In this contribution, a microoptical imaging system is demonstrated that is inspired by the insect compound eye. The array camera module achieves HD resolution with a z-height of 2.0 mm, which is about 50% compared to traditional cameras with comparable parameters. The FOV is segmented by multiple optical channels imaging in parallel. The partial images are stitched together to form a final image of the whole FOV by image processing software. The system is able to acquire depth maps along with the 2D video and it includes light field imaging features such as software refocusing. The microlens arrays are realized by microoptical technologies on wafer-level which are suitable for a potential fabrication in high volume.
The vast majority of cameras and imaging sensors relies on the identical single aperture optics principle with the human eye as natural antetype. Multi-aperture approaches – in natural systems so called compound eyes and in technology often referred to as array-cameras have advantages in terms of miniaturization, simplicity of the optics and additional features such as depth information and refocusing enabled by the computational manipulation of the system´s raw image data. The proposed imaging principle is based on a multitude of imaging channels transmitting different parts of the entire field of view. Adapted image processing algorithms are employed for the generation of the overall image by the stitching of the images of the different channels. The restriction of the individual channel´s field of view leads to a less complex optical system targeting reduced fabrication cost. Due to a novel, linear morphology of the array camera setup, depth mapping with improved resolution can be achieved. We introduce a novel concept for miniaturized array-cameras with several mega pixel resolution targeting high volume applications in mobile and automotive imaging with improved depth mapping and explain design and fabrication aspects.
We propose a microoptical approach to ultra-compact optics for real-time vision systems that are inspired by the compound eyes of insects. The demonstrated module achieves 720p resolution with a total track length of 2.0 mm which is about 1.5 times shorter than comparable conventional miniaturized optics. The partial images that are separately recorded in multiple optical channels are stitched together to form a final image of the whole FOV by means of image processing. The microlens arrays are realized by microoptical fabrication techniques on wafer-level which are suitable for a potential application in high volume e.g. for consumer electronic products.
There is a huge demand on miniaturized cameras in the field of mobile consumer electronics. These cameras are currently based on miniaturized single aperture optics. In order to further decrease the thickness of miniaturized camera systems, a multichannel imaging principle needs to be used. These artificial compound eye cameras permit a further decrease in thickness by a factor of two in comparison to miniaturized single aperture optics with same resolution and pixel size. Their fabrication process is currently based on the reflow of photoresist. Due to physical limitations of this technique, only spherical and ellipsoidal surface profiles of the single lenslets are achievable. Consequently, the potential for correcting optical aberrations is restricted leading to limited image quality and resolution. This can be improved significantly by the use of refractive freeform arrays. Due to the non-symmetrical and aspherical surface shapes of the single lenslets, the fabrication by the reflow of photoresist is no longer possible. Therefore, we propose an approach for the fabrication of these structures based on the combination of an ultra-precision machining process together with a microimprinting approach.
Artificial compound eye cameras are a prominent approach of next generation wafer level cameras for consumer
electronics due to their lower z-height compared to conventional single aperture objectives. In order to address low cost
and high volume markets, their fabrication is based on a wafer level UV-replication process. The image quality of
compound eye cameras can be increased significantly by the use of refractive freeform arrays (RFFA) instead of
conventional microlens arrays. Therefore, we present the fabrication of a RFFA wafer level molding tool by a step and
repeat process for the first time. The surface qualities of the fabricated structures were characterized with a white light
interferometer.
As demonstrated in microelectronics, the batch fabrication based on the processing of wafers can lead to a significant reduction in prize as well as in size. This concept was adapted to the fabrication of imaging optics extensively used in mobile phone cameras relying on small pixels and low resolutions such as VGA. We report on batch fabricated customer specific opto-electronical modules used in machine sensing and automotive applications relying on large pixel sizes and non-conventional sensor characteristics. We specially focus on the lens mold mastering for the subsequent UV-replication since comparatively large sag heights of 250μm are required. Two technological approaches were applied, first, based on reflow of photoresist and, second, using diamond turning for the generation of a single lens mold and a subsequent step&repeat-process for array mastering on 8" wafers. Aspects of the optical design and simulation, the batch fabrication based on 8" wafers and characterization results are provided by the example of an f/1.1 opto-electronic sensor and an objective for a global shutter imager using 550x550 pixels with 3.6μm pitch.
The fabrication of optical components based on UV-replication is spreading rapidly in the field of high volume and low
cost production. Hereby, a master stamp providing optical surface quality is imprinted into a liquid polymer material
which can be cured under UV-exposure. Most prominent is the fabrication of miniaturized camera objectives for mobile
phone applications done on wafer level. The required lens surfaces possess high sag and aspherical shape which leads to
a challenging fabrication of the master stamp which consists of an array of identical convex or concave optical surfaces.
We analyze the endurance of the stamp used in a step & repeat process for the fabrication of array-like structures used as
master molds for UV-replication.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.