A kind of producing device of holographic grating
Technical field
The present invention relates to holographic grating making field more particularly to a kind of producing devices of holographic grating.
Background technique
Grating scale is accurate measurement, the important measuring tool in Precision Machining, critical component of the grating as grating scale,
Play reference mark in measurement.Common preparing grating method has machinery to portray method and laser interferance method.It is wherein mechanical to carve
The technique of painting is easy to operate, is capable of processing complicated raster graphic, but limited in the actual processing process by tool dimension, grating week
Phase is typically only capable to reach dozens of micron, and process is very time-consuming.
Laser interference lithography compares the mechanical method of portraying can obtain the grating of submicron-scale periodicity in a short time, and grating is wide
Degree can achieve tens of milliseconds, be able to satisfy optical grating ruler measurement demand, but for laser interference photolithography technology, main limitation because
It is known as beam diameter, the size of universal optical element, the coherence length of laser light source, currently used He-Cd laser, Ar+
Laser is expensive, bulky, and general Study unit is difficult to undertake, and is unfavorable for popularizing for the technology.
The disclosure of background above technology contents is only used for auxiliary and understands design and technical solution of the invention, not necessarily
The prior art for belonging to present patent application, no tangible proof show above content present patent application the applying date
In disclosed situation, above-mentioned background technique should not be taken to the novelty and creativeness of evaluation the application.
Summary of the invention
In order to solve the above technical problems, the present invention proposes a kind of producing device of holographic grating, light source is greatly reduced
Cost simplifies structure, volume also greatly reduces.
In order to achieve the above objectives, the invention adopts the following technical scheme:
The invention discloses a kind of producing device of holographic grating, including light source, collimating mirror, diaphragm, beam splitter, two sides are anti-
Mirror and grating substrate are penetrated, wherein the light source uses laser diode, the light source, the collimating mirror and the diaphragm are along light beam
Successively the light beam is arranged in the optical path after the diaphragm in co-axial alignment, the beam splitter in the direction of advance, and described point
Shu Jing is used to for the light beam being reflected into two light beams, and reflecting mirror described in two sides is separately positioned on two after beam splitter reflection
In the optical path of light beam, reflecting mirror described in two sides is arranged by axis axial symmetry of the beam splitter, and the grating substrate setting is being interfered
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Preferably, reflecting mirror described in two sides is equipped with angle regulating unit, and the angle regulating unit is described for adjusting
The angle of reflecting mirror.
Preferably, reflecting mirror described in two sides is vertically arranged with the grating substrate respectively.
Preferably, the grating substrate is arranged in interference field the widest part.
Preferably, the grating substrate is the glass substrate for being coated with photoresist.
Preferably, the laser diode uses wavelength X for the blue light laser diode of 405nm.
Preferably, the half θ for the angle penetrated between the dual-beam on the grating substrate meets relational expression: g=λ/
2sin θ, in which: g is screen periods, and λ is the wavelength of the light source.
Preferably, the aperture D of the diaphragm meets relational expression: 2gLc/ λ < D/cos θ, in which: g is screen periods, and λ is
The wavelength of the light source, LcFor the coherence length of the laser diode, θ is to penetrate between the dual-beam on the grating substrate
Angle half.
Preferably, the width L of the reflecting mirror meets relational expression: L > D/sin (67.5 ° of-θ/2), and wherein D is the diaphragm
Aperture, θ is the half for the angle penetrated between the dual-beam on the grating substrate.
Compared with prior art, the beneficial effects of the present invention are: used in the producing device of holographic grating of the invention
Laser diode is as light source, it is convenient to omit costly, complicated outer such as beam expanding lens, spatial filter, optical resonator, membrance selection cavity
Portion's component first passes around collimating mirror and diaphragm by the light beam that laser diode emits, then after being split using beam splitter, point
It does not interfere to form interference field after reflecting mirror changes the direction of propagation, be formed on the grating substrate for be arranged in interference field holographic
Grating;The producing device of the holographic grating solves at high cost, the knot that the device of existing laser interferance method production grating has
The problems such as structure is complicated, bulky has many advantages, such as that at low cost, instrument and equipment is simple, compact layout.
