CN100338444C - Laser intensity adjusting device - Google Patents

Abstract

The present invention provides a laser intensity adjusting device which has the advantages of reducing the requirements for the precision of mechanical manufacture and routine maintenance. The laser intensity adjusting device comprises a neutral density filter and a step motor which can drive the neutral density filter to rotate to a definite angular position. In a system, laser beams transmitting the neutral density filter irradiate a gene chip to generate excited fluorescence signals, and the signals are focused to a field diaphragm of the focal surface of a convergent lens unit through the convergent lens unit and are received by a detector which is arranged behind the field diaphragm, wherein the surface normal of the neutral density filter forms a definite included angle alpha with the incident laser beams; the included angle alpha meets the following formula: alpha>=2 d/f, and d and f are respectively the diameter of the field diaphragm and the focal length of the convergent lens unit.

Description

A kind of laser intensity regulating device

Skill this area

The present invention relates to the laser intensity regulation technology, particularly a kind of device that adopts neutral density filter to regulate laser intensity.

Background technology

Laser is used as excitation source with its outstanding collimation and many characteristics such as monochromaticity and high light intensity in genetic chip scanning fluorescence detecting system.The Chinese patent application 00127926.2 that on Dec 18th, 2000 submitted to has disclosed a kind of confocal fluorescent detection optical system, it is made of object lens, catoptron or color separation film, convergent mirror, pin hole, laser beam after the reflection of catoptron or color separation film by object lens focusing on the genetic chip surface, thereby excite the fluorescent dye of genetic chip to produce fluorescence signal, wherein a part of fluorescence signal object lens are collimated into directional light, and focusing on pin hole or diaphragm on its focal plane through convergent mirror, the photoelectric sensor that is positioned at the pin hole place is surveyed.

The general photomultiplier that adopts is as photoelectric sensor, because the light intensity of laser is very strong, therefore the laser beam that always has quite a few to shine on the genetic chip is understood the directive photomultiplier, for photomultiplier, the fluorescence signal of its reception is the signal of wish gathering, and laser signal then is to wish the noise that reduces as far as possible.For this reason, on the one hand, can a filtering apparatus be set on the light path before the photomultiplier, it has different transmitances to fluorescence and laser, utilizes its low transmission to laser to stop the laser beam of excitation source to enter photomultiplier; On the other hand, also can select suitable laser intensity to obtain best signal to noise ratio (S/N ratio) according to the intensity of excited fluorescence.

In order to adjust the laser intensity that incides on the genetic chip, generally between laser instrument and genetic chip, neutral density filter is set.Neutral density filter is a disk that is coated with the reflective film of the along the circumferential direction ascending or descending continuous variation of reflectivity, therefore by making laser beam incident to the different band of position, angle of disk, can change the ratio of laser beam reflection and transmissive portions branchs, thereby reach the purpose of adjusting through the laser intensity of neutral density filter.

Utilize in the method that neutral density filter adjusts light intensity above-mentioned, this optical filter is when making light beam from laser instrument be transmitted through genetic chip, also the laser beam of returning from the genetic chip surface had very strong reflex, this makes laser beam repeatedly reflection back and forth between genetic chip surface and neutral density filter, thus on the genetic chip surface fluorescence excitation repeatedly.Because neutral density filter can not be absolute vertical with incoming laser beam, so the laser beam through neutral density filter reflected back genetic chip is no longer parallel with incoming laser beam, positions different on the genetic chip will be focused to, thereby make on the scanning genetic chip during a certain position, photomultiplier not only receives signal this position excited fluorescence signal, also receive other position excited fluorescence signals that are considered as parasitic light, these parasitic lights or noise will cause the reduction of whole detection system sensitivity this moment.

Summary of the invention

The purpose of this invention is to provide a kind of laser intensity regulating device that conjugation focuses on the genetic chip fluorescence detecting system that is used for, it has solved the problem of the detection system sensitivity reduction that causes because of neutral density filter and incoming laser beam out of plumb.

