Objective  As an infrared scene projector, the resistor array device played an important role in hardware-in-the-loop infrared simulation system. Due to the emitted infrared image similar to the real target, it can generate dynamic infrared scene for infrared detectors. Usually, the scale of the infrared detector was 512 × 512 or 640 × 480, meaning the scale of the target simulator should be four times larger to ensure high-quality simulations, and developing a 1 024 × 1 024 scale resistor array device is necessary. The pixel design is the basis of resistor array and it determines the achievable scale and performance of the resistor array. Therefore, a pixel array that can be scalable to 1 024 × 1 024, can operate at 200 Hz, and has an apparent temperature close to 600 K must be achieved. For this purpose, a design scheme for integrating the pixel driving circuit and MEMS structure was proposed, and a scalable high-fill-factor pixel was designed in this paper.

  Methods  A pixel circuit operating in snapshot mode was designed according to the functional requirements of the resistor array device (Fig.2). By investigating the design scheme for integrating the pixel driving circuit and MEMS structure, four key factors influencing the pixel performance were deduced, including fill factor, thermal conductance, heat capacity, and surface emissivity. Using the high extinction coefficient materials and an optical resonator structure, the surface emissivity of the micro emitter in mid-wave infrared and long-wave infrared reaches 0.7 (Fig.5). Through proper film thickness design and geometric structure design, the fill factor of the micro emitter array reaches 51% (Fig.4). The thermodynamic simulation was used to assist the design of the micro emitter and evaluate its performance (Fig.6). A MEMS fabrication process was proposed to prepare pixel array sample (Fig.8).

  Results and Discussions   The thermodynamic simulation results of the designed pixel show that the apparent temperature of mid-wave infrared and long-wave infrared at 0.6 mW power drive reaches 658 K and 582 K, respectively (Fig.7). The thermal response time for both heating and cooling is less than 5 ms, meaning the pixel can work at 200 Hz. The displacement of the emitter is less than 300 nm, which benefited from the geometry structure and the materials applied. The 640 × 410 array sample showed excellent geometry uniformity (Fig.9). The sample pixel was tested in air at 0.6 mW power drive and showed a long-wave infrared apparent temperature of about 400 K. The image result of this sample proved that the pixel design was achievable and functional (Fig.10).

  Conclusions  Aiming at the requirements of developing large-scale resistor array devices, a design scheme for integrating the CMOS driving circuit and the MEMS structure into the pixel was proposed. The pixel driving circuit can work in snapshot mode. Benefiting from the MEMS structure, the fill factor of the micro emitter reaches 51%, which is much higher than that of the traditional resistor array. The thermodynamic simulation results showed that the radiation efficiency of the designed pixel was sufficiently high and capable of being applied in 1 024 × 1 024 resistor array device design. An array sample was fabricated using the proposed MEMS process. The test result of this sample proved the pixel design is achievable. The design research indicates the direction for developing domestic large-scale and high-fill-factor resistor array devices.