This work demonstrates a micro electro mechanical system (MEMS) technology based infrared thin film, which converts absorbed visible light energy into infrared radiation. The principle of the film and the experiment for studying its thermodynamic characteristics are presented. The radiation spectrum of the thin film conforms to the characteristics of blackbody spectrum, and the average emissivity in infrared band is 0.638. The thermal diffusion distance decreases with the decrease of substrate thickness. Moreover, the fabrication of periodic pixel arrays on substrates can effectively reduce the thermal conductivity. The thermal conductivity of the pixel inscribed thin film with a substrate thickness of 360nm is 0.1W/m·K. The temporal constant decreases with the decrease of substrate thickness. The time constant of the film with a substrate thickness of 360nm is 2.72ms while the working temperature is 5 degrees Celsius. These characteristics indicate that the infrared thin film has a promising application prospect in infrared scene projection.

We investigated the design, optimization, and evaluation method of an infrared (IR)/microwave (MW) multilayered dielectric plate type of beam combiner. The MW multilayered dielectrics design theory and IR film design theory were unified using transmission line theory. The principles in designing the initial structure of a beam combiner were presented. An objective function was presented in optimizing the beam combiner. Six evaluation indices were constructed to evaluate the performance of the beam combiner. To verify the feasibility of the proposed method an example was given. The results showed that the method could meet the joint design, optimization, and evaluation requirements of a beam combiner’s IR and MW characteristics. Finally, the design, optimization, and evaluation procedure was summarized.

Self-suspended polyimide (PI) composite films were fabricated. Their diameter and thickness were 2.5 in. and 260 nm, respectively. A high ratio of diameter to thickness of 2.4 × 10⁵ was obtained. The multiwalled carbon nanotubes (MWCNTs) were filled into PI to improve the optical absorption and the photothermal response. By using the N-methyl pyrrolidone solvent for both MWCNTs and poly(amic acid), a homogeneous dispersion of MWCNTs with up to 15% content was obtained. Under the thermal treatment of 300 °C, the composite films were successfully synthesized, which was proved by the measurements of Fourier transform infrared spectrum and x-ray diffraction. Compared with the pure PI film, the optical absorption of the composite films at 532 nm wavelength increased from 10% to 28%. The steady and transient photothermal properties of the composite films were investigated. In the steady state, a temperature rise of 145 °C was obtained under 0.7 W/cm² illuminating laser power density. The temperature increased by 29 times compared with that of the pure PI film. The corresponding photothermal conversion efficiency improved to 70.8%. In the transient state, the photothermal response time was 7.5 ms, which was only half that of the pure PI film. The excellent photothermal properties of these self-suspended MWCNT/PI composite films highlight their potential applications in micro- and nanoscale devices for photo detection and thermal imaging.

We investigated the design method of an infrared (IR)/microwave (MW) micromirror array type of beam combiner. The size of micromirror is in microscopic levels and comparable to MW wavelengths, so that the MW will not react in these dimensions, whereas the much shorter optical wavelengths will be reflected by them. Hence, the MW multilayered substrate was simplified and designed using transmission line theory. The beam combiner used an IR wavefront-division imaging technique to reflect the IR radiation image to the unit under test (UUT)’s pupil in a parallel light path. In addition, the boresight error detected by phase monopulse radar was analyzed using a moment-of method (MoM) and multilevel fast multipole method (MLFMM) acceleration technique. The boresight error introduced by the finite size of the beam combiner was less than 1°. Finally, in order to verify the wavefront-division imaging technique, a prototype of a micromirror array was fabricated, and IR images were tested. The IR images obtained by the thermal imager verified the correctness of the wavefront-division imaging technique.

The ladar scene projector is a key device in the hardware-in-the-loop (HWIL) simulation system. Ladar scene modeling is a fundamental work of developing a ladar scene projector. A modeling method based on physically based rendering technology and OpenGL is proposed in this paper. This modeling method can quickly generate delay, amplitude, and pulse width data for all return signals in a large-array-scale ladar scene. A $100\times 100$-array-sized ladar scene model with a distance range of 0–3 km is simulated. The average data generation time is only 5.31 ms. Distance resolution is 1.5 m, and the peak-valley error is less than 0.15 m. This method achieves efficient modeling and fast hardware update rates, which greatly improves the real-time performance of the ladar scene projector. It has strong practicality and can be directly applied in the HWIL simulation system.

A radio-frequency intensity-modulated light source at 532 nm was built for underwater ranging. The maximum output power at 532 nm was 2.56 W, the highest efficiency from the fundamental to second harmonic generation was 22.6%. The watt level 532 nm light source was applied in underwater ranging experiments. Frequency domain reflectometry was applied to retrieve the distances of the objects to the transmitter in a water tank. When the modulation frequency was tuned from 10 MHz to 200 MHz, we obtained ranging accuracy better than 5 cm and ranging resolution smaller than 0.5 cm at 8.6 attenuation length. Two objects spacing by 0.8 m could be resolved simultaneously. The attenuation length at which the object could be detected was limited by the sensitivity of the silicon photodetector. Moreover, we did not use the full bandwidth of the modulation since the lock-in amplifier adopted for data processing had a bandwidth of 200 MHz. Both ranging distance and resolution can be improved if a photomultiplier tube and a high-speed data sampling board were used. Nevertheless, the experimental results showed that the watt level, broadband intensity modulated light source has great potential in underwater detection in terms of ranging accuracy and resolution.