A high-sensitivity, low-cost, ultrathin, hollow fiber micro bubble structure was proposed; such a bubble can be used to develop a high-sensitivity strain sensor based on a Fabry–Perot interferometer (FPI). The micro bubble is fabricated at the fiber tip by splicing a glass tube to a single mode fiber (SMF) and then the glass tube is filled with gas in order to expand and form a micro bubble. The sensitivity of the strain sensor with a cavity length of about 155 μm and a bubble wall thickness of about 6 μm was measured to be up to 8.14 pm/με.

A new fiber pressure sensor is proposed and analyzed in this paper. A commercial arc fusion splicer and pressure-assisted arc discharge technology are used here to fabricate a silica hollow microbubble from a common glass tube with the characteristics of a thin film. Then the single mode fiber is embedded into the microbubble to form a fiber Fabry–Perot interferometer by measuring the reflected interference spectrum from the fiber tip and microbubble end. As the wall thickness of the micro-bubble can reach up to several micrometers, it can then be used for measuring the outer pressure with high sensitivity. The fabrication method has the merits of being simple, low in cost, and is easy to control. Experimental results show that its pressure sensitivity can reach 164.56 pm/kPa and the temperature sensitivity can reach 4 pm/°C. Therefore, it also has the advantage of being insensitive to temperature fluctuation.

Design of a dc-dc converter operating at the frequency of MHz is presented. Digital control algorithm is implemented in FPGA and a high resolution PWM pulse generator is built based on the combination of fast clock counter and programmable delay line techniques. The output voltage of this converter is regulated using a phaseshifted PWM scheme. Planar topology for the transformer was adopted and the windings were fabricated by using the printed circuit board. The ability to control the electromagnetic interference of the SMPS was tested and proved to work well.

Existing switching mode power supply solutions cause unacceptable self-pollution within the infrared imaging system. The band unlimited PWM signal will be coupled to the input of ADC, and then be sampled. High order harmonics are aliased down to the frequency band of the image signal. With the use of the digital PWM controller, the switching frequency can be precisely synchronized with the ADC sampling clock. The predominant parts of the noise signal will be down converted into the DC signals and eliminated by image processing units. The noise immunity principle was tested and proved on an infrared image capture system.