CN117666115A - Super-resolution coded light source based on digital micromirror device - Google Patents

Abstract

The invention relates to a super-resolution coded light source based on a digital micromirror device, which comprises: the device comprises an optical signal input module, a two-dimensional dispersion module, a code modulation module and an optical coupling output module. Wherein the optical signal input module comprises a broadband light source (400-700 nm), an achromatic lens, a collimating mirror and an optical power adjuster for generating an adjustable intensity of parallel broadband white light; the two-dimensional dispersion module comprises a reflection type echelle grating, a reflection type dispersion prism and a relay reflector and is used for generating super-resolution two-dimensional spectrum distribution; the code modulation module comprises a relay lens, a digital micro-mirror device and a computer and is used for coding the two-dimensional spectrum distribution and realizing modulation of an output spectrum; the optical coupling-out module comprises a converging lens, an integrating sphere, a collimating lens and an adjustable aperture, and is used for carrying out beam combination, collimation and output on the light after spectrum coding and controlling the size of the output light beam. The invention obtains super-resolution two-dimensional spectrum distribution of light energy concentration by combining the echelle grating and the prism, and codes and modulates the spectrum of output light by utilizing a programmed control digital micromirror device to obtain the ultra-high-precision spectrum encodable light source, thereby solving the problems of incapability of encoding and modulating the spectrum of the existing light source or low modulation precision and insufficient signal to noise ratio of the output light.

Description

Super-resolution coded light source based on digital micromirror device

Technical Field

The invention belongs to the technical field of optical instruments and spectral imaging, and particularly relates to a super-resolution coded light source based on a digital micromirror device.

Background

The light source is an important element in the optical field, is a fundamental source of target optical information, and has wide application in aspects of microscopic illumination, optical imaging, polarization measurement and the like, and is particularly important in spectral imaging and detection. According to the bandwidth of the light source, the common light sources are classified into a broadband light source and a monochromatic light source, wherein the broadband white light source comprises an incandescent lamp, a halogen tungsten lamp, a mercury lamp, a sodium lamp and the like, and the monochromatic light source comprises a monochromatic Light Emitting Diode (LED), a laser, a monochromator and the like.

With the progress of science, the demands of various fields for light sources are gradually increased, and a modulated multiple color light source capable of obtaining specific wavelength components has become a novel demand. White light sources are complex colored lights containing multiple bands, but their spectral distribution needs to be measured and the composition of the complex colored light is not easily changed. Although the LED array can obtain multi-band complex color light, it is difficult to realize high-precision spectral modulation due to the large half-width of the peak of the single-color LED. Although lasers and monochromators can obtain monochromatic light with high precision, they cannot be used for broadband spectrum modulation, and have many limitations in practical use. Aiming at the limitations of the existing light source, the invention designs a super-resolution coded light source based on the modulation principle of a digital micro-mirror device (Digital Micromirror Devices, DMD) and the advantages of high spectrum resolution of an echelle grating and capability of realizing full-band blaze by concentrating the spectral energy.

Disclosure of Invention

Aiming at the defects of the existing light source, the invention provides a coded light source with high spectral resolution, which adopts an echelle grating and a prism to carry out two-dimensional dispersion, uses a DMD to carry out coded modulation on a dispersion result, outputs an aliased light source with a specific wave band, improves the spectral resolution of system coding, and solves the limitations that the spectral components of the existing broadband light source can not be modulated and the modulation precision of the coded light source is insufficient.

In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:

the invention discloses a super-resolution coded modulation light source based on a digital micromirror device, which comprises the following components: the device comprises an optical signal input module, a two-dimensional dispersion module, a code modulation module and an optical coupling output module.

Further, the optical signal input module comprises a broadband light source (400-700 nm), an optical power adjuster, an achromatic lens and a collimating mirror for generating achromatic parallel light. The broadband light source is arranged at the focus of the achromatic lens and is coaxially arranged with the achromatic lens and the collimating reflector in sequence. The light beam of the broadband light source becomes a parallel light beam after passing through the collimating reflector.

