JPH01132924A - Apparatus for evaluating phase change sensitive material - Google Patents

Abstract

PURPOSE:To measure the speed change of the reflectivity of a recording material at the time of writing and erasure, by providing a laser beam irradiation means, a laser beam irradiation condition setting means and a reflectivity measuring means to an object to be irradiated. CONSTITUTION:When the switch of an operation panel 18 is closed, the power setting signal of reading laser beam is outputted to a power control circuit 11 from the panel 18 and power is further stabilized by an LD control circuit 10 and reading laser beam is allowed to irradiate from the semiconductor laser 8 in an optical pickup 1. Next, when the switch on the panel 18 is closed, a focus servo circuit 9 functions to move the actuator 4 in the pickup 1 and an objective lens 7 is moved to match the focus thereof with an object 3 to be irradiated. Subsequently, when a start signal is outputted to a pulse timing circuit 13 from the panel 18, a writing/erasure timing signal is simultaneously outputted to the circuit 11 and a pulse width control circuit 12 from the circuit 13. The circuit 10 receiving said signal allows pulse beam to irradiate from the laser 8 and writing/erasure is performed to the same place of the sensitive material of the object 3 to be irradiated.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to optical recording, erasing characteristics, and repetition stability of phase change type optical recording materials capable of high-density, high-speed recording such as optical disks. This invention relates to an evaluation device.

(Prior art) Conventionally, optical recording materials capable of high-density, high-speed recording, such as optical disks, have been evaluated by, for example, placing a film of recording material, which is a measurement sample, on a metal plate. The laser power required for writing was estimated by heating the plate and measuring the temperature of the recording material and the reflectance of the recording material, which changes with temperature.

(Problem to be Solved by the Invention) The area where information is actually written on the optical disk is the area irradiated with a laser beam of approximately 1 μm, and the rate at which the reflectance changes occur is on the order of several hundred n5ec. With conventional methods, although it was possible to estimate the recordable laser power, it was difficult to elucidate the rate of change in reflectance.

Furthermore, in order to evaluate the recording material of a rewritable optical disc, it is necessary to evaluate the stability of repeated writing and erasing, but there was no means to do so.

(Means for Solving the Problems) The present invention provides a laser beam irradiation means for irradiating a wave object with a reading laser beam, a writing laser beam, and an erasing laser beam;
Evaluation of phase change sensitive materials, comprising means for setting irradiation conditions for reading laser light, writing laser light, and erasing laser light, and reflectance measuring means for measuring reflected laser light from an object and calculating reflectance. It is a device.

(Embodiment) An embodiment of the present invention is shown in FIG.
, an optical pickup 1 consisting of means for irradiating laser light, means for focusing the laser beam, and means for detecting reflected light from an object, and a signal for controlling the focus of the laser beam on the object 3. a focus servo circuit 9 that outputs the power to the optical pink-up 1; an LD (laser diode) control circuit 10 that detects the power fluctuation of the laser beam and outputs the fluctuation signal to the power control circuit 11; LD is used to generate and control the laser power to be constant.
It receives the fluctuation signal from the control circuit 1O and supplies the necessary current accordingly. The power control circuit 11 that supplies one circuit 10 and the signal that controls the pulse of a specific laser pulse light are connected to the LD*I? 11 A pulse width control circuit 12 that outputs to the circuit 10, and a pulse timing circuit 13 that outputs a timing signal for generation of a specific laser pulse light and a timing signal for measuring reflectance to the pulse control circuit 12 and the power control circuit 11. A pulse generator 14 that outputs a clock to the pulse timing circuit 13, a pulse count circuit 15 that counts the number of irradiations of a specific laser pulse light and outputs an end signal to the pulse timing circuit 13, and a pulse generator 14 that outputs a clock to the pulse timing circuit 13; A digital multimeter 16 receives the information signal of the reflectance of the projectile 3 and outputs a signal indicating completion of the reception to the pulse timing circuit 13, and a digital multimeter 16 stores the information received from the digital multimeter 16 and stores the information. A personal computer 17 that displays images on a CRT, and an optical pickup l.
The receiver consists of an oscilloscope 19 that displays changes in the reflectance of the target object 3, and an operation panel 18 that sets the irradiation conditions for each laser beam: reading laser beam, writing laser beam, and erasing laser beam. .

Explain the operation of the device. First, write and erase operations are
A case will be described in which M cycles are performed, with this process being repeated twice and then measuring the reflectance of the subject 3 as one cycle.

