KR20000043288A - Waveguide type collecting optical pickup device available for converging nth secondary beam - Google Patents

Abstract

PURPOSE: A waveguide type collecting optical pickup device is provided to increase light efficiency when an optical disc is modulated and to increase detecting amount of generated signals by collecting modulated light diffracted out of a lens to detect an error signal. CONSTITUTION: A laser beam via a primary beam object lens is irradiated to a hologram lattice unit(24). Laser beams via a first and a second secondary beam object lens(34) are irradiated to a front reflected face(22) formed the hologram lattice unit. The laser beam irradiated to the hologram lattice unit has a different optic passage from a prior optic passage discharging a laser beam from a laser diode(10). The laser beam through the converted passage is irradiated to primary beam detectors(40,42) installed in both sides of the laser diode. The diffracted light irradiated to the front reflected face is collected in each first and second secondary beam detectors(44,46). The primary beam detectors detect a focus error signal and a RF signal by converting a signal to an electric signal and amplifying the signal. The secondary beam detectors operate the RF signal by amplifying a signal and outputs a single RF signal from the operated signal.

Description

Waveguide Integrated Optical Pickup Device

The present invention relates to a waveguide-type integrated optical pickup device capable of performing secondary light convergence. In particular, the present invention includes a double lens for converging laser light reflected and scattered from an optical disc, thereby increasing the amount of light reduced to the photodetector, thereby improving reproduction efficiency. The present invention relates to a waveguide type integrated optical pick-up apparatus capable of performing sub-light beam convergence, which can easily detect an error signal.

In general, an optical pickup apparatus is used for condensing and diffracting laser light on a pit of an optical disk on which optical information is recorded to modulate the laser light, and converging the modulated laser light to a photodetector to reproduce the optical information.

As an example of such a conventional optical pickup apparatus, as shown in FIG. 1, a laser diode 100 in which a laser light having a predetermined wavelength is generated, and diffraction of a laser light formed and incident on the laser diode 100 is incident. The collimator which gives parallelism to the diffraction grating 105 which isolate | separates into 0th order diffraction light and +/- 1st order diffraction light, ie, three beam using the phenomenon, and the laser beam which passed through this diffraction grating 105 A lens 110, a beam splitter 120 for partially reflecting and transmitting the parallel light to separate incident light and reflected light, a wavelength plate 125 for converting the polarization of the laser light transmitted through the beam splitter 120; And an objective lens 130 for condensing the laser light via the wavelength plate 125 on the optical disk D, and the laser light reflected by the beam splitter 120 to the photodetector 150, thereby focusing a signal. It consists of a converging lens unit 140 to give.

In operation of the conventional optical pickup apparatus having such a configuration, first, a laser beam having a predetermined oscillation wavelength is incident on the diffraction grating 105 in the laser diode 100, and the incident laser light passes the diffraction grating 105. Transmitted and separated into 0th and ± 1st light, i.e., three beams. This three-beam is used for focusing and tracking errors, and the linearity is imparted while passing through the collimating lens 110 through the diffraction grating 105. The laser beam that goes straight is incident on the beam splitter 120, and the three beams are reflected and transmitted at a constant rate by the beam splitter 120. The laser beam is transmitted through the beam splitter 120 to the wavelength plate 125, and the laser light is converted into circularly polarized light while passing through the wavelength plate 125. This laser light is collected by the objective lens 130 and irradiated to the pit signal surface on the optical disc D. The laser light is reflected almost as it is in the absence of the pit on the optical disc D and returns to the objective lens 130. Where the pit is located, the laser light is diffracted by the pit and emitted outside the range of the objective lens 130, thereby causing only part of the incident light to be returned, thereby causing a light quantity difference in the photodetector 150.

The modulated reflected light reflected back from the optical disk D is converted into linearly polarized light which is inverted by 90 ° from the time of incidence while passing through the wave plate 125, so that the light splitter 120 can reflect the light. Is converted. The reflected light of which the optical path is converted is given a focus error signal while passing through the converging lens unit 140 and received by the photodetector 150. The converged laser light is converted into an RF (RF), focus and tracking error detection signal by a photo detector, and the converted current is demodulated and reproduced by an original signal by a control circuit (not shown).

