JP2006309886A - Optical output measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure a light output of a pickup using a region having good linearity without being affected by a restriction due to a dynamic range of an optical sensor.
An optical output measuring device for measuring an optical output from a pickup of an optical disc device, the pickup having a function of irradiating light to the disc, and a transmittance according to a drive signal supplied from the pickup. According to the liquid crystal filter that attenuates the light, the optical sensor that receives the optical output from the pickup that has passed through the liquid crystal filter, the intensity and wavelength of the optical output of the pickup, and the wavelength sensitivity characteristics of the optical sensor, Control means for generating a drive signal for controlling the transmittance of the liquid crystal filter and variably controlling the transmittance of the liquid crystal filter.
[Selection] Figure 1

Description

  The present invention relates to an optical output measuring device that measures the optical output of a pickup of an optical disc apparatus that uses a CD, DVD, MD, MO disc or the like as a recording medium.

  In an optical disc apparatus using an optical disc such as a CD, DVD, MD, or MO disc as a recording medium, information recorded on the optical disc is read during reproduction, and information is recorded on the optical disc during recording. Irradiate.

  Here, at the time of reproduction, it is necessary to irradiate the pickup with light having such intensity that sufficient reflected light can be obtained from the optical disk. Further, at the time of recording, it is necessary to irradiate the pickup with light having an intensity necessary for causing a change on the recording surface of the optical disk.

For this reason, it is necessary to measure whether light of appropriate intensity is output from the pickup using a dedicated measuring device.
When measuring the intensity of light from such a pickup, it is necessary to adjust so that the sensor of the measuring device does not saturate, that is, does not exceed the light reception allowable level. As such adjustment, a method is generally used in which an ND filter or the like is disposed on the front surface of the sensor to attenuate the amount of light reaching the sensor.

  Since the ND filter has a fixed attenuation rate control as described above, a plurality of ND filters having different transmittances are prepared in advance according to the required transmittance, and the ND filter having a desired transmittance is measured at the time of measurement. It needs to be replaced.

A method of measuring the pickup while exchanging a plurality of ND filters in this way is actually performed in each company.
Note that the measurement method using the combination of the ND filter and the pickup as described above is described in the following patent documents, although the purpose of the measurement is different.
JP-A-9-153252 (first page, FIG. 1)

  In recent years, in devices that handle CDs and DVDs, the power of the light source has become higher as the recording speed increases. For this reason, the permissible light reception level of the light receiving sensor of the measuring device has not caught up with the light intensity of such a pickup.

  FIG. 8 shows an example in which the optical output intensity (LD power) from the pickup is plotted on the horizontal axis and the sensor voltage is plotted on the vertical axis when measuring the laser power of a CD / DVD pickup with a CD wavelength of 780 nm. FIG.

  In this characteristic diagram, from a region where the LD power exceeds about 100 mW, the sensor output does not correspond linearly to the LD power, and the linearity is deteriorated. As a countermeasure, generally, the light transmittance is lowered, the light receiving power on the sensor side is reduced, and the straight line portion before saturation is used. As a means for this, normally, a polished ND filter is installed in front of the light receiving sensor in accordance with the light receiving sensitivity of the sensor to lower the transmittance. As a result, as shown in the graph of the voltage with a filter in FIG. 8, it becomes possible to measure the LD power around 200 mW, which is about double.

  However, this method requires an ND filter that is polished to a thickness that provides a desired transmittance. For such production, the delivery time is more than twice as long as a standard product prepared in advance, which causes a delay in delivery date and an increase in cost of the measuring device.

  Also, as shown in the graph of FIG. 9, when measuring the LD power of a DVD or the like whose wavelength is short, the sensitivity of the sensor is low. As described above, in the case of LD power measurement for DVD, if the ND filter is not removed and the measurement is not performed, the disassembling ability will be lowered. Need to be removed.

In addition, since the output varies depending on the type of pickup and the test conditions, it is necessary to prepare several types of ND filters with different transmittances and perform the attaching / detaching operation according to the measurement conditions, which is an obstacle to automatic measurement.

  The present invention is an optical device capable of accurately measuring the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium, using a region with good linearity, without being affected by the restriction due to the dynamic range of the optical sensor. It aims at realizing an output measuring device.

