Roland V. Shack

Influence Of Alignment Errors Of A Telescope System On Its Aberration Field

It is shown that, for each field-dependent aberration type, the effect of tilts and decentrations is to produce a more complicated field dependence and local orientation of the aberration without otherwise changing its character. Particular attention is given to astigmatism.

Aberrations of diffracted wave fields.

This paper is an attempt to provide new insight into the behavior of near-field scalar diffraction phenomena by showing that the Rayleigh-Sommerfeld diffraction integral is equivalent to the Fourier transform integral of a generalized pupil function which includes a term that represents phase errors in the aperture. This term can be interpreted as describing a conventional wavefront aberration function. The resulting aberration coefficients are calculated and expressed in terms of the aperture diameter, observation distance, and appropriate field parameter for several different geometrical configurations of incident beam and observation space. These aberrations, which are inherently associated with the diffraction process, are precisely the effects ignored when making the usual Fresnel and Fraunhofer approximations.

Ultrafast laser scanner microscope.

Advances in monolayer deposition of cervical cells have removed one of the last serious obstacles to the design of high-resolution automated diagnostic assessment systems. In this article, we describe the design considerations for a system that is capable of acquiring, within 60 sec, a 0.5 micron digitized image of a 4 cm2 area on a standard glass slide. The most feasible approach is found to be a system using a rotating polygon to sweep the focused spot from a laser across a 2-mm scan line while the slide is uniformly translated perpendicular to the scan direction the use of laser sources (a helium-neon laser at 632 nm and a krypton ion laser at 568 and/or 476 nm) as compared to the incoherent light sources used in conventional microscope systems alleviates many of the optical design problems and provides the proper wavelengths needed for recognition of Papanicolaou stained cells. We also find that focus control of the scanning spot should be achievable using a technique involving a holographic grating. Other relevant considerations such as sample heating problems, multiphoton absorption by the sample, detector signal-to-noise ratios, laser amplitude noise control, and the digitization and buffering of the data stream are also discussed.

The Influence of Image Motion and Shutter Operation on the Photographic Transfer Function

In Part I a general two-dimensional expression for the transfer function of the photographic exposure image is derived, including as factors the optical transfer function, the transfer function arising from scattering of light in the emulsion, the shutter function, and the motion of the image. The effect of shutter operation in the absence of image motion is discussed and it is shown that a focal-plane shutter acts as an independent agent with its own effective transfer function, whereas a between-the-lens shutter is not independent but acts as an apodizing agent. In Part II, the effect of image motion is discussed, with the assumption that the optical transfer function is independent of the shutter action. The concept of an equivalent spread function for image motion is developed, and uniform linear image motion and harmonic image motion are discussed in detail, the latter especially for the case where there are at simple the most only a few periods in the exposure time. An approximation for small degradations is then obtained in which all possible combinations of uniform linear motion and simple harmonic motion are contained. Throughout the paper the functions discussed are functions of two-dimensional space.

Sorting method to extend the dynamic range of the Shack–Hartmann wave-front sensor

We propose a simple and powerful algorithm to extend the dynamic range of a Shack-Hartmann wave-front sensor. In a conventional Shack-Hartmann wave-front sensor the dynamic range is limited by the f-number of a lenslet, because the focal spot is required to remain in the area confined by the single lenslet. The sorting method proposed here eliminates such a limitation and extends the dynamic range by tagging each spot in a special sequence. Since the sorting method is a simple algorithm that does not change the measurement configuration, there is no requirement for extra hardware, multiple measurements, or complicated algorithms. We not only present the theory and a calculation example of the sorting method but also actually implement measurement of a highly aberrated wave front from nonrotational symmetric optics.

Effects of Dilution on a Six-Element Synthetic Aperture

An investigation was made of the effects of dilution on a six-element synthetic aperture. The characteristics of both the spread function and the transfer function were obtained for several degrees of dilution. It is shown that small degrees of dilution result in a significant gain over the performance of a single element, whereas more dilute apertures are inferior for direct imagery.

Analytic System Design With Pencil And Ruler--The Advantages Of The y-y Diagram

It is well known that the first-order properties of an optical system are sufficiently specified by the tracing of two meridional paraxial rays through the system, namely the marginal ray, which originates at the center of the object plane and passes through the edge of the stop, and the chief ray, which originates at the edge of the object and passes through the center of the stop. Wherever the marginal ray crosses the axis an image plane is located and wherever the chief ray crosses the axis a pupil plane is located. Moreover, the height of the chief ray at an image plane gives the size of the image and the height of the marginal ray at a pupil plane gives the size of the pupil.

The Use Of Normalization In The Application Of Simple Optical Systems

In choosing a configuration for an optical image-forming system, one is usually given several prescribed parameters, such as focal length, field, aperture, or magnification, and the required performance. The required performance is usually specified as some tolerance on a quality factor which ultimately depends on the aberrations of the system. In this paper we deal only with simple systems where the performance is limited by third-order aberrations, although the approach outlined is not restricted to such systems.

Image processing by an optical analog device

Abstract An optical image processor and its capabilities are described. As an image restoring device it works by corrective convolution rather than by complex spatial filtering. A transparency to be restored is scanned by an extended, purely real corrective function and the optically processed signal is simultaneously played back, using the same scanning drum. Apart from restoration the device can also be used to perform other linear operations, such as differentiation and matched function correlation. In addition, an incorporated flexible function generator permits quantization, contour generation and other non-linear operations to be performed in the playback, with or without the optical processing.

Space Telescope Low-Scattered-Light Camera: A Model

A design approach for a camera to be used with the Space Telescope is given. Camera optics relay the system pupil onto an annular Gaussian ring apodizing mask to control diffracted light. Image plane intensity distributions for both one- and two-dimensional models of ripple on the primary mirror were calculated. Calculations using ripple amplitudes between X/20 and X/200 with spatial correlations of the ripple across the primary mirror between 0.2 and 2.0 cm indicate that the detection of an object 109 times fainter than a bright source in the field is possible. We thus conclude that detection of a Jovian-type planet in orbit about a Centauri with a camera on the Space Telescope may be possible.