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Beam Shaping: A Review
Published in Fred M. Dickey, Scott C. Holswade, David L. Shealy, Laser Beam Shaping Applications, 2018
Fred M. Dickey, Scott C. Holswade
Figure 8.19 illustrates an imaging multiaperture beam integrator. This type of integrator is especially appropriate for sources with low spatial coherence. From a ray optics perspective, these sources produce a wavefront incident over a range of field angles on the lenslet apertures. The first lenslet array segments the beam as before and focuses the beamlets onto a second lenslet array. That is, each lenslet in the first array is designed to confine the incident optical radiation within the corresponding aperture in the second array. A second lenslet array, separated from the first by a distance equal to the focal length of the secondary lenslets, together with the primary focusing lens, forms a real image of the subapertures of the first lenslet array on the target plane. The primary lens overlaps these subaperture images at the target to form one integrated image of the subapertures of the first array element. Reimaging the lenslet apertures mitigates the diffraction effects of the integrator in Figure 8.4. Imaging integrators are more complicated than diffracting integrators in that they require a second lenslet array with an associated alignment sensitivity. Diffracting integrators are thus more frequently the integrators of choice.
A Review
Published in Fred M. Dickey, Todd E. Lizotte, Laser Beam Shaping Applications, 2017
Fred M. Dickey, Scott C. Holswade
Figure 12.19 illustrates an imaging multiaperture beam integrator. This type of integrator is especially appropriate for sources with low spatial coherence. From a ray optics perspective, these sources produce a wavefront incident over a range of field angles on the lenslet apertures. The first lenslet array segments the beam as before and focuses the beamlets onto a second lenslet array. That is, each lenslet in the first array is designed to confine the incident optical radiation within the corresponding aperture in the second array. A second lenslet array, separated from the first by a distance equal to the focal length of the secondary lenslets, together with the primary focusing lens, forms a real image of the subapertures of the first lenslet array on the target plane. The primary lens overlaps these subaperture images at the target to form one integrated image of the subapertures of the first array element. Reimaging the lenslet apertures mitigates the diffraction effects of the integrator in Figure 12.4. Imaging integrators are more complicated than diffracting integrators in that they require a second lenslet array with an associated alignment sensitivity. Diffracting integrators are thus more frequently the integrators of choice.
Adaptive optics ophthalmoscopes
Published in Pablo Artal, Handbook of Visual Optics, 2017
The dominating WFS used in ophthalmic AO is by far the Shack–Hartmann WFS (Shack and Platt 1971). A Shack–Hartmann WFS combines a lenslet array, an array of small lenses with the same focal length, with an imaging sensor, typically a charge-coupled device (CCD) camera. The lenslet array is placed in a plane conjugate to the pupil so that each illuminated lenslet provides a local sample of an incoming wavefront by focusing the incoming light into a focal spot on the sensor. The local slope of the wavefront for each lenslet can then be calculated from the shift of the corresponding focal spot on the sensor. This allows the wavefront in the pupil plane to be approximated by a combination of slopes from all illuminated lenslets.
Progress in the development of the display performance of AR, VR, QLED and OLED devices in recent years
Published in Journal of Information Display, 2022
Ho Jin Jang, Jun Yeob Lee, Geun Woo Baek, Jeonghun Kwak, Jae-Hyeung Park
Two novel approaches to this design situation recently attracted great attention. One is the use of a lenslet array [20, 52] in place of the single large optics to form the virtual image. The smaller size of the individual lens in the lenslet array results in a shorter focal length, thus reducing the overall device thickness while maintaining the wide FOV. The lenslet array, moreover, can also be curved to give an even wider FOV [52]. The second emerging approach is the use of polarization folding optics, which is also called pancake optics [21, 53]. These polarization devices fold the optical path, thus reducing the system thickness by as much as half; in recent years, in fact, VR NEDs of a sub-centimeter thickness have been developed [20, 53]. Still another potential candidate for the slim VR NED in the metasurface lens owing to its large numerical aperture (NA) [54]. Table 4 summarizes the recent developments in the research for slim VR NEDs.