JPH0556569B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to memory members that optically record information signals such as data signals, audio signals, and video signals, such as optical disc memories, optical card memories, etc. The present invention relates to an evaluation device for an optical recording member that performs reproduction by irradiating a recording thin film formed on a laser beam with a laser beam and using an optical change in the irradiated portion as a signal.

Conventional Structure and Problems The optical memory member obtains a recorded state by condensing and irradiating a recording thin film with laser light and heating the irradiated portion. In addition, recording thin films are also evaluated using a method in which direct recording is performed by condensing laser light and observing optical changes in the thin film. However, the sensitivity of an optical recording member, such as the laser power required to start recording, has a close correlation with the thermal change temperature of the recording member. Here, the changing temperature is defined as follows. That is, when a recording member is left in a certain high-temperature atmosphere, a change occurs in the optical state of the recording member, and the lowest atmospheric temperature that causes this change is defined as the change temperature of the recording member. For example, the lower this temperature change is, the lower the laser light power will be needed when recording by focusing the laser light on a thin film in practical use.
Generally high sensitivity. On the other hand, if the changing temperature is too low, there is a correlation that the stability of the thin film deteriorates. Therefore, by measuring this temperature change, it is possible to estimate the characteristics when a disk-shaped or card-shaped memory member is irradiated with laser light and recorded.
This method is applicable to, for example, a Te-O thin film represented by TeO _x (0<x<2), a chalcogen compound thin film,
Other thin films mainly composed of Te are used for optical recording materials, etc.
It can be applied to all thin films that perform heat mode recording. In this case, as a measurement sample, use a substrate that is optically transparent, homogeneous, and stable against temperature changes, such as quartz glass, hard second-class glass, or soda glass. A sample provided with a memory member thin film is used, and optical changes after heating the sample are measured. However, conventionally, in order to measure the temperature change, a sample is heated with a heater that is kept at a certain temperature, then optical properties such as reflectance and transmittance are measured, and then the heater temperature is changed and a new sample is heated. It was necessary to repeat similar measurements using This method required a large number of identical samples and required a long measurement time. In addition, in order to accurately grasp the changing temperature, the set temperature of the heater was changed more precisely, which required a large number of measurements and a lot of effort.

Structure of the Invention An object of the present invention is to easily and more accurately measure the temperature-induced change process in the optical properties of an optical memory member when the temperature is increased.

OBJECTS OF THE INVENTION The present invention provides heating means for raising the temperature of a sample made of a thin film provided on a transparent substrate at a certain constant rate, a light source, means for irradiating the thin film with light from the light source, and The device comprises means for detecting at least one of reflected light and transmitted light.

DESCRIPTION OF EMBODIMENTS Hereinafter, the configuration of an embodiment of the present optical recording member evaluation apparatus will be described with reference to the drawings. This evaluation device is
It consists of a heating section 3, a light source 4, photodetectors 5 and 6, and a half mirror 7. The sample to be measured consists of a substrate 1 and a recording thin film 2 provided thereon.

The heating section 3 has a heat source having a sufficiently large heat capacity with respect to the heat capacity of the substrate 1 and the recording thin film 2, and is provided under the substrate 1 to also serve as a substrate support. The heating part has flatness, thermal conductivity,
A heating substrate made of a flat metal plate with good heat resistance is provided, and the heating substrate is heated to raise the temperature of the sample using heat conduction from the contact surface with the substrate 1. Heating methods for heating substrates include heater heating using nichrome wire, tungsten wire, etc.
Optical heating using a high-output laser or a lamp light source can be applied.

As the light source 4 for measuring optical characteristics, a monochromatic light source whose luminous flux is easily parallelized and whose emission wavelength width is narrow can be used as a monitor light, such as a light emitting diode, a semiconductor laser, a gas laser, etc.
Note that since light emitting diodes and semiconductor lasers emit light with a certain spread, a lens is provided immediately after the light emitting part to form a parallel beam of light. As the photodetectors 5 and 6,
A photocell, photodiode, etc. can be used.
The half mirror 7 may be any flat plate that partially transmits and partially reflects the light of the emission wavelength of the light source 4.
For example, a glass plate coated with a metal thin film can be used.