Further, the two-dimensional dispersion module comprises a reflective echelle grating, a reflective dispersion prism and a relay reflector, and is used for generating two-dimensional spectral distribution with high spectral resolution and transmitting the two-dimensional spectral distribution to the code modulation module through the relay reflector. The dispersion directions of the reflection type echelle grating and the reflection type dispersion prism are mutually perpendicular, so that the dispersion prism is ensured to separate multistage aliased spectrums after the dispersion of the echelle grating in the direction perpendicular to the multistage aliased spectrums. The reflective dispersion prism requires multiple retractions of the beam to improve the resolution of dispersion.

Further, the code modulation module includes: the relay lens, the DMD and the computer are used for carrying out code modulation on the dispersed two-dimensional spectrum distribution to obtain a coded light beam with a specific wave band. The relay lens is used for converging the two-dimensional spectral distribution to the DMD target surface so as to control the size of the light beam on the DMD target surface.

Further, the light out-coupling module includes: the converging lens, the integrating sphere, the collimating lens and the adjustable aperture are used for carrying out beam combination, collimation and output on the light after spectrum coding and controlling the size of the output light beam.

Preferably, the broadband light source is connected to the optical power regulator, and the optical power regulator provides the light source power and controls the input light intensity.

Preferably, the collimating mirror is a spherical mirror.

Preferably, the reflection echelle grating is placed at a certain offset angle in the non-dispersion direction, so that the diffracted light and the incident light are ensured not to overlap.

Preferably, the relay mirror is a spherical mirror.

Preferably, the DMD is connected to a computer and the coding pattern of the DMD is controlled by the computer.

Preferably, the light exit of the integrating sphere is located at the focal point of the collimating lens.

Preferably, the optical paths of the two-dimensional dispersion module and the code modulation module adopt an M-shaped Cheny-Turner (Czerny-Turner) symmetrical structure.

The super-resolution coded light source based on the digital micromirror device has the following gain effects:

1. the invention adopts a two-dimensional dispersion module, an echelle grating firstly carries out dispersion in a sagittal direction to obtain a dispersion result containing a plurality of diffraction orders, then a dispersion prism carries out dispersion again on a primary dispersion result in a meridian direction, an aliasing spectrum containing a plurality of diffraction orders is separated, and ultra-high resolution spectrum distribution is obtained on a two-dimensional image plane so as to realize finer spectrum light splitting.

2. The primary dispersion of the two-dimensional dispersion module in the invention uses echelle grating, has the advantages of full-band blaze and concentrated light intensity, and the output coded light source has higher signal-to-noise ratio.

3. The invention adopts DMD to modulate the spectrum of two-dimensional dispersion, the micro-mirror in the DMD corresponds to quasi-monochromatic light of a certain wavelength one by one, and the aliasing light source with a specific wave band component is output by controlling the angle of the micro-mirror in the DMD, thereby realizing the output spectrum modulation.

4. The optical path system of the invention adopts an M-shaped Cheny-Turner symmetrical structure, has higher spectral resolution, greatly shortens the optical path length and reduces the optical path volume.

Drawings

Fig. 1: the optical path structure of the invention is schematically shown; wherein: 1-a broadband light source (400-700 nm); 2-achromatic lenses; 3-collimating mirror; 4-reflective echelle grating; a 5-reflection type dispersion prism; a 6-relay mirror; 7-a relay lens; 8-DMD; 9-a converging lens; 10-integrating sphere; 11-a collimating lens; 12-adjustable aperture; 13-an optical power regulator; 14-computer.

Fig. 2: the DMD encoding pattern sample of the present patent wherein: white represents light that can be transmitted and black represents light that cannot be transmitted.

Fig. 3: examples of output spectral encoding results of the present patent wherein the output spectral encoding results of (a), (b) and (c) correspond to the DMD encoding patterns of (a), (b) and (c), respectively, in fig. 2.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present invention. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the inventor, are within the scope of the invention.

In the description of the present patent, it should be understood that the terms "center," "longitudinal," "transverse," "upper," "lower," "front," "rear," "left," "right," "horizontal," "vertical," "top," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate describing the present patent and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present patent. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The patent of the invention is further described below with reference to the accompanying drawings:

fig. 1 is a schematic diagram of an optical path structure of a super-resolution coded light source based on a digital micromirror device, which comprises an optical signal input module, a two-dimensional dispersion module, a coded modulation module and an optical coupling-out module.

