CN101799413B - Experimental apparatus for measuring refractive indexes of liquid and measuring method thereof - Google Patents

Abstract

The invention relates to an experimental apparatus for measuring refractive indexes of liquid. A luminescent device is arranged at the lower end of a cassette; a diaphragm is arranged on the cassette above the luminescent device; flat transmission glass is arranged on the upper surface of the diaphragm; flat image display glass is arranged on the upper surface of the flat transmission glass; a window is machined on the left side of the cassette, and the window is provided with a shading cover; bouffant shading paper is arranged at the upper end of the cassette; two stand columns are arranged on a base; millesimal position finder with scales is arranged at the upper ends of the two stand columns; a hand wheel is arranged at the end of the millesimal position finder; the hand wheel is connected with a lens cone of which the second lower part passes through the bouffant shading paper to penetrate into the cassette through a rotary translation switching mechanism; and a sealplate is arranged between the lens cone and the bouffant shading paper. A method for measuring the refractive indexes of liquid through the measuring device comprises the steps that: liquid to be measured forms a liquid film between the flat transmission glass and the flat image display glass; visible light passes through a clear aperture and the flat transmission glass, and the liquid film of the liquid to be measured to form a circular dart spot which takes an incidence point as the centre of a circle on a frosted surface of the flat image display glass; and the refractive indexes of the liquid to be measured are calculated.

Description

Experimental apparatus for measuring refractive indexes of liquid and measuring method thereof

Technical field

The invention belongs to and utilize optical instrument, promptly utilize infrared light, visible light or ultraviolet light are tested or the analysis of material technical field, are specifically related to utilize interferometry, utilize the refractive index of schlieren method test liquid.

Background technology

Liquid refractivity is the parameter that must survey in the experiments such as optics, chemical industry chemistry, biological food, also is important measuring parameter in industrial and agricultural production and the scientific research.At present, the measurement of liquid refractivity can be divided into geometrical optics approach and wave optics method two big classes.Although wave optics method measuring accuracy is higher, required instrument constitutes the cost height, operation easier is big, and measuring condition is strict, and accommodation is less, and required instrument also is of little use, therefore, this method more is used for the scientific experiment chamber, and student experimenting and commercial Application are all less.That the geometrical optics approach instrument constitutes is simple, easy to operate, measuring condition requires lowly, and measuring accuracy can meet the demands, therefore at present geometrical optics approach to measure the application of refractive index more extensive.

Abbe refractometer is measured the common instrument of liquid refractivity as geometrical optics approach, not only uses with a long historyly, and usable range is very wide.But in use, still there is following problem in Abbe refractometer:

In Abbe refractometer used, it was critical angle that Abbe refractometer is directly measured, and the measurement of critical angle must have a process, promptly by regulating the refraction angle, find out the angle of critical ray correspondence in the visual field, so this instrument belonged to the non real-time surveying instrument; In the Abbe refractometer, optical device is two optical prisms in addition, complex structure, and instrument constitutes the cost height; Secondly the direct measuring amount in the Abbe refractometer is an angle, and air line distance is measured relatively, and measurement of angle complexity, precision also are difficult to improve.

Summary of the invention

A technical matters to be solved by this invention is to overcome the problem that above-mentioned Abbe refractometer exists, and a kind of simple in structure, easy to operate, the testing liquid consumption is few, measuring accuracy is high experimental apparatus for measuring refractive indexes of liquid is provided.

Another technical matters to be solved by this invention is to provide a kind of method of using experimental apparatus for measuring refractive indexes of liquid to measure liquid refractivity.

Solving the problems of the technologies described above the technical scheme that is adopted is: the lower end in magazine is provided with luminescent device, be provided with on the magazine of luminescent device top and have the diaphragm that the aperture is 0.5～2mm light hole, the center line of the center line of light hole and the emitted light beam of luminescent device is on same straight line, the upper surface of diaphragm is provided with dull and stereotyped transmissive glass, it is optical surface that dull and stereotyped transmissive glass upper surface is provided with lower surface, upper surface is that the lithograph picture of frosted face shows glass, the left side of magazine is processed with window, window is provided with shading cover, upper end in the magazine is provided with the bouffancy light-shielding sheet, on the base that is connected as a single entity with magazine 2 root posts are set, 2 root posts upper end is provided with thousand fens locators that indicate scale, the end of thousand fens locators is provided with handwheel, handwheel passes the lens barrel that the bouffancy light-shielding sheet is deep in the magazine by rotary translational movement throw-over gear and the latter half and links, and is provided with seal pad between lens barrel and the bouffancy light-shielding sheet.

