Tolerancing surface accuracy of aspheric lenses used for imaging purposes

Erdei, Gábor; Szarvas, G.; Lőrincz, Emőke

doi:10.1117/12.513256

Cited by 9 publications

(5 citation statements)

References 1 publication

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“…In the peripheral region, larger Δ Z is found in the range of −3.52 to 4.96 µm, but is still below the pixel dimension of 7.1 µm and the layer thickness of 5 µm. The experimentally measured manufacturing accuracy is comparable with conventional methods for fabricating aspheric lenses . Therefore, the ultrasmooth optical surface together with the subvoxel precision of surfaces make it possible for the rapid 3D printing of high‐quality optical lenses.…”

mentioning

confidence: 70%

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

et al. 2018

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Advancements in three-dimensional (3D) printing technology have the potential to transform the manufacture of customized optical elements, which today relies heavily on time-consuming and costly polishing and grinding processes. However the inherent speed-accuracy trade-off seriously constrains the practical applications of 3D-printing technology in the optical realm. In addressing this issue, here, a new method featuring a significantly faster fabrication speed, at 24.54 mm h , without compromising the fabrication accuracy required to 3D-print customized optical components is reported. A high-speed 3D-printing process with subvoxel-scale precision (sub 5 µm) and deep subwavelength (sub 7 nm) surface roughness by employing the projection micro-stereolithography process and the synergistic effects from grayscale photopolymerization and the meniscus equilibrium post-curing methods is demonstrated. Fabricating a customized aspheric lens 5 mm in height and 3 mm in diameter is accomplished in four hours. The 3D-printed singlet aspheric lens demonstrates a maximal imaging resolution of 373.2 lp mm with low field distortion less than 0.13% across a 2 mm field of view. This lens is attached onto a cell phone camera and the colorful fine details of a sunset moth's wing and the spot on a weevil's elytra are captured. This work demonstrates the potential of this method to rapidly prototype optical components or systems based on 3D printing.

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confidence: 70%

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

et al. 2018

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“…The MAORY optics manufacturing tolerances are summarized in Table 4 (Patti et al 2018). Surface irregularities can be described as waviness with a given period and amplitude (Erdei et al 2004). In general, the surface diameter sets the upper limit on the period when half cycle of waviness is over the whole surface affecting the nominal WF.…”

Section: Effect Of Optics Manufacturingmentioning

confidence: 99%

The impact of geometric distortions in multiconjugate adaptive optics astrometric observations with future extremely large telescopes

Patti¹,

Arcidiacono

Lombini³

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Astrometry is one of the main science case which drives the requirements of the next multiconjugate adaptive optics (MCAO) systems for future extremely large telescopes. The small diffraction limited point-spread function (PSF) and the high Signal-to-Noise Ratio (SNR) of these instruments, promise astrometric precision at the level of microarcseconds. However, optical distortions have to be as low as possible to achieve the high demanding astrometry requirements. In addition to static distortions, the optomechanical instabilities cause astrometric errors that can be major contributors to the astrometry error budget. The present article describes the analysis, at design level, of the effects of opto-mechanical instabilities when coupled with optical surface irregularities due to the manufacturing process. We analyse the notable example of the Multi-conjugate Adaptive Optics RelaY (MAORY) for the extremely large telescope (ELT). Ray-tracing simulations combined with a Monte Carlo approach are used to estimate the geometrical structure and magnitude of field distortion resulting from the optical design. We consider the effects of distortion on the MCAO correction showing that it is possible achieve the micro-arcseconds astrometric precision once corresponding accuracy is obtained by both optical design and manufacturing. We predict that for single-epoch observations, an astrometric error below 50 µas can be achieved for exposure times up to 2 min, provided about 100 stars are available to remove fifth-order distortions. Such performance could be reproducible for multi-epoch observations despite the time-variable distortion induced by instrument instabilities.

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“…This paper identifies another important difference in tolerancing panoramic systems. It is known that localized slope errors have different impact if they are on surfaces close or far from the aperture stop [2][3]. For panoramic imagers, these localized errors on the front surface were found to be even more critical.…”

Section: Introductionmentioning

confidence: 95%

“…Because of this, localized slope errors create wavefront tilt instead of contributing to wavefront RMS error as they do near the stop when the full surface is illuminated for each field of view. Also, these problems with localized slope errors become more complex on aspherical surfaces and new tolerancing indications have been proposed [3][4] for an optical system with a small field of view. In this paper, the influence of a small localized error is studied, but specifically on the spherical or aspherical front surfaces of panoramic systems.…”

Section: Introductionmentioning

confidence: 99%

Tolerancing panoramic lenses

Parent

Thibault

2009

SPIE Proceedings

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Tolerancing a lens is a basic procedure in lens design. It consists in first defining an appropriate set of tolerances for the lens, then in adding compensators with their allowable ranges and finally in selecting an appropriate quality criterion (MTF, RMS spot size, wavefront error, boresight error…) for the given application. The procedure is straightforward for standard optical systems. However, it becomes more complex when tolerancing very wide angle lenses (larger than 150 degrees). With a large field of view, issues such as severe off-axis pupil shift, considerable distortion and low relative illumination must be addressed. The pupil shift affects the raytrace as some rays can no longer be traced properly. For high resolution imagers, particularly for robotic and security applications, the image footprint is most critical in order to limit or avoid complex calibration procedures. We studied various wide angle lenses and concluded that most of the distortion comes from the front surface of the lens. Consequently, any variation of the front surface will greatly affect the image footprint. In this paper, we study the effects on the image footprint of slightly modifying the front surface of four different lenses: a simple double-gauss for comparison, a fisheye lens, a catadioptric system (omnidirectional lens) and a Panomorph lens. We also present a method to analyze variations of the image footprint. Our analysis shows that for wide angle lenses, on which the entrance pupil is much smaller than the front surface, irregularities (amplitude, slope and location) are critical on both aspherical and spherical front surfaces to predict the image footprint variation for high resolution cameras. Finally, we present how the entrance pupil varies (location, size) with the field of view for these optical systems.

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Tolerancing surface accuracy of aspheric lenses used for imaging purposes

Cited by 9 publications

References 1 publication

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

The impact of geometric distortions in multiconjugate adaptive optics astrometric observations with future extremely large telescopes

Tolerancing panoramic lenses

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