GB1594060A - Optically aligned element stabilised with off-axis inertial stabiliser - Google Patents

Optically aligned element stabilised with off-axis inertial stabiliser Download PDF

Info

Publication number
GB1594060A
GB1594060A GB12362/78A GB1236278A GB1594060A GB 1594060 A GB1594060 A GB 1594060A GB 12362/78 A GB12362/78 A GB 12362/78A GB 1236278 A GB1236278 A GB 1236278A GB 1594060 A GB1594060 A GB 1594060A
Authority
GB
United Kingdom
Prior art keywords
prism
apparatus
lens
gyroscope
axis
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.)
Expired
Application number
GB12362/78A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tracor Inc
Original Assignee
Tracor Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to US81424077A priority Critical
Application filed by Tracor Inc filed Critical Tracor Inc
Publication of GB1594060A publication Critical patent/GB1594060A/en
Application status is Expired legal-status Critical

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B25/00Eyepieces; Magnifying glasses
    • G02B25/001Eyepieces
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B27/00Other optical systems; Other optical apparatus
    • G02B27/64Imaging systems using optical elements for stabilisation of the lateral and angular position of the image
    • G02B27/644Imaging systems using optical elements for stabilisation of the lateral and angular position of the image compensating for large deviations, e.g. maintaining a fixed line of sight while a vehicle on which the system is mounted changes course

Description

(54) OPTICALLY ALIGNED ELEMENT STABILIZED WITH OFF-AXIS INERTIAL STABILIZER (71) We, TRACOR INC., a Corporation organised under the laws of the State of Delaware, United States of America, of 6500 Tracor Lane, Austin, Texas 78721, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention pertains to stabilized optics and more particularly to a stabilized monocular employing an erection prism located on the optical axis of the objective lens group and the eyepiece lens group.

Stabilized optics have been employed in monoculars to permit the use of higher powered optical systems (e.g. over a power of 7) in conditions where muscular and vehicular movements would otherwise so distort the received images so as to make them meaningless. Typical uses are aboard ship, reconnaissance aircraft, land vehicles and the like. Although the description is with respect to "monoculars," it is understood that such systems are employed not only in telescopes but in cameras and binoculars as well.

Although some early systems employed stabilization with respect to the objective lens system, it has long been recognized that a stabilized element operatively intermediate to the objective lens and the eyepiece lens is the most satisfactory element to stabilize.

An objective lens or lens group produces an image erection (inverting and reverting of the image) with the collimated light received from a distant object. In order to return the image to proper condition, it is necessary to have one or more elements that also invert and revert (i.e. erect) the image.

Another lens group might do this. There are also systems of mirrors and prisms that will do this. Various schemes have been employed in the prior art, but the most satisfactory ones employ an optically aligned erection prism, such as described in an article by David B. Fraser entitled, "Design of a Low Cost, High Magnification, Passively Stabilized Monocular, the Stedi-Eye" appearing in SPIE Proceedings, Vol. 39, August 1973 and in U.S. Patent No. 4,013,339 entitled "Optical Image Stabilizing System," Kunio Ando et al, issued March 22, 1977, both of which are incorporated herein by reference.

The techniques of stabilizing optics have varied from the gyro stabilized central afocal device in the Mark Systems Model 1610 to programmed stabilization employing hydrostatic techniques, to the use of springs and bearings to create what are mostly tuned and dampened isolators, to the axially oriented inertial stabilization systems shown in the '339 patent.

Although the various techniques are suc- cessful to some extent, most successful ones are large and cumbersome and expensive.

Embodiments of the present invention seek to provide an improved stabilization mechanism for an erecting element included in an aligned optical system, the stabilized mechanism being removed from the optical train, therefore allowing shortening thereof, and which uses conventional gyroscopic parts not having openings therethrough such as in the '339 patent.

Embodiments of the present invention also seek to utilize a combination of elements to obtain a shortened optical train when compared to prior art systems, the train comprising an objective lens group having a wide field of view, a roof Pechan prism stabilized by a mechanism removed from the optical axis, and an eyepiece lens group having a negative lens in front of the original image plane to provide shortening of the focal length without shortening the eye relief and a field lens to compensate for field curvature.

