CN101025956A - High-density blue light optical pick-up - Google Patents

Abstract

This invention relates to an optical head structure system using blue light laser including a laser, a collimator, a shaping prism, a polarization light splitting prism, a reflecting mirror, a 1/4 wave plate, an object lens, a disc plate, a single lens, a plane glass, a cylinder mirror, a signal detector, a signal collective, a laser power detector and a round diaphragm, in which, the character of the system includes: 1, the laser emits laser of the blue light wave band of P polarization laser, 2, the generated laser is processed by the collimator, the shaping prism and the round diaphragm to get round parallel beams with uniform distributed light strength, 3, the polarization light splitting prism splits the generated round parallel P polarization beams and small part is fed back to the power detector for constant power control while most of the parallel polarization lights pass through the 1/4 wave plate to become round ones to focus and collect sap signal data in the optical disc plate, 4, the 1/4 wave plate converts the round reflected by the surface sap of the disc plate to S light to be reflected to a signal detector by the polarization light splitting prism to read data.

Description

A kind of high-density blue light optical pick-up

Technical field

The present invention relates to a kind of high-density blue light (Blu-ray) optical read head, belong to field of optical storage technology based on blue laser.

Background technology

In light storage device Blu-ray Disc of future generation, optical read head still is its core.It is the blue laser of 450nm that the Blu-ray technology adopts wavelength, is 0.85 object lens by numerical aperture, with the focal beam spot reduced to DVD below half.In addition; adopted the thick optical clear protective seam of 0.1mm in the disc structure of Blu-ray Disc; with reduce disc in rotation process because the read-write of tilting to cause is not normal, and this makes reading of disc data be more prone to, and provide possibility for improving storage density greatly.

Because reducing of spot size, so the track pitch of Blu-ray Disc is decreased to 0.32 μ m, short message hole length is 0.14 μ m, the memory capacity of its single-surface single-layer dish is defined as 23.3GB, 25GB and 27GB, storage density has been expanded 5 times than the DVD dish, because blue light is supporting aspect HD digital TV (HD-TV) and the high density mobile storage huge advantage is arranged, so it will become the optical storage technology of main flow of future generation.

Summary of the invention

The objective of the invention is to propose a kind of high-density blue light (Blu-ray) optical read head, utilization according to the optical parametric of laser instrument, designs corresponding optical element based on the blue laser of blue laser, finish the design and the adjustment of whole light path then, to improve the capacity of optical disc storage.

High-density blue light (Blu-ray) optical read head that the present invention proposes comprises: laser instrument, first collimating mirror, shaping prism, circular iris, polarization splitting prism, second collimating mirror, laser power detector, catoptron, quarter wave plate, object lens, simple lens, sheet glass, cylindrical mirror, signal sensor; Wherein said laser instrument, first collimating mirror, shaping prism, circular iris, polarization splitting prism and catoptron are on the primary optic axis line; Described laser power detector, second collimating mirror, polarization splitting prism, simple lens, sheet glass, cylindrical mirror, signal sensor are on second optical axis, first and second optical axis are orthogonal, and polarization splitting prism places on the intersection point of first, second optical axis; Described catoptron, quarter wave plate, object lens and read disc and place on the 3rd optical axis, the 3rd and the primary optic axis line orthogonal, catoptron places on the intersection point of the first, the 3rd optical axis; The divergent beams that send from laser instrument are oval-shaped parallel beam through first collimating mirror collimation for center intensity, be shaped as center intensity through shaping prism again and be circular parallel beam, is the uniform circular parallel beam of intercepting one light distribution the circular parallel beam by circular iris from center intensity, through the polarization splitting prism beam split, make that wherein most of P polarized light passes through, wherein fraction P polarized light reflexes to second collimating mirror, converge on the signal sensor through second collimating mirror, power to laser instrument is adjusted in real time, the most of P polarized light that passes through is after mirror reflects, from become 90 ° direction to penetrate with incident direction, behind quarter wave plate, make the P polarized light become circularly polarized light, behind object lens, circularly polarized light is focused to a bit, and by being read the reflection of signal pit bank on the Blu-ray Disc, become parallel circularly polarized light by object lens once more, parallel circularly polarized light passes through quarter wave plate once more, become the S polarized light, by polarization splitting prism the S polarized light is reflexed on the simple lens once more and focus on, make directional light become converging beam, this converging beam is by sheet glass and cylindrical mirror, produce the astigmatism signal, signal sensor receives the astigmatism signal, obtains the signal that is write down on the disc and is used for focus error signal and the tracking error signal that optical head servo is controlled.