The optical system of this evaluation device has a structure in which parallel light from a light source 4 enters the recording thin film 2 on the substrate 1 perpendicularly, and the transmitted light from the recording thin film is detected by a photodetector 5 to calculate the transmittance. Measure. Further, the reflected light from the recording thin film is detected by a photodetector 6 via a half mirror 7 provided on the incident optical path, and the reflectance is measured.

In the optical system, the temperature of the heating section 3 is gradually increased, and the temperature of the recording thin film 2 is increased by heat conduction between the heating section 3, the substrate 1, the recording thin film 2, and the contact portion. By measuring the temperature, transmittance, and reflectance during the heating process of the thin film and recording the results using a pen recorder or the like, it becomes possible to continuously observe the displacement of the thermal optical properties of the recording thin film.

As the light source 4, a He-Ne laser with λ=632.8 nm is used. Silicon photocells are used for the photodetectors 5 and 6. The half mirror 7 is made of a glass substrate coated with a metal thin film, and is provided at an angle of 45° with respect to the laser beam.

The cross-sectional structure of the heating section 3 will be explained based on FIG. 2. The heating base 8 is made of a stainless steel flat plate with good heat resistance, and has a small hole 20 in the center having the same area as the laser beam spot. In addition, a thin groove 21 extends outward from a point 2 to 3 mm from the small hole position.
will be established. A thermocouple 9 for detecting the temperature of the substrate 1 is provided along the groove 21 . Note that the size of the small hole 20 is closely related to the difference between the temperature indicated by the output of the thermocouple 9 and the temperature at the point on the sample that is hit by the measuring monitor light. For example, the thickness of substrate 1 is 0.5 mm, the diameter
When a 10 mm disc-shaped hard secondary glass is used and the area ratio of the substrate to the small hole is 10:5, the difference between the temperature at point A of the monitor light irradiation part on the disc and the temperature indicated by the thermocouple 9 is: Maximum temperature is 20℃ when the temperature is raised from room temperature to 300℃,
When the area ratio is 10:3, the maximum temperature is 8℃ in the same range,
If the area ratio is 10:1, the maximum temperature will be 2°C or less within the same range. Accordingly, if the area of the small holes 20 is 10% or less of the area of the measurement sample, accurate and stable measurement of the sample temperature is possible. Heating substrate 8
As a heat source, a heater wire 10 is wound into a coil and placed close to the heating substrate 8. The output of the thermocouple 9 is fed back and the voltage applied to the heater wire is controlled so that the temperature of the substrate 1 rises at a constant rate. Further, the temperature increase rate is similarly variable by controlling the applied voltage.

FIG. 3 shows the overall configuration of an embodiment of this evaluation device. In order to examine the influence of the atmosphere during heating of the recording material, the bottom of the container 1 is sealed around the heating section 3.
A gas inlet 22 is provided on the side surface of the container upper part 12.
A hole 23 is provided in the center of the hole 23, which serves as a gas discharge port and a passage for the light beam from the light source. The sample to be measured may be affected by the atmosphere when heated. For example, it may be oxidized by oxygen in the air. In such a case, it is conceivable to place the entire apparatus in an inert atmosphere, but this requires a large amount of inert gas and the apparatus must be airtight. However, if the structure of this example is used, a small amount of inert gas is flowed out from the gas outlet and light is introduced through the outlet, making it possible to perform measurements while creating an inert atmosphere only in the heating substrate and its surroundings. Is possible. Furthermore, it can also be applied to measuring characteristics in special atmospheres. Gases introduced as the atmosphere include N ₂ , Ar, He, O ₂ and the like.

As an initial setting for the evaluation, compressed gas (e.g. N ₂ , Ar
etc.). This improves the measurement cycle.

