CN103293700A - Optical mixing rod vibration structure for laser illumination speckle reduction - Google Patents

Abstract

The invention provides an optical mixing rod vibration structure for laser illumination speckle reduction, and belongs to the technical field of laser illumination. The optical mixing rod vibration structure comprises a coupling lens, an optical mixing rod, a vibration mechanism and a control circuit; laser emitted by an optical source is gathered via the coupling lens, is outputted into an incident surface of the optical mixing rod and is outputted via an emergent surface of the optical mixing rod; the optical mixing rod is fixed into the vibration mechanism and vibrates vertically in a constant amplitude manner. The axis of the optical mixing rod is coincided with the optical axis of the laser outputted by the coupling lens when the optical mixing rod is in a non-vibration state. The control circuit controls the amplitude and the frequency of vibration of the vibration mechanism. The optical mixing rod vibration structure has the advantages that an extra shaping lens which is an optical device is omitted, efficient shaped illumination is implemented, and the size of a system is reduced; the energy efficiency and a polarization characteristic of the laser are maintained while speckles are reduced.; the shape of a speckle-free illumination spot is matched with that of a projection chip, and the energy utilization efficiency of illumination beams is improved.

Description

A kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle

Technical field

The present invention relates to a kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle, belong to the laser lighting technical field.

Background technology

Compare with conventional light source, have advantages such as colour gamut is wide, resolution is high, the life-span is long, brightness is high, optical system is compact, photoelectric transformation efficiency height with laser as the display technique of light source, be usually used in the projection lighting field.But when laser shone coarse surface (as projection screen), scattered beam can mutually be interfered, after communication space in form light distribution at random.This light distribution is observed by intensity detector (as human eye), namely is so-called speckle phenomena.Speckle has a strong impact on projected image quality, and this is one of bottleneck problem of laser lighting application.During laser projection was used, speckle must be suppressed.

The approach that addresses this problem is chiefly directed to places scatterer to realize the phase place modulation and to suppress speckle in the travel path of light beam.Use for laser projection, the loss that the method for employing scatterer can be brought illumination energy, this hinders the application of this method in practical Color Laser Projection Technology.

Another kind of technological approaches is based on the speckle technology for eliminating of rotation optical mixing rod, this technology can suppress speckle contrast when keeping the elementary beam energy, the laser facula after but this method of process suppresses is circular, and projection chip and the projection image used always at present are rectangle, in the actual illumination stage, because not matching of light spot shape and photo chip form can be brought the loss of energy, if want both to mate the extra shaping lens group of needs.

Summary of the invention

The invention discloses a kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle, not only solved the contradiction between energy efficiency and speckle suppress in the speckle process of inhibition, and guarantee the coupling of emergent light shape of spot and projection chip form further to have improved the beam energy utilization factor.

A kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle comprises coupled lens, optical mixing rod, vibrating mechanism and control circuit.Light source emission laser, laser enters coupled lens, and coupled lens converges the laser that light source sends, and exports in the plane of incidence of optical mixing rod.Optical mixing rod is fixed in the vibrating mechanism, and vibrating mechanism drives optical mixing rod and makes continuous vibration up and down.The axle of optical mixing rod and coupled lens are exported the optical axis coincidence of laser under the non-vibration state.Laser is by behind the optical mixing rod, from the exit facet output of optical mixing rod; Control circuit is finished the control to vibrating mechanism amplitude and frequency.

The amplitude of vibrating mechanism is set smaller or equal to the largest deformation amount w of optical mixing rod _Max:

$w_{\max }={2K}_{\mathrm{cD}}{a}^3/\left(\mathrm{Ebc}\sqrt{\mathrm{\πb}}\right)$

Wherein, E is elasticity modulus of materials, and b, c are respectively the length of xsect of optical mixing rod and wide, and a is half length of optical mixing rod, K _CDIt is the value of the dynamic fracture toughnes of optical mixing rod material.

The vibration frequency of vibrating mechanism arranges according to human eye integral time, and minimum set is 20Hz.

Advantage of the present invention and good effect are:

(1) need not extra shaping lens optical device, realized efficient shaping illumination, dwindled system dimension;

(2) adopt vibration optical mixing rod structure, when eliminating speckle, can keep energy efficiency and the polarization characteristic of laser, solved that speckle in the conventional laser speckle technology for eliminating is eliminated and energy efficiency between contradiction;

(3) realize the coupling of no speckle illumination light spot shape and projection chip, improved the energy utilization efficiency of illuminating bundle.

Description of drawings

Fig. 1 is the synoptic diagram of optical mixing rod vibrational structure of the present invention;

Fig. 2 is the cut-open view of vibrational structure of the present invention;

Fig. 3 is the front elevation of fixed component of the present invention;

Among Fig. 4, (a) for entering the speckle pattern before the optical mixing rod, (b) be the output pattern when the optical mixing rod whirling vibration cycle being 50ms.

