Optically stabilized camera lens system

• US 4,615,590 A
• Filed: 07/17/1984
• Issued: 10/07/1986
• Est. Priority Date: 07/17/1984
• Status: Expired due to Fees

• Current Assignee: Schwem Instruments
• Original Assignee: Schwem Instruments
• Inventors: Alvarez, Luis W., Schwemin, Arnold J.
• Primary Examiner(s): Punter, William H.
• Application Number:
  US06/631,670
• Time in Patent Office: 812 Days
• Field of Search: 350/500, 350/287, 350/631, 352/244, 344/70, 356/149
• US Class Current: 359/556
• CPC Class Codes: G02B 27/64 Imaging systems using optical elements for stabilisation of the lateral and angular position of the image
• CPC Class Codes: G02B 27/642 Optical derotators, i.e. systems for compensating for image rotation, e.g. using rotating prisms, mirrors
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/687 by shifting the lens or sensor position

Abstract

An optically stabilized camera lens system includes an objective lens mounted to the lens case and an optical train defining an optical path between the objective lens and a camera image plane. The optical train includes first a Humphrey prism, second a light reversing, cube corner element, third a zoom lens. Provision is made for replacement of the cube corner with a prism and use of a parity inverting prism such as a Dove or preferably a Pechan to provide an alternate path. Roll stabilization is provided by coupling the Pechan, Dove or equivalent parity reversing prism to a gyroscope so the prism becomes a derotating prism. The derotating prism rotates about the optical path at half the speed the case rotates about the optical axis to produce roll stabilization preferred in camera and video applications. The Humphrey prism is inertially mounted to the case, using a stabilizer to compensate for small accidental tilt and pan motions of the case. The tilt and pan stabilizer includes a Cardan suspension assembly including a first gimbal mounted to the case, a second gimbal pivotally mounted to the first gimbal and a precessor biased rotor mounted to the second gimbal. A third gimbal is pivotally mounted to the second gimbal; the Humphrey prism is pivotally mounted to the third gimbal. The Cardan suspension assembly provides a gyroscopically stabilized mount for the third gimbal.

Claims

1. A lens system for use with a camera having an image plane comprising:

a case;

an objective lens forming a first optical element mounted to the case for receipt of light along an optical axis; and

an optical train defining an optical path within the case between the first optical element and the image plane, said optical train comprising;

a second reflecting and displacing optical element positioned along the optical path following the first optical element, said second optical element arranged and adapted to redirect the light entering the second optical element from a first path segment of the optical path to a second, laterally spaced apart path segment of the optical path to form a first image along said second path segment;

means for inertially mounting said second optical element to said case to compensate for small accidental motions of the case so the first image is a stabilized image;

a third cube corner reflecting optical element mounted within said case following the second optical element, said corner cube optical element arranged and adapted to relay light from said second optical element to a third, laterally spaced apart path segment of said optical path;

said optical train arranged and adapted to relay light along said optical path from said third optical element to form a second image at the image plane; and

a zoom relay lens assembly mounted within the case and following the third optical element.

2. A lens system for use with a camera having an image plane comprising:

a case;

an objective lens mounted to the case for receipt of light along an optical axis forming a first optical element; and

an optical train defining an optical path within the case between the first optical element and the image plane, said optical train comprising;

a second reflecting and displacing optical element positioned along the optical path following the first optical element, said second optical element arranged and adapted to redirect the light entering the second optical element from a first path segment of the optical path to a second, laterally spaced apart path segment of the optical path to form a first image along said second path segment;

means for inertially mounting said second optical element to said case to compensate for small accidental motions of the case so the first image is a stabilized image;

a third optical element comprising two reflecting surfaces mounted within said case following the second optical element, said third optical element arranged and adapted to relay light from the second optical element to a third, laterally spaced apart and reversed path segment; and

a fourth optical element including a zoom relay lens assembly mounted within the case and following the third optical element; and

a fifth optical element comprising a parity inverting prism having reflective surfaces arranged and adapted to relay light along said optical path from said third optical element to form a second image at the image plane having even parity.

