In this work we propose the use of a quadratic phase distribution to implement continuous, full complex amplitude modulation proximity printing masks. The mask is calculated based on the inverse light propagation, determining values of both continuous phase and amplitude modulation. The novelty in this proposition is the use of a quadratic phase distribution in the desired reconstruction pattern in order to achieve a smooth phase and amplitude modulation during the mask calculation. The use of a quadratic phase distribution on the desired reconstruction pattern allows to spread the light of this pattern over a wide region of the calculated proximity-printing mask, generating a magnification of the information to be modulated by the mask. As a consequence, the feature sizes on the mask are larger than in the image reconstruction plane. We believe that this approach will allow the generation of a continuous variation of light in the final required pattern, allowing the generation of arbitrary 3D structures. The smooth phase and amplitude modulation distributions can also minimize the errors caused by using the scalar diffraction to calculate and encode the phase and amplitude modulation of the final mask.
Novolak type polymers are the basic material for most commercial photoresists used in microelectronic processes, but are not often used for micro-optic applications. In this work, three types of optical devices were implemented in AR P322 novolak-based resist, which can be used as a positive photoresist and a positive electron resist. Gratings of parabolic divergent microlenses with f-number of 0.5 were fabricated using traditional optical lithography, employing the diffraction characteristics of de-focused light during the photolithographic exposure. The contrast curve of the AR P322 used an electron sensitive resist, was determined and yielded a gamma factor of 3.02. This relatively low contrast allows to obtain structures with well controlled curved walls. Direct write electron beam lithography was employed to manufacture gratings of parabolic convergent microlenses with different diameter and focal length, what enables one to control the intensity of the different orders of the diffracted light. This technique was also used to obtain convergent parabolic microlenses, with different diameters and different heights, allowing the control of the focal length of these lenses. These structures have several applications in the fields of pattern recognition, robotic vision and optical sensors.
In this paper we describe the fabrication of an array of integrated cylindrical microlenses on top of a single GaAs MSM photodetector. Experimental data shows an increase of about 65% on the photocurrent of the MSM photodiode as a result of the improved optical coupling efficiency.
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.