Protein crystal growth in microgravity-temperature induced large scale crystallization of insulin.

One of the major stumbling blocks that prevents rapid structure determination using x-ray crystallography is macromolecular crystal growth. There are many examples where crystallization takes longer than structure determination. In some cases, it is impossible to grow useful crystals on earth. Recent experiments conducted in conjunction with NASA on various Space Shuttle missions have demonstrated that protein crystals often grow larger and display better internal molecular order than their earth-grown counterparts. This paper reports results from three Shuttle flights using the Protein Crystallization Facility (PCF). The PCF hardware produced large, high-quality insulin crystals by using a temperature change as the sole means to affect protein solubility and thus, crystallization. The facility consists of cylinders/containers with volumes of 500, 200, 100, and 50 ml. Data from the three Shuttle flights demonstrated that larger, higher resolution crystals (as evidenced by x-ray diffraction data) were obtained from the microgravity experiments when compared to earth-grown crystals.

Computerized Moiré analysis of progressive addition lenses.

A computerized image capture and analysis system capable of 256-level intensity resolution was used to digitize and store images as a 512 by 512 pixel array. The system was used to record a standard square-wave grating (0.80 lines/mm) located 1 m from the camera. Subsequently, an ophthalmic lens was interposed between the camera and the grating. Nonzero lens powers induced magnification and thus altered the spatial frequency of the grating image. Subtractive-type Moiré analysis was performed to compare the intensity distributions of the magnified and the unmagnified (reference) gratings. The Moiré patterns created using digital, pixel-by-pixel subtraction of the two images showed graphically the power distributions of the lenses studied. These patterns varied noticeably between different brands of progressive-addition lenses (PAL's) of the same nominal power. Using only commercially available components, this method of analysis was both fast and repeatable, and may be of value to manufacturers and large-volume finishers of progressive-addition lenses.

Matrix methods for the evaluation of lens systems with radial gradient-index elements.

Matrix methods have been used to examine the paraxial performance of homogeneous systems. This method has been extended to include the presence of gradient lens elements in the optical array. To accomplish this, an inhomogeneous rotation-translation matrix is developed to describe the path of a ray through the lens elements with quadratic radial index gradients. The system matrix elements are then used to predict the paraxial properties of the array. Three examples are examined: the Wood lens, two thin lenses coupled to a radial gradient index rod, and a model of the human eye which contains a radial gradient index crystalline lens.

The subjective quality (SQF) of Bausch and Lomb SoflensTM.

The visual acutiy of a person is examined in terms of his response to a unique target. This target is a sequence of black bars on a white background, where the spacing of the bars and their width is governed by a log periodic function. The generation of these targets is performed by a PDP-8 computer connected to an X-Y plotter. There are six sets of bars which vary in contrast and frequency. In a clinical situation, an observer notates the position where he can no longer resolve the bar pattern. A recroding of these positions produces a Subjective Quality Function (SQF) curve for the individual. On fitting with soft contact lenses, a new SQF curve is generated. A comparison of the SQF for soft lenses with that for spectacle corrections is given.

Computerized analysis of the image quality of the human eye with optical aids.

Spot diagrams are computer generated by skew ray tracing for a model of the human eye which is corrected by means of a contact lens and spectacle lens. An examination of the images of a point source of light at 0 degrees and 20 degrees off the optical axis of the eye-lens system are shown. For the correction of aphakia, the performance of the contact lens is shown to be superior in off-axis optical performance.