It has been challenging for medium wave infrared (MWIR) optical imaging system to work in a large temperature range and stationary effective focal length, on account of the thermal effect of optical elements and machinery. Performances of a MWIR space remote sensor in an advanced passive thermal-free design are presented with a fronting R-C system and a rear spherical lens group. A general analytical expression for eliminating thermal defocus and chromatic aberration is obtained, and it is demonstrated that these defocus and aberrations are minimized when this MWIR space remote sensor is operated at a broadband (3um to 5um) and large temperature range (-40°C to 40°C). The ZEMAX software is used to obtain the final parameters of space remote sensor by global optimization, which realize 100% cold shield efficiency. The MWIR space remote sensor has a focal length of 2150mm, F number of 3.58, full field of view of angle of 0.4°×0.4°and pixel size of 15μm. This optical system provides a high ground sample distance (GSD) of 251m and wide single landscape width (SLW) of 251km×251km in geosynchronous orbit. The imaging quality of the space optical remote sensor is almost diffraction limited which can be inferred from metrics such as root-mean-square spot diagram, MTF, wavefront function etc.
Performances of a novel solar extreme ultraviolet (EUV) slitless imaging spectrometer in a stigmatic design are presented with an aberration-correcting flat-field holographic concave grating (HCG). The instrument is based on a conventional off-axis Maksutov telescope with aberration-corrected holographic rulings on the secondary optic. These rulings with varied line-space enable stigmatic imaging in diffracted light with a minimum number of optical elements, thereby maintaining a high system efficiency. The novel design has improved temporal resolution prominently by throwing away the slit and no scanning, either spatially or spectrally, permitting EUV spectroscopy with a high time cadence in observation of the full solar disk. In this approach all data are taken simultaneously over the whole field of view, and hence no confusion of temporal evolution with spatial or spectral variation. ZEMAX software is used to obtain the final parameters of spectrometer through global optimization and multiple configuration. The slitless imaging spectrometer possesses imaging detectors at three orders of flat-field HCG, which provides cotemporal imaging and spectroscopy with high spatial resolving element (1.8arcsec/pixel) and spectral resolving element (60mÅ/pixel) for a narrowband at 304 Å and a wide field of view (36arcmin). The performance of the resulting optical design are evaluated, and the imaging quality obtained here is excellent which can be inferred from the root-mean-square spot diagram.
Far ultraviolet earth night airglow is related to total electron content(TEC) of Ionosphere. Observing the night airglow nadir at OI 135.6nm emission produced by ionospheric O+ and e recombination can get the distribution of ionosphere TEC. In this paper, a compact of ionospheric FUV photometer developed for micro satellite will be introduced. The instrument works in photo-counting mode to achieve high sensitivity for weak night airglow radiation detection. The design of this photo-counting detector will be described in detail.
Aluminum reflector, especially OAP (Off-Axis Parabolic) reflector, has been widely used in terahertz and infrared systems for its low cost, lightweight, good machinability, small size, simple structure, and having the same thermal expansion and contraction with the system structure which makes it have a wide temperature adaptability. Thorlabs, Daheng and other large optical components companies even have Aluminum OAP sold on shelf. Most of the precision Aluminum OAP is fabricated by SPDT (single point diamond turing). Affected by intermittent shock, the roughness of aluminum OAP mirrors through conventional single-point diamond lathes is around 7 nm which limits the scope of application for aluminum mirrors, like in the high power density terahertz/infrared systems and visible/UV optical systems. In this paper, a continuous process frock is proposed, which effectively reduces the influence of turning impact on the mirror roughness. Using this process, an off-axis parabolic aluminum reflector with an effective diameter of 50 mm, off-axis angle of 90 degree is fabricated, and the performances are validated. Measurement by VEECO NT1100 optical profiler with 20× objects, the surface roughness achieves 2.3 nm, and the surface figure error is within λ/7 RMS (λ= 632.8 nm) tested by FISB Aμ Phase laser interferometer with the help of a standard flat mirror. All these technical specifications are close to the traditional glass-based reflectors, and make it possible for using Aluminum reflectors in the higher LIDT (laser induced damage threshold) systems and even for the micro sensor of ionospheric for vacuum ultraviolet micro nano satellites.
For the space solar extreme ultraviolet telescope, the star point test can not be performed in the x-ray band (19.5nm band) as there is not light source of bright enough. In this paper, the point spread function of the optical system is calculated to evaluate the imaging performance of the telescope system. Combined with the actual processing surface error, such as small grinding head processing and magnetorheological processing, the optical design software Zemax and data analysis software Matlab are used to directly calculate the system point spread function of the space solar extreme ultraviolet telescope. Matlab codes are programmed to generate the required surface error grid data. These surface error data is loaded to the specified surface of the telescope system by using the communication technique of DDE (Dynamic Data Exchange), which is used to connect Zemax and Matlab. As the different processing methods will lead to surface error with different size, distribution and spatial frequency, the impact of imaging is also different. Therefore, the characteristics of the surface error of different machining methods are studied. Combining with its position in the optical system and simulation its influence on the image quality, it is of great significance to reasonably choose the processing technology. Additionally, we have also analyzed the relationship between the surface error and the image quality evaluation. In order to ensure the final processing of the mirror to meet the requirements of the image quality, we should choose one or several methods to evaluate the surface error according to the different spatial frequency characteristics of the surface error.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.