Lithograph picture of the present invention shows that the refractive index n of glass and dull and stereotyped transmissive glass is 1.5146～1.7496.

Lithograph picture of the present invention shows that glass is identical with the refractive index of dull and stereotyped transmissive glass.

The size of lithograph picture demonstration glass of the present invention is big or small identical with dull and stereotyped transmissive glass, and the thickness h of dull and stereotyped transmissive glass is at least 2.5 times of lithograph picture demonstration thickness of glass.

Luminescent device of the present invention is that semiconductor laser or luminous intensity are the light emitting diode of 10～100mcd.

Lens barrel of the present invention is: be provided with upper flat plate optical glass in lighttight housing upper end, the lower end is provided with the following planar optics glass that is carved with the cross line on the lower surface.

Adopt the method for above-mentioned experimental apparatus for measuring refractive indexes of liquid measurement liquid refractivity as follows:

1, opens the shading cover in magazine left side, take out the lithograph picture and show glass and dull and stereotyped transmissive glass, upper surface in dull and stereotyped transmissive glass drips testing liquid with buret, the lithograph picture is shown that the frosted face of glass makes progress, optical surface is pressed on the testing liquid downwards, testing liquid forms liquid film between dull and stereotyped transmissive glass and lithograph picture demonstration glass, the lithograph picture is shown that glass and dull and stereotyped transmissive glass pack in the magazine, close shading cover.

2, connect the power supply of luminescent device, the visible light that luminescent device sends passes the light hole of diaphragm, vertical incidence sees through dull and stereotyped transmissive glass, enter the lithograph picture through the testing liquid liquid film and show glass, forming with the incident luminous point on the frosted face of lithograph picture demonstration glass is the circular blackening image in the center of circle.

3, mobile lens barrel, the diameter of measuring circular blackening calculates radius r, presses following formula

$n_x=\frac{\mathrm{<figure-callout\; id="2"\; label="rn\; r"\; filenames="HSA00000048532000011.png"\; state="\{\{state\}\}">rn</figure-callout>}}{\sqrt{r^{}}}---\left(1\right)$

Calculate the refractive index of testing liquid, n in the formula _xFor the refractive index of testing liquid, radius that r is circular blackening, n show the refractive index of glass for the lithograph picture, h is the thickness that the lithograph picture shows glass.Corresponding standard deviation is:

${\mathrm{\&Delta;n}}_x=\frac{\mathrm{\&Delta;r}{(n^2-n_x^2)}^{\frac{3}{2}}}{2\mathrm{hn}}---\left(2\right)$

Δ n in the formula _xBe the refractive index standard deviation of testing liquid correspondence, Δ r is the measured deviation of circular blackening radius, and presses following formula

$\mathrm{\&epsiv;}=\frac{{|n}_s-n_x|}{n_s}\&times;100\%---\left(3\right)$

Calculate relative error, ε is a relative error in the formula, n _sBe standard value, n _xBe measured value.

The present invention and Abbe refractometer adopt the total reflection principle of light equally, but optical imagery then is a visible light shows testing liquid liquid film between the glass through dull and stereotyped transmissive glass and lithograph picture, forming with the incident luminous point on the frosted face of lithograph picture demonstration glass is the circular blackening in the center of circle, adopt lens barrel and thousand fens locators to measure the radius of circular blackening, by formula calculate the refractive index of testing liquid; Low in the measuring process to the measurement environment conditional request, the optical imagery relevant with the testing liquid refractive index, illumination promptly shows, need not debug, what show used lithograph picture glass and dull and stereotyped transmissive glass adopted is planar optics glass, reduced the Instrument structure cost, formed image is the plane optical imagery, clear picture.The present invention has easy to operate, advantage such as the testing liquid consumption is few, measuring accuracy is higher, optical phenomena is directly perceived simple in structure, can be widely used in that student experimenting and industry generate and scientific research in measuring refractive indexes of liquid.

Description of drawings

Fig. 1 is the structural representation of one embodiment of the present of invention.

Fig. 2 is the structural representation of lens barrel 4 among Fig. 1.

Fig. 3 adopts the inventive method to measure the circular blackening photo of distilled water refractive index.

Embodiment

The present invention is described in more detail below in conjunction with accompanying drawing and example, but the invention is not restricted to these embodiment.

