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非接觸Point sensor感應器種類
a.雷射三角形:Laser Triangulation
b.動態聚焦型:Dynamic Focusing
c. Conoscopy
d.色彩共焦: Chromatic Confocal
a.雷射三角形:Laser Triangulation
•
This type of sensor uses a laser that
projects a spot on the surface to be
measured. The position of the spot on
the surface is located by a detector on
one side at a specific angle. The
altitude is derived from knowledge
of the parallax between the laser
and the point of observation.
優點:
*量測範圍大,從幾十um到幾十mm.
h
缺點:
*易受陰影及試片表面透明度的影響.
*雷射點太大 ,易干擾量測結果
b.動態聚焦型:Dynamic Focusing
•
h
This sensor uses a laser to project
a spot on the surface to be
measured. The objective is
displaced in real time to guarantee
that the spot is focused on the
surface. The altitude signal is
deduced from the control signal
that displaces the objective.
優點:高解析度,同步光學系統
缺點:量測速度慢
c.Conoscopy
•
This type of sensor uses a laser
that projects a spot on the surface
to be measured. The reflected
light is sent back to a detector via
a birefringence crystal which
modifies the speed of the wave in
proportion to its angle of diffusion,
which is itself proportional to the
distance of the object with respect
to the source. This creates
interferences on the detector
which are analysed in order to
derive the distance of the object.
優點: 可以量測非常高傾斜的試片
缺點: 解析度不高,無法量測粗糙度
d.色彩共焦:Confocal Chromatic
•
This type of sensor uses a source
of white light that projects a light
beam on the surface through a
chromatic objective, dispersing the
wavelengths along the optical axis.
The altitude of the surface point is
located by a spectrometer which
determines what wavelength is
focused on the surface.
優點: 高垂直解析度.
可以量測透明的玻璃及薄膜.
高量測速度.
缺點: 在反射的材料上對陡坡比較
敏感.