Among the figure:

1-coupled lens, 2-optical mixing rod, 3-vibrating mechanism

4-control circuit, 5-fixed component, 6-supporting member

7-screw 8-buffering fixed component 31-piezoelectric ceramics A

32-piezoelectric ceramics B, 51-stationary fixture, 52-transparent optical cement

Embodiment

The present invention is described in further detail below in conjunction with drawings and Examples.

The present invention is a kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle, as shown in Figure 1, comprises coupled lens 1, optical mixing rod 2, vibrating mechanism 3 and control circuit 4.

Light source emission one-wavelength laser, laser enters coupled lens 1, and the laser that 1 pair of light source of coupled lens sends converges, and exports in the plane of incidence of optical mixing rod 2.

Optical mixing rod 2 is arranged in vibrating mechanism 3, and vibrating mechanism 3 drives optical mixing rod 2 and makes continuous vibration.The optical axis coincidence of the axle of optical mixing rod 2 and coupled lens 1 output laser under the non-vibration state, laser is exported from the exit facet of optical mixing rod 2 by behind the optical mixing rod 2.

Described optical mixing rod 2 adopts the cylindricality solid construction, and the cross section is rectangle, and barred body employing refractive index is 1.518 K9 glass, and four lateral surfaces of optical mixing rod 2 all are coated with one deck and increase anti-film, and the plane of incidence of optical mixing rod 2 and exit facet respectively plate one deck anti-reflection film.Optical mixing rod 2 is of a size of 3.2mm * 1.8mm * 40mm in the embodiment of the invention, and the Aspect Ratio of xsect is 16:9.The Aspect Ratio of exit facet is the Aspect Ratio of xsect just, with projection chip coupling, improves projection lighting efficient.

Described optical mixing rod 2 is accompanied by crooked deformation in vibration processes, according to theory of mechanics of materials, and elastic modulus E=79.2GPa, the statistical value K of static fracture toughness _CS=0.82MPam ^1/2, the value of dynamic fracture toughnes generally is 30% of static fracture toughness statistical value, so the value K of dynamic fracture toughnes _CD=0.25MPam ^1/2, a is half length of optical mixing rod, and a is half of 40mm in the embodiment of the invention, and b, c are respectively the length of xsect of optical mixing rod and wide, and b is 3.2mm in the embodiment of the invention, c is 1.8mm.Can extrapolate the largest deformation amount w of optical mixing rod 2 according to following formula _Max=699.6 μ m.

$w_{\max }={2K}_{\mathrm{cD}}{a}^3/\left(\mathrm{Ebc}\sqrt{\mathrm{\πb}}\right)$

As shown in Figure 2, optical mixing rod 2 is fixed in the vibrating mechanism 3, and vibrating mechanism 3 comprises fixed component 5, supporting member 6, buffering fixed component 8, piezoelectric ceramics A31 and piezoelectric ceramics B32.The two ends of optical mixing rod 2 are fixed on the supporting member 6 by fixed component 5, and fixed component 5 is fixed on the supporting member 6 by screw 7.Piezoelectric ceramics A31 and piezoelectric ceramics B32 are vibrating mass, and vibrating mass links to each other with the middle part of optical mixing rod 2, drive optical mixing rod 2 and make up-down vibration, and optical mixing rod 2 each vibrations are accompanied by crooked deformation.Piezoelectric ceramics A31 and piezoelectric ceramics B32 are perpendicular to the systematic optical axis under the non-vibration state, and symmetry is placed on optical mixing rod mid point both sides, and piezoelectric ceramics A31 links to each other with optical mixing rod 2 by buffering fixed component 8 with optical mixing rod 2 with piezoelectric ceramics B32.The amplitude of piezoelectric ceramics A31 and piezoelectric ceramics B32 and frequency adjustable, to satisfy the different demands in the illumination, peak swing is to be exactly the largest deformation amount w of optical mixing rod 2 _MaxThe vibration frequency of vibrating mechanism arranges according to human eye integral time, and minimum set is 20Hz.

As shown in Figure 3, fixed component 5 comprises stationary fixture 51 and transparent optical cement 52, and optical mixing rod 2 is fixedly connected by transparent optical cement 52 with stationary fixture 51, and stationary fixture 51 is fixed on the supporting frame 6 by screw 7.

Control circuit 4 adopts DSP, finishes the control to vibrating mechanism 3 amplitudes and frequency, according to the largest deformation amount setting of top optical mixing rod 2.In the embodiment of the invention at optical mixing rod 2 material that adopts, but the maximal value of set amplitude is 600 μ m, guarantees can not fracture in the vibration processes, the cycle maximal value is 50ms, satisfies the integration demand of human eye.Be, control circuit 4 controlled amplitude and frequencies of neutralizing electroceramics 31 and piezoelectric ceramics 32 are respectively 600 μ m and 20Hz.

