This PDF file contains the front matter associated with SPIE Proceedings Volume 7433, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

This paper presents three characteristics in the simulated active alignment strategy of the James Webb Space Telescope. The first includes the analysis and comparison of a baseline active alignment strategy with a damped least squares strategy. This baseline utilizes prior knowledge by means of direct human operator interaction to engage sets of telescope compensators to target specific aberration signatures. The baseline is compared to a damped least-squares strategy that utilizes simultaneous engagement of all telescope compensators without explicit human operator interaction to achieve a least-squares telescope compensation. Second, we discuss how the active alignment of the JWST is encapsulated in a linear optical model developed at the Space Telescope Science Institute. This linear optical model provides a framework for an efficient and robust description of the optical control properties of the JWST and clearly articulates the necessity for having a multi-instrument multifield wavefront sensing strategy to overcome control system non independence and the effects of non-common path errors in the main wavefront sensing camera. Finally, we present analytical results that explicitly map the telescope wavefront responses to the telescope control modes, and we present Monte-Carlo optical performance simulation results that demonstrate the efficacy of the damped least-squares active alignment and the priorknowledge active alignment schemes.

The Optical Telescope Element (OTE) consists of a 6.6 m, all-reflective, three-mirror anastigmat. The 18-segment primary mirror (PM) presents unique and challenging assembly, integration and alignment requirements. To integrate and verify each of the Primary Mirror Segment Assemblies (PMSAs), an integrated network of laser trackers will be used in the Ambient Optical Assembly Stand (AOAS). The AOAS consists of an optical bench (OB) to support the JWST Optical Telescope Element (OTE), a personnel access platform structure (PAPS), an optics integration gantry system (OIGS), and a PMSA alignment and integration fixture (PAIF). The PAIF and OIGS are used to deliver; offload and precision align each PMSA segment and the aft optical subsystem (AOS) to their integration locations. This paper will introduce the functional design of this ground support equipment (GSE), illustrate the coordinate systems used for integration, and detail the integration processes.

The James Webb Space Telescope is a large infrared observatory with a segmented primary mirror, part of the Optical Telescope Element (OTE), and four science instruments supported by the Integrated Science Instrument Module (ISIM). We present the calibration plan for the ISIM Test Platform (ITP) which replicates the ISIM-to-OTE interface: to calibrate the location and orientation of metrology features at ambient and cryogenic environmental conditions, to verify that ITP behavior (deflection under load, warm-to-cold alignment shift) can be modeled, predicted, and tested, to prove that the ITP is stable (upon repeated cryogenic cycles, and after loading and handling), and to calibrate the relationship between the Master Alignment Target Fixture and the ITP at ambient and cryogenic conditions.

NASA's James Webb Space Telescope (JWST) is a 6.6m diameter, segmented, deployable telescope for cryogenic IR space astronomy (~40K). The JWST Observatory architecture includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM) element that contains four science instruments (SI) including a Guider. The SIs and Guider are mounted to a composite metering structure with outer dimensions of ~2.2x2.2x1.7m. The SI and Guider units are integrated to the ISIM structure and optically tested at NASA Goddard Space Flight Center as an instrument suite using a telescope simulator (Optical telescope element SIMulator; OSIM). OSIM is a high-fidelity, cryogenic JWST telescope simulator that features a ~1.5m diameter powered mirror. The SIs are aligned to the structure's coordinate system under ambient, clean room conditions using optomechanical metrology. OSIM is aligned to the ISIM mechanical coordinate system at the cryogenic operating temperature via internal mechanisms and feedback from alignment sensors in six degrees of freedom. SI performance, including focus, pupil shear, pupil roll, boresight, wavefront error, and image quality, is evaluated at the operating temperature using OSIM. This work updates the assembly and ambient and cryogenic optical alignment, test and verification plan for ISIM.

NASA's James Webb Space Telescope (JWST) will be a premier space science program for astrophysics following launch scheduled for 2014. JWST will observe the early universe, with emphasis on the time period during which the first stars and galaxies began to form. JWST has a 6.5 m diameter (25 square meters of collecting area), deployable, active primary mirror operating at cryogenic temperatures.

We have designed and manufactured an optical system with dual field of view (FOV) for an uncooled IR camera. Fnumber of the optical system with five elements is given by F/1.04. FOVs are given by 8°x6° for narrow FOV and 24° x 18° for wide FOV. One of the five lenses is linearly moved along the optical axis not only to change FOV but also to athermalize for the optical system. The movement of the lens is fulfilled with a stepping motor within a few micrometers' accuracy. The athermalization is compensated for 100 K of the temperature difference. The optical system is integrated into an uncooled IR detector engine to verify the optical performance of the dual FOV IR system. The uncooled IR detector consists of 320x240 pixels with 25μm pitch. Minimum resolvable temperature difference (MRTD) as measured values at each FOV will be presented in this paper.

We present a method for the precision alignment of cylinder lenses which has been employed for the null lenses used to test the segmented mirrors for the IXO x-ray telescope. We also present a design for a housing for such a lens.

The author discusses recent alignment problems from his personal practice of optomechanical engineering.

