Determination of off-axis aberrations of imaging systems using on-axis measurements

Burge, James H.; Zhao, Chunyu; Dubin, Matthew; Lampen, Sara

doi:10.1117/12.903385

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…The pupil mapping error involves the calculation based on the sine condition and the measurement of the ray intersections at the first monitor. The sine condition is a mathematical solution for removing linearly field-dependent aberrations [16,17]. It establishes a relationship between the ray angles (θ) in the camera space and their corresponding ideal heights (ℎ 𝑖𝑑𝑒𝑎𝑙 ) in the monitor space given as follows:…”

Section: The New Alignment Method: Deflectometry and The Sine Conditi...mentioning

confidence: 99%

Comparing novel and conventional methods for optical system alignment using deflectometry

Yoo,

Dubin

2023

Optomechanical Engineering 2023

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This paper compares two different ways of aligning optical systems using deflectometry: a novel method incorporating the sine condition test and deflectometry, and conventional multi-field points measuring deflectometry. The study aims to provide experimental evidence that the novel method is effective and has advantages over the conventional method. The experiment was carried out using a singlet as the unit-under-test with visible deflectometry composed of a camera and a monitor. In the conventional approach, the camera is moved to multiple field points to measure transmitted wavefront aberrations. For the accurate measurement of the aberrations, accurate knowledge of the camera positions is desired for conventional deflectometry. In the novel approach, the camera is fixed at an on-axis field point, while the monitor is moved to at least two positions in the longitudinal direction. Even if the camera is fixed, the new method can derive the linear behavior of aberrations over the field as it measures pupil mapping error and slope mapping error instead of wavefront error directly. Also, it is insensitive to positional errors in the monitor. This is made possible by discovering the complementary aspects of the sine condition test and deflectometry. We emphasize that the new alignment method is not performing two independent tests separately. The test can be done via one test setup requiring a camera and a monitor equivalent to a deflectometry system. The results demonstrate the benefits of the novel alignment method, which eliminates the need for accurate control of the test instrument movement during the alignment process.

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Section: The New Alignment Method: Deflectometry and The Sine Conditi...mentioning

confidence: 99%

Comparing novel and conventional methods for optical system alignment using deflectometry

Yoo,

Dubin

2023

Optomechanical Engineering 2023

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“…In our previous works [7][8][9] we explained the theoretical background of the SCTest and provided a proof of concept experiment, which showed how to implement the test with a point source and grating. In this paper, we will review the background of the test and then expand on the methods of implementing the test by explaining how a flat-panel display, such as an LCD television or computer monitor, can be used to measure the pupil mapping, as well as some of the advantages and disadvantages between the two approaches.…”

Section: Introductionmentioning

confidence: 99%

Use of a flat panel display for measurement of sine condition violations

2012

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Previous works have shown the viability of using the Sine Condition Test (SCTest) to verify the alignment of optical systems. The SCTest uses the Abbe sine condition to measure the mapping between the entrance and exit pupils of an optical system. From this pupil mapping, the linearly-field dependent aberrations can be measured and used to verify the alignment. Specifically, the linear astigmatism is used as a metric to determine how well the optical system is aligned. An advantage to using the sine condition to measure the off-axis performance is that the measurement equipment can be placed on-axis. By doing this, the uncertainty of the measurement is reduced, making this test especially useful for verifying systems with large inherent aberrations. In this paper, we expand the design space of the SCTest by exploring the two different source options: a point source with a grating or a flat-panel display. Additionally, we show experimental results of implementing the SCTest using a flat-panel display. Last, we explain how the SCTest can be implemented on more complex systems, such as a three-mirror anastigmat (TMA) and a double Gauss. By exploring the design space, we provide more design options for selecting the SCTest source, increasing the flexibility and utility of the SCTest.

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Alignment with a combination of deflectometry and the sine condition test

Yoo¹,

Dubin²

2023

Appl. Opt.

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We propose a new alignment method that is based on relative measurements with an on-axis test setup composed of a pixelated camera and a monitor. By combining deflectometry and the sine condition test, the new method eliminates the necessity of moving a test instrument to multiple field points but still estimates the state of alignment by measuring both the off-axis and on-axis performances of the system. Additionally, it can be a very cost-effective option for certain projects as a monitor, and a camera may be substituted for the return optic and the interferometer required in a conventional interferometric method. We explain the concept of the new alignment method using a meter-class Ritchey–Chrétien telescope. Additionally, we present a new metric, the Metric for Misalignment Indicators (MMI), which represents the transmitted wavefront error caused by misalignment in the system. Then we demonstrate the validity of the concept using simulations where a poorly aligned telescope is the starting point to show that this method has a larger dynamic range compared to the interferometric method. Even considering realistic levels of noise, the new alignment method works successfully, as there is an improvement of two orders of magnitude in the final MMI after three iterations of alignment. The MMI of perturbed telescope models is about 10 µm but, after alignment, the MMI converges to one-tenth of a micrometer.

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Determination of off-axis aberrations of imaging systems using on-axis measurements

Cited by 3 publications

References 17 publications

Comparing novel and conventional methods for optical system alignment using deflectometry

Comparing novel and conventional methods for optical system alignment using deflectometry

Use of a flat panel display for measurement of sine condition violations

Alignment with a combination of deflectometry and the sine condition test

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