A kind of high-density blue light optical pick-up based on blue light (Blu-ray) laser instrument that the present invention proposes can obtain comparatively desirable focal beam spot and astigmatism hot spot.Optical head characteristics of the present invention are, what LASER Light Source was used is the shorter blue laser of wavelength, and the numerical aperture of the object lens of use is 0.85, by the focal beam spot radius:

$R=0.61\frac{\mathrm{\λ}}{\mathrm{NA}}$

This high-density blue light optical pick-up can obtain than dvd pickup little focal beam spot on first watch as can be known, and dwindling of focal beam spot makes the high density storage become possibility.

Description of drawings

Fig. 1 is the light path principle figure of the blue light optical pick-up that proposes of the present invention.

Among Fig. 1, the 1st, laser instrument, 2 is first collimating mirrors, the 3rd, shaping prism, the 4th, polarization splitting prism, the 5th, catoptron, the 6th, quarter wave plate, the 7th, object lens, the 8th, disc, the 9th, simple lens, the 10th, sheet glass, the 11st, cylindrical mirror, the 12nd, signal sensor, 13 is second collimating mirrors, 14 laser power detectors, the 15th, circular iris.

Embodiment

High-density blue light (Blu-ray) optical read head that the present invention proposes, its light path principle figure comprises laser instrument 1, first collimating mirror 2, shaping prism 3, circular iris 15, polarization splitting prism 4, second collimating mirror 13, laser power detector 14, catoptron 5, quarter wave plate 6, object lens 7, disc 8, simple lens 9, sheet glass 10, cylindrical mirror 11, signal sensor 12 as shown in Figure 1; Wherein said laser instrument, first collimating mirror, shaping prism, circular iris, polarization splitting prism and catoptron are on the primary optic axis line; Described laser power detector, second collimating mirror, polarization splitting prism, simple lens, sheet glass, cylindrical mirror, signal sensor are on second optical axis, first and second optical axis are orthogonal, and polarization splitting prism places on the intersection point of first, second optical axis; Described catoptron, quarter wave plate, object lens and read disc and place on the 3rd optical axis, the 3rd and the primary optic axis line orthogonal, catoptron places on the intersection point of the first, the 3rd optical axis.The divergent beams that send from laser instrument are oval-shaped parallel beam through first collimating mirror collimation for center intensity, be shaped as center intensity through shaping prism again and be circular parallel beam, is the uniform circular parallel beam of intercepting one light distribution the circular parallel beam by circular iris from center intensity, through the polarization splitting prism beam split, make that wherein most of P polarized light passes through, wherein fraction P polarized light reflexes to second collimating mirror, converge on the signal sensor through second collimating mirror, power to laser instrument is adjusted in real time, the most of P polarized light that passes through is after mirror reflects, from become 90 ° direction to penetrate with incident direction, behind quarter wave plate, make the P polarized light become circularly polarized light, behind object lens, circularly polarized light is focused to a bit, and by being read the reflection of signal pit bank on the Blu-ray Disc, become parallel circularly polarized light by object lens once more, parallel circularly polarized light passes through quarter wave plate once more, become the S polarized light, by polarization splitting prism the S polarized light is reflexed on the simple lens once more and focus on, make directional light become converging beam, this converging beam is by sheet glass and cylindrical mirror, produce the astigmatism signal, signal sensor receives the astigmatism signal, obtains the signal that is write down on the disc and is used for focus error signal and the tracking error signal that optical head servo is controlled.

High-density blue light (Blu-ray) optical read head of the present invention's design, its debug process is as follows:

At first utilize collimator and u table to adjust the laser read head mounting base, make its bottom surface all parallel with the optical bench guide rail with the side; Before mounting base, place a receiving screen on the square guide rail, be used for observing hot spot; Adjust the orientation of laser instrument, the elliptical light major axis that makes laser instrument send is in vertical direction, and laser instrument is fixed on the mounting base; Place collimating mirror in mounting hole, adjust the front and back position of collimating mirror, the feasible receiving screen that moves forward and backward on the optical bench, spot size on the receiving screen and position be no change all; On the shaping prism erecting bed of pedestal, place shaping prism, the angle of fine setting shaping prism on erecting bed, the feasible receiving screen that moves forward and backward on the optical bench, spot size on the receiving screen and position be no change all; Behind shaping prism, place a diameter and be 4 circular light and block, on receiving screen, obtain the uniform circular parallel beam of light distribution; On mounting base, place polarization splitting prism, place an external diameter 10 simultaneously at LD luminous power FEEDBACK CONTROL place, internal diameter is 6, the sleeve of long 40mm, the hot spot on the place ahead receiving screen of observation polarization splitting prism and the sleeve outgoing hot spot of process are adjusted the polarization Amici prism, make to move forward and backward receiving screen, spot size position no change on the receiving screen, and be positioned at the sleeve center through the outgoing hot spot of sleeve; Adjust collimator, make the vertical installation base surface with catoptron of the shoot laser of collimator, have on the screen of collimator at this moment the ruddiness hot spot in screen in the heart.Close the laser of collimator, place catoptron, make the blue light of outgoing be injected into collimator inside, the blue light hot spot that occurs a circle at this moment on the screen of collimator, the position of fine setting catoptron, make the blue light hot spot be positioned at collimator screen center, explanation this moment light beam vertical level behind catoptron upwards penetrates; Quarter wave plate is installed in the mechanical flat board of center pit, this mechanical flat board is placed on the top of catoptron, observe hot spot, require the outgoing hot spot to be positioned at the center of quarter wave plate through quarter wave plate; The torquer that will have object lens is placed on the mechanical parts that designs, and then whole mechanical parts is placed on the dull and stereotyped top of the machinery that has quarter wave plate, guarantees that by physical construction object lens are coaxial with quarter wave plate; Simple lens, sheet glass and cylindrical mirror are assembled in a mechanical sleeve the inside, to overlap the inside, hole that the tax tube is positioned over mounting base then, place Blu-ray Disc above object lens, place a microscope in cylindrical mirror sleeve outside, observation is through the astigmatism hot spot behind the cylindrical mirror.Adjust the distance of Blu-ray Disc and object lens, can observe an oval spot at microscopically, the rotating machinery sleeve makes the major axis of oval spot spend from the horizontal by 45.

Claims (1)

1, a kind of high-density blue light optical pick-up is characterized in that this optical head comprises: laser instrument, first collimating mirror, shaping prism, circular iris, polarization splitting prism, second collimating mirror, laser power detector, catoptron, quarter wave plate, object lens, simple lens, sheet glass, cylindrical mirror, signal sensor; Wherein said laser instrument, first collimating mirror, shaping prism, circular iris, polarization splitting prism and catoptron are on the primary optic axis line; Described laser power detector, second collimating mirror, polarization splitting prism, simple lens, sheet glass, cylindrical mirror, signal sensor are on second optical axis, first and second optical axis are orthogonal, and polarization splitting prism places on the intersection point of first, second optical axis; Described catoptron, quarter wave plate, object lens and read disc and place on the 3rd optical axis, the 3rd and the primary optic axis line orthogonal, catoptron places on the intersection point of the first, the 3rd optical axis; The divergent beams that send from laser instrument are oval-shaped parallel beam through first collimating mirror collimation for center intensity, be shaped as center intensity through shaping prism again and be circular parallel beam, is the uniform circular parallel beam of intercepting one light distribution the circular parallel beam by circular iris from center intensity, through the polarization splitting prism beam split, make that wherein most of P polarized light passes through, wherein fraction P polarized light reflexes to second collimating mirror, converge on the signal sensor through second collimating mirror, power to laser instrument is adjusted in real time, the most of P polarized light that passes through is after mirror reflects, from become 90 ° direction to penetrate with incident direction, behind quarter wave plate, make the P polarized light become circularly polarized light, behind object lens, circularly polarized light is focused to a bit, and by being read the reflection of signal pit bank on the Blu-ray Disc, become parallel circularly polarized light by object lens once more, parallel circularly polarized light passes through quarter wave plate once more, become the S polarized light, by polarization splitting prism the S polarized light is reflexed on the simple lens once more and focus on, make directional light become converging beam, this converging beam is by sheet glass and cylindrical mirror, produce the astigmatism signal, signal sensor receives the astigmatism signal, obtains the signal that is write down on the disc and is used for focus error signal and the tracking error signal that optical head servo is controlled.

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