The present invention as means for solving the above-described problems is as described in the following (1) to (5).
(1) The invention described in claim 1 is an optical output measuring device for measuring the optical output from the pickup of the optical disc apparatus, wherein the pickup has a function of irradiating the disc with light and the drive signal given thereto. A liquid crystal filter for attenuating light from the pickup by the transmittance, an optical sensor for receiving optical output from the pickup that has passed through the liquid crystal filter, intensity and wavelength of optical output of the pickup, and wavelength of the optical sensor A light output measuring device comprising: a control unit that generates a drive signal for controlling the transmittance of the liquid crystal filter according to sensitivity characteristics, and variably controls the transmittance of the liquid crystal filter. is there.

  In the present invention, when measuring the optical output from the pickup of the optical disk device, the drive signal for controlling the transmittance of the liquid crystal filter according to the intensity and wavelength of the optical output of the pickup and the wavelength sensitivity characteristic of the optical sensor is obtained. The control means generates, and the light output from the pickup that has passed through the liquid crystal filter controlled in this way is received by the light sensor.

  (2) The invention according to claim 2 is characterized in that the control means generates a drive signal by pulse control and controls the transmittance of the liquid crystal filter. is there.

  According to the present invention, when measuring the optical output from the pickup of the optical disk device, by pulse control that controls the transmittance of the liquid crystal filter according to the intensity and wavelength of the optical output of the pickup and the wavelength sensitivity characteristic of the optical sensor. The control signal is generated by the control means, and the optical output from the pickup that has passed through the liquid crystal filter that is pulse-controlled in this way is received by the optical sensor.

  (3) The light output according to claim 3, wherein the control means generates a drive signal by pulse control with variable frequency and controls the transmittance of the liquid crystal filter. It is a measuring device.

  In this invention, when measuring the optical output from the pickup of the optical disk apparatus, the frequency variable variable for controlling the transmittance of the liquid crystal filter according to the intensity and wavelength of the optical output of the pickup and the wavelength sensitivity characteristic of the optical sensor. The control means generates a drive signal by pulse control, and the light output from the pickup that has passed through the frequency-controlled pulse-controlled liquid crystal filter is received by the optical sensor.

  (4) The invention according to claim 4 is characterized in that the control means generates a drive signal by pulse control based on a combination of variable frequency and variable duty ratio, and controls the transmittance of the liquid crystal filter. The optical output measuring device according to claim 1.

  In this invention, when measuring the optical output from the pickup of the optical disk device, the duty ratio variable for controlling the transmittance of the liquid crystal filter according to the intensity and wavelength of the optical output of the pickup and the wavelength sensitivity characteristic of the optical sensor The control means generates a drive signal by pulse control with variable frequency, and the optical sensor receives the optical output from the pickup that has passed through the liquid crystal filter with pulse control with variable duty ratio and variable frequency.

  (5) In the invention according to claim 4, the control means controls the transmittance of the liquid crystal filter so that the light reception output of the optical sensor is constant, and the light of the pickup is detected from the change in the transmittance. 4. The optical output measuring device according to claim 1, wherein the output intensity is calculated.

  In the present invention, when measuring the optical output from the pickup of the optical disk device, the drive signal for controlling the transmittance of the liquid crystal filter according to the intensity and wavelength of the optical output of the pickup and the wavelength sensitivity characteristic of the optical sensor is obtained. Further, the transmittance of the liquid crystal filter is controlled so that the light reception output of the optical sensor is constant, and the optical output from the pickup that has passed through the controlled liquid crystal filter is converted into the optical sensor. And the intensity of the optical output of the pickup is calculated from the change in transmittance.

According to the present invention, the following effects (1) to (5) can be obtained.
(1) In the invention of the optical output measuring device according to the first aspect, when measuring the optical output from the pickup of the optical disc device, the optical output intensity and wavelength of the pickup and the wavelength sensitivity characteristic of the optical sensor are determined. The control means generates a drive signal for controlling the transmittance of the liquid crystal filter, and the optical sensor receives the light output from the pickup that has passed through the liquid crystal filter thus controlled.

  As a result, the light output from the pickup that has passed through the liquid crystal filter whose transmittance has been controlled is measured in a state that falls within the dynamic range of the optical sensor. As a result, the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium can be accurately measured using a region with good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor. It becomes possible.