According to the invention there is provided a stabilized optical apparatus comprising an objective lens, an eye lens, an erection prism located on the optical axis between the objective lens and the eye lens, and a system for inertially stabilizing the prism, said lenses being fixedly mounted in the casing of the apparatus and the stabilizing prism being mounted for pivotal movement about first and second axes perpen dicular to each other and to the optical axis relative to the casing, the system comprising: a gimbal mounted for pivoting with respect to the first axis, the erecting prism being pivotally connected to said gimbal for pivotal movement about the second axis, a gyroscope having a casing pivotally connected to said gimbal for pivotal movement about a third axis parallel with the second axis, the gyroscope being operative to tilt the prism at a common angle therewith to achieve inertial elevation stabilization.

A preferred embodiment of the present invention includes a system for stabilizing an erecting prism, itself located axially between an objective lens group and an eyepiece lens group, but the stabilizing mechanism located on an axis parallel with the optical axis. The prism is gimballed with respect o a yoke also gimbally connected to a gyroscope. The prism and gyroscope are connected together so that movement in elevation or in azimuth of the gyroscope is tracked by the prism.

The erecting prism is preferably a roof Pechan prism that operates in converging light from the objective lens and ahead of the image plane. The objective lens not only has a relatively long focal length (i.e. 10 x the eyepiece f.1), but also has a wide field of view.

The overall optical train if further shortened by the eyepiece lens group that includes a negative lens in front of the image plane to cause diverging light to be placed on the field lens thereof. This keeps the eye relief satisfactorily long, while permitting further shortening of the eye lens focal length and flattening of the field curvature attendant in large diameter lenses used with wide field-of-view optics.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 is a side view in cross section of a preferred embodiment of the present invention, Figure 2 is an oblique view illustrating the inverting action of a Pechan prism, Figure 3 is an oblique view illustrating the reverting action or a roof vertex on a prism, Figure 4 is an enlarged sectional view of the gyroscope and related parts of the embodiment shown in Figure 1, Figure 5 is an end view in cross section of the embodiment shown in Figure 1, and Figure 6 is a schematic of the optical components of the eyepiece lens group of the embodiment shown in Figure 1.

Now referring to the drawings and first to Figure 1, a cross sectional side view of a stabilized monocular in accordance with the present invention is illustrated. The housing or casing of the monocular comprises many precision parts typically made by casting and machining techniques and assembled in accordance with methods well known in the art. Although many parts are illustrated, not all parts are identified since these assembly procedures are well known.

Generally speaking, however, casing 10 houses objective lens group 12 and eyepiece lens group 14, these lens groups each being centered on optical axis 16. Each of these lens groups is fixed against movement lateral to their axial location, although in typical fashion, the eyepiece lens group can be translated axially to obtain precision in focusing. Objective lens group 2 includes a front cover lass or filter 18 and three optical lenses 20, 22 and 24. As illustrated, lenses 20 and 24 are positive lenses and lens 22 is a negative lens. Together they may be referred to as a "triplet" of high off-axis performance and required focal length, although in any given system the focal length and performance may be lesser or greater. The high off-axis performance is required to allow the instrument's instantaneous FOV of 6.5 degrees of apparent movement, due to the prism's angular perturbation cone of + 6.5 degrees. The objective group must therefore cover a total FOV of greater than 19 degrees.

Precision eyepiece lens group 14 includes six lenses, the purpose of these lenses being more fully described below.

Located between objective lens group 12 and eyepiece lens group 14 along the optical axis is an erecting element in the form of a roof Pechan prism 26. To more fully appreciate the effects of a roof Pechan prism reference is made to Figures 2 and 3. A Pechan prism is made up from two prism halves, having respective diagonal facing surfaces 45 degrees with respect to the entrance face of the half prism nearest the object and the exit face of the half prism nearest the image. The air gap between these faces is typically 2 millimeters. In a non-roof Pechan prism, light reflects five times before exiting on the same axis as it enters, namely, off the diagonal surface of the first prism, the silvered outside surface of the first half prism, the exit face of the first into the second half prism, the exit face of the second half prism, and upwards and off the upper slant face to the entrance face of the second half prism, and finally out of the exit face of the second half prism. Such a non-roof Pechan prism inverts the incoming image. However, for reasons to be more fully explained hereinafter, it is also necessary to revert the image. Therefore, it is well known that a roof may be added to one of the half prisms, such as shown in Figure 3, to provide a sixth reflecting surface and achieve both inverting and revertinf of the image. In this case the roof apex is located on the upper slant face of the exit element or second prism half. This inverting and reverting is known as image erection. The roof Pechan prism may conveniently be referred to as an erecting prism having a strong foreshortening effect due to its folded configuration.

