CN201083671Y - Sample postpositive type double focal plane detection laser particle sizer - Google Patents

Abstract

The utility model discloses a sample postposition type double focal plane detection laser particle size analyzer which comprises a laser transmitter and a space filter which are orderly positioned at an optical axis, a first lens, a sample (cell), a first multi-pixel photoelectric probe positioned at an equivalent focal plane behind the first lens, a second lens, and a second multi-pixel photoelectric probe positioned at a combined equivalent focal plane of the first lens and the second lens. The laser particle size analyzer provided by the utility model can finish the particle size measurement within the whole measurement range at one time without needing to change the focal length or the equivalent focal length, and enlarges the dynamic range; the large-sized probe is changed into the small-sized probe to ensure that the processing is easier; the multi-pixel photoelectric probe can be integrally produced, which has good consistency of photoelectric characteristics, thereby contributing to the signal collection; signals in the non-detection blind zone are easy to obtain.

Description

The laser particle analyzer that the rearmounted type bifocal segment of sample is surveyed

[technical field]: the utility model relates to a kind of laser particle analyzer, is especially guaranteeing to measure the big laser particle analyzer of dynamic range under the little situation of measurement lower limit.

[background technology]: laser particle analyzer is the grain graininess surveying instrument of present widespread use, and it is according to the work of diffraction of light (or scattering) principle.The angle of diffraction that photodetector (ring) is measured is big more, and the particle diameter that can survey is more little.In traditional structure, angle of diffraction is big more, and then to control aberration difficult more, increased the difficulty that small particle diameter is measured.Simultaneously, measure small particle diameter and generally adopt short focal length lens, this structure has limited the measurement upper limit again.

The aberration of wide-angle diffraction light can adopt the way that sample is placed the fourier transform lens back in order to reduce to measure small particle diameter.According to Fourier optics conversion principle, sample is an equivalent focal length to the distance of lens focal plane, and the wide-angle diffraction light is directly received by detector without lens, so more small-bore lens can satisfy measurement requirement, the control aberration is also than being easier to.Because the finiteness of detector size, equivalent focal length can not be too big, so the dynamic range of measurement size is still less; Or use bigger equivalent focal length while additional side to separate detectors, when having enlarged the measurement dynamic range,, side minder reduced the resolution of small particle diameter because of existing detection blind area.

[summary of the invention]: the purpose of this utility model is that the existing laser particle analyzer measurement of solution dynamic range is less, measures the relatively problem of difficulty of big particle diameter and small particle diameter simultaneously, and the laser particle analyzer of the rearmounted type bifocal segment detection of a kind of sample is provided.

The laser particle analyzer that the rearmounted type bifocal segment of sample that the utility model provides is surveyed comprises the generating laser and spatial filter, first lens, sample or the sample cell that are positioned at successively on the optical axis, is positioned at more than first yuan of photodetector, second lens on the equivalent focal plane behind first lens, is positioned at more than second yuan of photodetector on the combination equivalence focal plane of first and second lens.

This laser particle analyzer does not need independent collimation lens.First lens and second lens are all as fourier transform lens.

More than first yuan of photodetector and plane, more than second yuan of photodetector place are about the second lens conjugation.

Advantage of the present utility model and good effect: the laser particle analyzer that the utility model provides need not change focal length or equivalent focal length, once just can finish the granulometry in the whole range ability, has enlarged dynamic range; The large scale detector is turned to the small size detector, processing is more prone to; But polynary photodetector integral manufacturing, so the photoelectric characteristic high conformity is favourable for signals collecting; Obtain the signal of no detection blind area easily.

[description of drawings]:

Fig. 1 is the systematic schematic diagram of the laser particle analyzer that provides of the utility model.

[embodiment]:

Embodiment 1

As shown in Figure 1, the laser particle analyzer surveyed of the rearmounted type bifocal segment of the sample that provides for utility model.Comprise generating laser 1 and spatial filter 2, first lens 3, sample or sample cell 4, more than first yuan of photodetector 5, second lens 6, more than second yuan of photodetector 7, their printing opacity is centered close on the same light transmission shaft.

More than first yuan of photodetector 5 and plane, more than second yuan of photodetector 7 place are about second lens, 6 conjugation.Oarse-grained diffraction light can shine on more than the second yuan of photodetector 7 by the medium pore of more than first yuan of photodetector 5, the small-particle diffracted signal is directly received by more than first yuan of photodetector 5, enlarges dynamic range thereby can use two diffraction light signals on the test surface to handle simultaneously.

Sample or sample cell 4 are equivalent focal length f to the distance on plane, more than first yuan of photodetector 5 place ₁', second lens, 6 focal lengths are f ₂'.f ₁' and f ₂' combined focal length is f '.As shown in Figure 1, the aberration on focal plane, more than first yuan of photodetector 5 place has only the light beam of incident to cause, and general incident light bore is little, so the aberration on this plane is very little, especially off-axis aberration is little, does not require that first lens 3 have big bore.Measurement range according to laser particle analyzer designs, and it is that 5-10, numerical aperture are about 0.1 microcobjective that second lens 6 are equivalent to enlargement ratio, adopts the cemented doublet group to realize.

The distance of more than second yuan of photodetector 7 to second lens 6 is according to f ' f ₁' and f ₂' determine by the compound lens imaging formula.More than first yuan of photodetector 5 and more than second yuan of photodetector 7 are generally semicircle or sector structure, and radius is respectively S from inside to outside ₁ ⁽¹⁾～S _N+1 ⁽¹⁾And S ₁ ⁽²⁾～S _M+1 ⁽²⁾, N, M represent the gauging ring sequence number of more than first yuan of photodetector 5 and more than second yuan of photodetector 7 respectively, increase successively from inside to outside, for the signal that obtains not have detection blind area need satisfy following relational expression

$S_1^{\left(1\right)}/{f_1}^{\′}=S_{M+1}^{\left(2\right)}/f^{\′}$ ①

More than first yuan of photodetector 5 and more than second yuan of photodetector 7 are surveyed light signal and are converted electric signal to, change computing machine over to and handle after amplifying, and can draw test result.

During measurement, at first measure bias light, feed sample then, make incident light that generating laser 1 sends by the sample diffraction, its diffraction light produces electric signal through lens lighting on more than first yuan of photodetector 5, more than second yuan of photodetector 7, electric signal is amplified back input Computer Processing, draw test result.

Before the measurement, lens 6 are measured its transmission coefficient in advance, to revise the data of input computing machine.

Claims (2)

1. the laser particle analyzer surveyed of the rearmounted type bifocal segment of a sample, it is characterized in that this laser particle analyzer, comprise the generating laser and spatial filter, first lens, sample or the sample cell that are positioned at successively on the optical axis, be positioned at more than first yuan of photodetector, second lens on the equivalent focal plane behind first lens, be positioned at more than second yuan of photodetector on the combination equivalence focal plane of first and second lens.

2. the laser particle analyzer that the rearmounted type bifocal segment of sample according to claim 1 is surveyed is characterized in that more than first yuan of photodetector and plane, more than second yuan of photodetector place are about the second lens conjugation.