Proposal for Machining Optical Free Form Surfaces Using Atmospheric Pressure Plasma Jet

Optics with free form surface can be achieve special imaging effects and reduce component amounts in optical systems. However, it is difficulty to fabricate high accuracy, damage-free optical surface with free form surfaces by conventional method. Atmospheric plasma machining is a non-contact chemical processing method which can fabricate optics without damaged layer. Numerical controlled atmospheric pressure plasma machining (NC-APPM) method is proposed to machine optical free form surfaces. A new atmospheric pressure plasma jet generator was designed to get Gaussian rotational symmetry removal spot and the spot maximum diameter is 1.5mm. Base on dwelling time algorithm, a sinusoidal wave structure, the pitch 2mm and the amplitude 500 nm, is fabricated on a pre-polished flat silica quartz surface using three-axis numerically controlled machine made by ourselves. The result shows that the amplitude error is 59 nm compare to the expectation value surfaces using numerical controlled atmospheric plasma machining method.

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Development of a Multihole Atmospheric Plasma Jet for Growth Rate Enhancement of Broccoli Seeds

Processes ◽

10.3390/pr9071134 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1134

Author(s):

Khattiya Srakaew ◽

Artit Chingsungnoen ◽

Waraporn Sutthisa ◽

Anthika Lakhonchai ◽

Phitsanu Poolcharuansin ◽

...

Keyword(s):

Growth Rate ◽

Atmospheric Pressure ◽

Seed Treatment ◽

Treatment Time ◽

Atmospheric Pressure Plasma ◽

Plasma Jet ◽

Atmospheric Plasma ◽

Atmospheric Pressure Plasma Jet ◽

Pressure Plasma ◽

Significant Difference

This work aims to develop a multihole atmospheric pressure plasma jet (APPJ) device to increase the plasma area and apply it to a continuous seed treatment system. Broccoli seed was used to study the effects of an atmospheric pressure plasma jet on seed germination and growth rate. An argon flow rate of 4.2 lpm, a plasma power of 412 W, and discharge frequency of 76 kHz were used for seed treatment. The contact angle decreased strongly with the increase in treatment time from 20 s to 80 s. The broccoli seed’s outer surface morphology seemed to have been slightly modified to a smoother surface by the plasma treatment during the treatment time of 80 s. However, the cross-sectional images resulted from Synchrotron radiation X-ray tomographic microscopy (SRXTM) confirmed no significant difference between seeds untreated and treated by plasma for 80 s. This result indicates that plasma does not affect the bulk characteristics of the seed but does provide delicate changes to the top thin layer on the seed surface. After seven days of cultivation, the seed treated by plasma for 30 s achieved the highest germination and yield.

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High-Accuracy Surface Topography Manufacturing for Continuous Phase Plates Using an Atmospheric Pressure Plasma Jet

Micromachines ◽

10.3390/mi12060683 ◽

2021 ◽

Vol 12 (6) ◽

pp. 683

Author(s):

Huiliang Jin ◽

Caixue Tang ◽

Haibo Li ◽

Yuanhang Zhang ◽

Yaguo Li

Keyword(s):

Surface Topography ◽

Atmospheric Pressure ◽

High Efficiency ◽

Atmospheric Pressure Plasma ◽

Plasma Jet ◽

Continuous Phase ◽

High Accuracy ◽

Phase Plate ◽

Atmospheric Pressure Plasma Jet ◽

Pressure Plasma

The continuous phase plate (CPP) is the vital diffractive optical element involved in laser beam shaping and smoothing in high-power laser systems. The high gradients, small spatial periods, and complex features make it difficult to achieve high accuracy when manufacturing such systems. A high-accuracy and high-efficiency surface topography manufacturing method for CPP is presented in this paper. The atmospheric pressure plasma jet (APPJ) system is presented and the removal characteristics are studied to obtain the optimal processing parameters. An optimized iterative algorithm based on the dwell point matrix and a fast Fourier transform (FFT) is proposed to improve the accuracy and efficiency in the dwell time calculation process. A 120 mm × 120 mm CPP surface topography with a 1326.2 nm peak-to-valley (PV) value is fabricated with four iteration steps after approximately 1.6 h of plasma processing. The residual figure error between the prescribed surface topography and plasma-processed surface topography is 28.08 nm root mean square (RMS). The far-field distribution characteristic of the plasma-fabricated surface is analyzed, for which the energy radius deviation is 11 μm at 90% encircled energy. The experimental results demonstrates the potential of the APPJ approach for the manufacturing of complex surface topographies.

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