The view of the image seen from the roof of the roof Pechan prism corresponds to an upside down view of the image shown in Figure 3. It will be appreciated that this image will appear to the viewer to be inverted (i.e. upside down) and reverted (i.e. a mirror image).

In the present system, the prism is located in front of the image plane of the objective lens group and hence operates with respect fo converging light. It does not add or subtract magnification and does not effect the effective focal length. Due to its index of refraction, the prism has a lengthening effect on the back focal length of the objective lens group, however.

Continuing with a description of the assembly shown in Figure 1, prism 26 is somewhat fragile and hence is held in prism support casting 28, which also permits the prism to be connected for inertial stabilization. First, an outer gimbal 30 is mounted perpendicularly to casing 10 via bearings 32.

These bearings permit main gimbal 30 to swivel about an axis in the azimuth. Prism 26 is connected to outer gimbal 30 on the optical axis at a point 34 mid distant between the nocal point of the objective lens group and the nodal point of the eye lens group, as more fully explained hereinafter.

This connection at point 34 permits prism 26 to tilt in elevation. Nominal movement of prism 26 is 6.5 degrees off centre in either azimuth or elevation, although a lesser or greater movement freed may be included if desired.

Gyroscope 36 is connected to outer gimbal 30 at a location displaced from optical axis 16 and parallel therewith, connecting point 38 being directly over point 34 so that a line from point 38 to 34 would, in this implementation, form a perpendicular with optical axis 16.

A secondary brace 40 connects gyroscope or motor gimbal 36 to the casting enclosing prism 26 through pivot points 42 and 44, respectively. It is illustrated that point 44 is axially aligned with respect to point 34 and point 42 is axially aligned with respect to point 38. In actual practice this is not necessary. However, it is necessary that points 42 and 44 form a parallelogram with points 38 and 34. It may now be seen that when gyro scope 36 tilts about point 38, prism 26 will tilt a like amount because of the linkage provided by secondary brace 40. Likewise, gyroscope 36 cannot swivel about point 42 without causing prism 26 to swivel a like amount.

Now referring to Figure 4, a detailed cross sectional view of gyroscope 36 is shown.

The part of the gyroscope connected to outer gimbal 30 is motor gimbal 36, which is bolted to motor gimbal housing 48 and separated by bearings 51 from the rotating shaft 52 connected to armature 54. The commutator of the motor is identified by numeral 56 and the brush assembly by the numeral 58. The gyro spin axis wheel 60 is in essence a large flywheel connected to the rotating shaft.

Attached to this wheel 60 is aluminum precessor disc 62, this disc being spherically shaped and having a large central opening.

A magnet 64, which may be either a permanent magnet or an electromagnet, includes a core 66, the overall structure having slots into which disc 62 moves when gyroscope 36 tilts.

It is well known that when a gyroscope is forced off axis, it tends to react at 90 degrees to the applied force. In order to counteract this reaction, it is necessary to include a specially designed precessor. The precessor is designed so that as disc 62 cuts the magnetic field of magnet 64, a drag force is produced proportional in the eddy currents formed in the precessor disc.

Due to laws of precession, the gyro requires damping to remove nutational energy. Prior art schemes that include a lossy coupling with damping between gyroscopic components and a stabilized element minimize such nutational disturbances, but at the expense of causing delayed following or misalignment of the stabilized element.

Hence, during scanning or the like, the element tends to swim or moves off axis. This is avoided in the present structure by the stiff coupling of the gyroscopic components and the stabilized element provided by brace 40.

Nutational damping is provided by damper flywheel 68 connected to outer gimbal 30.

The main mass of the flywheel is bolted to a ring of energy-absorbing vinyl polymer having a large damping coefficient, connection being made via bolts 70 at a number of spoked locations. The ring is connected via washer 72 and bolts 74 to a surface of gimbal 30. Bearings 76 permit freedom of back-and-forth movement of the flywheel mass without changing the center of gravity.

