scispace - formally typeset
Search or ask a question
Proceedings ArticleDOI

Optically fast, wide field-of-view, five-mirror anastigmat (5MA) imagers for remote sensing applications

06 Sep 2011-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 8158, pp 815804
TL;DR: The design and development of the first-ever 5MA imager is discussed and some potential air- and space-borne remote sensing applications are discussed.
Abstract: Recent trends in focal plane array (FPA) technology have led naturally to the development of very large format remote sensors that require optically fast, wide field-of-view (FOV) imaging optics. Systems that cover broad spectral ranges, such as multispectral imagers (MSI) and hyperspectral imagers (HSI), require reflective optics to provide aberration and distortion control without the complication of wavelength dependent errors induced by powered refractive elements. These large format systems require even wider fields-of-view than offered by the conventional three-mirror anastigmat (TMA) and four-mirror anastigmat (4MA) designs. Recently, Raytheon has demonstrated in hardware the first-ever aligned and tested five-mirror anastigmat (5MA) imager. The 5MA was designed with an F/3.0 optical speed and a 36 degree cross-scan FOV for use with a large format imaging spectrometer. The 5MA imager has useful features such as: (1) a real entrance pupil to support a full-aperture calibrator or a small scan mirror, (2) an intermediate image for stray light control, and (3) a real exit pupil for optimal cold-shielding in infrared applications. A computer-aided alignment method was used to align the 5MA imager with a final target of balanced wavefront error (WFE) across the full 36 deg FOV. This paper discusses the design and development of the first-ever 5MA imager and some potential air- and space-borne remote sensing applications.
Citations
More filters
Proceedings ArticleDOI
TL;DR: In this paper, the authors describe a design concept for a Landsat-class imaging spectrometer, which matches the data parameters, including a 185 Km swath and a 30 meter ground sample distance (GSD) from a 705 Km-synchronous orbit with a sensor that has contiguous spectral coverage of the solar reflected spectrum (400 to======1500 nm).
Abstract: This paper describes a design concept for a Landsat-class imaging spectrometer. The challenge is to match the Landsat data parameters, including a 185 Km swath and a 30 meter ground sample distance (GSD) from a 705 Km sun-synchronous orbit with a sensor that has contiguous spectral coverage of the solar reflected spectrum (400 to 2500 nm). The result is a remote sensing satellite that provides global access imaging spectrometer data at moderate spatial resolution. Key design trades exist for the spectrometer, focal plane array, dispersive element, and calibrator. Recent developments in large format imaging spectrometers at Raytheon are presented in support of a monolithic spectrometer approach. Features of the design include (1) high signal-to-noise ratio, (2) well-corrected spectral fidelity across a 6,000 pixel push-broom field-of-view, (3) straightforward calibration of the data to units of absolute spectral radiance, and (4) real-time simulation of Thematic Mapper bands, vegetation indices, and water vapor maps for direct continuous downlink.

13 citations


Cites background from "Optically fast, wide field-of-view,..."

  • ...The 5MA has useful optical features, such as (1) a small, real entrance pupil to support a scan mirror or full system calibrator, (2) an intermediate image for stray light control, and (3) a real exit pupil for optimal cold shielding in thermal infrared applications [13]....

    [...]

  • ...As a result, a five-mirror anastigmat (5MA) [12] imager design was selected, an optical form that had never before been realized in hardware [13]....

    [...]

Proceedings ArticleDOI
16 Oct 2012
TL;DR: An alignment experiment of coaxial three-mirror system with 4m focal length and 500mm aperture was carried out, proving the effectiveness of computer-aided alignment (CAA) method in alignment guidance.
Abstract: How to implement high accuracy measurement of large-aperture coaxial optical system is crucial to the optical alignment and optical property evaluation. The methods of image quality measurement including interferometer-collimating testing, wave front testing by using Hartmann, image processing and analysis of out-of-focus image were introduced. Both the advantages and disadvantages of the three methods were compared, which showed that the alignment method based on interferometer-collimating testing is the one with the highest accuracy. The method of computer-aided alignment (CAA) based on interferometer-collimating was discussed in detail. By using a ZYGO interferometer, interferograms with different field of views and a series of Zernike coefficients were obtained to express the disalignment of the system, and then these incorrect parameters were calculated by CAA algorithms. An alignment experiment of coaxial three-mirror system with 4m focal length and 500mm aperture was carried out. The RMS value of the system is lower than 0.07λ after iterations, which is close to the optical diffraction limit, proving the effectiveness of CAA method in alignment guidance.