However, such a conventional optical pickup apparatus converges only the 0th order diffracted light into the objective lens among the light diffracted upon modulation in the optical disc D and discards the modulated light diffracted by ± 1st order, thereby significantly reducing the light efficiency, thereby reproducing the RF signal. Since the signal is poor, and the tracking and focus error signals are detected in the 0th order diffraction light, the circuit configuration of the error signal detection becomes difficult, thereby deteriorating the reliability of the optical pickup apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and improves the optical signal deteriorated during modulation on an optical disc to improve the reproduction signal, and receives the modulated light diffracted out of the lens range to improve the detection amount of the reproduction signal. An object of the present invention is to provide a waveguide-type integrated optical pickup device capable of easily detecting a sub-light.

The present invention for achieving the above object, the primary light objective for converging the zero-order diffraction light diffracted in the optical disk, and the secondary light objective to be integrally formed on both sides of the main light objective lens to converge ± 1 light A double lens configured; A laser diode installed on one side of the wall and emitting a laser beam having a predetermined wavelength, and a hologram lattice part formed on an ear path of the laser light on an upper surface of the side where the laser diode is installed to separate an optical path between incident light and convergent light; The first and second daylight detectors, which are formed over the upper surface of the hologram lattice, and are configured to totally reflect incident light and convergent light, and are arranged on both sides of the laser diode to collect zero-order diffracted light reflected from the optical disk. And an integrated element formed on both sides of the main light detector and including an integrated element in which the first and second sub-detectors are integrated to collect diffraction light of ± 1 order reflected from the optical disk. This is achieved by providing an integrated optical pickup device.

1 is a block diagram of a conventional optical pickup device;

2 is a side view of an optical pickup apparatus according to an embodiment of the present invention;

3 is a plan view of FIG.

Figure 4 is an operating state in accordance with an embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

10: laser diode 20: integrated device

22: total slope 24: hologram grid portion

30: double lens 32: daylight objective lens

34: first secondary light objective lens 36: second secondary light objective lens

40: first daylight detector 42: second daylight detector

44: first light detector 46: second light detector

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the present invention contemplates a laser diode 10 that emits laser light, a laser lens condensing the laser light onto an optical disc D, and simultaneously converging the multi-diffraction light diffracted on the optical disc D. 30 and an integrated device 20 which emits a laser beam to the double lens 30 and has a plurality of optical paths through which the multi-order diffraction light is guided through the double lens 30.

The double lens 30 is integrally formed at both sides of the main light objective lens 32 for converging the zero-order diffracted light diffracted by the optical disk D, and converges ± 1 order light on both sides of the main light objective lens 32. The first secondary light objective 34 and the second secondary light objective 36 are formed.

On the other hand, the integrated device 20 is formed on the laser diode 10, which is provided on one side wall to emit a laser light of a predetermined wavelength, and the return path of the laser light on the upper surface of the side on which the laser diode 10 is installed A hologram lattice part 24 for separating the optical paths of incident light and converging light, a total reflection surface 22 for total reflection of incident light and converging light, and the laser diode The first daylight detector 40 and the second daylight detector 42 and the daylight detectors 40 and 42 which are disposed on both sides of the light source 10 and collect the zeroth order diffracted light reflected from the optical disc D. The first and second sub-detectors 44 and 46 are integrally formed on both sides to collect diffraction light of ± 1 order reflected from the optical disc D.

Next will be described the operation of the present invention made as described above.

As shown in FIGS. 3 and 4, laser light having a predetermined wavelength is emitted from the laser diode 10 provided inside the integrated device 20 and irradiated onto the total reflection surface 22, and the laser light is reflected on the total reflection surface 22. ) Is totally reflected to maintain a constant light path.

The laser light, the optical path of which is maintained, is reflected back from the bottom surface of the integrated device 20 to be emitted to the outside of the integrated device 20, and the emitted laser light is emitted from the integrated device 20 toward the double lens 30. Is investigated.

As described above, the laser light emitted from the integrated device 20 is focused on the optical disk D by the main light objective lens 32 formed at the center of the double lens 30, and the focused laser light is fit into the optical disk D. It is modulated according to the presence and absence of diffraction.

The laser light modulated in this way is diffracted and scattered by multi-order diffracted light such as 0th, ± 1st, ± 2nd, .. etc., and this diffraction order is accompanied by the same amount of modulation of light. Since it is distributed and scattered by the number of procedures, optical information is accompanied by diffracted light in which all of the multiple diffraction lights are individually modulated.

