CN102147289A

CN102147289A - Illumination system for portable spectrograph

Info

Publication number: CN102147289A
Application number: CN 201110007371
Authority: CN
Inventors: 张荣福; 鲁康; 林炜卫; 周进波; 曹斐
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2011-01-14
Filing date: 2011-01-14
Publication date: 2011-08-10

Abstract

The invention relates to an illumination system for a portable spectrograph. In the illumination system, light-emitting diodes (LED) are used to replace the conventional light sources. Two groups of light sources, namely a white-light LED and a blue-light LED, are in vertical arrangement. By respective collimating components, two parallel light beams, which are vertical to each other, are output, then mixed into one light beam by a light filter and finally output by a lens group. The illumination system contributes to the development of the spectrograph in microminiaturization, environmental friendliness, energy conservation, long service life and portability. Light output by the illumination light path has the characteristics of small divergence angle, uniform illumination, high light utilization ratio and the like; and the illumination system overcomes the defects caused by using the LED as the light source of the spectrograph effectively.

Description

A kind of portable spectrometer illuminator

Technical field

The present invention relates to a kind of illuminator, particularly a kind of portable spectrometer illuminator.

Background technology

LED is a kind of light emitting semiconductor device that electric energy can be changed into luminous energy, belongs to solid state light emitter.LED is a cold light source, plurality of advantages such as have the light efficiency height, operating voltage is low, power consumption is little, volume is little, firm in structure and life-span is long, but and planar package, be suitable for light and thin type and low-power consumption product.

In traditional spectrometer, the combination of using tungsten lamp or tungsten lamp and deuterium lamp mostly is as light source.Conventional light source has shortcomings such as thermal value height and life-span weak point.Along with the development of LED technology, make it will substitute conventional light source in a plurality of fields.

LED is to use dry cell as power supply as another advantage of the light source of spectrometer, the volume of spectrometer light source is reduced, thereby accomplish to carry, and most micro spectrometers in the market is not to be with light source.So led light source is trend of the times as following spectrometer light source.

Although LED development is very rapid, as the light source of spectrometer, the some shortcomings part is arranged still, do not match such as luminescent spectrum and the receiving device of single LEDs lighting source, so need carry out appropriate design to illuminator, make it reach requirement.

Summary of the invention

The present invention be directed to present spectrometer light source thermal value height, not energy-conservation, not environmental protection, not portative problem, proposed a kind of portable spectrometer illuminator, utilize LED to replace traditional light source.Designed unique led light source illumination path, not only make outgoing divergence of beam angle very little, and the collection of energy rate of light source has been higher.Utilize optical filter as closing color device, a branch of two bundle LED light compositings, thus make output spectrum intensity comparatively even.Be positioned at one group of positive and negative lens of output terminal, output facula is dwindled, obtain satisfactory hot spot, and the collimation better performances.

Technical scheme of the present invention is: a kind of portable spectrometer illuminator, comprise white light LEDs, cyan light LED, collimating element, optical filter and lens combination, white light LEDs, cyan light LED become vertical angle to place, light passes through collimating element separately, the mutually perpendicular directional light of output two bundles, synthetic a branch of by optical filter again, last scioptics group output.

Described collimating element is the integrated devices of reflector lens, the optical axis coincidence of the axle of lens and corresponding LED wherein, and the outside surface of reflector plates anti-film film, and whole collimating element is a central shaft rotation symmetry with the LED optical axis.

Plated film on the described optical filter.

Described lens combination is made up of a slice positive lens and a slice negative lens, has to dwindle illumination hot spot and achromatic function.

Beneficial effect of the present invention is: portable spectrometer illuminator of the present invention, and utilize LED to replace traditional light source, will help spectrometer and develop to microminiaturization, environmental protection, energy-conservation, long-life, light direction.Illumination path output light has characteristics such as the angle of divergence is little, illumination is even, capacity usage ratio height, has solved the some shortcomings part of LED as the spectrometer light source effectively.

Description of drawings

Fig. 1 is illumination path synoptic diagram in the portable spectrometer illuminator of the present invention;

Fig. 2 is reflector and lens integrated design synoptic diagram in the portable spectrometer illuminator of the present invention;

Fig. 3 is reflector and lens integrated design entity cut-open view in the portable spectrometer illuminator of the present invention;

Fig. 4 is the spectrum relative intensity scatter chart of illumination path output light in the portable spectrometer illuminator of the present invention;

Fig. 5 is the hot spot Illumination Distribution figure of illumination path output light in the portable spectrometer illuminator of the present invention;

Fig. 6 is the illumination and the angular relationship figure of illumination path output light in the portable spectrometer illuminator of the present invention.

Embodiment

Illumination path figure in the portable spectrometer illuminator comprises white light LEDs 1, cyan light LED2, collimating element 3, optical filter 4 and lens combination 5 as shown in Figure 1, utilizes LED to replace conventional light source.Designed unique led light source illumination path, white light LEDs 1, cyan light LED2 become vertical angle to place, light passes through collimating element 3 separately, the mutually perpendicular directional light of output two bundles, synthetic a branch of by optical filter 4 again, by being positioned at one group of positive negative lens 5 of output terminal, output facula is dwindled at last, the hot spot that obtains suiting the requirements, and collimation better performances.

Spectrometer is owing to its feature, and the spectral width of light source should meet the demands, and the relative intensity of spectrum will be mated with receiver.Because monochromatic LED spectrum is narrow all narrow, so single monochromatic LED can not need many to use simultaneously to expand spectral coverage as the light source of spectrometer.The characteristics of white light LEDs are the spectrum broads, can cover the visible light of 400nm to 800nm, and shortcoming to be the relative light intensity of spectrum distribute and receiving device does not match.Therefore, the combination by choose reasonable white light LEDs and monochromatic light LED is to solve unmatched problem.

