Page 54 - MSAM-2-2

Materials Science in Additive Manufacturing Biomimetic structures for optical focusing

of light reflections in the microchannel increased. In all with a diffuse background was obtained on the focus
analysis surfaces with light intensity, the light intensity plate of each LPBF-processed BLES, which was formed
increased from top to bottom, and the light intensity by focusing part of incident parallel light (Type 2) and
of the analysis surface increased as the analysis surface transmitting light directly (Type 1). If the incident light in
was away from the center of BLES (optical axis), which the microchannel conforms to even reflection, those lights
reflected the increase of the amount of indicated light will be unfocused on the focus plate and become part of
in the microchannel. However, increasing the number the diffuse background (Type 3). It is worth noting that the
of light reflections was detrimental to the optical focus light of Type 2 was linearly focused in a one-dimensional
[41]
performance of BLES. Therefore, properly reducing the direction and formed a focal arm ; thus, a cross with
aperture of microchannels and increasing the number two focal arms was obtained in a two-dimensional
of microchannels around the optical axis to reduce the direction, and a bright central focal facula with a diffuse
[42]
number of light reflections in the channel is a good way to background was formed in the center of the cross . In
improve the focusing performance of BLES. the microchannels near the axis of the light source, the
light was reflected in the form of Type 2. Therefore, the
Figure 9 lists the types of light which were incident
into the microchannel of BLES. The transmitted light was microchannel near the axis of the light source has a higher
contribution to the optical focusing of BLES. To improve
inevitably produced in the process of light focus due to the the focus performance of the structure, the aperture of
feature of microchannel of BLES (Type 1), which results the microchannel can be reduced as much as possible to
in the background light or stray light formed on the focus increase the number of microchannels around the axis of
plate. To realize the reflection-type focus of the incident the light source.
light by BLES (Type 2), the incident light reflected in the
microchannel needs to meet the odd reflection, but the light From our studies, it can be concluded that it is a
reflected the excessive odd number of times was unfocused possible way to manufacture the BLES structure with good
(Type 4). As shown in Figure 6, a bright central focal facula light-focusing ability using LPBF. However, the inevitable
defects (such as high surface roughness) generated in
the LPBF-processed BLES structures can affect it and
deliver the best outcome in light focusing. Therefore, it is
necessary to perform post-treatment on LPBF-processed
BLES structures, such as electropolishing, abrasive flow
machining, or surface coating, to obtain the required
surface finishing and improve the optical performance
of LPBF-processed BLES structures in the future. In
addition, according to our previous discussion, the micro
LPBF process could be used to process microchannels
with the small channel width to increase the number of
microchannels around the light source axis and improve the
light-focusing ability of the manufactured BLES structures.

Figure 10 shows the potential application of BLES on
satellites. As shown in Figure 10A, the satellite skin is
designed as BLES. When the light shines on the satellite,
BLES can concentrate the light into the interior of the
Figure 9. Reflective type of incident rays in a microchannel. satellite. On the one hand, the light capture function of

A B C

Figure 10. (A) Concept map of satellite equipped with bionic lobster eye structure (BLES) as satellite skin; (B) satellite skin with BLES structure to be taken
out in the laser powder bed fusion equipment (LPBF); and (C) LPBF-processed satellite skin with BLES structure.

Volume 2 Issue 2 (2023) 9 https://doi.org/10.36922/msam.0361