ISO/IEC 15486:1998
(Main)Information technology — Data interchange on 130 mm optical disk cartridges of type WORM (Write Once Read Many) using irreversible effects — Capacity: 2,6 Gbytes per cartridge
Information technology — Data interchange on 130 mm optical disk cartridges of type WORM (Write Once Read Many) using irreversible effects — Capacity: 2,6 Gbytes per cartridge
Technologies de l'information — Échange de données sur cartouches de disque optique de 130 mm de type WORM utilisant des effets irréversibles — Capacité: 2,6 Gbytes par cartouche
General Information
Standards Content (Sample)
INTERNATIONAL
STANDARD
First edition
1998-05- 15
Information technology - Data interchange
on 130 mm optical disk cartridges of type
WORM (Write Once Read Many) using
- Capacity: 2,6 Gbytes
irreversible effects
per cartridge
Technologies de I’informa tion - khange de donrkes sur cartouches de
disque optique de 130 mm de type WORM utilisant des effets
irr&ersibles - Capacitk: 2,6 Gbytes par cartouche
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PSO/IEC 15486:1998 (E)
Contents
1
Section 1 - General
1
1 Scope
2 Conformance
2.1 Optical Disk Cartridge (ODC)
2.2 Generating system
2.3 Receiving system
2.4 Compatibility statement
1
3 Normative reference
2
4 Definitions
2
4.1 band
2
4.2 case
2
4.3 clamping zone
2
4.4 control track
2
4.5 Cyclic Redundancy Check (CRC)
2
4.6 defect management:
3
4.7 disk reference plane
1
4.8 entrance surface
2
4.9 Error Correction Code (ECC)
2
4.10 format
2
4.11 hub
2
4.12 interleaving
2
4.13 land and groove
2
4.14 logical track
2
4.15 mark
2
4.16 mark edge
2
4.17 mark edge recording
2
4.18 optical disk
2
4.19 optical disk cartridge (ODC)
2
4.20 physical track
2
4.21 polarization
2
4.22 pre-recorded mark
2
4.23 read power
2
4.24 recording layer
2
4.25 Reed-Solomon code
3
4.26 space
3
4.27 spindle
3
4.28 substrate:
3
4.29 track pitch
3
4.30 write-inhibit hole
3
4.31 zone
0 ISO/IEC 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm,
without permission in writing from the publisher.
ISO/IEC Copyright Office * Case Postale 56 * CH-1211 Geneve 20 * Switzerland
Printed in Switzerland
11
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ISO/IEC15486:1998 (E)
OISO/IEC
3
5 Conventions and notations
3
5.1 Representation of numbers
3
5.2 Names
3
6 List of acronyms
7 General description of the optical disk cartridge
8 General requirements
8.1 Environments
8.1.1 Test environment
8.1.2 Operating environment
8.1.3 Storage environment
8.1.4 Transportation
8.2 Temperature shock
8.3 Safety requirements
8.4 Flammability
9 Reference Drive
9.1 Optical system
9.2 Optical beam
9.3 Read Channels
9.4 Tracking
9.5 Rotation of the disk
7
Section 2 - Mechanical and physical characteristics
7
10 Dimensional and physical characteristics of the case
7
10.1 General description of the case
8
10.2 Relationship of Sides A and B
8
10.3 Reference axes and case reference planes
8
10.4 Case Drawings
8
10.5 Dimensions of the case
8
10.5.1 Overall dimensions
9
10.5.2 Location hole
9
10.5.3 Alignment hole
10
10.5.4 Surfaces on Reference Planes P
11
10.5.5 Insertion slots and detent features
11
10.5.6 Gripper slots
11
10.5.7 Write-inhibit holes
12
10.5.8 Media sensor holes
13
10.5.9 Head and motor window
13
10.5.10 Shutter
14
10.5.11 Slot for shutter opener
14
10.5.12 Shutter sensor notch
14
10.5.13 User label areas
15
10.6 Mechanical characteristics
15
10.6.1 Materials
15
10.6.2 Mass
15
10.6.3 Edge distortion
15
10.6.4 Compliance
15
10.6.5 Shutter opening force
15
10.7 Drop test
15
11 Dimensional, mechanical and physical characteristics of the disk
15
11.1 General description of the disk
15
11.2 Reference axis and plane of the disk
16
11.3 Dimensions of the disk
16
11.3.1 Hub dimension
. . .
