Search

A process for flexible, scalable photonic manufacturing is described. Optical components are actively pre-aligned and secured to precision mounts. In a subsequent operation, the mounted optical components are passively placed onto a substrate known as an Optical Circuit Board (OCB). The passive placement may be either manual for low volume applications or with a pick-and-place robot for high volume applications. Mating registration features on the component mounts and the OCB facilitate accurate optical alignment. New photonic circuits may be created by changing the layout of the OCB. Predicted yield data from Monte Carlo tolerance simulations for two fiber optic photonic circuits is presented.

Triangulation based range sensors have long been used for making large scale measurements, however, when triangulation techniques are used in metrology applications with very tight tolerances, new concerns appear. In particular, the design of very high resolution range sensors requires an understanding of surface microstructure effects that can severely limit the accuracy of a system. For triangulation based sensors to enter the regime where interferometry has traditionally been used, the problems of surface microstructure induced noise must be overcome. In this paper we discuss the factors that limit the resolution of triangulation based range sensors, and the theoretical limitations on the accuracy of such sensors.

New optical systems containing several laterally displaced lenses or lens segments operating in parallel are discussed. Such systems are useful for high resolution imaging of small, widely separated regions of an object or for producing custom illumination patterns for applications such as triangulation based range sensing using multiple stripe illumination. Inspection problems well suited to multiple aperture imaging are described and design rules are given. Examples of both imaging and illumination applications are given.

An optical system containing multi- faceted holographic optical elements (HOEs) was constructed to correctfor aberrations introduced by a non -flat window in NASA Laser Doppler Velocimetry (LDV) experiments in aninternal combustion engine. For this experiment, two green beams separated by 82 mm in a vertical plane, andtwo blue beams separated by 82 mm in a horizontal plane, are brought into coincident focus inside a thickwalled sapphire cylinder. The focal power to bring these beams to a common focus and the aberrationcorrection required by the presence of the cylinder were built into the holographic elements.A modular optical breadboard system was configured to fabricate, test, and use the custom made HOE's.Additional HOE's were also fabricated to provide aberration correction and color separation for themultispectral output waves emerging from the focal volume. Compensation for the birefringence of a thicksapphire cylindrical window in the experiments is also accomplished.A general system such as we have built is useful wherever high efficiency, localized optical correction ofwavefront errors is needed in LDV or other optical experiments.IntroductionLaser Doppler velocimetry (LDV) has become an important tool to researchers interested in makingnon -invasive flow measurements for a wide class of engineering problems. Figure 1(a) shows a normal 4 -beamLDV setup where 2 pairs of parallel input beams are brought to focus at a common intersection position.Because the beams arrive from different angles at the focal volume, two sets of linear, equally spaced,orthogonal interference fringes exist within the intersection zone. Particles moving through this measurementvolume will scatter light, with the fluctuation rate of the scattered light being directly proportional to thevelocity of the particles. The use of two wavelengths allows the simultaneous measurement of two orthogonalvelocity components.A major impediment to the use of LDV is gaining optical access to the system of interest. This problem isparticularly difficult if nonflat windows are a part of the system under consideration. Experimenters haverecognized the problems associated with making laser velocimetry measurements through windows whgsq surfacesare not normal to the incident wave fronts and have reported on various aspects of this problem. '0 Ofparticular interest in this paper is the measurement of flows within a cylinder. More specifically, aninternal combustion engine has been built in which the engine cylinder is fabricated from a single crystal

In this paper we discuss the properties of optical elements fabricated by holographically recording an ultra-high spatial-frequency pattern in a photoresist mask followed by reactive ion etching to transfer this pattern into the surface of a quartz substrate. Such optical elements are envionmentally durable, potentially easy to replicate, and exhibit diffraction efficiencies in excess of 85%. In addition, two other properties are reported. Such elements at normal (00) incidence are antireflective, with broadband reflection coefficients as low as 0.035%. Also, the elements exhibit artificially produced birefringence making them useful as wave plates. These results may be particularly significant in the UV and IR, where damage-resistant antireflection coatings and transparent birefringent materials may not exist.

The specification and design of structured light triangulation systems are discussed. Custom optical systems for optimal illumination and signal detection are described. In addition to general concepts that are applicable to all triangulation sensors, several special cases are examined. In particular, the effects of surface roughness on measurement accuracy and the problems of long range triangulation are discussed.

In this paper we describe the use of a multifacet holographic optical element which utilizes nearly all the energy in an incident Gaussian laser beam to form a gray tone output pattern or image.

The design and fabrication of a holographic beamsplitter that will produce multiple phase and amplitude matched output beams from a collimated laser beam is discussed. Multiple exposures are recorded in a dichromated gelatin (DCG) plate to make the output beams seem to emanate from a single point with high diffraction efficiency and low scattering. During fabrication, a technique was developed to verify that the relative phasefronts of all the output beams are matched. The holograting can be designed such that any relative phase, amplitude and angle between the output beams as well as different recording/readout wavelengths can be specified for a variety of applications. A deterministic method of calculating the optimum Bragg angles for the recording beams has been developed to compensate for the wavelength shift between the recording laser and the readout laser. A special emphasis is given to the application of using a laser diode for readout. Specifically, a double grating method is utilized for making the element less sensitive to wavelength drift common to laser diodes. A single small component has been fabricated with output beams in-line with respect to the input beam axis such that it can be configured into compact and rugged optical systems.© (1989) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.