5 citations


Cites background from "Optically fast, wide field-of-view,..."

  • ...As the development of ground cover area and resolution, it requires the modern space image sensor([1]) to meet the demand of long focus length([2,3]), big field of view([4,5]) and large aperture....

    [...]

Proceedings ArticleDOI
27 Sep 2016
TL;DR: In this article, the authors discussed the manufacturing, alignment and measurement of reflective triplet (RT) optics used in a long wave infrared grating spectrometer by CMM and interferometer.
Abstract: Reflective triplet (RT) optics is an optical form with decenters and tilts of all the three mirrors. It can be used in spectrometer as collimator and reimager to get fine optical and spectral performances. To alleviate thermal and assembly stress deformation, opto-mechanical integrated design suggests that as with all the machine elements and the mainframe, the mirrors substrates are aluminum. All the mirrors are manufactured by single-point diamond turning technology and measured by interferometer or profilometer. Because of retro-reflection by grating or prism and reimaging away from the object field, solo three mirrors optical path of RT has some aberrations. So its alignment and measurement needs an aberration corrected measuring optical system with auxiliary plane and sphere mirrors and in which the RT optics used in four pass. Manufacture, alignment and measurement for a RT optics used in long wave infrared grating spectrometer is discussed here. We realized the manufacture, alignment and test for the RT optics of a longwave infrared spectromter by CMM and interferometer. Wavefront error test by interferometer and surface profiles measured by profilometer indicate that performances of the manufactured mirrors exceed the requirements. Interferogram of the assembled RT optics shows that wavefront error rms is less than 0.0493λ@10.6μm vs design result 0.0207λ.

3 citations

Proceedings ArticleDOI
13 Jul 2018
TL;DR: Refractive, reflective and catadioptric designs for the Thirty Meter Telescope Fiber Wide Field Optical Spectrograph (WFOS) instrument concept are discussed and a tolerance analysis has been performed based on best engineering practices to assess performance robustness against opto-mechanical errors.
Abstract: This paper discusses refractive, reflective and catadioptric designs for the Thirty Meter Telescope Fiber Wide Field Optical Spectrograph (WFOS) instrument concept. Custom macros were written to evaluate performance at the detector plane with the grating at the pupil as a function of fiber position in the pseudo-slit and wavelength, and a tolerance analysis has been performed for each design based on best engineering practices to assess performance robustness against opto-mechanical errors. The catadioptric camera appears to provide the best compromise in this regard.
Patent
Sitter Jr David N1
17 Sep 2020
TL;DR: An unobscured five-mirror AFocal telescope includes an aperture configured to direct electromagnetic radiation to first, second, third, fourth and fifth mirrors, each configured to receive electromagnetic radiation and reflect electromagnetic radiation along a beam path as mentioned in this paper.
Abstract: An unobscured five-mirror afocal telescope includes an aperture configured to direct electromagnetic radiation to first, second, third, fourth and fifth mirrors, each configured to receive electromagnetic radiation and reflect electromagnetic radiation along a beam path. The five mirrors are arranged to sequentially reflect from one another electromagnetic radiation received via the aperture to produce a collimated output beam of the electromagnetic radiation at an exit pupil, with the five mirrors consisting of a three-element objective and a two-element eyepiece. A beam splitter may be disposed between the first mirror and the second mirror to direct short-wavelength electromagnetic radiation toward a device along a separate path.
References
More filters
Journal ArticleDOI
TL;DR: A generalized reverse-optimization alignment solution algorithm using Zernike sensitivity, and proposes the minimum number of fields to take interferograms that was successfully applied on a Cassegrain telescope design for Earth observation from space with arbitrary misalignments and a model including some primary mirror deformation.
Abstract: When aligning catoptric or catadioptric telescopes for space cameras, it is difficult to align precisely if the field of view is large or there are several reflective surfaces. The quantitative knowledge of mirror misalignments greatly helps align a misaligned telescope precisely, and also reduce the alignment time. This paper describes a generalized reverse-optimization alignment solution algorithm using Zernike sensitivity, and proposes the minimum number of fields to take interferograms. This method was successfully applied on a Cassegrain telescope design for Earth observation from space with arbitrary misalignments and a model including some primary mirror deformation.