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OISO/IEC
ISO/IEC 15486: 1998 (E)
17
11.4 Mechanical characteristics
17
11.4.1 Material
17
11.4.2 Mass
17
11.4.3 Moment of inertia
17
11.4.4 Imbalance
17
11.4.5 Axial deflection
17
11.4.6 Axial acceleration
18
11.4.7 Radial runout
18
11.4.8 Radial acceleration
18
11.4.9 Tilt
18
11.5 Optical characteristics
18
11.5.1 Index of refraction
18
11.5.2 Thickness
18
11.5.3 Birefringence
18
11.5.4 Vertical Birefringence
19
11.5.5 Reflectance
19
12 Interface between cartridge and drive
19
12.1 Clamping method
19
12.2 Clamping force
19
12.3 Capture cylinder
20
12.4 Disk position in the operating condition
35
Section 3 - Format of information
35
13 Track geometry
35
13.1 Track shape
35
13.2 Direction of track spiral
35
13.3 Track pitch
35
13.4 Logical track number
35
13.5 Physical track number
35
14 Track format
35
14.1 Physical track layout
35
14.2 Logical track layout
36
14.3 Radial alignment
36
14.4 Sector number
36
15 Sector format
36
15.1 Sector layout
36
15.2 Sector Mark
37
15.3 VFO fields
38
15.4 Address Mark (AM)
38
15.5 ID fields
38
15.6 Postamble (PA)
39
15.7 Gap
39
15.8 Flag
39
15.9 Auto Laser Power Control (ALPC)
39
15.10 Sync
39
15.11 Data field
40
15.11.1 User data bytes
40
15.11.2 CRC and ECC bytes
40
15.11.3 Bytes for Defect Management Pointers (DMP)
40
15.11.4 Resync bytes
40
15.12 Buffer field
40
16 Recording Code
41
17 Formatted Zone
41
17.1 General description of the Formatted Zone
1v
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ISO/IEC 15486:1998 (E)
OISO/IEC
41
17.2 Division of the Formatted Zone
43
17.2.1 Lead-in Zone
43
17.2.2 Manufacturer Zones
44
17.2.3 User Zone
44
17.2.4 Reflective Zone
44
17.2.5 Control Track Zones
44
17.3 Control Track PEP Zone
44
17.3.1 Recording in the PEP Zone
45
17.3.2 Format of the tracks of the PEP Zone
49
17.4 Control Track SFP Zones
49
17.4.1 Duplicate of the PEP information
49
17.4.2 Media information
51
17.4.3 System Information
52
18 Layout of the User Zone
52
18.1 General description of the User Zone
52
18.2 Divisions of the User Zone
52
18.2.1 Reserved Area Use
53
18.3 User Area
54
18.4 Defect Management Areas (DMAs)
55
18.5 Disk Structure Table (DST)
56
18.6 Write Once Read Many (WORM) Zone
57
18.6.1 Location
57
18.6.2 Partitioning
57
19 Defect Management for WORM Media
57
19.1 Initialization of the disk
57
19.2 Defect Management Pointers
58
19.3 Write procedure
58
19.3.1 Read Procedure
60
Section 4 - Characteristics of embossed information
60
20 Method of testing
60
20.1 Environment
60
20.2 Use of the Reference Drive
60
20.2.1 Optics and mechanics
60
20.2.2 Read power
60
20.2.3 Read Channels
60
20.2.4 Tracking
60
20.3 Definition of signals
62
21 Signal from grooves
62
21.1 Cross-track signal
62
21.2 Push-pull signal
62
21.3 Divided push-pull signal
63
21.4 Phase depth
63
21.5 Track location
63
22 Signals from Headers
63
22.1 Sector Mark Signals
63
22.2 VFO signals
63
22.3 Address Mark, ID and PA signals
64
22.4 Timing jitter
64
23 Signals from embossed Recording fields
64
23.1 Signal amplitude
64
23.2 Modulation method offset
64
23.3 Timing Jitter
65
23.4 Byte Errors
V
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OISO/IEC
ISO/IEC 15486: 1998 (E)
65
24 Signals from Control Track PEP marks
66
Section 5 - Characteristics of the recording layer
66
25 Method of testing
66
25.1 Environment
66