The caging mechanism may also best be seen by reference to Figure 4. A pin or plunger 78 pressed outwardly along the axis from gyroscope 36 from frame member 80 mates with internal cone surface 82 of piston 84 fitting over the plunger. The cone reduces to a mating hole at its center. A rocker arm 86 operates the plunger, the illustrated position being the caged position.

Note that the caging of the gyroscope mechanically holds it on an axis parallel to the optical axis. Spring 88 provides a slight inward bias on plunger 84. The entire caging mechanism is bolted to casing 10 via bolts 90. A momentary push button 91 (Fig. 1) provides actuation of the caging mechanism to uncage the gyro.

Balancing weights 92 are provided via nut 94 positioned via threaded bolt 96. Electrical leads 98 provide power connections from the power supply printed circuit board 100 (Fig. 1) to the gyro motor gimbal 102 and the battery connection is made through wires 98. Wires or leads 98 pass through point contacts 104 at a number of locations.

although other means of getting power to the gyroscope motor can be employed. The on-off push button is identified by numeral 106 (Fig. 1).

In a typical embodiment, full operating speed is obtained in about 25 seconds after turn on. The starting torque is equal to about 1.3 in. oz. The unit uses 1.6 watts of power at a 10 volt input and uses three 4.5 volt batteries.

In this embodiment. the entire assembly is tightly sealed by various means illustrated, but not completely. described. However, once sealed, the assembly is pressurized via a purging valve 108.

Eyepiece lens group 14 is contained within its own housing 110, having a pin 112 operating within a slot in casting 115 as operated by eyepiece focus control 114. The eyepiece lens group is protected by eye shield 118 with which the eye of the user is located. The eye shield 118 provides a complete mask against the forehead of the user to protect against glare due to its eyesurrounding nature and to provide a means by which the entire assembly can be steadied with respect to the user.

Figure 5 illustrates more completely the shape of outer gimbal 30 and secondary brace 40. To ensure against relative movement of the prism with respect to the gyroscope, the bearings at the pivot points are preloaded about points 42 and 44.

Also illustrated in Figure 5 is the optimal electrical feed-through connection at contact 104.

Now turning to Figure 6, a schematic representation of the eyepiece lens group in accordance with the present invention is illustrated. In precision eyepieces, six or more lenses are commonly employed. However, the system illustrated in connection with the stabilized optical system just described achieves some distinct advantages not available in the prior art. These advantages are obtained by the location of negative lens 126 and field lens 128.

The dotted location 130 is the location for the image plane resulting from the objective lens group, as further slightly displaced by the refractive qualities of the prism. It is evident that location of the field lens at the conventional location without the benefit of lens 126 would not have the desirable effect of flattening the field curvature of the system that is required under the wide field of view characteristics of the objective lens.

This requires a rather large field lens.

Further, to obtain magnification by the eyepiece lens group on the order of 1.6 power, a rather strong negative lens is required. By locating the negative lens just forward of the original image plane location (toward the objective lens group), then both of these requirements are satisfied. Further, the effective focal point is not so preshortened so as to make an unreasonably short eye relief, even with further magnification provided by the additional lenses of the group.

To more fully understand the relationship of the lenses in the eyepiece lens group, the lens group is constructed so that the distance between the eye of the user and the last face of the lens of the eyepiece measured along the optical axis is greater than the focal length of the eyepiece. As a result of this relationship such an eyepiece may also be used by persons wearing eyeglasses, to permit the use of a large eyeshield and the like without the necessity for restricting the field of vision under these conditions.

The wide-angle . eyepiece lens group essentially comprises four components which are axially aligned with respect to each other and which have spaces therebetween. The first component has a dispersing effect and is positioned in front of the real image projected by an objective used in conjunction with the eyepiece. Thus, the real image is formed only after the light rays have passed through the dispersing member.

The second component is positioned at or in the vicinity of this real image and has a light collecting effect. The third and fourth components also have a light collecting effect.

The several components of the eyepiece lens group are constructed in the following manner: The first component consists of two lenses one of which, preferably the first lens, which is the closest to the objective, has a light collecting effect. This first lens may also comprise a collecting meniscus lens, the concave surface of which is directed toward the objective. The second lens of the first component is a double concave lens. The first and second lenses of this first component can be cemented together.

The second component consists of a single light collecting lens, the surface of which is directed toward the eye having a smaller radius of curvature than the surface directed toward the objective.