The New Solar Telescope (NST) is an off-axis Gregorian telescope at Big Bear Solar Observatory (BBSO). This paper presents the expected aberrations due to misalignments of the secondary mirror for a general Gregorian telescope using an optical model of the on-axis "parent" telescope version of NST. The sensitivities of linear astigmatism and constant coma found by perturbing the axisymmetric model are presented and shown to match those predicted by the theory. Then we discuss how the actual aberrations are different due to the off-axis nature of the NST. Finally, we discuss the effect of the misalignments on the pointing of the telescope.

The alignment of three mirror anastigmatic (TMA) telescopes has been studied since their invention in the 60s. Recently, Thompson et al.¹ reported that other than the conventional uniform coma over the field caused by misalignment, TMA telescopes display only one other misalignment induced aberration, field-asymmetric, field-linear astigmatism. Currently, an instrument with three TMAs is under development as the primary spectrometer on the James Webb Space Telescope. This paper will report on the application of Nodal Aberration Theory (NAT) to understanding the optical design of an optical system with multiple TMAs as a first step towards investigating and potentially independently analyzing the sensitivities to alignment of this key instrument.

The precise alignment of multiple element large optical system is a challenging task. In order to increase the alignment process efficiency, computer aided alignment methods utilizing Zernike polynomial coefficients have been developed over the last few decades. Recently, differential wavefront sampling(DWS) algorithm revealed that derivative information about the wavefront is a very useful to separate wavefront coupling effect between optical elements of the target system. We compared the alignment performance of the DWS, sensitivity table method and merit function regression method. Even though DWS showed the best performance in simulation, it revealed weak points in terms of high sensitivity to the experimental conditions when applied to the real alignment of Korsch type optical system. In this paper, we explain three different alignment algorithms and discuss the problems in DWS method under current experimental situation, and show the alignment result for Korsch type optical system using merit function regression method.

Tolerancing a lens is a basic procedure in lens design. It consists in first defining an appropriate set of tolerances for the lens, then in adding compensators with their allowable ranges and finally in selecting an appropriate quality criterion (MTF, RMS spot size, wavefront error, boresight error...) for the given application. The procedure is straightforward for standard optical systems. However, it becomes more complex when tolerancing very wide angle lenses (larger than 150 degrees). With a large field of view, issues such as severe off-axis pupil shift, considerable distortion and low relative illumination must be addressed. The pupil shift affects the raytrace as some rays can no longer be traced properly. For high resolution imagers, particularly for robotic and security applications, the image footprint is most critical in order to limit or avoid complex calibration procedures. We studied various wide angle lenses and concluded that most of the distortion comes from the front surface of the lens. Consequently, any variation of the front surface will greatly affect the image footprint. In this paper, we study the effects on the image footprint of slightly modifying the front surface of four different lenses: a simple double-gauss for comparison, a fisheye lens, a catadioptric system (omnidirectional lens) and a Panomorph lens. We also present a method to analyze variations of the image footprint. Our analysis shows that for wide angle lenses, on which the entrance pupil is much smaller than the front surface, irregularities (amplitude, slope and location) are critical on both aspherical and spherical front surfaces to predict the image footprint variation for high resolution cameras. Finally, we present how the entrance pupil varies (location, size) with the field of view for these optical systems.

The design and development of an optical system includes completing detailed drawings that specify allowable error limits, commonly referred to as tolerances. The process of deriving tolerances is iterative, requires attention in the nominal design process, must take into account adjustments in production (compensators), and is highly dependent on designer skill. The performance of the resulting as-built systems will clearly be dependent upon the specified tolerances. Additionally, while frequently overlooked, the cost of the lenses is also strongly dependent on the difference between the specified tolerances and the limits of the optics manufacturer, the coater, and the metrologist. In spite of this relationship, many drawing tolerances are not reviewed at all, and default values are frequently used. In this paper, methodologies for assessing design robustness and tolerancing optical systems are covered. Typical "default" tolerances are evaluated for effectiveness and cost. Finally, the paper has a case study that explicitly shows a design with different sets of tolerances and relative costs, along with associated expected performance.

The key to high quality optics is a set of guidelines. Create an understanding of the Criteria for Quality. Focus on understanding and controlling process variation. Examine verification and validation of methods. Take a view of the horizon as well as drilling down so you know when to put down the shovel.

In contrast to microelectronics which may be considered two-dimensional in first approximation, micro-optical systems extend over three dimensions. Due to the lack of a uniform material system, complex micro-optical systems are constructed using a modular concept. The modular setup of such hybrid systems results in an isolated manufacture of the individual components and their later assembly in a single system. Designing a micro-optical system, all relevant requirements and constraints defined by the manufacturing processes and the application of the system in a real ambience must be considered. Furthermore, every individual manufacturing step adds its own tolerances to the system. To maintain the overall function of a system under the given manufacturing conditions, the system design has to be robust with respect to the expected tolerances. The system's robustness will result from considering process knowledge in the state of modeling already. Process knowledge of non-silicate manufacturing processes is collected and stored in a knowledge database. On basis of these data, process-dependent inaccuracies and tolerances can be used to design robust functional components and functional units (subsystems). This approach of robust, tolerance compensating design is applied to the design of an infrared gas sensor, a micro-optical distance sensor, and a lens of variable refraction power.