The amount of incident incident light from the laser beam to the primary light objective lens 32 where only the zeroth order diffracted light is returned is about 30%. Other ± first order diffracted light is transferred to the first secondary light objective lens 34 and the second part. When the light is returned through the light-shielding objective lens 36, the amount of diffracted light is increased to amplify a satisfactory light amount even with a small input amount when amplifying the optical signal, and at the same time, the noise ratio is reduced by the amount of light to be reduced, thereby improving the S / N ratio. Therefore, the reproducibility of the optical information can be improved.

Of the laser light diffracted as described above, the zero-order diffraction light is again irradiated to the main light objective lens 32, and the ± first order diffraction light is formed on both sides of the main light objective lens 32. And the second secondary light objective 36, respectively. This is because the + 1st diffraction light and the −1st diffraction light are symmetrically diffracted around the 0th diffraction light, so that the first sub-light objective 34 and the symmetry are formed on both sides of the main light objective 32. Each of the two secondary light objectives 36 is irradiated.

As described above, the multi-diffraction light passing through the double lens 30 is irradiated to the integrated device 20, and the laser light is reflected from the bottom surface of the integrated device 20 to maintain a constant optical path, while maintaining the inside of the integrated device 20. Is guided without loss of light at.

Among the laser beams conducted inside the integrated device 20 as described above, the laser beam passing through the main light objective lens 32 is irradiated to the hologram grid 24 and the first sub-light objective 34 and the first sub-light objective 34 are irradiated. The laser beam passing through the secondary light blocking objective lens 36 is symmetrically irradiated to the total reflection surface 22 on which the hologram grid portion 24 is formed.

Thus, the laser light irradiated to the hologram lattice part 24 of the laser light has a different light path than when emitted from the laser diode 10, and the laser beam whose path is converted as described above is the laser diode 10. Diffracted light of ± 1st order light irradiated by the chief day light detectors 40 and 42 provided on both sides of the first and second total light reflectors 26 is received by the first and second negative light detectors 46 and 46, respectively. .

Therefore, the signals converted into electrical signals by the daylight detectors 40 and 42 are amplified and used to detect the focus error signal and the RF signal, respectively, and the first secondary light detector 44 and the second secondary light detector ( By amplifying the signal of 46), an RF signal is calculated, and a single RF signal is output from the calculated signal.

As described above, the present invention re-condenses the laser light that is diffracted and scattered by ± 1 order among the laser light that is collected and scattered from the optical disk D, and then reduced to the first and second negative light detectors 44 and 46, thereby reducing the electrical signal. Since the amount of light to be reduced is increased to reduce the signal amplification ratio, the reproduction of optical information is improved, and the photodetectors 40 and 42 are separately provided for each converging light. will be.

In the present invention, the waveguide type integrated optical pickup apparatus capable of performing secondary light convergence reduces laser light scattered according to whether optical information accompanies the light and converges the light through a separate lens unit, thereby increasing the amount of converged light, thereby increasing the reproduction efficiency of the optical pickup device. Since the number of laser beams is received by the plurality of photodetectors, the error signal can be easily detected, thereby improving the reliability of the optical pickup apparatus.

Claims (1)

A main light objective lens 32 for converging the zero-order diffracted light diffracted by the optical disk D, and secondary light objective lenses 34 and 36 which are integrally formed at both sides of the main light objective lens 32 to converge ± 1 order light; Double lens 30 composed of; And A laser diode (10) installed on one wall and emitting laser light of a predetermined wavelength, and formed on an ear environment path of laser light on an upper surface of the side on which the laser diode (10) is installed to separate an optical path between incident light and convergent light The hologram lattice part 24 and the hologram lattice part 24 are formed on the upper surface, and the total reflection surface 22 for totally reflecting the incident light and the converging light, and disposed on both sides of the laser diode 10 and the main light The first and second detectors 40 and 42, which are focused on the zeroth order diffracted light via the objective lens 32, are provided on both sides of the main detectors 40 and 42, respectively. It characterized in that it comprises an integrated device 20 formed integrally with the first light detector 44 and the second light detector 46 for collecting the first-order diffraction light via the lens (34, 36) Waveguide-type integration that can perform secondary light blocking procedure Pickup device.