The high degree of polarisation of light source emission and relevant laser, laser is finished repeatedly total reflection in the optical mixing rod 2 of continuous vibration up and down, the multi beam illuminating bundle of outgoing has different optical path differences and phase differential, finish the superposed average in the finite aperture, superposed average can't form stable speckle striped each other, reaches the purpose of eliminating speckle.

Compare with traditional speckle technology for eliminating, the present invention drives optical mixing rod 2 by vibrating mechanism 3 and makes the constant amplitude up-down vibration along plane, optical axis place, amplitude and frequency adjustable, when adopting the vibration period of 50ms, finish mutual superposition to the light beam of out of phase in integral time in (50ms) at human eye, be equivalent to the sample averaging of several separate speckle pattern, reach the purpose of eliminating speckle, can under the prerequisite that keeps elementary beam 90% energy, speckle contrast be dropped to below 6% in the actual test of the present invention.

The cross sectional shape of optical mixing rod 2 of the present invention is corresponding with projection chip form ratio, and the light beam that goes out to inject optical mixing rod 2 from LASER Light Source is constrained to a rectangular light spot identical with aspect ratio, and illumination efficiency is up to 90%.

The result that speckle of the present invention is eliminated as shown in Figure 4, (a) of Fig. 4 is for entering the speckle pattern before the optical mixing rod 2, the output pattern when (b) of Fig. 4 is 50ms for the 2 whirling vibration cycles of optical mixing rod can find that speckle has obtained eliminating effectively.

Claims (6)

1. one kind is used for the optical mixing rod vibrational structure that the laser lighting speckle is eliminated, and it is characterized in that, comprises coupled lens, optical mixing rod, vibrating mechanism and control circuit; Light source emission laser, laser enters coupled lens, and coupled lens converges the laser that light source sends, and exports in the plane of incidence of optical mixing rod; Optical mixing rod is fixed in the vibrating mechanism, and vibrating mechanism drives optical mixing rod and makes continuous vibration up and down, and the axle of optical mixing rod and coupled lens are exported the optical axis coincidence of laser under the non-vibration state; Laser is by behind the optical mixing rod, from the exit facet output of optical mixing rod; Control circuit is finished the control to vibrating mechanism vibration frequency and amplitude;

The setting of the amplitude of vibrating mechanism is smaller or equal to the largest deformation amount w of optical mixing rod _Max:

$w_{\max }={2K}_{\mathrm{cD}}{a}^3/\left(\mathrm{Ebc}\sqrt{\mathrm{\πb}}\right)$

Wherein, E is elasticity modulus of materials, and b, c are respectively the length of xsect of optical mixing rod and wide, and a is half length of optical mixing rod, K _CDIt is the value of the dynamic fracture toughnes of optical mixing rod material;

The vibration frequency of vibrating mechanism arranges according to human eye integral time, and minimum set is 20Hz.

2. a kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle according to claim 1 is characterized in that described vibrating mechanism comprises fixed component, supporting member, buffering fixed component, piezoelectric ceramics A and piezoelectric ceramics B; The two ends of optical mixing rod are fixed on the supporting member by fixed component, and fixed component is fixed on the supporting member by screw; Piezoelectric ceramics A and piezoelectric ceramics B are perpendicular to the systematic optical axis under the non-vibration state, and symmetry is placed on optical mixing rod mid point both sides, and link to each other with the middle part of optical mixing rod by the buffering fixed component, drive optical mixing rod and make up-down vibration.

3. a kind of optical mixing rod vibrating mechanism of eliminating for the laser lighting speckle according to claim 2, it is characterized in that, described fixed component comprises stationary fixture and transparent optical cement, optical mixing rod is fixedly connected by transparent optical cement with stationary fixture, and stationary fixture is fixed on the supporting frame by screw.

4. according to claim 2 or 3 described a kind of optical mixing rod vibrational structures for the elimination of laser lighting speckle, it is characterized in that, described optical mixing rod adopts the cylindricality solid construction, the cross section is rectangle, barred body employing refractive index is 1.518 K9 glass, four lateral surfaces of optical mixing rod all are coated with one deck and increase anti-film, and the plane of incidence of optical mixing rod and exit facet respectively plate one deck anti-reflection film.

5. a kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle according to claim 4 is characterized in that the Aspect Ratio of the exit facet of described optical mixing rod is 16:9.

6. a kind of optical mixing rod vibrational structure for the elimination of laser lighting speckle according to claim 1 is characterized in that described control circuit adopts DSP.

Images