Axisymmetric aspheric optical surfaces deviating from conicoids are becoming more common due to their significant optical design advantages. Their practical use is being further enabled by ever-improving manufacturing and metrology methods. In order to effectively utilize such surfaces, tolerances must be applied that tie the manufacturability of the aspheric component to the optical design. In this paper tolerancing of aspheric surfaces in orthogonal bases, specifically Forbes aspheres, is covered. The significant advantages of such an orthogonal representation are highlighted and reinforced with an example.

Toroidal variable-line-space (VLS) gratings are very important in the design of an efficient VUV solar telescope that will measure the CIV (155nm) and MgII (280nm) emissions lines in the Sun's transition region. In 1983 Kita and Harada described spherical VLS gratings but the technology to commercially fabricate these devices is a recent development, especially for toroidal surfaces. This paper will describe why this technology is important in the development of the Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket program (the good), the delays due to the conversion between the TVLS grating design and the optical fabrication (the bad), and finally the optical testing, alignment and tolerancing of the gratings (the ugly).

The design and assembly of a nine-element lens that achieves >2000 lp/mm resolution at a 355-nm wavelength (ultraviolet) has been completed. By adding a doublet to this lens system, operation at a 532-nm wavelength (green) with >1100 lp/mm resolution is achieved. This lens is used with high-power laser light to record holograms of fast-moving ejecta particles from a shocked metal surface located inside a test package. Part of the lens and the entire test package are under vacuum with a 1-cm air gap separation. Holograms have been recorded with both doubled and tripled Nd:YAG laser light. The UV operation is very sensitive to the package window's tilt. If this window is tilted by more than 0.1 degrees, the green operation performs with better resolution than that of the UV operation. The setup and alignment are performed with green light, but the dynamic recording can be done with either UV light or green light. A resolution plate can be temporarily placed inside the test package so that a television microscope located beyond the hologram position can archive images of resolution patterns that prove that the calibration wires, interference filter, holographic plate, and relay lenses are in their correct positions. Part of this lens is under vacuum, at the point where the laser illumination passes through a focus. Alignment and tolerancing of this high-resolution lens are presented. Resolution variation across the 12-mm field of view and throughout the 5-mm depth of field is discussed for both wavelengths.

The Dark Energy Survey (DES) will produce high quality images covering over 5000 square degrees of the sky, with precise photometric redshifts between z = 0.2 to z = 1.3, using g, r, i, z and Y filters. The Dark Energy Camera (DECam), under construction for this survey, consists of wide field corrector optics and a CCD detector array that will give a 2.2 square degree field of view. It will be placed at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile. The Optical Science Laboratory (OSL) at University College London (UCL) is undertaking the alignment of the five lenses in the imaging system. These lenses range in diameter from 0.60 - 0.98 meters. The lenses must be held within tight tolerance limits in order to meet the DES science requirements. The tolerances are especially driven by the accuracy in the measurement of the weak lensing signal. This paper details the design for the cells that will hold the lenses and the alignment procedure for the mounting of the lenses and cells. Also presented is the expected static shear distortion pattern that will be generated and the impact of this pattern on the weak lensing signal measurement.

Sequential and non-sequential optical codes can be used for much more than the initial design and analysis of idealized optical and illumination systems. The design process usually assumes ideal components, ignoring realistic properties such as surface and volume scatter, Fresnel reflections, and polarization aberrations. These codes can also be used to perform tolerance analysis on these designs to help determine manufacturability limits. An important extension in the use of these programs is to create simulations based on the as-built components which include realistic optical surface and scatter scenarios. For example, modeling the measured optical quality of a fabricated primary mirror surface provides the opportunity to modify other optical or mechanical parameters to compensate for any surface errors, which in turn, can relieve critical tolerance limits. Optical analysis codes can also be used to model the performance of an optical system during assembly and testing to isolate defects and perturbations which cause the system performance to be out of specification. Interferometric or polarimetric data measured at several locations across the field of view can be used in the optical program to help identify out of tolerance components. These capabilities are of particular importance in eccentric systems as well as in polarization critical systems, provided the optical code can realistically model data in this form.

The Mid Infrared Instrument (MIRI), one of the four instruments on the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST), supports all of the science objectives of the observatory. MIRI optical alignment is an important step in the verification process, directly affecting mission success. The MIRI optical alignment is verified on the ground at the integrated ISIM level using an element in the MIRI Filter Wheel, the pupil alignment reference (PAR), developed by NASA GSFC and provided to MIRI. It is a ~2.3g aluminum piece that has a flat, specularly reflective, 3mm diameter surface in its center, with laser-etched fiducials within its aperture. The PAR is illuminated via an optical stimulus (ground support equipment) and imaged using a pupil imaging camera, during the ISIM test program in order to determine absolute and relative changes in the alignment that impact pupil shear and roll. Here we describe the MIRI PAR; its physical properties and challenges during its design, manufacturing, and testing.