November 10, 2008 / Vol. 6, No. 11 / CHINESE OPTICS LETTERS 833
Calculation on diffraction aperture of
cube corner retroref lector
Song Li (
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), Bei Tang (
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), and Hui Zhou (
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)
School of Electronic Information, Wuhan University, Wuhan 430079
Received April 8, 2008
On the basis of optical property of cube corner retroreflector (CCR), a new perception and calculation
approach for diffraction aperture of CCR in two different forms is presented. The relationship between
diffraction apertures and incident light with six different combinations of reflection order and incident
angle is established. Far-field diffraction patterns of CCR under various incident conditions are also
provided.
OCIS codes: 050.1220, 050.1940, 050.1960.
doi: 10.3788/COL20080611.0833.
Retroreflector has been widely used in various laser mea-
surement systems as a cooperative target based on its
direct reflecting
[1,2]
. Satellite laser ranging (SLR) which
is a high-precision space measurement technology comes
forth in the 1960s. The laser cooperation target in SLR
system is laser cube corner retroreflector (CCR) or laser
retroreflector array which is installed on the surface of
the satellite. The orbital altitude of satellite is generally
several hundred kilometers to tens of thousands of kilo-
meters. Therefore, the SLR system can be regarded as a
Fraunhofer diffraction optical system. On the one hand,
CCRs on the satellite directionally reflect the laser pulse
which comes from the observing station; on the other
hand, CCRs diffract and redistribute energy of the laser
pulse as diffraction aperture. The light field distribution
diffracted by CCRs is of great significance for the laser
ranging system to receive laser pulse echo correctly and
to accomplish the ranging function exactly.
The most important parameter which influences the
far-field diffraction characteristics of CCR is the inte-
gral region of diffraction aperture. However, previous
researches into the far-field diffraction of CCR take the
diffraction aperture as a whole. We want to explore the
deeper reason what makes the light field distribution of
CCR be taken on like that and why the certain part of
light spot is much better than other parts of light spot
for the reception. In this paper, the diffraction aperture
theory of oblique incidence on the CCR is established.
The CCR consists of three mutually orthogonal planar
surfaces and one flat bottom surface. The light which en-
ters the CCR through the bottom surface is reflected by
the three planar surfaces in turn. There are six different
reflection orders of light as three reflective surfaces have
six different sequences of arrangements
[3]
. The reflection
order of light depends on the incident direction and co-
ordinates of light on the bottom surface of CCR. Take
the vertex of CCR as the origin and three edges of CCR
as X, Y , Z axes to establish the coordinate system, as
shown in Fig. 1. Without regard to refraction, for an
incident light with any direction (a, b, c), the light direc-
tion converts to (−a, −b, −c) after being reflected by the
three reflective surfaces respectively.
As shown in Fig. 2, taking the midpoint of bottom sur-
face as the origin o, the bottom surface as x-y plane, and
the direction of light which comes out of the CCR after
being reflected by the three reflective surfaces sequently
as z-axis, we establish the oxyz coordinate system. Draw
a vertical line to one of the bottom surface borders across
point O in X-Z plane, with the foot of the perpendicular
labeled as point T . It is assumed that the angle between
line OT and z-axis is ϕ, and the angle between line OT
and line Oo is ω. These two sets of coordinates are pro-
vided with coordinate transformation matrix as
[4]
M =
cos ϕ − sin ϕ sin ω − sin ϕ cos ω
0 cos ω − sin ω
sin ϕ cos ϕ sin ω cos ϕ cos ω
!
. (1)
Fig. 1. Cartesian coordinates of CCR.
Fig. 2. Schematic diagram of coordinate transformation of
CCR.
1671-7694/2008/110833-04
c
2008 Chinese Optics Letters