CN2543179Y - Laser read head - Google Patents

Abstract

The utility model falls into the technical field of optical disk storage, and relates to a laser optical head. The laser optical head comprises a dual-wavelength laser, a tribeam grating, a half-mirror, a collimating mirror, a reflector, an object lens, and a photoelectric receiver; wherein the tribeam grating and the half-mirror are arranged on the incident light axis of the dual-wavelength laser, the collimating mirror and the reflector are arranged on the reflective light path of the half-mirror, the photoelectric receiver is arranged on the transmissive light path of the half-mirror, and the object lens is arranged on the reflective light path of the half-mirror. The utility model is characterized in that a path compensator is arranged between the photoelectric receiver and the half-mirror. The utility model can save one light source, requires no special photoelectric receiver, and has simple light path and low production cost.

Description

The laser readings head

Technical field

The utility model belongs to the CD storage technique field, particularly is applied to the compatible optical head technical scheme of multiple deielectric-coating

Background technology

Family expenses DVD-PLAYER and CD-R laser readings head (abbreviation optical head) are the gordian technique parts in the CD storage technique field, according to several companies of Japan (TOSHIBA, SHARP) last word (LASER Light Source is sent the different laser of two bundle wavelength), use this light source, certain company of Japan designs a kind of novel optical head.Its structure is made up of dual laser 101, three light beam gratings 102, semi-transparent semi-reflecting lens 103, collimating mirror 104, object lens 105, optoelectronic receiver 107 as shown in Figure 1.Its light channel structure and principle of work are: the dual wavelength light beam that LASER Light Source is sent through three light beam gratings by semi-transparent semi-reflecting mirror reflection, become directional light through collimating mirror again, converge to through object lens on the disc 106 of DVD or CD and read and write, return by former road then, through the semi-transparent semi-reflecting lens transmission, receive by photelectric receiver.The optoelectronic receiver of this optical head is a new twin-beam photelectric receiver, as shown in Figure 2, is made up of two receiving elements (ABCDEF and abcd) at a distance of certain distance (0.11mm).The shortcoming of this scheme is: because the distance of two receiving elements of the existing twin-beam photelectric receiver that adopts is fixing, distance between these LASER Light Source two wavelength optical axises that just require to produce in enormous quantities must be consistent, because (wavelength 650nm) accepts with the right photoelectricity receiving element abcd when reading DVD, and (wavelength 780nm) accepts with left side ABCDEF photoelectricity receiving element when reading CD-R or CD, if the distance between the LASER Light Source two wavelength optical axises is inconsistent, just can't adjust, the yield rate of optical head is reduced, increased production cost.

The utility model content

The purpose of this utility model is for overcoming the weak point of prior art, proposing a kind of laser readings head, on the basis of prior art light channel structure, adds an optical path compensator, can use a common photoelectric receiver.Have and realize easily the yield rate height of optical head, the advantage that production cost is low.

A kind of laser readings head of the utility model design comprises dual laser, three light beam gratings, semi-transparent semi-reflecting lens, collimating mirror, object lens, optoelectronic receiver; Wherein, this three light beams grating, semi-transparent semi-reflecting lens are arranged on the incident light axis of dual laser, and this collimating mirror, these object lens are arranged on the reflected light path of said semi-transparent semi-reflecting lens, and this optoelectronic receiver is arranged on the transmitted light path of said semi-transparent semi-reflecting lens; It is characterized in that, also comprise the optical path compensator that is arranged between optoelectronic receiver and the semi-transparent semi-reflecting lens; This optical path compensator be used for the two-beam axle after the light beams of different wavelengths of certain distance sees through it, intersect on the photelectric receiver a bit.

For reducing the length of a laser readings light path, in such scheme, also a reverberator can be set on the reflected light path of said semi-transparent semi-reflecting lens, said collimating mirror and object lens are respectively on the input path and reflected light path of this reverberator.

Said optical path compensator can adopt wedge mirror or grating.

Characteristics of the present utility model are on the basis of existing optical head structure, add an optical path compensator, the two-beam of double light beam laser device can be received by common photelectric receiver, its light channel structure is simple, produce the yield rate height of optical head, production cost is low, is a kind of compatible optical head of multiple deielectric-coating that can be applicable to.

Description of drawings

Fig. 1 is the optical texture synoptic diagram of existing a kind of laser readings head.

Fig. 2 is the synoptic diagram of the photelectric receiver among Fig. 1.

Fig. 3 is the optical texture synoptic diagram of laser readings head of the present utility model.

Embodiment

The laser readings head of the utility model design reaches embodiment in conjunction with the accompanying drawings and is described in detail as follows:

Light channel structure of the present utility model as shown in Figure 3.Formed by dual laser 1, three light beam gratings 2, semi-transparent semi-reflecting lens 3, collimating mirror 4, reverberator 5, object lens 6, optoelectronic receiver 7 and optical path compensator 9.Its light channel structure and principle of work are: the dual wavelength light beam that LASER Light Source 1 is sent is reflected by semi-transparent semi-reflecting lens 3 through three light beam gratings 2, become directional light through collimating mirror 4 again, reflect again on object lens 6 converge to the disc 8 of DVD or CD by reverberator 5 and to read and write, return by former road then, through semi-transparent semi-reflecting lens transmission 3, and compensator 9 is received by photelectric receiver 7.Characteristics of the present utility model are: added an optical path compensator 9 in the photelectric receiver front and made the parallel but light of different wave length of two bundles that return from CD 8, because the effect of optical path compensator intersects at a point, and can be by 7 receptions of common photoelectric receiver.