  (2) In the invention of the optical output measuring apparatus according to claim 2, when measuring the optical output from the pickup of the optical disc apparatus, the optical output intensity and wavelength of the pickup and the wavelength sensitivity characteristic of the optical sensor are determined. The control means generates a drive signal by pulse control that controls the transmittance of the liquid crystal filter, and the optical sensor receives the light output from the pickup that has passed through the pulse-controlled liquid crystal filter.

  As a result, the light output from the pickup that has passed through the liquid crystal filter whose transmittance is pulse-controlled is measured in a state of being within the dynamic range of the optical sensor. As a result, the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium can be accurately measured using a region with good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor. It becomes possible.

  (3) In the invention of the optical output measuring device according to the third aspect, when measuring the optical output from the pickup of the optical disc apparatus, the optical output intensity and wavelength of the pickup and the wavelength sensitivity characteristic of the optical sensor are determined. The control means generates a drive signal by frequency-variable pulse control for controlling the transmittance of the liquid crystal filter, and the optical output from the pickup that has passed through the frequency-variable pulse-controlled liquid crystal filter in this way is detected by an optical sensor. receive.

  As a result, the light output from the pickup that has passed through the liquid crystal filter whose transmittance is controlled by the frequency variable pulse is measured in a state of being within the dynamic range of the optical sensor. As a result, the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium can be accurately measured using a region with good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor. It becomes possible.

  (4) In the invention of the optical output measuring device according to claim 4, when measuring the optical output from the pickup of the optical disc apparatus, the optical output intensity and wavelength of the pickup and the wavelength sensitivity characteristic of the optical sensor are determined. The control means generates a drive signal by pulse control with variable duty ratio and variable frequency that controls the transmittance of the liquid crystal filter, and thus the pickup that has passed through the pulse control liquid crystal filter with variable duty ratio and variable frequency The light output from is received by the optical sensor.

  As a result, the light output from the pickup that has passed through the liquid crystal filter whose transmittance is controlled by a pulse with a variable duty ratio and a variable frequency is measured in a state of being within the dynamic range of the optical sensor. As a result, the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium can be accurately measured using a region with good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor. It becomes possible.

  (5) In the invention of the optical output measuring apparatus according to claim 4, when measuring the optical output from the pickup of the optical disc apparatus, the optical output intensity and wavelength of the pickup and the wavelength sensitivity characteristic of the optical sensor are determined. In addition, the control means generates a drive signal for controlling the transmittance of the liquid crystal filter, and further controls the transmittance of the liquid crystal filter so that the light reception output of the optical sensor is constant. The optical output from the pickup that has passed through the filter is received by an optical sensor, and the intensity of the optical output of the pickup is calculated from the change in transmittance.

  As a result, the light output from the pickup that has passed through the liquid crystal filter whose transmittance has been controlled is measured in a state that falls within the dynamic range of the optical sensor. As a result, the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium can be accurately measured using a region with good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor. It becomes possible. Moreover, it becomes possible to continue using the area | region where the SN ratio of an optical sensor is the best, and the reliability of a measurement result improves.

The best mode (embodiment) for carrying out the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a block diagram showing functional blocks of means for each function of the optical output measuring apparatus 100 of the present embodiment.

In FIG. 1, reference numeral 101 denotes a control unit serving as a control unit configured by a CPU or the like that controls each unit of the optical output measurement device 100.
The control unit 101 executes various controls together with the control program, and generates a drive signal for controlling the transmittance of the liquid crystal filter in accordance with the intensity and wavelength of the optical output of the pickup and the wavelength sensitivity characteristic of the optical sensor. And the transmittance of the liquid crystal filter is variably controlled.

  An optical sensor 110 receives light output from a pickup that has passed through a liquid crystal filter, which will be described later. As this optical sensor 110, various sensors that perform photoelectric conversion can be used.

  Reference numeral 120 denotes an I / V converter that converts a current signal as a detection result of the optical sensor 110 into a voltage signal, and reference numeral 130 denotes an analog voltage signal from the I / V converter 120 that is A / D converted into digital data A -D conversion unit. Reference numeral 140 denotes a calculation unit that performs a measurement calculation for measuring the light output from the pickup of the optical disk apparatus.

