angle "B" (Figure 3), which forms an angle of 18° with the horizon, resulting in a horizontal field of view of 28°. occurs. Reflector 23
is placed at an angle "C" (FIG. 5) of 27 degrees with respect to the vertical plane.

By orienting axes 24 and 25 orthogonally to each other, a two-dimensional, undistorted raster scan waveform having essentially straight horizontal scan lines as depicted in FIG. 7 is obtained. However, axes 24 and 25 need not be so positioned to scan a two-dimensional area. Moreover, the objective lens assembly consisting of lenses 35, 36 and 37 does not have to be placed in the optical path 29,
In fact, it may be located at any position within the continuous optical path starting with optical path 28 and ending with optical path 29. Furthermore, the folding reflector 23 allows the light beam to reach the detector 30.
bends the light beam before it enters. detector 30,
If the reflecting mirrors 21 and 22 take different positions and different azimuths, naturally the folding reflector 23 must also take different positions and different azimuths. It is also possible to dispense with the folding reflector 23 altogether and to place the objective arrangement and the detector directly in the optical path that aligns the footprints 33 and 34. In that case, the invention would be implemented with only two reflectors, namely reflectors 21 and 22. Furthermore, it will be appreciated that object plane reflectors could be used in place of plane reflectors 21 and 22 in order to avoid the use of an objective lens assembly without departing from the scope of the invention. A focal plane error occurs. For small scan angles, slight focal plane errors can be ignored.

FIG. 8 illustrates another reflector arrangement that can be constructed in accordance with the present invention. The first beam 61 travels along the optical axis 62 and reaches the vertical scanning reflector 58, forming a footprint 63 on the surface of this reflector. The radiant energy flux 64 emerging from the footprint 63 hits the horizontal scanning reflector 59 and forms a footprint 65 on the surface of this reflector.
This radiant energy flux 64 is then reflected from a footprint 65 as an energy flux 66 and hits the reflector 58 to form a footprint 67, from which the energy flux 66 proceeds as an energy flux 69 to a fixed third reflection. reaching mirror 57, thereby causing footprints 68
is formed on the surface of the reflecting mirror 57. Fixed reflector 5
The radiant energy flux 70 emitted from the mirror 7 collides with the horizontal scanning reflector 58 for the third time and forms a footprint 71 on the surface of the reflector 58 as shown in the figure. is such that the reflected energy flux 72 from the footprint 71 passes along the axis 73 and avoids the horizontal scanning reflector 59, which is ultimately directed to a detector or radiant energy source according to the aforementioned dimensions. . With this arrangement, three reflections occur on the surface of the vertical scanning reflector 58, so that the reflector 58 can be swept by a predetermined angle to obtain a larger sweep angle at any time within the vertical object field. become.

Similarly, multiple reflections can occur simultaneously on the horizontal and vertical scanning mirrors. Such an arrangement is illustrated in FIG. As far as reference numerals 61 to 71 are concerned, the paths and footprints of the radiant energy bundles in FIGS. 8 and 9 are similar. By repositioning the fixed reflector 57 such that the radiant energy bundle 72 advances and impinges directly on the horizontal scanning reflector 59 and forms a second footprint 80 on the same reflector 59, Multiple reflections can be realized on the reflecting mirror 59. Two reflections therefore occur on the horizontal scanning reflector 59, thereby making it possible to increase the effective sweep angle in the horizontal object field. The radiant energy flux 81 emanating from the footprint 80 can travel directly to the detector, or alternatively, the radiant energy flux 81 can be directed to the vertical scanning reflector 58.
A fourth impact is made with the reflector to form the footprint 82 shown on the same reflector, after which the radiant energy flux 83 is intercepted by the fixed reflector 57 along the axis 84 leading to the detector or source of radiant energy. It is possible to proceed without it, but it depends on the situation. As in the case of Figure 8,
It goes without saying that a detector or a radiant energy source and/or a lensed fold reflector can be arranged to receive or focus the radiant energy bundle 83.

Thus, it will be apparent that various modifications of the invention may be made in accordance with the teachings of the illustrated embodiments. For example, the exact angular relationship between the reflectors, the alignment of the axes of each reflector, the relative position of the optical paths 28 and 29, and the position of the lens assembly can be changed and still result in optical interference or reflection. In order to avoid blocking of the optical path by the mirrors, it is possible to perform multiple reflections between the two reflecting mirrors so that the central axis of the radiant energy flux traveling between the two reflecting mirrors is included in another plane. The above-mentioned modifications can be implemented both in the projection device and in the sensing device. Therefore, the examples and descriptions set forth above are not intended to limit the scope of the invention.