The selected receiving device of the present invention is an ILX553B type ccd sensor, for making the spectrum relative intensity and the CCD light sensitive characteristic of illuminator output light be complementary.The design proposal of LED illumination path is to use two LEDs, and one blue light is relative with green-yellow light stronger in the spectrum for model is the white light LEDs of LCW_G5SP, and another selects model is the cyan light LED of LV_543C.The white light LEDs luminophor can be regarded a kind of Lambertian source approx as, and the light intensity on assigned direction can be expressed as

（1）

In the formula

Be the light intensity on the luminous flat normal direction,

Be the angle of direction of observation and normal direction, then at one Luminous flux in the three-dimensional cone angle can be expressed as

（2）

The angle of divergence of white light LEDs is near 180 degree, and then maximum angle, so total light flux is

（3）

When subtended angle is 60 degree, just spend, then

（4）

Subtended angle is that the luminous flux of the light of 60 degree only accounts for 1/4 of total light flux.Most of luminous flux is in the bigger zone of scattering angle.When designing, collimating element need consider the problem of scattering angle.

Collimating element 3: the basic thought of design is to utilize the high-effective concentration optical device to obtain compactness, efficient and uniform hot spot.Reflector generally adopts the structure of the paraboloid of revolution, so that reflected light is a directional light, but will be divergent beams at the axial light without the reflector reflection, therefore needs collimate to this part light.

Analyze from the shooting angle of white light LEDs, can be divided into two classes to light.The first kind is that emergence angle is less, the light that energy is comparatively concentrated.Second class is that shooting angle is bigger, the marginal ray that energy is less.Because the angle of divergence of first kind light is less, can't collimate with reflector, uses lens to collimate in the present invention; The second lightlike line angle of divergence is bigger, collimates with reflector.The curvature by the optimal design lens and the parameter of reflector are to obtain the uniform hot spot of illumination.

When design, at first to set up a rotational symmetric parabolic equation, as follows:

（5）

The formula of index plane is as follows in ZEMAX:

（6）

Wherein , k is the circular cone coefficient.When k=-1,

（7）

Formula (5) can get with formula (7),

（8）

Behind the collimation through the parabolic reflector, the emergence angle of light has narrowed down to-1 to 1 degree (50%) by original-60 to 60 degree (50%).The collimation effect is obvious.

In light path, add lens, can play the effect of collimation first kind light and harvest energy.For ease of processing, so reflector and lens are accomplished one.Fig. 2 is reflector and lens integrated design schematic diagram.The wherein axle and the optical axis coincidence of LED of lens, the outside surface of reflector need be coated with high-reflecting film, entire device rotational symmetry structure, the first half of only drawing sectional view among the figure.Just obtained solid model after the schematic diagram of Fig. 2 pivots, shown in Figure 3 is the cut-open view of solid model.

The angle of divergence that obtains the reflector collimated light on the detector of distance reflector 35mm is-1.8 to 1.8 degree.Under the situation of not considering absorbed, the energy that receives on the detector be LED send luminous energy 90%.

Splicer spare 4: the present invention adopts the combination of white light and cyan light LED, uses optical filter as splicer spare, and it is synthetic a branch of that two LED are sent two-beam, thereby makes spectral light intensity and receiving device light sensitive characteristic coupling.

If with the luminous energy stack of two kinds of LED, can not satisfy the requirement of illumination light spectrum relative intensity and receiving device light sensitive characteristic coupling so simply.Therefore when the optical filter of color device is closed in the design conduct, need take all factors into consideration the relative distribution of spectral light intensity of two kinds of LED and the light sensitive characteristic of CCD.By optimal design and be coated with suitable wavelengths selectivity filter coating, be illustrated in figure 4 as the spectral light intensity curve of illuminator output light.

Collector lens group 5: after the light that light source penetrates collimated by reflector, the output radius was the light of the angle of divergence of 15mm for-1.8 to 1.8 degree.In order to improve the efficiency of light energy utilization, behind optical filter, add the lens combination of forming by positive lens and negative lens, to reach the purpose of dwindling hot spot.The structure of similar Galileo telescope is adopted in design, and two lens adopt low chromatic dispersion material, reduce the chromatic dispersion of light.

As the light source of spectrometer, the size of hot spot and the homogeneity of illumination there is certain requirement.Figure 5 shows that the hot spot illumination figure of illumination path output light, its spot radius is about 1.5mm, and the hot spot illuminance uniformity is more than 90%.Fig. 6 can obtain output facula for illumination and angular relationship figure scattering angle for-3 to 3 degree about (50%).

Claims

1. portable spectrometer illuminator, it is characterized in that, comprise white light LEDs, cyan light LED, two collimating elements, optical filter, lens combination, white light LEDs, cyan light LED become vertical angle to place, white light LEDs, cyan light LED are contained in respectively in separately the collimating element, the collimating element of light by separately, the mutually perpendicular directional light of output two bundles, synthetic a branch of by optical filter again, last scioptics group output.

2. according to the described portable spectrometer illuminator of claim 1, it is characterized in that, described collimating element is the integrated devices of reflector lens, the optical axis coincidence of the axle of lens and corresponding LED wherein, the outside surface of reflector plates anti-film film, and whole collimating element is a central shaft rotation symmetry with the LED optical axis.

3. according to the described portable spectrometer illuminator of claim 1, it is characterized in that plated film on the described optical filter.

4. according to the described portable spectrometer illuminator of claim 1, it is characterized in that described lens combination is made up of a slice positive lens and a slice negative lens, have and dwindle illumination hot spot and achromatic function.