3. The lens system of claim 2 and wherein said parity inverting prism is a Pechan prism.

4. The lens system of claim 2 and wherein said prism assembly is a Dove prism.

5. A lens system for use with a camera having a image plane comprising:

a case;

a first optical element mounted to the case of receipt of light along an optical axis;

an optical train defining an optical path within the case between said first optical element and the image plane, said optical plane comprising;

means for stabilizing to said image plane an image received through said optical train;

a derotating prism mounted to said case for pivotal movement about said optical path;

a roll stabilizing gyro mounted to the case, said gyro including a gimbal pivotally mounted to said case for movement about a gimbal axis parallel to said optical axis, a rotor pivotally supported by said gimbal to spin about a gyro axis, the gyro axis being oriented in a direction other than parallel to said optical axis; and

means for operably coupling the gyro and the derotating prism to rotate said derotating prism at one-half the gimbal motion to obtain stabilization of an image.

6. The invention of claim 5 and wherein said derotating prism comprises a Pechan prism.

7. A camera lens system comprising a case defining an optical path for receipt of light along an optical axis to an image plane;

an objective lens, mounted to the case and

an optical train mounted within the case comprising;

a reflecting and displacing optical element positioned along the optical path following the objective lens;

a reversing and displacing optical element positioned along the optical axis, following said reflecting and displacing optical element, the reflecting and displacing optical element being arranged and adapted to laterally offset and reverse the direction of light from the reflecting and displacing optical element; and

means for inertially mounting said reflecting and displacing optical element to the case so as to maintain an original angular orientation with respect to the optical axis in response to small tilts and hand movements of the case, said means for inertially mounting including a Cardan suspension system including first and second gimbals and a rotor, said first gimbal mounted to the case for pivotal movement about a first axis, said second gimbal mounted to said first gimbal for pivotal movement about a second axis, said rotor mounted to said second gimbal for rotation about a third axis;

means for restoring said rotor as mounted to said first and second gimbals to a preselected position of excursion of each of said first and second gimbals to enable maximum excursion of said rotor relative to the case;

a third gimbal pivotally mounted to the second gimbal for rotation about a fourth axis;

said reflecting and displacing optical element being mounted to said third gimbal for pivotal movement about a fifth axis; and

said third gimbal and said reflecting and displacing prism biased to a preselected position of excursion of said third gimbal and said reflecting and displacing prism and damped sufficiently to substantially inhibit vibrations above a chosen frequency from reaching the optical element.

8. An image position stabilizing assembly comprising:

a Cardan suspension assembly including;

a first gimbal pivotally secured to a base for pivotal movement about a first axis;

a second gimbal mounted to said first gimbal for pivotal movement about a second axis; and

a rotor rotatably mounted to said second gimbal for rotation about a third axis;

means for restoring said rotor to a preselected orientation with respect to said case whereby said first and second gimbals are predisposed for excursion relative to said case relative to said base;

a reflecting and displacing optical element; and

a low frequency mechanical bandpass filter mounting means for mounting said reflecting and displacing optical element to said second gimbal, said low frequency mechanical bandpass filter including a third and fourth gimbals mounted on respective fourth and fifth axes.

9. An optical element stabilizer comprising:

a case;

a Cardan suspension system including first and second gimbals and a rotor, said first gimbal mounted to the case for pivotal movement about a first axis, said second gimbal mounted to said first gimbal for pivotal movement about a second axis, said rotor mounted to said second gimbal for rotation about a third axis;

means for restoring said rotor to a preselected position relative to said case to dispose said first and second gimbals for excursion relative to said case;

a third gimbal pivotally mounted to said second gimbal for rotation about a fourth axis;

reflecting and displacing prism mounted to said third gimbal for pivotal movement about a fifth axis; and

said third gimbal and said prism biased to respective home positions and damped sufficiently to substantially inhibit vibrations about a chosen frequency from reaching said optical element.

10. The stabilizer of claim 9 wherein said chosen frequency is about 2 Hz.

11. A method for stabilizing an optical element comprising the following steps:

pivotally mounting a Cardan suspension assembly, including first and second gimbals and a rotor, to the case of an optical instrument through the first gimbal;

restoring said rotor to a home orientation relative to the case;

pivotally mounting a third gimbal to the second gimbal;

pivotally mounting a reflecting and displacing optical element to the third gimbal; and

biasing and damping said third gimbal relative to said second gimbal and said optical element relative to said third gimbal to bias said third gimbal and said optical element to respective home orientations and to substantially inhibit vibrations above a chosen frequency from being transmitted to the optical element.