Preferably, the optical signal input module comprises a broadband light source 1, an achromatic lens 2, a collimating mirror 3 and an optical power adjuster 13 for generating an achromatic parallel light input.

Preferably, the two-dimensional dispersion module includes a reflective echelle grating 4, a reflective dispersion prism 5, and a relay mirror 6 for secondarily dispersing the incident light to generate a two-dimensional spectral distribution.

Preferably, the coded modulation module comprises a relay lens 7, a DMD 8 and a computer 14. For spectrally encoding a two-dimensional spectral distribution.

Preferably, the light out-coupling module comprises: the converging lens 9, the integrating sphere 10, the collimating lens 11 and the adjustable aperture 12 are used for carrying out beam combination, collimation and output on the light after spectrum coding and controlling the size of the output light beam.

In this embodiment, the light path of the super-resolution coded light source based on the digital micromirror device is as follows:

s1, broadband light source 1 generates broadband white light with the wavelength range of 400-700nm, and the broadband white light generates an input light signal after system achromatism and collimation.

S2, after the input optical signal is dispersed along the sagittal direction by the reflection type echelle grating 4, secondary dispersion is carried out in the meridian direction by the reflection type dispersion prism 5, so that overlapping spectrums of multiple diffraction orders after grating dispersion are separated, and finer two-dimensional spectrum distribution is generated on a two-dimensional plane.

S3, the relay reflector 6 reflects the two-dimensional spectral distribution, the two-dimensional spectral distribution is focused on the DMD 8 by the relay lens 7, and a coding pattern is input on the computer 14 to control the coding effect of the DMD 8 on the two-dimensional spectral distribution.

S4, the converging lens 9 converges the light after spectrum coding into the integrating sphere 10, the light with different wavelengths is continuously reflected in the integrating sphere, the combined beam is uniform broadband light, and then the uniform broadband light is emitted at the light emitting port of the integrating sphere. The collimating lens 11 collimates the outgoing light, and the size of the light beam is adjusted by the adjustable aperture 12 and then output.

Specifically, in the above step S1, the intensity of the input optical signal is controlled by the optical power adjuster 13 connected to the broadband light source 1.

Specifically, in the above step S1, the dispersion direction (horizontal direction) of the reflection echelle grating 4 is referred to as a sagittal plane, and the direction perpendicular thereto is referred to as a meridional plane, with the reflection echelle grating 4 as a reference system.

Specifically, in the above step S2, under the quasi-Littrow condition, the dispersion of the echelle grating 4 is described as:

where d is the grating period, i is the angle of incidence, θ is the angle of diffraction, ω is the grating offset angle, λ is the wavelength, and m is the diffraction order.

The angular dispersion of the grating is:

the dispersion resolution of the grating is:

where N is the number of raster lines. The dispersion prism separates the multi-stage overlapped spectrum after the echelle grating is split, and the dispersion resolution of the dispersion prism is as follows:

where t is the geometric length of the light passing through the upper and lower edges of the prism and n is the refractive index of the prism.

Specifically, in the step S2, the spectrum distribution after the two-dimensional dispersion increases from left to right in the sagittal direction, and increases from bottom to top in the meridional direction.

Specifically, in the above step S3, the relay lens 7 has the functions of focusing the dispersion result and filtering out stray light in the two-dimensional spectral distribution, thereby correcting astigmatism.

Specifically, in step S3, the DMD 8 is an array having a plurality of micromirrors, and the direction of each micromirror is controlled by computer programming, so that the undesired light is reflected out of the optical path to realize modulation. The DMD 8 discretizes the spectrum distribution after the two-dimensional dispersion, the micromirrors are in one-to-one correspondence with the wavelengths, and the coding pattern of the DMD 8 is set by the computer 14, so that the direction of each micromirror is adjusted, and the coding of the two-dimensional spectrum distribution is realized.