Embodiment 1

In Fig. 1, the experimental apparatus for measuring refractive indexes of liquid of present embodiment shows by magazine 1, handwheel 2, thousand minutes locators 3, lens barrel 4, seal pad 5, bouffancy light-shielding sheet 6, column 7, fixed head 8, lithograph pictures that glass 9, dull and stereotyped transmissive glass 10, diaphragm 11, semiconductor laser 12, base 13, shading cover 14, screw rod swivel nut rotary translational movement throw-over gear 16 connect and constitutes.

On base 13, be connected as a single entity by magazine 1 with base 13, the magazine 1 of present embodiment is stainless steel or lighttight engineering plastics magazine 1, lower end in magazine 1 is fixedly connected with the screw threads for fastening connector semiconductor laser 12 is installed, semiconductor laser 12 is embodiment of luminescent device, and semiconductor laser 12 is for the invention provides light source.Be connected to diaphragm 6 agreeing without prior consultation to stick with glue on the magazine 1 above the semiconductor laser 12 in 1, be processed with light hole a on the diaphragm 6, the aperture of the light hole a of present embodiment is 1.5mm, and the laser beam center line that the center line of light hole a and semiconductor laser 12 are emitted and the center line of magazine 1 coincide.The upper surface of diaphragm 11 is placed with dull and stereotyped transmissive glass 10 in magazine 1, dull and stereotyped transmissive glass 10 upper surfaces are placed with the lithograph picture and show glass 9, the lithograph picture shows that the lower surface of glass 9 is that optical surface, upper surface are frosted face, the lithograph picture shows that the thickness of glass 9 is that h is 4mm, the size of lithograph picture demonstration glass 9 is big or small identical with dull and stereotyped transmissive glass 10, the thickness h of dull and stereotyped transmissive glass 10 is 10mm, the lithograph picture shows that glass 9 and dull and stereotyped transmissive glass 10 are H-K9 planar optics glass, and its refractive index n is 1.5146.The left side of magazine 1 is processed with window, is stamped shading cover 14 on the window.When measuring liquid refractive index, open shading cover 14, the lithograph picture is shown that glass 9 and dull and stereotyped transmissive glass 10 are from magazine 1 interior the taking-up, drip testing liquid at dull and stereotyped transmissive glass 10 upper surfaces, after the lithograph picture shows that glass 9 is pressed on the liquid, show formation one deck liquid film 15 between glass 9 and the dull and stereotyped transmissive glass 10 at the lithograph picture, lithograph picture demonstration glass 9 and dull and stereotyped transmissive glass 10 are put into magazine 1, cover shading cover 14.With fixed head 8 and the screw threads for fastening connector bouffancy light-shielding sheet 6 that has been fixedly connected, bouffancy light-shielding sheet 6 is used for shading in the upper end of magazine 1.On base 13, be fixedly connected with the screw threads for fastening connector and 3, thousand fens locators 3 of thousand fens locators are installed are marked with the scale that is used for Displacement Measurement be fixedly connected upper end that 2 root posts, 7,2 root posts 7 are installed of screw threads for fastening connector.The left end of thousand fens locators 3 is equipped with handwheel 2 by thread connection, be carved with the centigrade system of measuring length on the handwheel 2, handwheel 2 links by screw rod swivel nut rotary translational movement throw-over gear 16 and lens barrel 4, screw rod swivel nut rotary translational movement throw-over gear 16 is design conventional in the mechanical design handbook, being about to process 2 on threaded handwheel is installed in the swivel nut by thread connection, swivel nut is fixedlyed connected with lens barrel 4, rotates handwheel 2, and lens barrel 4 is move left and right in magazine 1.Handwheel 2 also can link by throw-over gear of rack-and-pinion rotary translational movement and lens barrel 4, the throw-over gear of rack-and-pinion rotary translational movement is design conventional in the mechanical design handbook, promptly on 2 on the handwheel gear is installed, and lens barrel is fixed on the tooth bar, rotate handwheel 2, lens barrel 4 is move left and right in magazine 1.The latter half of lens barrel 4 is passed bouffancy light-shielding sheet 6 and is deep in the magazine 1, between lens barrel 4 and the bouffancy light-shielding sheet 6 seal pad 5 is installed, and seal pad 5 is used for shading.

