The natural compound eye is a striking imaging device with a wealth of fascinating optical features such as a wide field of view (FOV), low aberration, and high sensitivity. Dragonflies in particular possess large, sophisticated compound eyes that exhibit high resolving power and information-processing capacity. Here, a large-scale artificial compound eye inspired by the unique designs of natural counterparts is presented. The artificial compound eye is created by a high-efficiency strategy that combines single-pulse femtosecond laser wet etching with thermal embossing. These eyes have a macrobase diameter of 5 mm and ≈30 000 close-packed ommatidia with an average diameter of 24.5 μm. Moreover, the optical properties of the artificial compound eyes are investigated; the results confirm that the eye demonstrates advanced imaging quality, an exceptionally wide FOV of up to 140°, and low aberration.

Dragonfly-Eye-Inspired Artificial Compound Eyes with Sophisticated Imaging

Alight source device includes: a light emission portion; a cooling channel configured to guide air toward the light emission portion; a rotational member disposed within the cooling channel in such a condition as to be rotatable around a predetermined rotation shaft by gravity, and configured to switch the cooling channel to a first channel branched from the cooling channel in the downstream when the light source device is set in a first position, and to a second channel different from the first channel when the light source device is set in a second position, wherein a position of the center of gravity of the rotational member is located at a position shifted from the center between the rotation shaft and an end of the rotational member away from the rotation shaft toward the end.

Light source device and projector

The natural compound eye has received much attention in recent years due to its remarkable properties, such as its large field of view (FOV), compact structure, and high sensitivity to moving objects. Many studies have been devoted to mimicking the imaging system of the natural compound eye. The paper gives a review of state-of-the-art artificial compound eye imaging systems. Firstly, we introduce the imaging principle of three types of natural compound eye. Then, we divide current artificial compound eye imaging systems into four categories according to the difference of structural composition. Readers can easily grasp methods to build an artificial compound eye imaging system from the perspective of structural composition. Moreover, we compare the imaging performance of state-of-the-art artificial compound eye imaging systems, which provides a reference for readers to design system parameters of an artificial compound eye imaging system. Next, we present the applications of the artificial compound eye imaging system including imaging with a large FOV, imaging with high resolution, object distance detection, medical imaging, egomotion estimation, and navigation. Finally, an outlook of the artificial compound eye imaging system is highlighted.

https://iopscience.iop.org/article/10.1088/1748-3190/aaffb5/pdf

Review of state-of-the-art artificial compound eye imaging systems.

An artificial compound eye system is the bionic system of natural compound eyes with much wider field-of-view, better capacity to detect moving objects and higher sensitivity to light intensity than ordinary single-aperture eyes. In recent years, renewed attention has been paid to the artificial compound eyes, due to their better characteristics inheriting from insect compound eyes than ordinary optical imaging systems. This paper provides a comprehensive survey of the state-of-the-art work on artificial compound eyes. This review starts from natural compound eyes to artificial compound eyes including their system design, theoretical development and applications. The survey of artificial compound eyes is developed in terms of two main types: planar and curved artificial compound eyes. Finally, the most promising future research developments are highlighted.

Artificial compound eye: a survey of the state-of-the-art

The purpose of the present invention is to provide an image display device capable of preventing the creation of stray light due to external light, improving the visibility for a user, and reducing the size of an optical system. The image display device according to the present invention comprises: a light source (1) for emitting light; a display element (3) for generating display light by receiving light from the light source; a light guide plate (5) for propagating the display light therethrough; an incidence element (4) for introducing the display light from the display element into the light guide plate; and a dynamic light-emitting diffraction grating (6) provided in the light guide plate for emitting the display light outside the light guide plate. The dynamic light-emitting diffraction grating (6) includes a plurality of divided dynamic diffraction grating elements in which light diffracting function is enabled or disabled in accordance with the application of a voltage. The image display device further includes a control unit for controlling the dynamic light-emitting diffraction grating so that the plurality of divided dynamic diffraction elements may only be enabled with the light diffracting function one at a time.

Image display device

Included are, a module fixing body having a plurality of mounting holes into which laser modules are fitted and accommodated, respectively; an electricity-supplying member having an end provided with electricity-supplying terminals, which are connected to electricity-receiving terminals of the laser module accommodated in the mounting hole; and a cooling member that cools each of the laser modules. A groove in which the electricity-supplying member is accommodated is formed in a surface of the module fixing body, and the cooling member is closely arranged on the surface of the module fixing body.

Light source device

We designed a new image scanner using the reflective optics of a compound eye system that can easily assemble plural imaging optical units (called imaging cells) and is compact with a large depth of field (DOF). Our image scanner is constructed from 32 reflective imaging cells, each of which takes an image of approximately a 10-mm field of view (FOV) that slightly overlap the adjacent imaging cells. The total image is rebuilt by combining the 32 images in post processing. We studied how to fold the optical path in the imaging cells and simplified the structure, resulting in the following three advances of our previous work: 1) greater compactness (50 × 31 mm2 in the cross section), 2) less variable optical characteristics among the imaging cells, and 3) easy assembly thanks to small number of optical components constructing the imaging cell.

Practical design for compact image scanner with large depth of field by compound eye system

A laser output measuring apparatus in which an optical separator is disposed in a position that is rotated by a predetermined angle about an optical axis of a laser beam converged by a lens, and further rotated by a predetermined angle about the optical axis of the laser beam and a straight line perpendicular to an incident surface of the laser beam.

Laser output measuring apparatus

We designed a compact and large depth of field image scanner targeted for auto document feeders (ADF) by using a compound eye system design with plural optical units in which the ray paths are folded by a reflective optics. Though we have previously proposed the principle concept, we advance the design using a free-form surface mirror to reduce the F-number for less illumination energy and to shrink its optical track width to 40 mm. We achieved large depth of field (DOF) of 1.2 mm, defined as a range exceeding 30% modulation transfer function (MTF) at 300 dpi, which is about twice as large as a conventional gradient index (GRIN) lens array contact image sensor (CIS). The aperture stop has a rectangular-shaped aperture, where one side length is as large as 4.0mm for collecting much light, and another side length is as small as 1.88mm for avoiding interference of folded ray paths.

Compact and large depth of field image scanner for auto document feeder with compound eye system

A laser output measurement mechanism includes a light splitter 2 that is disposed in a state rotated by a predetermined angle about an optical axis 6 of laser light incident thereon, and that reflects a part of the laser light according to a Fresnel reflectivity that depends on a polarization direction and an incident angle of the laser light at a reflection surface thereof, and a light detector 4 that measures an intensity of the laser light reflected by the light splitter 2.

Tetsuo Funakura

Papers

Light source device

Practical design for compact image scanner with large depth of field by compound eye system

Laser output measuring apparatus

Compact and large depth of field image scanner for auto document feeder with compound eye system

Laser output measurement mechanism