For small aberrations, the Strehl ratio of an imaging system depends on the aberration variance. If the aberration function is expanded in terms of a complete set of polynomials that are orthogonal over the system aperture, then the variance is given by the sum of the square of the aberration coefficients. One such set is that of Zernike polynomials, which are orthogonal over a circular pupil. Its advantage lies in the fact that Zernike polynomials can be identified with the classical aberrations that are balanced to yield minimum variance, and thus a maximum Strehl ratio. We discuss classical aberrations, balanced aberrations, and Zernike polynomials for systems with circular pupils. How these polynomials change for an annular or a Gaussian pupil are also discussed.

Design examples are given for imaging spectrometer systems operating in the solar reflected spectrum. Design considerations and procedures are outlined for incoherently and coherently coupled systems. The case of a partially coupled system is also examined and it is shown why it is generally to be avoided.

The National Ignition Facility (NIF) requested an optical diagnostic for measuring shock velocities, shock breakout times, and shock emission of objects with sizes of 1 to 10 mm. For the polar port of the target chamber, an 8-inch triplet lens collects light at f/3 inside a 30-foot-diameter vacuum chamber and uses an optical relay to send the image into two interferometers located at a distance of 160 feet. Light propagates through a VISAR (Velocity Interferometry System for Any Reflector) interferometer employing a Mach-Zehnder configuration. After exiting the interferometers the images are recorded, both by streak cameras and CCD gated imagers. Discrete magnification changes are accomplished by swapping out optical elements. Large dove prisms are used to rotate the image to align a selected region of the object with the slits of the streak cameras. Unique mounting structures are required to remotely control the alignment of the optical axis. Finite Element Analysis (FEA) was performed on all mounting structures. The first 8-inch triplet can be no closer than 500 mm from the target chamber center and is protected by a blast window that has to be replaced after every event. The first several lens groups have to be fused silica for radiation resistance. A frequency-doubled Nd:YAG laser, operating at 659.5 nm, is used to illuminate the moving object. The VISAR laser wavelength had to be different than the first, second, and third harmonics of the NIF drive lasers.

Injection molded optics are frequently applied in many high volume applications. Bar code scanners, CD / DVD systems, CMOS cameras are a few examples. In all of these applications cost effective and fast design cycles are essential. At Philips High Tech Plastics we developed a design system that touches on all different aspects of the system design. Starting with traditional lens design (sequential ray tracing) and tolernacing we transport the initial design into mechanical solid modeling. During mechanical modeling, tolerances, injection molding design rules and integration of mechanical features, reference marks, etc. are incorporated as well. Here the full advantage of injection molding can be utilized. After the opto - mechanical modeling the system is ported back to non - sequential ray tracing for ghost - and stray light analysis. Finally extended tolerancing is performed in order to come to a robust high volume product. If necessary all or several steps in this design process are repeated in order to arrive at the final design. As an additional requirement the metrology possibilities for the design are checked in at an early stage. This integral system approach to optical design, including optical modeling (sequential and non-sequential) combined with mechanical solid modeling is presented using some recent examples.

The design of critical automotive lamp reflectors, e.g. headlamps and fog lamps, is dominated by trial-and-error methods and rules-of-thumb, supported by optical ray-tracing tools like ASAP etc. In many cases these reflectors are designed by aiming small sections to construct the required illumination distribution, which is a time-consuming task and in which case it is very difficult to maintain a continuous reflector surface. The design method presented here is a more structured approach in which the total available front surface is divided in a few relatively large sections, each section designated to produce a certain part of the required light distribution. An optimizing algorithm is used to optimize the separate polynomial reflector sections in combination with a specific burner. In the final step, the separate sections are put together to form a more-or-less continuous reflector surface. Some iteration afterwards is still required because the intersection lines of the polynomial surfaces will generally change the original section boundaries. The design of a front fog reflector lamp is used as a carrier to demonstrate the approach. Three reflector sections are used to design a high-efficiency fog lamp. The light distribution has an excellent horizontal cut-off that basically meets the SAE requirements.

Laser encoders overcome the fundamental resolution limit of geometrical optical encoders by cleverly converting the diffraction limit to phase coded information so as to facilitate nanometer displacement measurement. As positioning information is coded within the optical wavefront of laser encoders, interferometry principles must be adopted in the design of the laser encoders. This effect has posed a very strong alignment tolerance among various components of the whole laser encoder, which in turn imposes a serious user adaptation bottleneck. Out of all alignment tolerances, the head-to-scale alignment tolerance represents the most important hindrance for wider ap-plications. This paper presents a novel laser planar encoder, which serves as a two-dimensional position detection apparatus for precision machine applications and can provide a measuring resolution less than 1 nm. Improving the IBM laser optical encoder design by taking into consideration manufacturing tolerance of various optical components, an innovative two-dimensional laser encoder with ultra high head-to-scale tolerance is presented. It was identified that this newly proposed laser encoder design could avoid the effect of differences in polarization diffraction efficiencies for the 2-D grating scale used. Optimizing the system performance by cleverly designing the profile of the 2-D grating scale was also detailed. The effect of non-uniform temperature field within the head-to-scale range that can yield a nonzero initial phase so as to decrease the system measurement accuracy was analyzed. In addition, misalignment of the polarizers located in front the photodiodes were identified to be the main cause for imperfect Lissajous circles, which may lower the measuring resolution when traditional arctangent algorithm was adopted for circular polarization interferometers. The resolution of the newly developed laser planar encoder was verified by experiments and was found to agree well with the theoretical predictions.