42 citations


"Optically fast, wide field-of-view,..." refers methods in this paper

  • ...The second stage of alignment uses a computer-aided alignment (CAA) method [16] to determine final imager compensator motions....

    [...]

Proceedings ArticleDOI
24 Sep 1999
TL;DR: The ALI telescope as discussed by the authors is a reflective triplet design having a 15-degree cross-track field-of-view that employs silicon carbide mirrors, and it incorporates a multispectral detector and filter array with 10 spectral bands covering a wavelength range from the visible to the short-wave IR.
Abstract: The ALI, which will be flown on the NASA New Millennium Program's EO-1 mission, has been completed and is being integrated with the spacecraft. The motivation for the EO-1 mission is to flight-validate advanced technologies that are relevant to next generation satellites. The ALI telescope is a reflective triplet design having a 15-degree cross-track field-of-view that employs silicon carbide mirrors. It incorporates a multispectral detector and filter array with 10 spectral bands that cover a wavelength range from the visible to the short-wave IR. The paper will describe the instrument and its operation, review test result, and suggest application to a future Landsat instrument.

38 citations

Proceedings ArticleDOI
05 Oct 1999
TL;DR: The QuickBird telescope as mentioned in this paper is the first large-aperture, high-resolution, totally unobscured optical system developed as a fixed-price commercial product, which was aligned and tested in a dedicated facility at Ball Aerospace and Technologies Corp. designed to reduce the total process time of building and testing complex optical systems.
Abstract: The QuickBird telescope represents a significant accomplishment as the first large-aperture, high-resolution, totally unobscured optical system developed as a fixed-price commercial product. The telescope was aligned and tested in a dedicated facility at Ball Aerospace and Technologies Corp. specially developed to reduce the total process time of building and testing complex optical systems. This presentation summarizes design features, mirror- manufacturing results, telescope alignment, and test results.

24 citations

Proceedings ArticleDOI
TL;DR: An overview of OLI is presented along with background on filter performance and manufacture, and performance results versus requirements are presented for all key performance metrics.
Abstract: This paper presents a summary of the performance of the Landsat Operational Land Imager (OLI) spectral filters. An overview of OLI is presented along with background on filter performance and manufacture. Performance results versus requirements are presented for all key performance metrics.

16 citations


"Optically fast, wide field-of-view,..." refers background in this paper

  • ...Table 1 shows some examples of three and four mirror imagers used in remote sensing applications [3]-[8]....

    [...]

Proceedings ArticleDOI
TL;DR: In this paper, the authors describe a design concept for a Landsat-class imaging spectrometer, which matches the data parameters, including a 185 Km swath and a 30 meter ground sample distance (GSD) from a 705 Km-synchronous orbit with a sensor that has contiguous spectral coverage of the solar reflected spectrum (400 to======1500 nm).
Abstract: This paper describes a design concept for a Landsat-class imaging spectrometer. The challenge is to match the Landsat data parameters, including a 185 Km swath and a 30 meter ground sample distance (GSD) from a 705 Km sun-synchronous orbit with a sensor that has contiguous spectral coverage of the solar reflected spectrum (400 to 2500 nm). The result is a remote sensing satellite that provides global access imaging spectrometer data at moderate spatial resolution. Key design trades exist for the spectrometer, focal plane array, dispersive element, and calibrator. Recent developments in large format imaging spectrometers at Raytheon are presented in support of a monolithic spectrometer approach. Features of the design include (1) high signal-to-noise ratio, (2) well-corrected spectral fidelity across a 6,000 pixel push-broom field-of-view, (3) straightforward calibration of the data to units of absolute spectral radiance, and (4) real-time simulation of Thematic Mapper bands, vegetation indices, and water vapor maps for direct continuous downlink.

13 citations


"Optically fast, wide field-of-view,..." refers methods in this paper

  • ...DESIGN, ALIGNMENT, AND TEST OF THE FIRST-EVER 5MA IMAGER The first-ever 5MA imager was assembled in 2010 for use with a reflective triplet (RT) imaging spectrometer [14] consisting of 8,192 cross-scan pixels at 7 μm pitch [15]....

    [...]