SENSORS OPTIMIZED FOR 3D
DIGITIZATION
ARYA MURALI
S7EA 08119
CONTENTS
Introduction
3-D imaging Technology
Sensors For 3-D imaging
Proposed Sensors
Case Implementation
Advantages
Applications
Future Scope
Conclusion
Reference
INTRODUCTION
Digital 3D imaging can benefit from advances in VLSI
technology in order to accelerate its deployment in many
fields like visual communication and industrial automation
High-resolution 3D images can be acquired using laserbased vision systems.
Optimization of sensors means integrating them as small
chips , which accelerate the development of imaging
devices.
3D IMAGING TECHNOLOGY
Machine Vision
It analyses the properties of luminous flux reflected
by the object. There are two types of methods for
finding the structure and dimension they are
1.
Passive Vision
2.
Active Vision
Passive Vision
Analyses the structure under ambient light
Produces uncertainty in imaging
Active Vision
q Reduces the uncertainty by structuring the image
q
It eliminates most of the irregularities found in 2-D
imaging
q
This method is sensitive to each and every micro
structure
q Triangulation based laser range cameras are examples of
active vision technique.
AUTOSYNCHRONIZED SCANNER
It utilizes triangulation technique for imaging
SENSORS FOR 3-D IMAGING
Two types
1.Synchronization Circuit Based Upon Dual Cells
o
Ensures the stability and repeatability in range measurement on
varying temperature
These are bulky
On integrating reduces size of devices used for 3-D digitization
2. Optimized 3-D position sensor
Position sensors measures position of light spot in one or
two dimension.
v
Specification of 2-D position sensors will be different
from 3-D.
v
In 3-D a small spot of noise means large amount of pixels
which is not compactable with 2-D imaging.
v
When VLSI technologies are implemented 3-d imaging
become widely accepted
v
POSITION SENSITIVE DETECTOR
Position Sensitive Detector
(PSD) is an optical position
sensor (OPS), that can measure a
position of a light spot in one or
two-dimensions on a sensor
surface . The PSD is a precision
semiconductor optical sensor
which produces output currents
related to the centre of mass of
light incident on the surface of
the device.
DUAL AXIS PSD
This particular PSD is a five
terminal device bounded by four
collection surfaces; one terminal
is connected to each collection
surface and one provides a
common return. Photocurrent is
generated by light which falls on
the active area of the PSD will
be collected by these four
perimeter electrodes.
PROPOSED SENSORS
Based on the way light spot sensed two types
1.CRPSDs
Continuous Response Position Sensitive Detectors
It includes lateral effect photodiode and geometrically
shaped photodiodes
Used for color identifying
2. DRPSDs
Discrete Response Position Sensitive Detectors
Composed of detectors , charge coupled device , array of
photo diodes equipped with a MUX.
CASE IMPLEMENTATION
OVER ALL ARCHITECTURE
CHIP DESIGN OF ONE SUCH DRPSDs
Contains an array of optical sensor
It has a variable gain channel with a read out window of
16 neighboring pixels
Pixel area of 48 x 500micrometer square
Pixel dimension too large so that it can handle spots of
noise
SENSORS ON 3D DIGITIZATION
ADVANTAGE:
v
v
v
Reduced size and cost
Better resolution at a lower system cost
High reliability that is required for high accuracy
3D vision systems
Complete images of visible surfaces that are
rather featureless to the
Human eye or a video camera can be generated
DISADVANTAGES:v
The elimination of all stray light in an optical system
requires sophisticated
APPLICATIONS
Intelligent digitizers will be capable of measuring
accurately and simultaneously color and 3D
For the development of hand held 3D cameras
Multi resolution random access laser scanners for fast
search and tracking of 3D features
FUTURE SCOPE
Anti reflecting coating film deposition and RGB filter
deposition can be used to enhance sensitivity and for
colour sensing.
CONCLUSION
The results obtained so far have shown that optical sensors
have reached a high level of development and reliability
those are suited for high accuracy 3D vision systems.
The availability of standard fabrication technologies and the
acquired know-how in the design techniques, allow the
implementation of optical sensors that are application
specific: Opto-ASICs. The trend shows that the use of the low
cost CMOS technology leads competitive optical sensors.
REFERENCES
L.GONZO, A.SIMONI, A.GOTTARDI, DAVID STAPPA, J.A
BERNALDIN,Sensors optimized for 3D digitization, IEEE transactions
on instrumentation and measurement, vol 52, no.3, June 2003, pp.903908.
P.SCHAFER, R.D.WILLIAMS. G.K DAVIS, ROBERT A. ROSS,
Accuracy of position detection using a position sensitive detector,
IEEE transactions on instrumentation and measurement, vol 47, no.4,
August 1998, pp.914-918
l www.ieee.org
l www.wikipedia.org
www.sensors.com
Q&A
