US 4,471,448 A · Method and apparatus for aligning an optical system

Abstract

A complex optical system may be aligned by means of a technique in which an analytical model of the system is utilized which is assumed to be capable of essentially optimal performance. A physical example of the same system design is then assembled and a plurality of performance characteristics measured. A plurality of specific adjustments are then calculated which would have the effect of degrading the performance of the analytical model to equal that measured for the physical example, whereupon compensating physical adjustments are made to the physical example. For many applications, the performance measurements may relate to aberrations to the wavefront of the point source image quantified by means of a Hartmann mask or the like. In that event, the estimation technique may be a straight-forward linear approximation technique including possible damping and/or weighting factors. The performance measurements may also be related to the intensity function associated with the image of a point source, in which case a second order estimation technique is required.

Claims30

Dependent claims

A method for realigning a complex optical system having several degrees of alignment freedom comprising the steps of:

(a) measuring a plurality of optical performance characteristics, said plurality of characteristics having at least as many separate components as the number of said alignment degrees of freedom;
(b) determining whether or not the alignment of the system is satisfactory by comparing a figure of merit derived from said plurality of performance components with a pre-established performance criterion;
(c) if the said performance is determined not to be adequate, then,
(i) calculating successive approximations to an estimated set of adjustments that would alter the calculated performance of an analytical model of said system to a degraded performance comparable to said measured performance;
(ii) deriving a set of physical adjustments for said adjustment parameters from said estimated set of adjustments so as to compensate at least partially for the alignment errors associated with said system;
and
(iii) applying said physical adjustments to the optical system for correcting any alignment errors;
(iv) repeating steps (a) through (c) (iv) until a satisfactory alignment results.

5 more elements

An improved optical system having an automatic realignment capability comprising:

an optical system having a number of individual optical units with complementary optical characteristics and spatial relationships to each other positioned on an optical axis extending from an object to an image side, at least a plurality of optical units being movably mounted relative to the optical axis and having an interactive effect on the image transmitting ability of image side optical units;
means for moving the movably mounted optical units to change their respective spatial positions;
means for providing signals indicative of an analytical optical model of an optimized optical system capable of providing the predetermined optical performance desired by the optical system;
means for measuring a plurality of predetermined characteristics indicative of the optical performance of the optical system and producing corresponding measurement signals including a multi-apertured member removably mounted on the optical axis for quantifying aberrations in the wavefront from an image source and an image detector positioned at the focal plane of the optical system on the image side of the apertured member;
computer means for comparing the measurement signals with the signals indicative of the analytical model and providing adjustment signals necessary to conform the optical performance of the analytical model to that of the measured optical system, and
means for automatically applying the adjustment signals to the means for moving the optical units to realign the spatial position of the optical units for conformance with the predetermined optical performance of the analytical optical model.

3 more elements

A method of aligning an optical system comprising the steps of;

providing an optical system having a number of individual optical units with complementarily optical characteristics and spatial relationships to each other positioned on an optical axis extending from an object to an image side, at least a plurality of optical units being movably mounted relative to the optical axis and having an interactive effect on the image transmitting ability of image side optical units;
providing signals indicative of an analytical optical model of an optimized optical system capable of providing the predetermined optical performance desired by the optical system;
measuring a plurality of predetermined characteristic indicative of the optical performance of the optical system and producing corresponding measurement signals;
comparing the measurement signals with the signals indicative of the analytical model and providing adjustment signals necessary to conform the optical performance of the analytical model to that of the measured optical system, and
automatically moving the optical units in response to the measurement signals to align the spatial position of the optical units for conformance toward the predetermined optical performance of the analytical optical model.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for aligning an optical system

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Method and apparatus for aligning an optical system

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Abstract

Claims30