The wavelength of the dual laser that the utility model adopts is 650nm and 780nm, and the optical axis of two-beam is at a distance of 0.11mm; Object lens are aspheric surface object lens.

The embodiment of optical path compensator of the present utility model can adopt wedge mirror or grating, and other element all can adopt the device of known general-purpose, and the method for designing of wedge mirror or grating and effect thereof are described below respectively:

1, wedge mirror:

After selecting specific glass material (refractive index is n), go out its locking angle and apart from the distance L of photelectric receiver through designing and calculating, the light that make two bundle different wave lengths (different refractivity) intersect at a point after through the wedge mirror.Its principle is described as follows:

When locking angle was very little, behind the light process wedge mirror, deflection angle δ=(n-1) α two restrainted the light of different refractivities, drift angle difference Δ δ=(n ₁-n ₂) the known two parallel beam optical axises of α (1) are at a distance of being 0.11mm, promptly $\mathrm{\Δ\δ}=\frac{0.11}{L}.........\left(2\right)$ Known n ₁, n ₂, α can obtain Δ δ, adjusts the distance L of wedge mirror and photelectric receiver, can make two-beam intersect at a bit of photelectric receiver.

2, grating

Diffraction does not take place in this grating pair wavelength 650nm, its imaging is still on O level light incidence point, and diffraction is taken place in wavelength 780nm, launch (Fourier expand) with Fu Shi and obtain phasing degree and grating depth, near zero ,+1 grade of light or-1 grade of light and wavelength 650nm light intersect at a point the light that makes wavelength 780nm through the efficient of 0 grade of light behind the optical grating diffraction.Its principle is described as follows: the phase grating function:

During light normal incidence, complex amplitude transmission function t (x)=[2f (x)-1] sin δ+icos δ (2) phase differential $\mathrm{\&delta;}=(n-1)\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="Y0223554200071.png"\; state="\{\{state\}\}">h</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}.........\left(3\right)$

λ: the 780nm light wavelength is launched (Fourier expand) to f (x) Fu Shi $f\left(x\right)=\underset{-\&infin;}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{\sin \mathrm{m\&pi;}}{\mathrm{m\&pi;}}\exp (\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="Y0223554200071.png"\; state="\{\{state\}\}">i</figure-callout>}2\mathrm{m\&pi;x}/d).......\left(3\right)$ With (3) substitution (1) then: $t\left(x\right)=\sin \mathrm{\&delta;}+i\cos \mathrm{\&delta;}+2\sin \mathrm{\&delta;}\frac{\sin \mathrm{\&pi;}}{\mathrm{\&pi;}}({\mathrm{<figure-callout\; id="2"\; label="e\; i"\; filenames="Y0223554200071.png"\; state="\{\{state\}\}">e</figure-callout>}}^i+e^{-\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="Y0223554200071.png"\; state="\{\{state\}\}">i</figure-callout>}2\mathrm{\&pi;x}/d})$ The complex amplitude of 0 grade of light and ± 1 grade of light is respectively: A ₀=sin δ+icos δ $A_{\&PlusMinus;1}=2\sin \frac{\sin \mathrm{\&pi;}}{\mathrm{\&pi;}}{e}^{\&PlusMinus;\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="Y0223554200071.png"\; state="\{\{state\}\}">i</figure-callout>}2\mathrm{\&pi;x}/d}$ The ratio of wishing 0 grade of light and ± 1 grade of light intensity is that α: β: α wishes promptly that also β is as far as possible little, and α is big as far as possible. (depending on manufacturing process) then has $A_1^2=\frac{\mathrm{\&alpha;}}{\mathrm{\&beta;}}{A}_0^2.$ Can solve δ and grating depth degree h like this.

Claims (4)

1, a kind of laser readings head comprises dual laser, three light beam gratings, semi-transparent semi-reflecting lens, collimating mirror, object lens, optoelectronic receiver; Wherein, this three light beams grating, semi-transparent semi-reflecting lens are arranged on the incident light axis of dual laser, and this collimating mirror, these object lens are arranged on the reflected light path of said semi-transparent semi-reflecting lens, and this optoelectronic receiver is arranged on the transmitted light path of said semi-transparent semi-reflecting lens; It is characterized in that, also comprise the optical path compensator that is arranged between optoelectronic receiver and the semi-transparent semi-reflecting lens.

2, laser readings head as claimed in claim 1 is characterized in that, a reverberator also is set on the reflected light path of said semi-transparent semi-reflecting lens, and said collimating mirror and object lens are respectively on the input path and reflected light path of this reverberator.

3, laser readings head as claimed in claim 1 is characterized in that, said optical path compensator adopts the wedge mirror.

4, laser readings head as claimed in claim 1 is characterized in that, said optical path compensator adopts grating.

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