High definition and magnification rigid endoscope is a significant equipment in the examination and surgery. In this paper, the design of a high definition (HD) rigid endoscope is presented with a FOV of 70°. The entrance pupil is 0.3 mm, achieved for the first time to our best knowledge. For the fabricated prototype, the theoretical resolution is 22.3 lp/mm at an object distance of 20 mm, the depth of field (DOF) is 115 mm and the stray light is eliminated effectively. The viewing angle of the developed endoscope is zero. However, the endoscope with non-zero viewing angle is more popular in some conditions, we present two designs with non-zero viewing direction for better observation and diagnosis of lesions on inner walls of organs and tissues.
Visible Light Communications (VLC) has become an emerging area of research since it can provide higher data
transmission speed and wider bandwidth. The white LEDs are very important components of the VLC system, because it
has the advantages of higher brightness, lower power consumption, and a longer lifetime. More importantly, their intensity
and color are modulatable. Besides the light source, the optical antenna system also plays a very important role in the VLC
system since it determines the optical gain, effective working area and transmission rate of the VLC system. In this paper,
we propose to design an ultra-thin and multiple channels optical antenna system by tiling multiple off-axis lenses, each of
which consists of two reflective and two refractive freeform surfaces. The tiling of multiple systems and detectors but with
different band filters makes it possible to design a wavelength division multiplexing VLC system to highly improve the
system capacity. The field of view of the designed antenna system is 30°, the entrance pupil diameter is 1.5mm, and the
thickness of the system is under 4mm. The design methods are presented and the results are discussed in the last section of
this paper. Besides the optical gain is analyzed and calculated. The antenna system can be tiled up to four channels but
without the increase of thickness.