In further embodiment, the holographic grating of specified screen periods is made, need to only adjust and penetrate on grating substrate
Dual-beam between angle, wherein can by adjust two-face mirror angle, or pass through adjust light source project light
The angle for adjusting and penetrating between the dual-beam on grating substrate can be realized in the incident angle on beam splitter for beam.
In further scheme, the aperture of the diaphragm and mirror width conform to a predetermined condition and can make in grating substrate
The width of the grating of upper formation is twice of Lloyd's mirror structure.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the producing device of the holographic grating of the preferred embodiment of the present invention;
Fig. 2 is the structural schematic diagram for measuring the coherence length of the light source in Fig. 1;
Fig. 3 is the schematic diagram of the grating of preferred embodiment of the present invention processing;
Fig. 4 is microstructure schematic diagram of the grating after microscope amplifies 400 times in Fig. 3.
Specific embodiment
Below against attached drawing and in conjunction with preferred embodiment, the invention will be further described.
As shown in Figure 1, the producing device of the holographic grating of the preferred embodiment of the present invention includes light source 1, collimating mirror 2, diaphragm
3, beam splitter 4, the first reflecting mirror 5, the second reflecting mirror 6 and grating substrate 7, grating substrate 7 are the glass bases for being coated with photoresist 72
Plate 71, light source 1 use laser diode, and wherein light source 1, collimating mirror 2 and diaphragm 3 are along the direction that light beam advances successively coaxial row
Light beam is arranged in the optical path after diaphragm 3 in column, beam splitter 4, and beam splitter 4 is used to for light beam being reflected into two light beams, and first is anti-
It penetrates mirror 5 and the second reflecting mirror 6 is separately positioned in the optical path of two light beams after beam splitter 4 reflects, the first reflecting mirror 5 and second is anti-
Mirror 6 is penetrated with beam splitter 4 as the setting of axis axial symmetry, grating substrate 7 is arranged in interference field, and further, the setting of grating substrate 7 is dry
Relate to the widest part.
In the concrete realization, two light beams pass through the first reflecting mirror 5 respectively and the second reflecting mirror 6 reflects to form dual-beam and penetrates
On grating substrate 7, the half θ for the angle penetrated between the dual-beam on grating substrate 7 should meet relational expression: g=λ/2sin
θ, in which: g is screen periods, and λ is the wavelength of the light source, it is therefore desirable to which the grating for making predetermined screen periods only needs to adjust
Angle between dual-beam;And it is the angle adjusted between dual-beam, the light beam that on the one hand adjustable light source 1 projects is in beam splitting
Incident angle on mirror 4, i.e., by adjusting the angle between light source 1, collimating mirror 2 and the axis and beam splitter 4 of diaphragm 3, wherein this
When can fix the first reflecting mirror 5 and the second reflecting mirror 6 be vertically arranged respectively with grating substrate 7 (i.e. at this time light beam relative to point
The incidence angle of beam mirror 4 has played main function in determining screen periods);On the other hand the first reflecting mirror 5 and the can also be adjusted
Angle regulating unit can be respectively set on the first reflecting mirror 5 and the second reflecting mirror 6 in the angle of two-mirror 6, to adjust
One reflecting mirror 5 and the second reflecting mirror 6 angle between grating substrate 7 respectively, wherein the first reflecting mirror 5 and the second reflecting mirror 6
It also should be with beam splitter 4 after adjusting for the setting of axis axial symmetry, at this point, the adjusting of optical path is very convenient, and can be with fixed beam
Relative to the incidence angle of beam splitter 4, such as 45 °.
In a still further embodiment, in the coherence length of light source 1 to raster width LcRestriction effect prior to light
Under the conditions of beam diameter, mirror width, the width W of the grating formed on grating substrate 7cIt is twice of Lloyd's mirror structure, tool
Body structural formula are as follows: Wc=2gLc/ λ, wherein g is screen periods, and λ is the wavelength of light source 1.Wherein specifically, in the aperture D of diaphragm
(namely beam diameter) meets relational expression: 2gLc/ λ < D/cos θ, the width L of reflecting mirror meet relational expression: L > D/sin
When (67.5 ° of-θ/2), the coherence length of light source 1 is to raster width LcRestriction effect prior to beam diameter, mirror width.
