Development of a carbon fiber composite active mirror: design and testing

Kendrew, Sarah; Doel, P.; Dorn, Chris; Yates, Chris; Dwan, Richard Martin; Richardson, I.M.; Evans, Glynn

doi:10.1117/1.2179771

Cited by 9 publications

(4 citation statements)

References 10 publications

(7 reference statements)

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“…The monolithic Wolter-I mirror has the advantage of reducing the degradation of image performance due to alignment errors, and the reduction of the alignment error is particularly important to manufacture a large-area telescope. However, there are known disadvantages of using CFRP as a substrate for high-precision optics [18][19][20][21][22][23][24][25][26][27][28] and, in particular, x-ray mirrors. 29 One is the microscale deformation of the substrate surface, which is called print-through.…”

Section: Introductionmentioning

confidence: 99%

Effect of barrier layer on moisture absorption of thin carbon-fiber-reinforced plastic mirror substrates

Awaki

Yoshida

Oue

et al. 2019

J. Astron. Telesc. Instrum. Syst.

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Carbon-fiber-reinforced plastic (CFRP) has a higher strength-to-weight ratio and forming flexibility than metals, making it suitable for fabricating lightweight x-ray mirrors. However, CFRP has the disadvantages of print-through and deformation due to moisture absorption, which have prevented its use in optical mirrors. To expand the application of CFRP, we studied the formation of a moisture barrier layer on CFRP substrates. We formed a flattening layer a few micrometers thick on a CFRP substrate, following which we coated the substrate with SiO x as a moisture barrier. The effect of moisture absorption was then evaluated using accelerated aging tests. We found that the diffusivity of the CFRP substrate at 60°C and a relative humidity of 100% was ∼2 × 10 −6 mm 2 h −1 , which is 1/500th that of the barrier-less substrate. In the tests, the moisture absorption rate increased after ∼800 h. As we observed cracks on the flattening layer after 600 h, the rate increase could be associated with these cracks. Considering the damage to the barrier layer, we propose a modified model for the time profile, which is congruent with the observed time profile of the moisture content.

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Section: Introductionmentioning

confidence: 99%

Effect of barrier layer on moisture absorption of thin carbon-fiber-reinforced plastic mirror substrates

Awaki

Yoshida

Oue

et al. 2019

J. Astron. Telesc. Instrum. Syst.

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“…[7][8][9][10][11][12][13][14][15][16] According to the literature, the choice of mirror material and the technique for changing the mirror curvature are two aspects to consider when designing a VCM. This means that a large sagittal variation, which is defined as the central deformation of an optic system, should be provided.…”

Section: Introductionmentioning

confidence: 99%

Carbon-fiber-reinforced polymer variable-curvature mirror used for optical zoom imaging: prototype design and experimental demonstration

et al. 2015

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In recent years, optical zoom imaging without moving elements has received much attention. The key to realizing this technique lies in the design of the variable-curvature mirror (VCM). To obtain enough optical magnification, the VCM should be able to change its radius of curvature over a wide range. In other words, the VCM must be able to provide a large sagittal variation, which requires the mirror material to be robust during curvature variation, require little force to deform, and have high ultimate strength. Carbon-fiber-reinforced polymer (CFRP) satisfies all these requirements and is suitable for fabricating such a VCM. Therefore, in this research, a CFRP prototype VCM has been designed, fabricated, and tested. With a diameter of 100 mm, a thickness of 2 mm, and an initial radius of curvature of 1740 mm, this VCM can provide a maximum 23-μm sagittal variation and a minimum and maximum radius of curvature of 1705 and 1760 mm.

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“…A significant amount of work has been performed in an attempt to produce mirrors using replication techniques. [4][5][6][7][8] However, these technologies often suffer from a lack of surface accuracy as internal stresses developed during the replication process tend to cause distortions.…”

Section: Iniiiiiii Cfrp Substrate Active Layer ---Electrode Routing mentioning

confidence: 99%

Multilayer active shell mirrors for space telescopes

et al. 2016

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A novel active mirror technology based on carbon fiber reinforced polymer (CFRP) substrates and replication techniques has been developed. Multiple additional layers are implemented into the design serving various functions. Nanolaminate metal films are used to provide a high quality reflective front surface. A backing layer of thin active material is implemented to provide the surface-parallel actuation scheme. Printed electronics are used to create a custom electrode pattern and flexible routing layer. Mirrors of this design are thin (< 1.0 mm), lightweight (2.7 kg/m 2 ), and have large actuation capabilities. These capabilities, along with the associated manufacturing processes, represent a significant change in design compared to traditional optics. Such mirrors could be used as lightweight primaries for small CubeSat-based telescopes or as meter-class segments for future large aperture observatories. Multiple mirrors can be produced under identical conditions enabling a substantial reduction in manufacturing cost and complexity.An overview of the mirror design and manufacturing processes is presented. Predictions on the actuation performance have been made through finite element simulations demonstrating correctabilities on the order of 250 − 300× for astigmatic modes with only 41 independent actuators. A description of the custom metrology system used to characterize the active mirrors is also presented. The system is based on a Reverse Hartmann test and can accommodate extremely large deviations in mirror figure (> 100 µm PV) down to sub-micron precision. The system has been validated against several traditional techniques including photogrammetry and interferometry. The mirror performance has been characterized using this system, as well as closed-loop figure correction experiments on 150 mm dia. prototypes. The mirrors have demonstrated post-correction figure accuracies of 200 nm RMS (two dead actuators limiting performance).

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Development of a carbon fiber composite active mirror: design and testing

Cited by 9 publications

References 10 publications

Effect of barrier layer on moisture absorption of thin carbon-fiber-reinforced plastic mirror substrates

Effect of barrier layer on moisture absorption of thin carbon-fiber-reinforced plastic mirror substrates

Carbon-fiber-reinforced polymer variable-curvature mirror used for optical zoom imaging: prototype design and experimental demonstration

Multilayer active shell mirrors for space telescopes

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