The CAFADIS camera: a new tomographic wavefront sensor for Adaptive Optics

Rodriguez, Julie; Femenia, Bruno; Montilla, I.; Rodríguez-Ramos, L. F.; Marichal-Hernández, José G.; Luke, J. P.; López, Roberto López; Díaz, J. J.; Martín, Y.

doi:10.1051/ao4elt/201005011

Cited by 8 publications

(8 citation statements)

References 8 publications

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“…For depth extraction the plenoptic sensor acts as a multiview stereo system, whereas, for wavefront phase extraction, it can be understood as a global sensor containing as extreme cases the Shack--Hartmann sensor and the pyramid sensor (2 2 microlens array at focus). The tomographic capability of the plenoptic sensor was demonstrated by Rodríguez-Ramos et al [4], [5].…”

Section: Introductionmentioning

confidence: 97%

Design and Laboratory Results of a Plenoptic Objective: From 2D to 3D With a Standard Camera

Montilla

Puga

Luke

et al. 2015

J. Display Technol.

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The plenoptic camera was originally created to allow the capture of the light field, a four-variable volume representation of all rays and their directions, which allows the creation by synthesis of an image of the observed object. This method has several advantages with regard to 3D capture systems based on stereo cameras since it does not need frame synchronization or geometric and color calibration. It also has many applications, from 3DTV to medical imaging. A plenoptic camera uses a microlens array to measure the radiance and direction of all the light rays in a scene. The array is placed at a distance from the principal lens, which is conjugated to the distance where the scene is situated, and the sensor is at the focal plane of the microlenses. We have designed a plenoptic objective that incorporates a microlens array and a relay system that reimages the microlens plane. This novel approach has proven successful. Placing it on a camera, the plenoptic objective creates a virtual microlens plane in front of the camera CCD, allowing it to capture the light field of the scene. In this paper we present the experimental results showing that depth information is perfectly captured when using an external plenoptic objective. Using this objective transforms any camera into a 3D sensor, opening up a wide range of applications from microscopy to astronomy.

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Section: Introductionmentioning

confidence: 97%

Design and Laboratory Results of a Plenoptic Objective: From 2D to 3D With a Standard Camera

Montilla

Puga

Luke

et al. 2015

J. Display Technol.

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“…Wavefront sensing: The purpose of this approach is to extract an estimation of the wavefront phase in the scene. This technique has been widely explored in astrophyshics to perform adaptive optics in telescopes [50,51,52,53,54]. Tracking and pose estimation: As the light field encodes 3D information about the scene, it can be used in visual odometry and navigation.…”

Section: Introductionmentioning

confidence: 99%

Implementation of a Depth from Light Field Algorithm on FPGA

Conde

Luke

Rosa

2019

Sensors

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A light field is a four-dimensional function that grabs the intensity of light rays traversing an empty space at each point. The light field can be captured using devices designed specifically for this purpose and it allows one to extract depth information about the scene. Most light-field algorithms require a huge amount of processing power. Fortunately, in recent years, parallel hardware has evolved and enables such volumes of data to be processed. Field programmable gate arrays are one such option. In this paper, we propose two hardware designs that share a common construction block to compute a disparity map from light-field data. The first design employs serial data input into the hardware, while the second employs view parallel input. These designs focus on performing calculations during data read-in and producing results only a few clock cycles after read-in. Several experiments were conducted. First, the influence of using fixed-point arithmetic on accuracy was tested using synthetic light-field data. Also tests on actual light field data were performed. The performance was compared to that of a CPU, as well as an embedded processor. Our designs showed similar performance to the former and outperformed the latter. For further comparison, we also discuss the performance difference between our designs and other designs described in the literature.

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“…Wavefront phase gradients at telescope pupil plane are extracted from the plenoptic frame taken by the CAFADIS, and wavefront maps from different viewpoints are obtained. Hence, tomographic wavefront reconstruction could be accomplished from only one plenoptic frame ( Figure 1 ) [ 4 ]. For example, Figure 2 shows a section of the plenoptic frame obtained for CAFADIS, containing data from five artificial laser guide stars (data simulation assuming a 10 m diameter telescope, and every subpupil sampled by 32 × 32 pixels [ 4 ]).…”

Section: Introductionmentioning

confidence: 99%

“…Hence, tomographic wavefront reconstruction could be accomplished from only one plenoptic frame ( Figure 1 ) [ 4 ]. For example, Figure 2 shows a section of the plenoptic frame obtained for CAFADIS, containing data from five artificial laser guide stars (data simulation assuming a 10 m diameter telescope, and every subpupil sampled by 32 × 32 pixels [ 4 ]). With this information, the CAFADIS camera has the capability of refocusing at several distances and selecting the best focus as object distance.…”

Section: Introductionmentioning

confidence: 99%

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An Efficient Pipeline Wavefront Phase Recovery for the CAFADIS Camera for Extremely Large Telescopes

Magdaleno

Rodríguez

Rodríguez-Ramos

2009

Sensors

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In this paper we show a fast, specialized hardware implementation of the wavefront phase recovery algorithm using the CAFADIS camera. The CAFADIS camera is a new plenoptic sensor patented by the Universidad de La Laguna (Canary Islands, Spain): international patent PCT/ES2007/000046 (WIPO publication number WO/2007/082975). It can simultaneously measure the wavefront phase and the distance to the light source in a real-time process. The pipeline algorithm is implemented using Field Programmable Gate Arrays (FPGA). These devices present architecture capable of handling the sensor output stream using a massively parallel approach and they are efficient enough to resolve several Adaptive Optics (AO) problems in Extremely Large Telescopes (ELTs) in terms of processing time requirements. The FPGA implementation of the wavefront phase recovery algorithm using the CAFADIS camera is based on the very fast computation of two dimensional fast Fourier Transforms (FFTs). Thus we have carried out a comparison between our very novel FPGA 2D-FFTa and other implementations.

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The CAFADIS camera: a new tomographic wavefront sensor for Adaptive Optics

Cited by 8 publications

References 8 publications

Design and Laboratory Results of a Plenoptic Objective: From 2D to 3D With a Standard Camera

Design and Laboratory Results of a Plenoptic Objective: From 2D to 3D With a Standard Camera

Implementation of a Depth from Light Field Algorithm on FPGA

An Efficient Pipeline Wavefront Phase Recovery for the CAFADIS Camera for Extremely Large Telescopes

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