In Fig. 2, the lens barrel 4 of present embodiment is made of housing 4-1, upper flat plate optical glass 4-2, following planar optics glass 4-3 connection.Housing 4-1 is light tight, the upper end of housing 4-1 is equipped with upper flat plate optical glass 4-2, the lower end is equipped with down planar optics glass 4-3, be carved with the cross line on the lower surface of following planar optics glass 4-3, lens barrel 4 is move left and right in magazine 1, the cross of following planar optics glass 4-3 lower surface line move left and right can be measured visible light and show the diameter of the circular blackening that forms on glass 9 frosted faces and calculate the size of radius r at the lithograph picture through testing liquid.

Adopt the experimental apparatus for measuring refractive indexes of liquid and the Abbe refractometer of present embodiment to compare measurement distilled water, absolute ethyl alcohol, 1 in room temperature (20 ℃), the refractive index of 2-propylene glycol, and with distilled water, absolute ethyl alcohol, 1, the standard refraction rate of 2-propylene glycol (20 ℃) compares, and measuring method is as follows:

1, opens the shading cover 14 in magazine 1 left side, take out the lithograph picture and show glass 9 and dull and stereotyped transmissive glass 10, upper surface in dull and stereotyped transmissive glass 10 drips distilled water with buret, the lithograph picture is shown that the frosted face of glass 9 makes progress, optical surface is pressed on the distilled water downwards, distilled water shows formation liquid film 15 between the glass 9 in dull and stereotyped transmissive glass 10 and lithograph picture, the lithograph picture is shown that glass 9 and dull and stereotyped transmissive glass 10 pack in the magazine 1, close shading cover 14.

2, connect the power supply of sending out semiconductor laser 12, the visible light that semiconductor laser 12 sends passes the light hole a of diaphragm 11, vertical incidence sees through dull and stereotyped transmissive glass 10, enter the lithograph picture through testing liquid liquid film 15 and show glass 9, forming with the incident luminous point on the frosted face of lithograph picture demonstration glass 9 is the circular blackening image in the center of circle, sees Fig. 3.

3, mobile lens barrel 4, the diameter calculating radius r of measuring circular blackening is 14.836 ± 0.005, the standard deviation that calculates distilled water refractive index correspondence by the refractive index of (1) formula calculating distilled water, (2) formula of pressing is ± 0.0002, and by (3) formula calculating distilled water refractive index relative error, result of calculation sees Table 1.

The measurement absolute ethyl alcohol uses the same method, 1, the refractive index of 2-propylene glycol, forming with the incident luminous point on the frosted face of lithograph picture demonstration glass is the circular blackening in the center of circle, the radius r of the circular blackening of absolute ethyl alcohol is 16.446 ± 0.005mm, 1, the radius r of the circular blackening of 2-propylene glycol is 23.298 ± 0.005mm, calculate absolute ethyl alcohol by (1) formula, 1, the refractive index of 2-propylene glycol, calculate absolute ethyl alcohol by (2) formula, 1, the standard deviation of 2-propylene glycol refractive index correspondence is ± 0.0002, and by (3) formula calculating absolute ethyl alcohol, 1, the relative error of 2-propylene glycol refractive index, result of calculation sees Table 1.

Table 1 the present invention surveys distilled water, absolute ethyl alcohol, 1, the refractive index of 2-propylene glycol

Embodiment 2

In the present embodiment, the lithograph picture shows that the thickness of glass 9 is that h is 6.5mm, the size of lithograph picture demonstration glass 9 is big or small identical with dull and stereotyped transmissive glass 10, the thickness h of dull and stereotyped transmissive glass 10 is 17mm, the lithograph picture shows that glass 9 and dull and stereotyped transmissive glass 10 are H-K9 planar optics glass, its refractive index n is 1.5146, and the lithograph picture shows that the plane of incidence of glass 9 is that optical surface, exit facet are frosted face.The connecting relation of other parts and zero parts is identical with embodiment 1.

Adopt the experimental apparatus for measuring refractive indexes of liquid and the Abbe refractometer of present embodiment to compare measurement distilled water, absolute ethyl alcohol, 1, the refractive index of 2-propylene glycol, and with distilled water, absolute ethyl alcohol, 1, the standard refraction rate of 2-propylene glycol compares, measuring method is as follows:

The experimental apparatus for measuring refractive indexes of liquid of employing present embodiment and Abbe refractometer measurement of comparison distilled water, absolute ethyl alcohol, 1, the method for the refractive index of 2-propylene glycol and embodiment 1 are identical.Result of calculation sees Table 2.

Press the measuring method of instrument with Abbe refractometer and measure distilled water, absolute ethyl alcohol, 1, the refractive index of 2-propylene glycol, measurement result sees Table 2.

