We demonstrate that a pair of wedge prisms with opposite angular dispersion can be designed to have zero spherical aberration, zero coma, and zero astigmatism and be simultaneously achromatic in convergent rays, and the system can easily reach the diffraction limit and be utilized in precise three-dimensional imaging, special optical testing, etc., for widening the imaging range. Aberration equations of a pair of thin wedge prisms in paraxial optics are first derived, from which a special solution is obtained by making a few presuppositions. Then three initial structures are built to verify our inference. The near-zero Zernike standard coefficients and tiny rms radii of the image spots given by OpticStudio prove that the derived equations hold. After that the refractive indices of two prisms are both tested, where the testing results show that prisms with high-refractive indices are more capable of compensating monochromatic aberrations. With the aid of Monte-Carlo analysis method, tolerance analysis is carried on with the worst cases of the three optimized systems. The results show that a pair of wedge prisms with the opposite angular dispersion can effectively work within the diffraction limit even if the optical manufacturing and assembly errors are large. In the end, the system design limitations are given, and we suggest that the working F-number of the eyepiece should preferably be larger than 8.0.
The giant laser device used in inertial confined fusion (ICF) experimental research is the largest optical engineering ever built by humans. It requires thousands of large-diameter optical components, especially for optical components with diagonal dimensions close to or exceeding 1 meter, which leads to the manufacturing is extremely difficult. Wavefront characteristics are one of the key parameters of meter-size optical components. Since different degrees of wavefront error are introduced during the material preparation, manufacturing and coating processes, it requires precise measurement and precise control throughout the manufacturing process. In this paper, the research work on key problems such as measurement accuracy, measurement aperture and measurement efficiency in the wavefront error detection of meter-size optical components is carried out and summarized.
The deformation of the φ600mm reference mirror under gravity cannot be ignored when measuring optical components with a φ600mm interferometer. Therefore, it is necessary to choose a reasonable support and rotation mechanism to adjust the reference mirror of the interferometer in order to meet the accuracy requirements. In this paper, two mechanical structures for supporting and rotating the φ600mm reference mirror are analyzed. One is using the roller slings to provide tension, and the conveyor belt drives the reference mirror to rotate by friction; while the other one is using glue to connect the silica gel and the edge of the reference mirror where silica gel is fixed on the metal frame. The rotation of the reference mirror can be realized by manually rotating the frame. In order to analyze the influence of the two mechanisms on the mirror under working conditions, a three-dimensional model of the φ600mm reference mirror with its supporting system was established using the finite element analysis software ABAQUS, and the contact conditions and boundary conditions were reasonably applied to the reference mirror. Reference mirror is analyzed in both statical and dynamical states. The changes of internal stress and surface shape are compared when the reference mirror is supported and rotated on both mechanisms. The advantages of different mechanisms are elaborated, and the parameters of mechanisms are optimized theoretically. Analysis results can provide a useful guide for the support of the reference mirror and the adjustment of the φ600mm large aperture interferometer.
Satellite laser range system measures the distance between the satellite and the surface of the earth by figuring out the transit time of laser pulse. The beam is refracted when it goes through the atmosphere. The atmosphere refraction effect causes laser propagation delay and path bending, which is one of the key factors to restrict the accuracy of laser ranging. In order to improve the accuracy of atmospheric refraction delay correction, it is necessary to strengthen the study of atmospheric group refractivity models and atmospheric refraction delay correction method. According to the datum of Xuzhou upper air meteorological station, which are the monthly values of upper limit layers for 30 years (1981-2010) in China, three atmospheric group refractivity models were analyzed and compared. The atmospheric refraction delays to LiDAR were calculated by ray tracing method. The differences among the group refractivity models as a function of month and angle of direction were given, which lay the foundation for the practical application and precision evaluation of LiDAR.
The wavefront of coated optics is one of critical performances. Due to the interference between the coating layers, the measurement results will be totally different if the measurement wavelength is different from the working wavelength. However, all of the commercial interferometers have single measurement wavelength, which can’t treat the optical coatings working at various wavelengths. A wavelength-switchable interferometer (WSI) capable of detecting wavefront information in a wide wavelength range of 488-1064 nm is proposed in this paper. The principle of design and performance of the system are given in detail. Some typical measurement applications, such as reflection plate and optical filters will also be presented.
A common way to test high-quality aspherical lenses is to use a measurement system based on a set of null corrector and
a laser interferometer. The null corrector can either be a combination of spherical lenses or be a computer generated
hologram (CGH), which compensates the aspheric wave-front being tested. However, the null optics can’t be repeatedly
used once the shape of tested optics changes. Alternative active null correctors have been proposed based on dynamic
phase modulator devices. A typical dynamic phase modulator is liquid crystal spatial light modulator (LCSLM), which
can spatially change the refractive index of the liquid crystal and thus modify the phase of the input wave-front. Even
though the measurement method based on LCSLM and laser interferometer has been proposed and demonstrated for
optical testing several years ago, it still can’t be used in the high quality measurement process due to its limited accuracy.
In this paper, we systematically study the factors such as LCSLM structure parameters, encoding error and laser
interferometer performance, which significantly affect the measurement accuracy. Some solutions will be proposed in
order to improve the measurement accuracy based on LCSLM and laser interferometer.
The multi-object broadband imaging echellette (MOBIE) is the seeing-limited, visible-wavelength imaging multi-object spectrograph (MOS) planned for first-light use on the thirty meter telescope (TMT). The current MOBIE optical design provides two color channels, spanning the 310nm–550nm and 550nm-1000nm passbands. The involved large optics includes an atmospheric dispersion corrector (ADC) prism (1.4m in diameter), a collimator (1.7mx1.0m), a dichroic(680 mm x500 mm x 30 mm), a red folding mirror and two corrector lenses(570mm in diameter) for different channels. In the past two years, Shanghai Institute of Optics and Fine Mechanics (SIOM) has been included in the preliminary study of folding mirror sub-system in MOBIE, especially the study on the large optics manufacture techniques. The research progress of these large optics will be reviewed in this paper. The influence of optical quality of the large optics on the MOBIE is analyzed in order to define the specifications of the large optics. The manufacture methods are designed for different large optics. In order to testify the effectiveness of the manufacture methods, some samples have been processed and the final performance including wavefront error and spectral properties are tested. Finally, the future work including remaining problems and possible solutions are introduced.
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