Above-mentioned purpose of the present invention is achieved through the following technical solutions:

A kind of laser intensity regulating device that is used for conjugation focusing genetic chip fluorescence detecting system, comprise neutral density filter and can drive the stepper motor that it turns to position, certain angle, in system, transmission is crossed the laser beam irradiation of neutral density filter to genetic chip, the excited fluorescence signal that is produced focuses to the field stop place that is positioned on its focal plane and is received by the detecting device after being positioned at field stop through the convergent lens unit, wherein, the surface normal of neutral density filter and the laser beam of incident are certain included angle α, and described angle α satisfies following formula:

α≥2d/f

Here, d and f are respectively the focal length of described field stop diameter and convergent lens unit.

Reasonable is that in the above-mentioned laser intensity regulating device that is used for two laser conjugation focusing genescan instrument, the laser intensity range of adjustment of neutral density filter is 1～100%.

In the present invention, the normal of neutral density filter and laser beam are also not parallel but depart from an enough big angle [alpha], the spuious fluorescence that so just can make between genetic chip and neutral density filter repeatedly the laser light reflected bundle and be excited deflects away from outside the visual field of optical system, has removed the influence of the parasitic light of these similar noises.

Description of drawings

By below in conjunction with the accompanying drawing description of this invention, can further understand purpose of the present invention, feature and advantage, wherein:

Fig. 1 is the application exemplary plot of laser intensity regulating device of the present invention in gene chip scanning instrument.

Embodiment

Below by accompanying drawing laser intensity regulating device of the present invention is described.

In Fig. 1, neutral density filter 5 and stepper motor 6 constitute the laser intensity regulating device, and wherein, the band of position, neutral density filter 5 different angle has different reflectivity, and its variation range is between 1～100%.Neutral density filter 5 is fixed in the rotating shaft of stepper motor 6, laser beam 7 is with changeless direction incident, therefore when stepper motor 6 drives center density optical filter 5 rotating certain angle, laser beam 7 will be incident on the different bands of position, angle, thereby obtain the transmission laser bundle of respective strengths.

As shown in Figure 1, except the laser intensity regulating device, whole conjugation focuses on the genetic chip fluorescence detecting system and also comprises photomultiplier 1, field stop 2, convergent lens unit 3 and beam splitter 4.The laser beam 7 of coming from center density optical filter 5 transmissions reflexes on the genetic chip 8 through beam splitter 4, the dyestuff stimulated emission fluorescence signal of chip surface, and beam splitter 4 is crossed in wherein a part of fluorescence transmission, focuses on the focal plane through convergent lens unit 3.Field stop 2 is set on the focal plane of this convergent lens unit 3, and the 1 pair of fluorescence signal by diaphragm of photomultiplier that is positioned at after the field stop 2 detects.

In order to solve the problem of parasitic light, opposite with the design concept of routine, in the present invention, not to make neutral density filter 5 vertical as much as possible with incoming laser beam 7 or primary optical axis, but make 5 one bigger angle [alpha] of incoming laser beam 7 off-center density optical filters, as long as it is big that this angle enough gets, repeatedly laser light reflected bundle and the spuious fluorescence that excited thereof will depart from field stop and can't be received by photomultiplier 1 between genetic chip 8 and center density optical filter 5, thereby the parasitic light of these similar noises is masked.Can determine when angle α satisfies following relationship, can to guarantee between genetic chip 8 and the center density optical filter 5 repeatedly that by Fig. 1 laser light reflected bundle and the spuious fluorescence that is excited thereof depart from field stop:

α≥2d/f

Here d is a field stop diameter and f is the focal length of convergent lens unit.

Claims (2)

1. one kind is used for the laser intensity regulating device that conjugation focuses on the genetic chip fluorescence detecting system, comprise neutral density filter and can drive the stepper motor that it turns to position, certain angle, in system, transmission is crossed the laser beam irradiation of neutral density filter to genetic chip, the excited fluorescence signal that is produced focuses to the field stop place that is positioned on its focal plane and is received by the detecting device after being positioned at field stop through the convergent lens unit, it is characterized in that, the surface normal of neutral density filter and the laser beam of incident are certain included angle α, and described angle α satisfies following formula:

α≥2d/f

Here, d and f are respectively the focal length of described field stop diameter and convergent lens unit.

2. the laser intensity regulating device that is used for conjugation focusing genetic chip fluorescence detecting system as claimed in claim 1 is characterized in that the laser intensity range of adjustment of neutral density filter is 1～100%.

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