High-resolution writing using beams and lenses rotating at...

Details High-resolution writing using beams and lenses rotating at... High-resolution writing using beams and lenses rotating at...

2001-05-22

2003-02-18

Phan, James (Department: 2872)

Optical: systems and elements

Deflection using a moving element

Using a periodically moving element

C359S210100, C359S201100, C359S203100, C359S223100, C359S226200, C369S044170, C369S044390

Reexamination Certificate

active

06522443

ABSTRACT:

BACKGROUND—FIELD OF INVENTION
The invention relates to the field of reading, writing, inspecting, printing, engraving, plotting, and vision. In the reading aspect it particularly relates to the fields of machine vision and inspection machines, such as those used to read and/or inspect industrial products such as compact disks (CDs), computer disks, video disks, digital video disks (DVDs), Printed Circuit Boards (PCBs) and silicon wafers used in the integrated circuits (IC) industry. In the printing aspect it relates to the field of writing, engraving, and printing machines, such as those used in the industrial fields of digital printing, internal drum scanning, preprinting and pre-press industry, laser beam writing, and photolithography.
BACKGROUND—Prior Art
Conventional scanners which use external drum scanning, such as scanner
1
of
FIG. 1
, includes a rotating drum
2
, which carries a flexible plate
4
on its circumference and a read-write head
6
having a focusing lens
7
that emits and collects multiple beams
8
onto and from plate
4
. While drum
2
rotates around its axis
10
, head
6
moves parallel to axis
10
and along arrows
12
and
14
and thus the whole area of plate
4
is scanned.
FIG. 2
illustrate an internal drum scanner
19
including a flexible plate
20
bent into cylinder-like shape, a spinning tilted mirror
22
, and a head
24
having a focusing lens
25
that emits and collects a single beam
26
onto and from plate
20
. The optical path between plate
20
and head
24
includes mirror
22
. Mirror
22
spins around its axis
28
, along which beam
26
propagates between mirror
22
and head
24
. Mirror
22
and head
24
both move along and parallel to axis
28
along a rail
30
and thus scan the whole area of plate
20
.
External scanner
1
of
FIG. 1
has the advantages of using multiple beams
8
and head
6
with its focusing lens
7
that is close to plate
4
. These advantages allow multiple scans at high resolution. The disadvantage is the mechanical instability of its large rotating drum
2
that carries plate
4
. This disadvantage forces the use of a low rotational speed.
The advantage of internal scanner
19
of
FIG. 2
is the compact size of its spinning mirror
22
that allows it to spin at a very high rotational speed. The disadvantage is the relatively long optical path between its head
24
and its plate
20
via mirror
22
. This requires that lens
25
have a long focal length that provides only limited resolution.
The scan speed V of the scanner is proportional to the product of the number N of beams used, times the rotational speed; &ohgr;, i.e.,
V∝N·&ohgr;
The typical values of the above parameters for external scanning are N=30 and &ohgr;=500 rpm. Thus V is proportional to 15,000. The typical values of the above parameters for internal scanning are N=1 and &ohgr;=15,000 rpm. Thus V is also proportional to 15,000.
It can be seen that both scanner
1
and scanner
19
have a similar scan speed V, but scanner
1
is superior to scanner
19
due to its high resolution.
U.S. Pat. No. 5,557,438 to N. Schwartz and A. Shahar, entitled “Scanning And Tracking Using Rotating Polygons”, Sep. 17, 1996, discloses a unique scan system using polygonal mirrors. This system teaches how to convert a scanner
19
into an internal scanner that is capable of scanning multiple beams while maintaining the high performance of scanner
19
. In this scanner, if the typical number N of beams is 10, then the scan speed V is proportional to 2·10·15,000=300,000, which is 20 times faster than scanner
1
. While the scan speed is much faster, its resolution is still similar to the resolution of scanner
19
, which is inferior to the resolution of scanner
1
.
U.S. Pat. No. 5,828,483 to A. Shahar and N. Schwartz, entitled “Printing And Inspection System Using Rotating Polygon And Optical Fibers”, Oct. 27, 1998, teaches how to convert internal scanning-into wide planar scanning. In this system radiation is projected and collected onto and from a planar region by the outputs of the optical fibers. This system also suffers from the disadvantage of limited resolution.
OBJECTS and ADVANTAGES
Accordingly several objects and advantages of the invention are as follows:
(1) To provide an improved scan system.
(2) To provide writing and reading scanners for internal drum scanning which are capable of maintaining all the high performance of the system of the above '438 patent, with the additional advantage of high scan resolution.
(3) To provide writing and reading scanners for planar scanning which maintain all the high performance of the scanner of the above '483 patent, with the additional advantage of high scan resolution. Other objects and advantages are:
(4) To provide disk drivers using multiple beams for fast reading of CDs, computer disks, video disks and DVDs.
(5) To provide inspection systems using multiple beams for fast inspection of CDs, computer disks, videodisks and DVDs.
(6) To provide writing machines using multiple beams, such as writing machines for fast writing and engraving of CDs, computer disks, videodisks, and DVDs.
(7) To provide writing, laser writing, photolithography, and reading or inspecting systems using multiple beams, especially such systems for reading or inspecting PCBs.
(8) To provide writing, laser writing; photolithography, and reading or inspecting systems using multiple beams, especially for reading or inspecting wafers, such as silicon wafers used in the IC industry.
(9) To provide an internal drum scanner and planar scanner using at least one radiation beam for fast reading and writing with high resolution and for inspection by imaging and laser scattering.
(10) To provide internal drum and planar scanning at angular velocities that are equal to or twice the rotational speed of the scan device.
(11) To provide a rotating confocal microscope for reading, inspecting, and writing by inner drum scanning and planar scanning.
Still further objects and advantages will become apparent from a consideration of the ensuing description and accompanying drawings.


REFERENCES:
patent: 5557438 (1996-09-01), Schwartz et al.
patent: RE35350 (1996-10-01), Shahar et al.
patent: 5828483 (1998-10-01), Shahar et al.

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