  Reference numeral 150 denotes a signal generation unit that generates a pulse signal that is a source of a drive signal that controls the transmittance of the liquid crystal filter. It is a drive part which produces | generates.

  Here, the signal generator 150 can output a rectangular wave, and the drive frequency and duty ratio of the liquid crystal filter 170 can be varied. The driving unit 160 employs a circuit composed of a C-MOS inverter IC so that a rectangular wave pulse from the signal generating unit 150 can be output at +5 V in accordance with the characteristics of the liquid crystal.

  A liquid crystal filter 170 receives the drive signal from the drive unit 160 and has its transmittance variably controlled. The liquid crystal filter attenuates light from the pickup with the transmittance according to the given drive signal and guides it to the optical sensor 110.

As the liquid crystal filter 170, various general liquid crystal panels can be used. The structure of the liquid crystal filter 170 is, for example, as shown in FIG. 2, in which a liquid crystal material is filled between two polarizing filters having different polarization planes, and depending on the polarization state of the liquid crystal material,
Transmission is controlled as shown in FIG. 2A and non-transmission is controlled as shown in FIG. Further, an intermediate transmittance can be realized by applying an intermediate voltage or performing time-sharing control of transmission / non-transmission.

  The liquid crystal filter 170 having a shape shown in a plan view as shown in FIG. 3A and a cross-sectional view as shown in FIG. 3B is arranged on the incident surface of the optical sensor 110. ing. Here, an ITO film 1740 having a first ITO electrode 1710 and a second ITO electrode 1720 and having a size of about 10 mm × 10 mm is arranged in the TN liquid crystal 1730. The cross section has two members with a thickness of 0.7 mm, and the total is about 1.4 mm.

  Reference numeral 200 denotes an optical disc apparatus that is a measurement target of the optical output measurement apparatus 100. Reference numeral 210 denotes a pickup having a function of irradiating the disc with light in the optical disc apparatus 200, and 220 denotes a pickup driving unit that drives the pickup 210. In the optical disc apparatus 200, other known constituent elements are omitted.

Hereinafter, the operation of the optical output measuring device 100 of the present embodiment will be described.
In the embodiment of the optical output measuring apparatus 100, when measuring the optical output from the pickup 210 of the optical disc apparatus 200, the intensity and wavelength of the optical output of the pickup 210 (see FIG. 9) and the wavelength sensitivity characteristic of the optical sensor (see FIG. 9). 9), the signal generation unit 150 and the drive unit 160 generate a drive signal for controlling the transmittance of the liquid crystal filter 170 based on an instruction from the control unit 101.

  Here, if a plurality of ND filters are conventionally used, the transmittance of the liquid crystal filter 170 is controlled by an instruction from the control unit 101 so that the transmittance is the same as the transmittance of each ND filter. The optical output from the pickup 210 that has passed through the liquid crystal filter 170 controlled in this way is received by the optical sensor 110, and the calculation unit 140 performs measurement calculation to obtain the optical output of the pickup 210. The obtained light output is sent to the control unit 101 and is output to a display unit, an external recording device, etc. (not shown).

  In the above operation, when measuring the optical output from the pickup 210, the drive for controlling the transmittance of the liquid crystal filter 170 according to the intensity and wavelength of the optical output of the pickup 210 and the wavelength sensitivity characteristic of the optical sensor 110. The control unit 101 generates a signal.

  In this embodiment, since the transmittance of the liquid crystal filter 170 can be finely set by an instruction from the control unit 101, the transmittance can be made finer than when a conventional ND filter is used. Is possible. In this way, the light output from the pickup 210 that has passed through the liquid crystal filter 170 whose transmittance has been controlled is measured in a state where it falls within the dynamic range of the optical sensor 110. As a result, the optical output of the pickup 210 for the optical disc apparatus 200 using the optical disc as a recording medium is accurately measured using a region having good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor 110. It becomes possible to do.

  In addition, this can reduce the cost for preparing a plurality of ND filters having different transmittances, and further eliminates the need to replace the plurality of ND filters, thereby making it possible to handle automated processing.