25.2 Reference Drive
66
25.2.1 Optics and mechanics
66
25.2.2 Read power
66
25.2.3 Read Channel
66
25.2.4 Tracking
66
25.2.5 Signal detection for testing purposes
66
25.3 Write conditions
66
25.3.1 Write pulse and power
67
25.3.2 Pulse power determination
67
25.3.3 Media power sensitivity
67
25.4 Definition of signals
68
26 Imbalance of difference signal
68
27 Write characteristics
68
27.1 Resolution
68
27.2 Narrow-band signal-to-noise ratio
69
27.3 Cross-talk ratio
69
27.3.1 WORM track test method
69
27.4 Timing Jitter
69
27.5 Media thermal interaction
70
Section 6 - Characteristics of user data
70
28 Method of testing
70
28.1 Environment
70
28.2 Reference Drive
70
28.2.1 Optics and mechanics
70
28.2.2 Read power
70
28.2.3 Read amplifiers
70
28.2.4 Mark Quality
71
28.2.5 Channel bit clock
71
28.2.6 Binary-to-digital converters
71
28.2.7 Error correction
71
28.2.8 Tracking
71
29 Minimum quality of a sector
71
29.1 Headers
71
29.1.1 Sector Mark
71
29.1.2 ID fields
71
29.2 User-written data
71
29.2.1 Recording field
71
29.2.2 Byte errors
71
29.2.3 Modulation method offset
71
29.2.4 Timing jitter
71
30 Data interchange requirements
72
30.1 Tracking
72
30.2 User-written data
72
30.3 Quality of disk
Annexes
73
A - Air cleanliness class 100 000
Vi
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ISO/IEC 15486:1998 (E)
OISO/IEC
74
B- Edge distortion test
76
C- Compliance test
78
D- Test method for measuring the adsorbent force of the hub
80
I
E CRC for ID fields
81
F- Interleave, CRC, ECC, Resync for the Data Field
85
G- Determination of Resync pattern
90
H- Read Channel for measuring NBSNR and jitter
91
measuring procedure
Timing jitter
J-
92
K - Definition of write pulse shape
L - Implementation Independent Mark Quality Determination (IIMQD) for the interchange of recorded
93
media
96
M - Requirements for interchange
98
N - Measurement implementation for Cross-track signal
99
P - Values to be implemented in existing and future standards
100
Q - Office environment
101
R - Derivation of the operating climatic environment
106
S - Transportation
107
T - Sector retirement guidelines
108
U - Track deviation measurement
112
V - Measure of the vertical birefringence of the substrate
114
W - Laser Power Calibration for evaluation of media power sensitivity
vii
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OISO/IEC
ISO/IEC 15486:1998 (E)
Foreword
IS0 (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the
specialized system for worldwide standardization. National bodies that are members of IS0 or IEC participate in the
development of International Standards through technical committees established by the respective organization to deal with
particular fields of technical activity. IS0 and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with IS0 and IEC, also take part in the work.
In the field of information technology, IS0 and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft
International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the national bodies casting a vote.
International Standard ISO/IEC 15486 was prepared by ECMA (as ECMA-238) and was adopted, under a special “fast-track
procedure ”, by Joint Technical Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by national
bodies of IS0 and IEC.
Annexes A to N form an integral part of this International Standard. Annexes P to W are for information only.
