Null Hartmann test for the fabrication of large aspheric surfaces

Yang, Ho‐Soon; Lee, Yun-Woo; Song, Jae-Bong; Lee, Inwon

doi:10.1364/opex.13.001839

Cited by 9 publications

(5 citation statements)

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“…Figure 1 shows the schematic testing set-up for the small convex aspheric surface. This set-up is quite similar to that for large optics testing developed by Yang et al [5]. The interferometer generates the high-quality collimated beam.…”

Section: Introductionmentioning

confidence: 89%

“…Zverev et al tested a 6-m mirror, using the Hartmannn pattern to find that when a maximum deformation of surface was 6 µ m, the error of determining the surface deformation was approximately 0.02 µ m, compared to the interferometric measurement [4]. Yang et al tested a 1-m mirror using a Hartmann sensor with null corrector to increase the dynamic range automatically [5]. Without any post-processing at the Hartmann sensor, the [6][7].…”

Section: Introductionmentioning

confidence: 99%

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Real-time measurement of the small aspheric surface

et al. 2005

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Most aspheric surfaces have been measured by null lens test or computer generated hologram (CGH) method. This approach, however, often fails when there are many aspherical terms or target surface is very small because it is not easy to design the conventional null lens or CGH. Hartmann test is a good choice for this case because it has a larger dynamic range than the general interferometer. This means that the surface can be measured with a Hartmann test without null correctors or with incomplete null correctors. In this paper, we apply the Hartmann test to the measurement of convex aspheric surface of which diameter is about 16 mm and has 4 additional aspheric terms. In order to measure the surface in real-time, we developed some CGH target that simulates the ideal target surface and the simple optical system. The measurement result can be served as a reference so that the form error of the target surface can be obtained by the subtraction of this reference, to achieve highly accurate measurement in real-time.

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Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Real-time measurement of the small aspheric surface

et al. 2005

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“…Figure 5 shows the testing set-up for the primary mirror. Detailed description of this testing configuration is described by Yang et al [1]. For the interferometric measurement, the null corrector is used as well in the test beam path.…”

Section: Development Of Primary Mirrormentioning

confidence: 99%

Development of Cassegrain type 0.9-m collimator

et al. 2005

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Collimator is essential to evaluate and assemble the other telescopes. Its diameter should be larger than that of the target telescope for the correct use. We are currently developing the Cassegrain type collimator of which diameter is 0.9 m. The primary mirror is light-weighted so that its weight is only 70 kg. Due to its structure, the primary mirror can be supported only at the backside of the mirror. This mirror is tested with the combination of null Hartmann test and interferometer. The secondary mirror is tested with a Hindle method. This method requires 600 mm high quality spherical mirror. The distance between the primary and secondary mirror is maintained by the Carbon composite material. The assembly of two mirrors is carried out by the computer aided alignment method. The whole structure is designed to maintain the performance of the collimator under +/-5 degrees of temperature variation.

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“…Motivated by a nondeterministic method, Jones et al proposed a machine for manufacturing large aspheric optics with CNC polishing through interferometric inspection [5]. To accelerate the fabrication of mirrors which are utilized in large telescopes, Yang et al used CNC combined with a proposed test device to polish and detect the remaining surface error [6]. Considering deterministic finishing, Hu et al studied the principles based on residual errors to achieve corrective polishing [7].…”

Section: Introductionmentioning

confidence: 99%

Development of a Novel Three Degrees-of-Freedom Rotary Vibration-Assisted Micropolishing System Based on Piezoelectric Actuation

Yan

Chen

et al. 2019

Micromachines

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The limited degrees of freedom (DOF) and movement form of the compliant vibration-assisted processing device are inherent constraints of the polishing technique. In this paper, a concept of a 3-DOF rotary vibration-assisted micropolishing system (3D RVMS) is proposed and demonstrated. The 3-DOF means the proposed vibration-assisted polishing device (VPD) is driven by three piezo-electric (PZT) actuators. Compared with the current vibration-assisted polishing technology which generates a trajectory with orthogonal actuators or parallel actuators, a novel 3-DOF piezoelectrically actuated VPD was designed to enable the workpiece to move along the rotational direction. Meanwhile, the proposed VPD can deliver large processing stoke in mrad scale and can be operated at a flexible non-resonant mode. A matrix-based compliance modeling method was adopted for calculating the compliance and amplification ratio of the VPD. Additionally, the dynamic and static properties of the developed VPD were verified using finite element analysis. Then, the VPD was manufactured and experimentally tested to investigate its practical performance. Finally, various polished surfaces which used silicon carbide (SiC) ceramic as workpiece material were uniformly generated by the high-performance 3D RVMS. Compared with a nonvibration polishing system, surface roughness was clearly improved by introducing rotary vibration-assisted processing. Both the analysis and experiments verified the effectiveness of the present 3D RVMS for micro-machining surfaces.

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Null Hartmann test for the fabrication of large aspheric surfaces

Cited by 9 publications

References 0 publications

Real-time measurement of the small aspheric surface

Real-time measurement of the small aspheric surface

Development of Cassegrain type 0.9-m collimator

Development of a Novel Three Degrees-of-Freedom Rotary Vibration-Assisted Micropolishing System Based on Piezoelectric Actuation

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