  FIG. 4 is a characteristic diagram showing a change in transmittance with respect to the frequency of the liquid crystal filter driving signal by the signal generating unit 150 and the driving unit 160 in a pickup that emits laser light having a wavelength of 780 nm using a CD as a recording medium.

  As shown in FIG. 4, the transmittance is the lowest near 100 Hz, and the transmittance is the highest near 40 kHz. Note that if the frequency is 10 Hz or less, the liquid crystal filter 170 blinks, which is not desirable.

  As shown in FIG. 5, in the liquid crystal filter 170 using two polarizing plates, the transmittance is 40%, which is the brightest state. However, the transmittance can be improved to about 50% by using a liquid crystal plate for a liquid crystal projector.

  As can be seen from this characteristic diagram, by changing the frequency of 100 Hz to 40 kHz as the drive signal, the transmittance of the liquid crystal filter 170 is changed from 20% to 40 in 0.1% steps based on an instruction from the control unit 101. % Can also be controlled over a wide range.

  In this case, the transmittance control range is 20% to 40%, and there is a 20% variable range. This means that the allowable sensitivity of the optical sensor 110 is raised to 2.5 to 5 times in a variable range. When the transmittance is set to 50% using a liquid crystal plate for a liquid crystal projector, the transmittance control range is 20% to 50%, and the allowable sensitivity of the optical sensor 110 is increased to 2.0 to 5 times. , Meaning to raise in a variable range.

Note that the above transmittance control can be performed even if the duty ratio of the drive signal of the liquid crystal filter 170 is varied.
FIG. 5 is a characteristic diagram showing a change in transmittance of the liquid crystal filter drive signal by the signal generator 150 and the drive unit 160 with respect to the duty ratio in a pickup that emits a laser beam having a wavelength of 780 nm using a CD as a recording medium. As a result, the transmittance variable range is about 20 to 30%, which is narrower than the frequency variable (FIG. 4), and only half of the frequency variable.

Here, the characteristic is shown with the horizontal axis representing the value of the duty ratio when the frequency is 50 Hz, but similar characteristics can be obtained even at other frequencies.
Therefore, regarding the control of the transmittance of the liquid crystal filter 170, it is desirable to use a rectangular wave pulse for frequency control or a combination of frequency control and duty ratio control.

  As described above, the light output from the pickup that has passed through the liquid crystal filter whose transmittance is pulse-controlled, preferably variable in frequency, is measured in a state where it falls within the dynamic range of the optical sensor. As a result, the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium can be accurately measured using a region with good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor. It becomes possible.

  FIG. 6 is a characteristic diagram showing a change in transmittance with respect to the frequency of the liquid crystal filter drive signal by the signal generation unit 150 and the drive unit 160 in a pickup that emits laser light having a wavelength of 650 nm using a DVD as a recording medium.

  As shown in FIG. 6, the transmittance is lowest at around 100 Hz, and the transmittance is maximized at around 40 kH. Note that if the frequency is 10 Hz or less, the liquid crystal filter 170 blinks, which is not desirable.

  As can be seen from this characteristic diagram, by changing the frequency of 100 Hz to 40 kHz as the drive signal, the transmittance of the liquid crystal filter 170 is changed from 20% to 40 in 0.1% steps based on an instruction from the control unit 101. % Can also be controlled over a wide range.

  Compared with the wavelength of 780 nm in the case of the CD in FIG. 4, the transmittance at 650 nm of the DVD is generally small and wavelength-dependent, but there is no problem because the measurement is corrected and converted.

  In this case, the transmittance control range is 14% to 30%, and there is a variable range of about 160%. This means that the allowable sensitivity of the optical sensor 110 is increased by 3 to 7 times in a variable range.

Note that the transmittance at 650 nm in the case of the above DVD can be controlled by changing the duty ratio of the drive signal of the liquid crystal filter 170.
FIG. 7 is a characteristic diagram showing a change in transmittance of the liquid crystal filter drive signal by the signal generator 150 and the drive unit 160 with respect to the duty ratio in a pickup that emits laser light having a wavelength of 650 nm using a DVD as a recording medium. As a result, the variable range of the transmittance is about 14 to 24%, which is narrow compared with the variable frequency (FIG. 6), and there is only half of the variable frequency.