Following combination specific examples carry out into one the producing device production holographic grating using holographic grating of the invention
Walk explanation.
(1) glass substrate 71 is cleaned first, and glass substrate 71 is placed in supersonic wave cleaning machine and is cleaned, second is then successively used
Alcohol, alcohol, deionized water cleaning are placed on dryer dry finally with being dried with nitrogen;It is then spin coated onto photoresist 72, by one
Certainty ratio prepare photoresist solution, substrate of glass 71 is placed on spin coater, choose on a small quantity prepared photoresist solution drop in
On glass substrate 71, setting Reasonable Parameters carry out spin coating, it is ensured that and photoresist solution can equably be covered on 71 surface of glass substrate,
Preparation forms grating substrate 7.
(2) producing device as shown in Figure 1 is built, illustrates to be built according to above-mentioned producing device, forms such as Fig. 1
Shown in optical path, strictly ensure the accuracy of optical path, process specific fixed device for light source 1, while providing for it stable
Current source, and the power for being adjustable laser by adjusting current source;Wherein light source 1 uses wavelength X for 405nm in this example
Blue light laser diode.
(3) interference fringe is detected, since interference fringe naked eyes are difficult to differentiate, and effectively interference width is extremely narrow (about 5mm),
An object lens (100 times of amplification factor) is placed at interference field to have checked whether that interference field is formed, if nothing, repeats step (2) relaying
It is continuous to adjust optical path;If so, carrying out in next step.
(4) by the glass substrate 71 of resist coating 72 is placed in interference field the widest part in step (1), the suitable time is chosen
It is exposed and develops, the holographic grating that disposable obtained raster width is 5mm, as shown in Figure 3 and Figure 4, wherein Fig. 4 is Fig. 3
In grating amplify 400 times of microstructure, as can be seen from the figure the screen periods are 2508nm, and the width of the grating is Lip river
Twice of raster width made from angstrom mirror structure.
Wherein in step (2) during adjusting optical path, need to measure the coherence length L of light source 1 in advancec, measurement
The coherence length L of light source 1cMeasurement structural representation as shown in Fig. 2, light source 1, collimating mirror 2, diaphragm 3, beam splitter 4 and first
Along the direction that light beam advances, successively co-axial alignment, beam splitter 4 are in 45° angle with light beam to reflecting mirror 5, and the setting of the second reflecting mirror 6 is dividing
In the optical path of another divided beams of beam mirror 4, the second reflecting mirror 6 is arranged on displacement platform 8, and the setting of observation screen 9 is forming interference
In the interference field of striped 10.The light that light source 1 emits passes through collimating mirror 2,3 adjusting size of diaphragm, is divided into two-beam by beam splitter 4,
The front-rear position for adjusting the first reflecting mirror 5 and the second reflecting mirror 6 makes the first reflecting mirror 5 and the second reflecting mirror 6 respectively and beam splitter
, there is clearly interference fringe 10, moving displacement platform 8 on observation screen 9 at this time in 4 be equidistant, until interference fringe disappears
It loses, records the moving distance d of displacement platform 8, then the coherence length L of light source 1c=2d.
The producing device of holographic grating through the invention, it is convenient to omit beam expanding lens, spatial filter, optical resonator,
The costly, complicated external component such as membrance selection cavity first passes around collimating mirror and diaphragm by the light beam that laser diode emits, then adopts
It after being split with beam splitter, interferes to form interference field after reflecting mirror changes the direction of propagation respectively, interfere in setting
Holographic grating is formed on the grating substrate of field;The producing device of the holographic grating solves existing laser interferance method production grating
Device have it is at high cost, structure is complicated, bulky the problems such as.
The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be said that
Specific implementation of the invention is only limited to these instructions.For those skilled in the art to which the present invention belongs, it is not taking off
Under the premise of from present inventive concept, several equivalent substitute or obvious modifications can also be made, and performance or use is identical, all answered
When being considered as belonging to protection scope of the present invention.