Table 2 the present invention surveys distilled water, absolute ethyl alcohol, 1, the refractive index of 2-propylene glycol

Embodiment 3

In the present embodiment, the lithograph picture shows that the thickness of glass 9 is that h is 3mm, the size of lithograph picture demonstration glass 9 is big or small identical with dull and stereotyped transmissive glass 10, the thickness h of dull and stereotyped transmissive glass 10 is 8mm, the lithograph picture shows that glass 9 and dull and stereotyped transmissive glass 10 are H-K9 planar optics glass, its refractive index n is 1.5146, and the lithograph picture shows that the plane of incidence of glass 9 is that optical surface, exit facet are frosted face.The connecting relation of other parts and parts is identical with embodiment 1.

Adopt the experimental apparatus for measuring refractive indexes of liquid and the Abbe refractometer of present embodiment to compare measurement distilled water, absolute ethyl alcohol, 1, the refractive index of 2-propylene glycol, and with distilled water, absolute ethyl alcohol, 1, the standard refraction rate of 2-propylene glycol compares, measuring method is as follows:

The experimental apparatus for measuring refractive indexes of liquid of employing present embodiment and Abbe refractometer measurement of comparison distilled water, absolute ethyl alcohol, 1, the method for the refractive index of 2-propylene glycol and embodiment 1 are identical.Result of calculation sees Table 3.

Press the measuring method of instrument with Abbe refractometer and measure distilled water, absolute ethyl alcohol, 1, the refractive index of 2-propylene glycol, measurement result sees Table 3.

Table 3 the present invention surveys distilled water, absolute ethyl alcohol, 1, the refractive index of 2-propylene glycol

Embodiment 4

In above embodiment 1～3, the upper surface of diaphragm 11 is placed with dull and stereotyped transmissive glass 10 in magazine 1, dull and stereotyped transmissive glass 10 upper surfaces are placed with the lithograph picture and show glass 9, the lithograph picture shows that the lower surface of glass 9 is that optical surface, upper surface are frosted face, and the lithograph picture shows that glass 9 and dull and stereotyped transmissive glass 10 are ZF ₁Planar optics glass, its refractive index n are 1.6438, and the size of lithograph picture demonstration glass 9 is big or small identical with dull and stereotyped transmissive glass 10, and the lithograph picture shows that the thickness of glass 9 and dull and stereotyped transmissive glass 10 is identical with respective embodiments.The connecting relation of other parts and zero parts is identical with embodiment 1.

Embodiment 5

In above embodiment 1～3, the upper surface of diaphragm 11 is placed with dull and stereotyped transmissive glass 10 in magazine 1, dull and stereotyped transmissive glass 10 upper surfaces are placed with the lithograph picture and show glass 9, the lithograph picture shows that the lower surface of glass 9 is that optical surface, upper surface are frosted face, and the lithograph picture shows that glass 9 and dull and stereotyped transmissive glass 10 are ZF ₆Planar optics glass, its refractive index n are 1.7496, and the size of lithograph picture demonstration glass 3 is big or small identical with dull and stereotyped transmissive glass 4, and the lithograph picture shows that the thickness of glass 9 and dull and stereotyped transmissive glass 10 is identical with respective embodiments.The connecting relation of other parts and zero parts is identical with embodiment 1.

Embodiment 6

In above embodiment 1～5, the light hole a aperture of diaphragm 11 is 0.5mm.The connecting relation of other parts and parts is executed routine identical with reality accordingly.

Embodiment 7

In above embodiment 1～5, the light hole a aperture of diaphragm 11 is 2mm.The connecting relation of other parts and parts is identical with mutually deserved embodiment.

Embodiment 8

In above embodiment 1～7, the luminescent device that the lower end in magazine 1 is provided with is that luminous intensity is the light emitting diode of 10～100mcd.The connecting relation of other parts and zero parts is identical with respective embodiments.