An overview of optical systems utilized in JPL's Optical Communications research is provided here. These include discussions on the flight terminal optics, the ground receiver aperture and the uplink beacon or command optical system. On-going efforts on these and beam-coupling techniques will be described.

This paper provides an overview of the Tropospheric Emission Spectrometer (TES) and its mission, as a part of NASA’s Earth Observing System (EOS). The design of the re-imaging system and its detectors and the test set-up used to characterize the field of view response will be presented. Measured system Response.optical response profiles will be presented for each of the four infrared spectral bands (3.5-5.3, 5.1-9.1, 8.3-12.2 and 11.1 - 15.4μ ) supported by TES. Specific emphasis will be placed upon the comparison of these measured optical response functions with the results of an analytic model of the response. The model includes a simple yet accurate representation of the detector response function, which includes the photo-generated electron’s diffusion length.

With the increasing sensor development, smart sensor, advanced sensor, and intelligent sensor, especially, distributed sensors, sensor network and sensor integration are being taken into account for application of our environmental monitoring and Earth source investigation. This paper investigates the development of sensors in Earth observing (EO) satellites, analyzes the current high-resolution EO satellites and presents the direction of new imaging systems in future Earth observing satellite. The purpose of this paper is to contribute to those who are interested in knowing and keeping track of the details of the imaging system of earth observing satellites.

We present three designs and tolerances of wide-field imagers (30'30 arc-minutes or larger) for astronomical surveying. Two infrared cameras (CPAPIR and PANORAMIX II) were designed for the 0.8-2.4 μm band and a third one (WIRCAM) for the visible and near-infrared band extending from 410 nm to 950 nm. The cameras are installed on the telescopes of the Canada-France-Hawaii (Hawaii, USA) and Mont Megantic Observatories (Quebec, Canada). The three cameras are compact, use only spherical refractive components and have an internal pupil accessible for insertion of filtering components. A Lyot stop must be used in the infrared camera for background rejection. For PANORAMIX II, a set of filters is used at the internal pupil. Correction of the large off-axis aberrations generated by the telescopes, wide spectral coverage, material choices, cryogenic temperature and alignment were the main design challenges. Also, tolerancing was particularly critical for the infrared cameras because they are cryogenically cooled, thus forbidding adjustment of internal components. The cameras’ theoretical performances are presented in terms of point-spread function, encircled energy and distortion.

The display of 3D images containing all the depth cues required by the human vision system can be achieved using a reconfigurable Computer Generated Hologram (CGH) with high pixel count. A technique which has been developed to produce CGH's with the required number of pixels, and at video refresh rates, is known as Active Tiling^TM (AT). At the heart of an AT system is a set of replication optics which produces multiple images of a Spatial Light Modulator (SLM) onto the CGH. The design of two alternative optical systems for geneating a 5x5 tiled array of de-magnified images of a single object is discussed. Results are presented from a 4-channel AT system which has recently been built and demonstrated.

Blazed gratings have been fabricated using gray-scale X-ray lithography. The gratings have high efficiency, low parasitic light, and high groove quality. They can be generated over a considerable depth for use anywhere in the ultraviolet to middle infrared range. They can also be recorded on substrates of considerable curvature.

Convex and concave diffraction gratings are required for concentric imaging spectrometer forms. Direct-write electron-beam lithography has proven to be an effective method for fabricating high-efficiency blazed gratings on non-flat substrates. Recently fabricated convex gratings have demonstrated relative efficiency greater than 90%, diffuse scatter and ghosts less than 5x10^-4 of the main diffraction order, and zeroth-order wavefront error less than 1/4-wave at 633 nm. Such gratings can be fabricated on JPL’s JEOL JBX-9300FS electron-beam lithography system with a writing speed of approximately 1 to 2 cm² per hour. The technique was recently used to fabricate flight-qualified gratings for the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument that is scheduled to fly on the NASA Mars Reconnaissance Orbiter in 2005.

We present a new suggest on for treating skew rays. In the new suggestion, we hypothetically divide a spherical lens, at each point of intersection of the incident rays with the spherical lens, into two effective perpendicular lengthless cylindrical lenses. One of the hypothetical cylindrical lenses is effective in the vertical direction while the other is effective in the horizontal direction. A method is given for calculating the resulted vertical and horizontal angles of refraction. After calculating these angles one can combine, at that point of incidence, the two components into a vector sum to find the resultant refracted ray. The new suggested method is first discussed and demonstrated for one single lens, and then generalized to optical systems of many components. The method's power and effectiveness in lens and optical systems design is demonstrated. A software package is designed and written for the purpose of optical ray tracing. The new method is implemented in this software. The name we gave to this package is "CALOSD". CALOSD is an acronym for Computer Aided Lens and Optical Systems Design. CALOSD is capable of producing very accurate tabulated data as well as graphical displays of an optical system and rays traced from different points or angles of view; including a top view.

This paper presents a signal analysis method with the purpose of detecting frequency chande and acceleration amplitude of vibrating-type accelerometer's output. The method has potential application for newly developed oscillating micro accelerometers.