The third component consists of two lenses cemented together with the lens directed toward the objective having a dispersing effect. This lens is constructed as a meniscus lens with its concave surface being directed towards the eye. The second lens oi the third component is a double convex lens.

The fourth component consists of a single light-collecting meniscus lens, the concave surface of which is directed toward the eye.

Typically, the wide field eyepiece art yields, in an Erfle type, an eye relief of but 0.7 x the effective focal length of the eyepiece. However, with the implementation described in Figure 6, an eye relief of 18 mm is obtained with an effective focal length of 16.5 mm. This yields a wide field eyepiece producing a greater eye relief than the effective focal length by a factor of 1.09 x.

While a particular embodiment of the invention has been shown, it will be understood that the invention is not limited thereto, since many modifications within the scope of the appended Claims may be made and will become apparent to those skilled in the art.

WHAT WE CLAIM IS: 1. A stabilized optical apparatus, comprising an objective lens, an eye lens, an erection prism located on the optical axis between the objective lens and the eye lens, and a system for inertially stabilizing the prism, said lenses being fixedly mounted in the casing of the apparatus and the stabilizing prism being mounted for pivotal movement about first and second axes perpendicular each other and to the optical axis relative to the casing, the system compris- ing: a gimbal mounted for pivoting with respect to the first axis, the erecting prism being pivotally connected to said gimbal for pivotal movement about the second axis, a gyroscope having a casing pivotally connected to said gimbal for pivotal movement about a third axis parallel with the second axis, the gyroscope being operative to tilt the prism at a common angle therewith to achieve inertial elevation stabilization.

2. An apparatus as claimed in Claim 1, wherein the location of said prism is gimballed at a point mid way between the nodal point of the objective lens and the nodal point of the eye lens, to thereby establish a stabilized image to the eye of the user.

3. An apparatus as claimed in Claim 1 or Claim 2, wherein said erecting prism is a roof Pechan prism.

4. An apparatus as claimed in Claim 1, Claim 2 or Claim 3, including a precessor having an aluminum disc with a central opening therein mounted for rotation with the gyroscope spin axis wheel, and a magnet fixedly mounted to the casing slotted for receiving the edges of said disc when the gyroscope tilts off axis, the eddy currents created between said rotating disc and the magnet causing a drag force for centralizing said gyroscope.

5. An apparatus as claimed in any one of Claims 1 to 4, including mechanical caging means having a plunger and mating cone reducing to a central hole for receiving said plunger, one of said plunger and cone components being axially connected to said gyroscope and the other component being axially positionable with respect thereto to mechanically cage the gyroscope.

6. An apparatus as claimed in Claim 5, wherein said positionable component is spring biased toward said gyroscope when said component is in ite caging position.

7. An apparatus as claimed in any one of Claims 1 to 6, and including a damper flywheel connected to said gimbal for absorbing nutational energy.

8. An apparatus as claimed in Claim 7, wherein said damper flywheel includes an energy absorbing vinyl polymer having a high damping coefficient connected between said flywheel mass and said outer gimbal.

9. An apparatus as claimed in any preceding Claim, wherein said objective lens group in conjunction with said eye lens group achieves a 10 power magnification with an instantaneous field of view of 6.5 degrees.

10. An apparatus as claimed in any preceding Claim, wherein said erection prism is permitted + 6.5 degrees of elevation and azimuthal action.

11. An apparatus as claimed in any preceding Claim, wherein said objective lens includes three lenses to remove the effects of curvature at more than 9 degrees off axis and to achieve an overall field of view of 19.5 degrees.

12. An apparatus as claimed in Claim 11, wherein the eye lens achieves a ratio of eye relief to focal length of 1.09 so as to produce an optical vertex distance of 9.5 inches from front vertext to exit pupil plane.

13. An optical apparatus as claimed in any preceding Claim, comprising a secondary link pivotally connected to said gyroscope casing and erecting prism for pivotal movement about fourth and fifth axes parallel to the second and third axes, the intersection of said axes with a plane containing the optical axis and the first axis forming a parallelogram, said gimbal forming an outer gimbal and said gyroscope casing and said erecting prism forming inner gimbals to maintain stabilized axial alignment of said erecting prism.