. . .
Vlll
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ISO/IEC 15486:1998 (E)
INTERNATIONAL STANDARD 0 ISO/IEC
Data interchange on 130 mm optical disk cartridges of
Information technology -
type WORM. (Write Once Read Many) using irreversible effects - Capacity:
2,6 Gbytes per cartridge
Section 1 - General
1 Scope
This International Standard specifies the characteristics of a 130 mm optical disk cartridge (ODC) of Type WORM (Write
Once Read Many) with a capacity of 2,6 Gbytes. Type WORM ODCs use writing effects that are inherently irreversible.
Written marks cannot be erased and attempted modification of the written marks are detectable.
This International Standard specifies
-
the conditions for conformance testing and the Reference Drive;
-
the environments in which the cartridges are to be operated and stored;
-
the mechanical, physical and dimensional characteristics of the cartridge, so as to provide mechanical interchange ability
between data processing systems;
-
the format of the information on the disk, both embossed and user-written, including the physical disposition of the tracks
and sectors, the error correction codes, the modulation methods used;
-
the characteristics of the embossed information on the disk;
-
the recording characteristics of the disk, enabling processing systems to write data onto the disk;
-
the minimum quality of user-written data on the disk, enabling data processing systems to read data from the disk.
This International Standard provides for interchange between optical disk drives. Together with a standard for volume and file
structure it provides for full data interchange between data processing systems.
2 Conformance
21 . Optical Disk Cartridge (ODC)
An Optical Disk Cartridge shall be in conformance with this International Standard if it meets the mandatory requirements
specified herein. A claim of conformance shall state that the ODC is of Type WORM.
22 . Generating system
A generating system shall be in conformance with this International Standard if the ODC it generates is in accordance with 2.1.
23 . Receiving system
A receiving system shall be in conformance with this International Standard if it is able to handle an ODC according to 2.1
24 . Compatibility statement
A claim of conformance by a generating or receiving system with this International Standard shall include a statement listing
any other International Optical Disk Cartridge standard(s) supported by the system for which conformance is claimed. This
statement shall specify the number of the standard(s), including, where appropriate, the ODC Type(s), or the Types of side,
and whether support includes reading only or both reading and writing.
3 Normative reference
The following standard contains provisions which, through reference in this text, constitute provisions of this International
Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to
agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent
edition of the standard indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards.
Safety of information technology equipment.
IEC 950: 1991,
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OISOLIEC
ISO/IEC 15486:1998 (E)
4 Definitions
For the purposes of this International Standard, the following definitions apply.
41 0 band: An annular area within the user zone on the disk having a constant clock frequency.
42 l case: The housing for an optical disk, that protects the disk and facilitates disk interchange.
clamping zone: The annular part of the disk within which the clamping force is applied by the clamping device.
43 l
44 0 control track: A track containing the information on media parameters and format necessary for writing, reading and
erasing (read/write disks only) the remaining tracks on the optical disk.
45 0 method for detecting errors in data.
Cyclic Redundancy Check (CRC): A
46 0 defect management: A method for handling the defective areas on the disk.
47 l disk reference plane: A plane defined by the perfectly flat annular surface of an ideal spindle onto which the
clamping zone of the disk is clamped, and which is normal to the axis of rotation.
entrance surface: The surface of the disk on to which the optical beam first impinges.
48 0
kinds of errors in data.
49 0 Error Correction Code (ECC): A n error-detecting code designed to correct certain
format: The arrangement or layout of information on the disk.
4.10
to provide radial centring and
4.11 hub: The central feature on the disk which interacts with the spindle of the disk drive
the clamping force.
4.12 interleaving: The process of allocating the physical sequence of units of data so as to render the data more immune
to burst errors.
any information, and used to
4.13 land and groove: A trench-like feature of the disk, applied before the recording of
define the track location. The groove is located nearer to the entrance surface than the land with which it is paired to
form a track.
4.14 logical track: 17 consecutive sectors in one or more physical tracks. The first sector of each logical track is assigned
sector number 0.