Here, the characteristic is shown with the horizontal axis representing the value of the duty ratio when the frequency is 50 Hz, but similar characteristics can be obtained even at other frequencies.
Therefore, regarding the control of the transmittance of the liquid crystal filter 170, it is desirable to use a rectangular wave pulse for frequency control or a combination of frequency control and duty ratio control.

  As described above, the light output from the pickup that has passed through the liquid crystal filter whose transmittance is pulse-controlled, preferably variable in frequency, is measured in a state where it falls within the dynamic range of the optical sensor. As a result, the optical output of a pickup for an optical disc apparatus using an optical disc as a recording medium can be accurately measured using a region with good linearity without being affected by the restrictions due to the dynamic range and wavelength sensitivity characteristics of the optical sensor. It becomes possible.

In the above embodiment, measurement with the following two types of transmittance control (1) and (2) is possible.
(1) The transmittance of the liquid crystal filter 170 is controlled by the control unit 101 in a stepwise manner according to the dynamic range of the optical sensor 110, the intensity of light output of the pickup 210, and the like.

In this case, the transmittance of the liquid crystal filter 170 is switched in the same manner as in the conventional exchange of a plurality of ND filters. In this case, ND filter replacement costs and labor can be saved, and cost reduction and automatic processing are possible.
(2) The transmittance of the liquid crystal filter 170 controls the transmittance of the liquid crystal filter 170 so that the light reception output of the optical sensor 110 is constant, and the pickup 210 that has passed through the liquid crystal filter 170 controlled in this way. The optical output from the optical sensor 110 is received by the optical sensor 110, and the intensity of the optical output of the pickup 210 is calculated from the change in transmittance.

  In this case, the cost and labor of ND filter replacement can be saved, and not only cost reduction and automatic processing can be performed, but also measurement using the region with the best SN ratio of the optical sensor 110 is possible, and reliability is improved. To do.

It is a block diagram which shows the electric constitution of the optical output measuring device which is embodiment of this invention as a functional block. It is principle explanatory drawing which shows the operation principle of the principal part of the optical output measuring device which is embodiment of this invention. It is a block diagram which shows the structure of the principal part of the optical output measuring device which is embodiment of this invention. It is a characteristic view which shows the characteristic in the case of the measurement of the optical output measuring device which is embodiment of this invention. It is a characteristic view which shows the characteristic in the case of the measurement of the optical output measuring device which is embodiment of this invention. It is a characteristic view which shows the characteristic in the case of the measurement of the optical output measuring device which is embodiment of this invention. It is a characteristic view which shows the characteristic in the case of the measurement of the optical output measuring device which is embodiment of this invention. It is a characteristic view which shows the characteristic in the case of the measurement of the conventional optical output measuring device. It is a characteristic view which shows the characteristic in the case of a measurement of an optical output measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical output measuring device 101 Control part 110 Optical sensor 140 Calculation part 150 Signal generation part 160 Drive part 200 Drive 210 Pickup 220 Pickup drive part

Claims (5)

An optical output measuring device for measuring optical output from a pickup of an optical disc device,
A pickup having a function of irradiating the disc with light;
A liquid crystal filter for attenuating light from the pickup with a transmittance according to a given drive signal;
An optical sensor that receives optical output from the pickup that has passed through the liquid crystal filter;
Control for generating a drive signal for controlling the transmittance of the liquid crystal filter according to the intensity and wavelength of the optical output of the pickup and the wavelength sensitivity characteristic of the optical sensor, and variably controlling the transmittance of the liquid crystal filter Means,
An optical output measuring device comprising: The control means generates a drive signal by pulse control, and controls the transmittance of the liquid crystal filter;
The optical output measuring device according to claim 1. The control means generates a drive signal by pulse control with variable frequency, and controls the transmittance of the liquid crystal filter.
The optical output measuring device according to claim 1. The control means generates a drive signal by pulse control by a combination of variable frequency and variable duty ratio, and controls the transmittance of the liquid crystal filter.
The optical output measuring device according to claim 1. The control means controls the transmittance of the liquid crystal filter so that the light reception output of the optical sensor is constant, and calculates the intensity of the optical output of the pickup from the change in the transmittance.
The optical output measuring device according to any one of claims 1 to 3, wherein

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