David Oury King

A large area reconfigurable MOEMS microshutter array for coded aperture imaging systems

Coded aperture imaging has been used for astronomical applications for several years. Typical implementations used a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. Recently applications have emerged in the visible and infra red bands for low cost lens-less imaging systems and system studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. Previously we reported on the early feasibility of realising such a mask based on polysilicon micr-opto-electromechanical systems (MOEMS) technology and early results in the visible and near IR bands. This employs interference effects to modulate incident light - achieved by tuning a large array of asymmetric Fabry-Perot optical cavities via an applied voltage whilst a hysteretic row/column addressing scheme is used to control the state of individual elements. In this paper we present transmission results from the target mid-IR band (3-5μm), compare them with theory and describe the scale up from a 3x3 proof-of-concept MOEMS microshutter array to a 560 x 560 element array (2cm x 2cm chip) with the associated driver electronics and embedded control - including aspects of electronic design, addressing control and integration. The resultant microsystem represents a core building block to realise much larger reconfigurable masks using a tiled approach with further integration challenges in the future.

A 2x2 multi-chip reconfigurable MOEMS mask: a stepping stone to large format microshutter arrays for coded aperture applications

Coded aperture imaging has been used for astronomical applications for several years. Typical implementations used a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. Recently applications have emerged in the visible and infra red bands for low cost lens-less imaging systems and system studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. Previously reported work focused on realising a 2x2cm single chip mask in the mid-IR based on polysilicon micro-optoelectro- mechanical systems (MOEMS) technology and its integration with ASIC drive electronics using conventional wire bonding. It employs interference effects to modulate incident light - achieved by tuning a large array of asymmetric Fabry-Perot optical cavities via an applied voltage and uses a hysteretic row/column scheme for addressing. In this paper we report on the latest results in the mid-IR for the single chip reconfigurable MOEMS mask, trials in scaling up to a mask based on a 2x2 multi-chip array and report on progress towards realising a large format mask comprising 44 MOEMS chips. We also explore the potential of such large, transmissive IR spatial light modulator arrays for other applications and in the current and alternative architectures.

A scalable multi-chip architecture to realise large-format microshutter arrays for coded aperture applications

Coded aperture imaging has been used for astronomical applications for several years. Typical implementations used a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. Recently applications have emerged in the visible and infra red bands for low cost lens-less imaging systems and system studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. Previously we reported on the realization of a 2x2cm single chip mask in the mid-IR based on polysilicon micro-opto-electro-mechanical systems (MOEMS) technology and its integration with ASIC drive electronics using conventional wire bonding. The MOEMS architecture employs interference effects to modulate incident light - achieved by tuning a large array of asymmetric Fabry-Perot optical cavities via an applied voltage and uses a hysteretic row/column scheme for addressing. In this paper we present the latest transmission results in the mid-IR band (3-5μm) and report on progress in developing a scalable architecture based on a tiled approach using multiple 2 x 2cm MOEMS chips with associated control ASICs integrated using flip chip technology. Initial work has focused on a 2 x 2 tiled array as a stepping stone towards an 8 x 8 array.

Multi-Degree-of-Freedom Simulation of Micro-Machined Sensors Under Mixed-Signal Control

A general method of modeling and simulating a micro-machined inertial sensor under closed-loop control by a sigma-delta modulator is presented. The model of the mechanical subsystem captures all 6 mechanical degrees of freedom and the complex electrostatic fields in electrostatic comb drives. A technique is presented that makes transient simulations of the sophisticated mechanical model in conjunction with a modulator more tractable. The benefits of the modeling and simulation approach are demonstrated on an example consisting of a single-axis accelerometer and a second-order sigma-delta modulator. The example shows that transient simulations of the complete system can be performed in relatively short time while capturing cross coupling between mechanical modes of the sensor.Copyright