14. An apparatus as claimed in Claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (16)

**WARNING** start of CLMS field may overlap end of DESC **. The third component consists of two lenses cemented together with the lens directed toward the objective having a dispersing effect. This lens is constructed as a meniscus lens with its concave surface being directed towards the eye. The second lens oi the third component is a double convex lens. The fourth component consists of a single light-collecting meniscus lens, the concave surface of which is directed toward the eye. Typically, the wide field eyepiece art yields, in an Erfle type, an eye relief of but 0.7 x the effective focal length of the eyepiece. However, with the implementation described in Figure 6, an eye relief of 18 mm is obtained with an effective focal length of 16.5 mm. This yields a wide field eyepiece producing a greater eye relief than the effective focal length by a factor of 1.09 x. While a particular embodiment of the invention has been shown, it will be understood that the invention is not limited thereto, since many modifications within the scope of the appended Claims may be made and will become apparent to those skilled in the art. WHAT WE CLAIM IS:
1. A stabilized optical apparatus, comprising an objective lens, an eye lens, an erection prism located on the optical axis between the objective lens and the eye lens, and a system for inertially stabilizing the prism, said lenses being fixedly mounted in the casing of the apparatus and the stabilizing prism being mounted for pivotal movement about first and second axes perpendicular each other and to the optical axis relative to the casing, the system compris- ing: a gimbal mounted for pivoting with respect to the first axis, the erecting prism being pivotally connected to said gimbal for pivotal movement about the second axis, a gyroscope having a casing pivotally connected to said gimbal for pivotal movement about a third axis parallel with the second axis, the gyroscope being operative to tilt the prism at a common angle therewith to achieve inertial elevation stabilization.
2. An apparatus as claimed in Claim 1, wherein the location of said prism is gimballed at a point mid way between the nodal point of the objective lens and the nodal point of the eye lens, to thereby establish a stabilized image to the eye of the user.
3. An apparatus as claimed in Claim 1 or Claim 2, wherein said erecting prism is a roof Pechan prism.
4. An apparatus as claimed in Claim 1, Claim 2 or Claim 3, including a precessor having an aluminum disc with a central opening therein mounted for rotation with the gyroscope spin axis wheel, and a magnet fixedly mounted to the casing slotted for receiving the edges of said disc when the gyroscope tilts off axis, the eddy currents created between said rotating disc and the magnet causing a drag force for centralizing said gyroscope.
5. An apparatus as claimed in any one of Claims 1 to 4, including mechanical caging means having a plunger and mating cone reducing to a central hole for receiving said plunger, one of said plunger and cone components being axially connected to said gyroscope and the other component being axially positionable with respect thereto to mechanically cage the gyroscope.
6. An apparatus as claimed in Claim 5, wherein said positionable component is spring biased toward said gyroscope when said component is in ite caging position.
7. An apparatus as claimed in any one of Claims 1 to 6, and including a damper flywheel connected to said gimbal for absorbing nutational energy.
8. An apparatus as claimed in Claim 7, wherein said damper flywheel includes an energy absorbing vinyl polymer having a high damping coefficient connected between said flywheel mass and said outer gimbal.
9. An apparatus as claimed in any preceding Claim, wherein said objective lens group in conjunction with said eye lens group achieves a 10 power magnification with an instantaneous field of view of 6.5 degrees.
10. An apparatus as claimed in any preceding Claim, wherein said erection prism is permitted + 6.5 degrees of elevation and azimuthal action.
11. An apparatus as claimed in any preceding Claim, wherein said objective lens includes three lenses to remove the effects of curvature at more than 9 degrees off axis and to achieve an overall field of view of
19.5 degrees.
12. An apparatus as claimed in Claim 11, wherein the eye lens achieves a ratio of eye relief to focal length of 1.09 so as to produce an optical vertex distance of 9.5 inches from front vertext to exit pupil plane.
13. An optical apparatus as claimed in any preceding Claim, comprising a secondary link pivotally connected to said gyroscope casing and erecting prism for pivotal movement about fourth and fifth axes parallel to the second and third axes, the intersection of said axes with a plane containing the optical axis and the first axis forming a parallelogram, said gimbal forming an outer gimbal and said gyroscope casing and said erecting prism forming inner gimbals to maintain stabilized axial alignment of said erecting prism.
14. An apparatus as claimed in Claim
13, wherein the fifth axis intersects the optical axis and the parallelogram is a rectangle.
15. An optical apparatus as claimed in any preceding Claim, in the form of a monocular.
16. An optical apparatus substantially as herein described with reference to and as shown in the accompanying drawings.
GB12362/78A 1977-07-08 1978-03-30 Optically aligned element stabilised with off-axis inertial stabiliser Expired GB1594060A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US81424077A true 1977-07-08 1977-07-08