4.15 mark: A feature of the recording layer which may take the form of a crystalline region a pit, or any other type or
form that can be sensed as a reflectivity change by the optical system. The pattern of marks represents the data on the
disk.
Note - Subdivisions of a sector which are named “mark” are not marks in the sense of this definition
mark edge: The transition between a region with a mark and one without a mark or vice versa, along the track.
4.16
4.17 mark edge recording: A recording method which uses a mark edge to represent a Channel bit.
optical disk: A disk that will accept and retain information in the form of marks in a recording layer, that can be read
4.18
with an optical beam.
4.19 optical disk cartridge (ODC): A device consisting of a case containing an optical disk.
4.20 physical track: The path which is followed by the focus of the optical beam during one revolution of the disk. This
path is not directly addressable.
4.21 polarization: The direction of polarization of an optical beam is the direction of the electric vector of the beam.
Note - The plane of polarization is the plane containing the electric vector and the direction of propagation of the beam. The polarization is right-handed
when, to an observer looking in the direction of propagation of the beam, the end-point of the electric vector would appear to describe an ellipse in the
clockwise sense.
4.22 pre-recorded mark: An unalterable mark recorded or embossed onto the disk prior to customer use.
4.23 read power: The read power is the optical power, incident at the entrance surface of the disk, used when reading.
Note - It is specified as a maximum power that may be used without damage to the written data. Lower power may be used providing that the signal-to-noise
ratio and other requirements of this International Standard are met.
4.24 recording layer: A layer of the disk on, or in, which data is written during manufacture and/or use.
Reed-Solomon code: An error detection and/or correction code which is particularly suited to the correction of
4.25
errors which occur in bursts or are strongly correlated.
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OISO/IEC ISO/IEC 15486:1998 (E)
4.26 space: The area between marks along the track.
4.27 spindle: The part of the disk drive which contacts the disk and/or hub.
4.28 substrate: A transparent layer of the disk, provided for mechanical support of the recording layer, through which the
optical beam accesses the recording layer.
track pitch: The distance between adjacent track centrelines, measured in a radial direction.
4.29
4.30 write-inhibit hole: A hole in the case which, when detected by the drive to be open, inhibits write operations.
zone: An annular area of the disk.
4.31
5 Conventions and notations
51 l Representation of numbers
- A measured value is rounded off to the least significant digit of the corresponding specified value. It implies that a specified
value of 1,26 with a positive tolerance of +O,Ol, and a negative tolerance of -0,02 allows a range of measured values from
1,235 to 1,275.
- Letters and digits in parentheses represent numbers in hexadecimal notation.
The setting of a bit is denoted by ZERO or ONE.
-
- Numbers in binary notation and bit combinations are represented by strings of digits 0 and 1.
- Numbers in binary notation and bit combinations are shown with the most significant bit to the left.
- Negative values of numbers in binary notation are given in TWO ’s complement.
In each field the data is recorded so that the most significant byte (byte 0) is recorded first. Within each byte the least
-
significant bit is numbered 0 and is recorded last, the most significant bit (numbered 7 in an 8-bit byte) is recorded first.
This order of recording applies also to the data input of the Error Detection and Correction circuits and their output.
52 0 Names
The names of entities, e.g. specific tracks, fields, etc., are given with a capital initial.