In order to reduce measurement errors due to disturbance light of this device, the entire optical system is provided with an outer box 14 and a door 15.
In addition, the door 15 and the monitor light shielding plate 16 are interlocked so that the monitor light does not enter the sample when the door is open, which has the effect of protecting the eyes of the measurer from reflected light from the sample.

Before material evaluation is performed using this apparatus, the photodetector 5 receives monitor light from a light source without a recording thin film, and the transmittance is calibrated to 100%. Furthermore, a reflector whose reflectance is known is provided in place of the recording thin film, and the reflectance is calibrated. The power fluctuation of the monitor light during temperature rise can be constantly observed by the photodetector 17 via the half mirror 7 on the optical path.

FIG. 4 shows optical measurements taken during the heating process of the recording thin film using this evaluation apparatus having the above-described configuration. Note that the temperature increase rate was 2° C./sec.
Curve B is a change in transmittance, and curve C is a change in reflectance from the recording thin film side. Curve D shows the change in reflectance when the recording thin film 2 and substrate 1 are reversed and the substrate faces the light source side.

In this example, transmitted light or reflected light was measured using two photodetectors, but since the curves in Figure 4 show almost the same temperature changes, either one of the light is detected. It is also possible to measure temperature changes in a thin film using this method.

In this way, temperature changes in the optical properties of the thin film could be measured continuously, and the measurement time was also about 2 to 3 minutes from room temperature to 300°C.

The information obtained includes transmittance and reflectance before change, transmittance and reflectance after change, and temperature change. Furthermore, by changing the heating rate, the activation energy can be estimated when the change is considered as an activation process. Based on such results, materials can be evaluated in terms of recording sensitivity, reproduction signal magnitude, and reliability.

Effects of the Invention As described above, the material evaluation device according to the present invention has the following features:
In a short period of time, the optical characteristics of optical memory components relative to temperature can be measured.
and can be easily and accurately measured.
It has become possible to predict the optical recording sensitivity and thermal stability of thin films. Furthermore, the temperature change and optical constants of the thin film obtained from the measurement results are closely related to the material composition and manufacturing method, and are useful for analyzing material properties and for evaluating reproducibility during thin film formation.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of essential parts of an embodiment of the optical recording member evaluation device of the present invention, FIG. 2 is a cross-sectional view of a heating section, and FIG. 3 is a configuration of an embodiment of the same evaluation device. The cross-sectional view, FIG. 4, is a diagram showing an example of measurement of the optical characteristics of the recording thin film with respect to temperature using the same evaluation apparatus. 1... Substrate, 2... Recording thin film, 3... Heating section,
4... Light source, 5, 6... Photodetector, 7... Half mirror, 8... Heating substrate, 9... Thermocouple, 10
... Heater wire, 11 ... Container bottom, 12 ... Container top, 13 ... Nozzle, 14 ... Outer box, 15 ...
Door, 16...shielding board.

Claims (1)

[Scope of Claims] 1. A heating unit that heats up an optical recording member having a recording thin film on a transparent substrate at a constant heating rate, a light source that irradiates the optical recording member, and a light source that irradiates the optical recording member. An evaluation device for an optical recording member, which includes a photodetector for detecting at least one of reflected light and transmitted light. 2. The heating unit is composed of a heating substrate of an optical recording member, a heat source for heating the heating substrate, and a temperature detector, and the heating substrate has a small hole for passing light from a light source. An evaluation device for an optical recording member according to scope 1. 3. The optical recording member evaluation device according to claim 2, wherein the opening area of the small holes is 1/10 or less of the area of the recording member. 4. The optical recording member evaluation device according to claim 1, wherein the temperature increase rate of the heating section can be freely set by varying the input to the heat source. 5. Claim 1, which comprises a container for storing a heating part, a gas introduction part and a gas discharge part provided in the container, and a light source provided on an extension of the gas discharge part and the heating part. An evaluation device for optical recording members. 6. An evaluation device for an optical recording member according to claim 1, comprising a box for storing a heating section and a photodetector, a door provided on the box, and a light shielding plate interlocked with the door.