Claims (7)

1. experimental apparatus for measuring refractive indexes of liquid, it is characterized in that: the lower end in magazine (1) is provided with luminescent device, luminescent device top magazine (1) is gone up to be provided with has the diaphragm that the aperture is 0.5～2mm light hole (a) (11), the center line of light hole (a) and the center line of the emitted light beam of luminescent device are on same straight line, the upper surface of diaphragm (11) is provided with dull and stereotyped transmissive glass (10), it is optical surface that dull and stereotyped transmissive glass (10) upper surface is provided with lower surface, upper surface is that the lithograph picture of frosted face shows glass (9), the left side of magazine (1) is processed with window, window is provided with shading cover (14), upper end in the magazine (1) is provided with bouffancy light-shielding sheet (6), on the base (13) that is connected as a single entity with magazine (1) 2 root posts (7) are set, 2 root posts (7) upper end is provided with thousand fens locators (3) that indicate scale, thousand minutes locator (3) the end be provided with handwheel (2), handwheel (2) passes the lens barrel (4) that bouffancy light-shielding sheet (6) is deep in the magazine (1) by rotary translational movement throw-over gear (16) and the latter half and links, be provided with seal pad (5) between lens barrel (4) and the bouffancy light-shielding sheet (6), described lens barrel (4) is: be provided with upper flat plate optical glass (4-2) in lighttight housing (4-1) upper end, the lower end is provided with the following planar optics glass (4-3) that is carved with the cross line on the lower surface.

2. according to the described experimental apparatus for measuring refractive indexes of liquid of claim 1, it is characterized in that: said lithograph picture shows that the refractive index of glass (9) and dull and stereotyped transmissive glass (10) is 1.5146～1.7496.

3. according to the described experimental apparatus for measuring refractive indexes of liquid of claim 2, it is characterized in that: said lithograph picture shows that glass (9) is identical with the refractive index of dull and stereotyped transmissive glass (10).

4. according to claim 1 or 2 described experimental apparatus for measuring refractive indexes of liquid, it is characterized in that: the size of said lithograph picture demonstration glass (9) is big or small identical with dull and stereotyped transmissive glass (10), and the thickness h of dull and stereotyped transmissive glass (10) is at least 2.5 times of lithograph picture demonstration glass (9) thickness.

5. according to the described experimental apparatus for measuring refractive indexes of liquid of claim 3, it is characterized in that: the size of said lithograph picture demonstration glass (9) is big or small identical with dull and stereotyped transmissive glass (10), and the thickness h of dull and stereotyped transmissive glass (10) is at least 2.5 times of lithograph picture demonstration glass (9) thickness.

6. according to the described experimental apparatus for measuring refractive indexes of liquid of claim 1, it is characterized in that: said luminescent device is that semiconductor laser (12) or luminous intensity are the light emitting diode of 10～100mcd.

7. claim 1 experimental apparatus for measuring refractive indexes of liquid is measured the method for liquid refractivity, it is characterized in that this method is made up of following step:

A, open the shading cover (14) in magazine (1) left side, take out the lithograph picture and show glass (9) and dull and stereotyped transmissive glass (10), upper surface in dull and stereotyped transmissive glass (10) drips testing liquid with buret, the lithograph picture is shown that the frosted face of glass (9) makes progress, optical surface is pressed on the testing liquid downwards, testing liquid forms liquid film (15) between dull and stereotyped transmissive glass (10) and lithograph picture demonstration glass (9), the lithograph picture is shown that glass (9) and dull and stereotyped transmissive glass (10) pack in the magazine (1), close shading cover (14);

The power supply of B, connection luminescent device, the visible light that luminescent device sends passes the light hole (a) of diaphragm (11), vertical incidence sees through dull and stereotyped transmissive glass (10), enter the lithograph picture through testing liquid liquid film (15) and show glass (9), forming with the incident luminous point on the frosted face of lithograph picture demonstration glass (9) is the circular blackening image in the center of circle;

C, mobile lens barrel (4), the diameter of measuring circular blackening calculates radius r, presses following formula

$n_x=\frac{\mathrm{rn}}{\sqrt{r^2+4h^2}}---\left(1\right)$

Calculate the refractive index of testing liquid, n in the formula _xFor the refractive index of testing liquid, radius that r is circular blackening, n show the refractive index of glass (9) for the lithograph picture, h shows the thickness of glass (9) for the lithograph picture, and corresponding standard deviation is:

$\mathrm{\&Delta;}{n}_x=\frac{\mathrm{\&Delta;r}{(n^2-n_x^2)}^{\frac{3}{2}}}{2\mathrm{hn}}---\left(2\right)$

Δ n in the formula _xBe the refractive index standard deviation of testing liquid correspondence, Δ r is the measured deviation of circular blackening radius, and presses following formula

$\mathrm{\&epsiv;}=\frac{|n_s-n_x|}{n_s}\&times;100\%---\left(3\right)$

Calculate relative error, ε is a relative error in the formula, n _sBe standard value, n _xBe measured value.

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