6 List of acronvms
aI
ALPC Auto Laser Power Control
Address Mark
Cyclic Redundancy Code
CRC
DMA Defect Management Area
DMP Defect Management Pointers
DST Disk Structure Table
ECC Error Correction Code
Error Detection And Correction Code
EDAC
ID Identifier
LBA Logical Block Address
LSB Least Significant Byte
Magneto-Optical
MO
MSB Most Significant Byte
ODC Optical Disk Cartridge
PA Postamble
Primary Defect List
PDL
PRA Primary Reserved Area
PEP Phase-Encoded Part of the Control Tracks
Run Length Limited (code)
=w,v
Reed-Solomon (code)
R-S
Rewritable
R-ULDC Reed-Solomon Long Distance Code
SCSI Small Computer System Interface
Secondary Defect List
SDL
SFP Standard Formatted Part of the Control Tracks
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ISO/IEC 15486: 1998 (E) OISO/IEC
SM Sector Mark
SRA Secondary Reserved Area
Time Interval Analyzer
TIA
VFO Variable Frequency Oscillator
wo Write Once
WORM Write Once Read Many
ZCAV Zoned Constant Angular Velocity
7 General description of the optical disk cartridge
The optical disk cartridge which is the subject of this International Standard consists of a case containing an optical disk.
The case is a protectiv -e enclosure for the disk. It has access windows covered by a shutter. The windows are automatically
when the cartridge is inserted into it.
uncovered the drive
by
The optical disk consists of two sides assembled together with their recording layers on the inside.
The optical disk is recordable on both sides. Data is written onto the disk with a focused optical beam as marks in the recording
layer using irreversible effects, such that the marks cannot be erased or transformed back into an unrecorded state. The marks
can be formed by either a phase transformation process, an ablative process, or any other irreversible process. The data are read
by detecting the intensity modulation of the reflected beam caused by the difference of reflectivity of the recorded marks and
the unrecorded regions. The beam accesses the recording layer through the transparent substrate of the disk.
8 General requirements
81 0 Environments
8.1.1 Test environment
The test environment is the environment where the air immediately surrounding the optical disk cartridge has the following
properties:
temperature : 23 “C ~fi 2 “C
relative humidity : 45 % to 55 %
atmospheric pressure :60kPato 106kPa
air cleanliness : Class 100 000 (see annex A)
No condensation on or in the optical disk cartridge shall occur. Before testing, the optical disk cartridge shall be conditioned in
this environment for 48 h minimum. It is recommended that, before testing, the entrance surface of the disk be cleaned
according to the instructions of the manufacturer of the disk.
Unless otherwise stated, all tests and measurements shall be made in this test environment.
Operating environment
8.1.2
This International Standard requires that an optical disk cartridge which meets all requirements of this International Standard in
the specified test environment provides data interchange over the specified ranges of environmental parameters in the operating
environment (See also annex Q).
The operating environment is the environment where the air imediakly surrounding the optical disk car&idge has the
following properties:
temperature : 5 “C to 55 “C
relative humidity : 3 % to 85 %
absolute humidity : 1 g/m3 to 30 g/m3
atmospheric pressure : 60 kPa to 106 kPa
temperature gradient : lO ”C/hmax.
relative humidity gradient : 10 %/h max.
air cleanliness : office environment (see Q. 1)
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OISOKIEC ISO/IEC 15486: 1998 (E)
No condensation on or in the optical disk cartridge shall occur. If an optical disk cartridge has been exposed to conditions
outside those specified in this clause, it shall be acclimatized in an allowed operating environment for at least 2 hours before
use. (See also annex R).
8.1.3 Storage environment
The optical disk cartridge without any protective enclosure shall not be stored in an environment outside the range allowed for
storage. The storage environment is defined as an environment where the air immediately surrounding the optical disk cartridge
has the following properties:
temperature : -10 “C to 55 “C
relative humidity : 3 % to 90 %
absolute humidity : 1 g/m3 to 30 g/m3
atmospheric pressure : 60kPato 106kPa
temperature gradient : 15 “C/h max.
relative humidity gradient : 10 %/h max.
: Office environment (see Q.1)
air cleanliness
No condensation on or in the optical disk cartridge shall occur.
8.1.4 Transportation
This International Standard does not specify requirements for transportation; guidance is given in annex S.
82 l Temperature shock
The optical disk cartridge shall withstand a temperature shock of up to 20 “C when inserted into, or removed from, the drive.
Safety requirements
83 0
The cartridge shall satisfy the safety requirements of IEC 950, when used in the intended manner or in any foreseeable use in an
information processing system.