First, the following settings are made on the operation panel 18. Power of each laser beam for writing, erasing, and reading. Pulse width of each laser beam for writing and erasing, number of repetitions N times. M
Number of repeat cycles.

Further, in the pulse generator 14, the time from one write operation to the next write operation is set.

Next, when the main switch of the operation panel 18 is turned on, a signal for setting the power of the reading laser beam is output from the operation panel 18 to the power control circuit 11, the current is amplified by the power control circuit 11, and the LD! The power is stabilized by the Im circuit 10, and a reading laser beam is irradiated from the semiconductor laser 8 in the optical pickup 1. Next, when the focus servo inch on the operation panel 18 is turned on, the focus servo circuit 9 is activated, and the actuator 4 in the optical pickup 1 is moved to move the objective lens 7, so that the subject 3 is brought into focus.

Next, a start signal is output to the pulse timing circuit 13 from the operation panel 18 which turns on the measurement start switch on the operation panel 1st. When a start signal is received, a write/erase timing signal is sent from the pulse timing circuit 13 to the power control circuit 11 sequentially at predetermined time intervals.
and the pulse width control circuit 12 at the same time. In response to the signal, the power control circuit 11 switches the supply current for generating a predetermined laser power, and the pulse width control circuit 12 switches the pulse width. The LD control circuit 10 receives a current for generating a predetermined laser pulse light and an information signal in the pulse from a power control circuit 11 and a pulse width control circuit 12, respectively, and causes the semiconductor laser 8 to emit a predetermined laser pulse light. . Therefore, writing and erasing operations are sequentially repeated on the same portion of the sensitive material of the subject 3 where the pulse is focused. The number of repetitions is counted by the counter circuit 15,
When the set number of times N is reached, the counter circuit 15 sends a signal indicating the end of counting the number of repetitions to the pulse timing circuit 13.
is output, and the write/erase operation is completed. Next, the reflectance of the object is measured. When the writing and erasing operations are completed, the laser light returns to the reading laser light irradiation.

Therefore, the pulse timing circuit 13 which has previously received the repetition count end signal from the counter circuit 15
When a request signal for reflectance measurement is output to the digital multimeter 16, the output from the focus servo circuit 9, which is the reflectance measurement data, is stored in the data buffer of the digital multimeter 16. Now l
The cycle ends.

When the storage in the data buffer is completed, a measurement end signal is sent from the digital multimeter 16 to the pulse timing circuit 1.
3, and is output to the pulse count circuit 15. When the pulse count circuit 15 determines that the number of repetition cycles has not reached M times, the number of repetitions of N times is cleared and a continuation signal is output to the pulse timing circuit 13, so that the number of repetition cycles has not reached M times. , write and erase operations begin. This series of operations is repeated for M cycles, and when the set number of cycles has been reached, the count circuit 15
A transfer request is made to the data buffer of the digital multimeter 16 based on the repeat cycle count end signal output from the personal computer 17.
Data is transferred to the floppy disk. FIG. 2 illustrates the above series of operations.

Next, based on the data stored in the floppy disk, the reflection level measurement graph after writing and erasing shown in Figure 3 is displayed on the CRT of the personal computer 17, and this shows the stability of repeated writing and erasing. can be evaluated.

Further, the rate of change in writing and erasing can be determined by observing the output of the reading detector 5 during writing, erasing, and operations using the oscilloscope 19. Figures 4 and 5 illustrate the observed reflectance changes during writing, erasing, and operation, respectively.
It is a diagram.

(Effects of the Invention) According to the present invention, it is now possible to measure changes in the reflectance speed of the recording material during writing and erasing, which could not be measured conventionally, and also to evaluate the stability of repeated writing and erasing. Ta.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining the timing of each write, erase, and read operation according to the embodiment, and FIG. Graphs displayed on the CRT to evaluate the stability of reflectance against repeated erasing, Figures 4 and 5, are diagrams of changes in reflectance displayed on an oscilloscope during writing and erasing, respectively. . 1. Optical pink-up 2, object fixed stage 3, object 4, actuator 5, reading detector 6, servo detector 7, objective lens 8, semiconductor laser (Fig. 1)

Claims (1)

[Claims] A laser beam irradiation means for irradiating a reading laser beam, a writing laser beam, and an erasing laser beam onto a target object; a means for setting irradiation conditions for the reading laser beam, a writing laser beam, and an erasing laser beam; A phase change sensitive material evaluation device comprising: reflectance measuring means for measuring reflected laser light and calculating reflectance.