Further, fig. 2 shows 3 examples of DMD 8 coding patterns in the present invention, wherein the white portions indicate that the micromirror is capable of transmitting light, and the black portions indicate that the micromirror is not capable of transmitting light.

Further, fig. 3 is a sample of the modulation results of the coded light source according to the present invention, wherein the light source modulation results of (a), (b) and (c) correspond to the DMD 8 coding patterns of (a), (b) and (c) in fig. 2, respectively, wherein the red line represents the spectrum curve of the input light and the black line represents the spectrum curve of the output light after coding. Therefore, through designing the coding pattern of the DMD 8, various modulations such as downsampling, bandpass filtering, random coding and the like of the spectrum of the light source can be realized, the design requirement of the invention is met, and the defects of the traditional light source are overcome.

The above is only for illustrating the technical ideas of the present invention, and the protection scope of the present invention is not limited by the above, and any modification made on the basis of the technical scheme according to the technical ideas of the present invention falls within the protection scope of the patent claims of the present invention.

Claims (10)

1. A digital micromirror device-based super-resolution coded light source, comprising: the device comprises an optical signal input module, a two-dimensional dispersion module, a code modulation module and an optical coupling output module.

2. A digital micromirror device based super-resolution coded light source according to claim 1, characterized in that the optical signal input module comprises a broadband light source (400-700 nm) (1), an achromatic lens (2), a collimating mirror (3) and an optical power adjuster (13).

3. A digital micromirror device-based super-resolution coded light source according to claim 1, characterized in that the optical power regulator (13) is connected to the broadband light source (1) to supply power to the broadband light source (1) and regulate its input light intensity; the broadband light source (1) is arranged at the focus of the achromatic lens (2) and is coaxially arranged with the achromatic lens (2) and the collimating reflector (3) in sequence; the light of the broadband light source (1) becomes a parallel light beam after passing through the collimating reflector (3); the collimating mirror (3) is a spherical mirror.

4. The super-resolution coded light source based on a digital micromirror device according to claim 1, wherein the two-dimensional dispersion module comprises a reflective echelle grating (4), a reflective dispersion prism (5) and a relay mirror (6).

5. The super-resolution coded light source based on a digital micromirror device according to claim 1, wherein the dispersion directions of the reflective echelle grating (4) and the reflective dispersion prism (5) are perpendicular to each other, so that the incident parallel light beam is ensured to be dispersed twice in the direction perpendicular to each other, and two-dimensional spectrum distribution is formed; the reflection echelle grating (4) is placed at a certain offset angle in the non-dispersion direction so as to avoid overlapping of diffracted light and incident light; the reflective dispersion prism (5) needs to fold back the light beam for a plurality of times to improve the resolution of dispersion; the relay mirror (6) is a spherical mirror.

6. A digital micromirror device based super resolution coded light source according to claim 1, characterized in that the coded modulation module comprises a relay lens (7), a digital micromirror device (Digital Micromirror Devices, DMD) (8) and a computer (14).

7. A super-resolution coded light source based on a digital micromirror device according to claim 1, characterized in that the computer (14) is connected to the DMD (8) to synchronously control the coding pattern of the DMD (8), the two-dimensional spectral distribution being coded modulated in the spectral dimension after passing the DMD (8).

8. The digital micromirror device-based super-resolution coded light source according to claim 1, wherein the light out-coupling module comprises: a converging lens (9), an integrating sphere (10), a collimating lens (11) and an adjustable aperture (12).

9. The super-resolution coded light source based on the digital micromirror device according to claim 1, wherein the converging lens (9) converges the coded two-dimensional spectrum into an integrating sphere (10), the integrating sphere (10) outputs the light after collimating the outgoing light by the collimating lens (11) to combine the light beams with different wavelengths; the adjustable aperture (12) is capable of adjusting the aperture size to control the spot size of the output beam; the light exit opening of the integrating sphere (10) is located at the focus of the collimating lens (11).

10. The super-resolution coded light source based on a digital micromirror device according to claim 1, wherein the light paths of the two-dimensional dispersion module and the coded modulation module adopt an M-shaped chernian-Turner (Czerny-Turner) symmetrical structure.