Flammability
84 .
The cartridge and its components shall be made from materials that comply with the flammability class for HB materials, or
better, as specified in IEC 950.
9 Reference Drive
The Reference Drive is a drive several critical components of which have well defined properties and which is used to test the
write and read parameters of the disk for conformance to this International Standard. The critical components vary from test to
test. This clause gives an outline of all components; components critical for tests in specific clauses are specified in those
clauses.
Optical system
91 .
The basic set-up of the optical system of the Reference Drive used for measuring the write and read parameters is shown in
figure 1. Different components and locations of components are permitted, provided that the performance remains the same as
that of the set-up in figure 1. The optical system shall be such that the detected light reflected from the entrance surface of the
disk is minimized so as not to influence the accuracy of the measurements.
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OISO/IEC
ISO/IEC 15486: 1998 (E)
r-----------------------------------------------------------------------------------------------------------------------------------------------------
I
Ch.2
I
I 0
I
K2
I
I
I
Ch.1
-0
,
1 I
F G
950041-A
A Laser diode H Optional half-wave plate
B Collimator lens II
Tracking signals from photodiode K,
1’ 2
C Optional shaping prism J Polarizing beam splitter
Ch.1 Channel 1 Photodiodes for Channels 1 and 2
K ,K
2
Ch.2 Channel 2 K1 Split photodiode
D Beam splitter d.c.-coupled amplifiers
L3,L2
E Polarizing beam splitter Ai Tracking Channel (see 20.3)
F Objective lens N Phase retarder
G Optical disk
Figure 1 - Optical system of the Reference Drive
In the absence of polarization changes in the disk, the polarizing beam splitter J shall be aligned to make the signal of detector
K1 equal to that of detector K2. The direction of polarization in this case is called the neutral direction. The phase retarder N
shall be adjusted such that the optical system does not have more than 2,5” phase retardation between the neutral polarization
and the polarization perpendicular to it. This position of the retarder is called the neutral position.
The phase retarder can be used for the measurement of the narrow-band signal-to-noise ratio (see 27.2 ).
The beam splitter J shall have a p-s intensity reflectance ratio of at least 100.
The beam splitter E shall have an intensity reflectance Rp from F to H of nominally 0,30 for the neutral polarization direction.
The reflectance R, for the polarization perpendicular to the neutral direction shall be nominally 0,95. The actual value of R,
shall not be smaller than 0,90.
The imbalance of the difference signal is specified for a beam splitter with nominal reflectance. If the measurement is made on
a drive with reflectance ’s Rp’ and R,’ for beam splitter E, then the measured imbalance shall be multiplied by
RsR’
P
S
RPg
6
to make it correspond to the nominal beam splitter E.
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OISO/IEC ISO/IEC 15486: 1998 (E)
The output of Channel 1 is the sum of the currents through photodiodes Kl and K2 , and is used for reading embossed marks
and the user-written marks. The output of Channel 2 is the difference between photo-diode currents.
92 0 Optical beam
The focused optical beam used for writing and reading data shall have the following properties:
+lO nm
Wavelength ( h )
685 nm
a>
-10 nm
Wavelength ( h) divided by the numerical
W
aperture of the objective lens (NA) h/NA=1,245~m~O,OlQ~m
Filling D/W of the aperture of the
C)
objective lens 0,85 & 0,05
Variance of the wavefront of the
d)
optical beam near the recording layer 0 to h2/ 330
Polarization Linear - parallel to the groove
e>
Extinction ratio 0,Ol max.
f>
The optical power and pulse width for writing and reading shall be as specified in later clauses of this International
g>
Standard.
D is the diameter of the lens aperture and W is the beam diameter of the Gaussian beam where the intensity is l/e2 of the
maximum intensity.
The extinction ratio is the ratio of the minimum over the maximum power observed behind a linear polarizer in the optical
beam, which is rotated over at least 180 ”.
93 . Read Channels
Channel 1 shall be provided to generate signals from the marks in the recording layer. Unless ot
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