Publications (1)

Publication Number Publication Date
GB1594060A true GB1594060A (en) 1981-07-30

Family

ID=25214513

Family Applications (1)

Application Number Title Priority Date Filing Date
GB12362/78A Expired GB1594060A (en) 1977-07-08 1978-03-30 Optically aligned element stabilised with off-axis inertial stabiliser

Country Status (10)

Country Link
JP (1) JPS5436744A (en)
DE (1) DE2829191A1 (en)
DK (1) DK141478A (en)
FR (1) FR2397041A1 (en)
GB (1) GB1594060A (en)
IT (1) IT7849196D0 (en)
NL (1) NL7803826A (en)
NO (1) NO782222L (en)
SE (1) SE7803724A (en)
ZA (1) ZA7801893B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2133147A (en) * 1983-01-05 1984-07-18 Litton Systems Inc A vibration absorber in a gyroscope
US5280387A (en) * 1989-09-06 1994-01-18 Asahi Kogaku Kogyo Kabushiki Kaisha Image stabilizing apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2422182B1 (en) * 1978-04-03 1982-10-08 Sopelem

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1450027A (en) * 1970-07-09 1976-09-22 Secr Defence Optical apparatus
JPS5311381B2 (en) * 1973-05-18 1978-04-21

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2133147A (en) * 1983-01-05 1984-07-18 Litton Systems Inc A vibration absorber in a gyroscope
US5280387A (en) * 1989-09-06 1994-01-18 Asahi Kogaku Kogyo Kabushiki Kaisha Image stabilizing apparatus
US5461513A (en) * 1989-09-06 1995-10-24 Asahi Kogaku Kogyo Kabushiki Kaisha Image stabilizing apparatus

Also Published As

Publication number Publication date
NO782222L (en) 1979-01-09
JPS5436744A (en) 1979-03-17
SE7803724A (en) 1979-01-09
FR2397041A1 (en) 1979-02-02
DE2829191A1 (en) 1979-01-18
DK141478A (en) 1979-01-09
ZA7801893B (en) 1979-03-28
IT7849196D0 (en) 1978-05-04
NL7803826A (en) 1979-01-10

Similar Documents

Publication Publication Date Title
US4761056A (en) Compact helmet mounted display
US4563061A (en) Night vision viewing systems
US4013339A (en) Optical image stabilizing system
KR100644189B1 (en) Wide-angle imaging optical system, and wide-angle imaging device, monitoring imaging device, on-vehicle imaging device, and projection device with the wide-angle imaging optical system
US5363235A (en) Dual field of view multi wavelength sensor
US4806011A (en) Spectacle-mounted ocular display apparatus
EP0834097B1 (en) Head gear display system
KR100258710B1 (en) Solid catadioptric lens
US4804258A (en) Four mirror afocal wide field of view optical system
KR100249965B1 (en) Optical system, and image observing apparatus and image pickup apparatus using it
US5880888A (en) Helmet mounted display system
JP2763055B2 (en) Reflective optical triplet with a real entrance pupil
US4383740A (en) Infinity image visual display system
US5631778A (en) Panoramic fish-eye imaging system
US4729634A (en) Reflective head-up display
US5526183A (en) Helmet visor display employing reflective, refractive and diffractive optical elements
US2504383A (en) Reflecting type telescope having a spherical mirror
US4218111A (en) Holographic head-up displays
US4269476A (en) Helmet-mounted display system
US5191469A (en) Afocal variation focusing system for mirrored optical systems
US4828378A (en) Night vision viewing systems
US4465347A (en) Helmet mounted telescope
US6078411A (en) Real-image finder optical system and apparatus using the same
US4235506A (en) Image stabilized optical system
US4322135A (en) Optical apparatus

Legal Events

Date Code Title Description
CSNS Application of which complete specification have been accepted and published, but patent is not sealed