CN102661854A - Method for testing minimum deviation angle of triple prism and refractive index of optical material of triple prism - Google Patents

Abstract

The invention provides a method for testing minimum deviation angle of a triple prism and refractive index of optical material of the triple prism. The method comprises the following steps of finding a corresponding minimum deviation angle at one side of emitted light of a certain top angle of a triple prism sample block, aligning a refraction image, turning over a telescope around the top angle direction (180 DEG-A), if the refraction image is precisely aligned, the triple prism sample block is located at the minimum deviation angle position of the illuminated monochromatic light; otherwise, turning the telescope to align the telescope to the refraction image, thus, the triple prism sample block can be accurately located at the minimum deviation angle position of the illuminated monochromatic light, and the minimum deviation angle value Delta minA corresponding to the top angle can be obtained. According to the method provided by the invention, the minimum deviation angle value corresponding to the three top angles of the triple prism sample block are measured through an angular instrument, thus, high precision test of optical material refraction index can be realized by low precision angular instrument.

Description

The method of testing of prism angle of minimum deviation and optical material refractive index thereof

Technical field

The present invention relates to a kind of three the pairing angle of minimum deviation of drift angle of prism appearance piece and the method for testing of optical material refractive index thereof.

Background technology

The refractive index parameter of optical material is the basis of carrying out optical design, has only the authentic data of accurate grasp optical material refractive index, could accomplish high-quality design effort as requested.And for optical material research fabricator; The refractive index performance index of definite optical material of being studied are important substances; It is the technical foundation of carrying out the material evaluation; Also be the reference frame of producing typing, therefore, the accurate mensuration of optical material refractive index be to use, develop the prerequisite of optical material.

Along with the development of optics industry, not only quantity is big to the requirement of optical material, and quality requirements is also increasingly high.Because the angular instrument measuring accuracy is high, and be absolute measurement, the refractometry precision is 10 usually ^-5, at present, generally adopt angular instrument to come the refractive index of optical material is carried out high-acruracy survey.But if to make the refractometry precision reach 10 ^-6, even higher, just need angle measurement accuracy 1 " more than the large-scale precision angular instrument.But precision goniometer price is high, and complex structure has higher requirements to environment for use and operator, is unfavorable for producing, the widespread use of aspect such as engineering.

When utilizing angular instrument to carry out refraction index test; The general minimum deviation horn cupping that adopts is tested; Need sample be processed into prism, single drift angle is adopted the minimum deviation horn cupping, the processing request of this drift angle for prism, the second optical parallel difference and logical light face is very high; It is big that the appearance piece prepares difficulty, and the cycle is long.In addition, when carrying out the angle of minimum deviation aiming, if the visual aligning of human eye, tested person personnel experience and test intensity effect easily; And adopt photoelectricity on time, and can receive factor affecting such as parasitic light and picture element, pointing accuracy all is very limited, and influences the bearing accuracy of angle of minimum deviation.

Summary of the invention

Technical matters to be solved by this invention provides a kind of method of testing of three pairing angle of minimum deviation of drift angle of prism appearance piece, and realizes adopting low precision angular instrument also can test accurately the optical material refractive index.

The technical scheme that technical solution problem of the present invention is adopted is: the method for testing of prism angle of minimum deviation; This method may further comprise the steps: 1) behind the angle value A of certain the drift angle A that measures prism appearance piece; Side at this drift angle beam projecting; After utilizing the telescope of angular instrument to search out corresponding angle of minimum deviation position and aiming at dioptric image, with telescope around this drift angle direction turn over (180 °-A); 2) observe through telescope,, just explain that prism appearance piece has been on the monochromatic angle of minimum deviation position of being thrown light on if just in time aim at reflection image; 3) if observe through telescope, not to aim at reflection image, then rotate telescope and make it aim at reflection image; And then telescope back turned over (180 °-A), get back to a side of beam projecting are observed whether to aim at dioptric image this moment through telescope around this drift angle; Do not aim at if; Rotate telescope again and make it aim at dioptric image, so repeated multiple times just can make prism appearance piece be in exactly on the monochromatic angle of minimum deviation position of being thrown light on; 4) through the angular instrument circle reading, obtain the pairing angle of minimum deviation value of this drift angle δ _MinA5) then according to said method, test the pairing angle of minimum deviation value of two other drift angle δ respectively _MinBAnd δ _MinC

Record three pairing angle of minimum deviation δ of drift angle of prism appearance piece according to said method _MinA, δ _MinBAnd δ _MinC, can calculate the refractive index n of the optical material of this prism appearance piece then according to following any formula, formula is:

Or

$\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}\right)}^2}+\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}\right)}^2}+\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}\right)}^2}=\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}\right)}^2}\×\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}\right)}^2}\×\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}\right)}^2}.$

The invention has the beneficial effects as follows: the present invention utilizes dioptric image and the complementary definite angle of minimum deviation position of reflection image; Measure the pairing angle of minimum deviation value of three drift angles of prism appearance piece through angular instrument; Realize adopting low precision angular instrument also can carry out high precision measurement to the optical material refractive index; Compare with traditional minimum deviation horn cupping, measuring accuracy can improve about twice.Method of testing of the present invention has been utilized dioptric image and the complementary definite monochromatic light minimum deviation position of reflection image, has improved bearing accuracy; Need not bring three drift angles of prism sample into calculating optical material refractive index, eliminate the influence of the drift angle measuring error and the second optical parallel difference; During measurement, three angle of minimum deviation are in same cross section, to measure, and only need three angle sums in same cross section to equal 180 °, reduced by three drift angle difficulty of processing of prism appearance piece, and the second optical parallel difference of this measuring method and sample are irrelevant basically.

Description of drawings

Fig. 1 is the synoptic diagram of method of testing of the present invention.

Embodiment

As shown in Figure 1, during the pairing angle of minimum deviation of three drift angles of test specimens piece of the present invention, adopt following method accurately to locate the angle of minimum deviation position, realize the test of three pairing angle of minimum deviation values of drift angle.

1) during the pairing angle of minimum deviation of certain drift angle A of test prism appearance piece; After measuring the angle value A of drift angle A; Side at this drift angle beam projecting; After utilizing the telescope of angular instrument to search out corresponding angle of minimum deviation approximate location and aiming at dioptric image, with telescope around this drift angle direction turn over (180 °-A) after, just arrive the reflected light position of light incident one side of this drift angle.This is because according to minimum deviation method relation derivation, angle of minimum deviation position and reflection ray locations complementary, and this is the high-precision assurance of the inventive method just also; 2) if observe, just in time aim at reflection image, just explain that prism appearance piece has been on the monochromatic angle of minimum deviation position of being thrown light on through telescope; 3) if observe through telescope; Be not to aim at reflection image, then rotate telescope and make it aim at reflection image, and then with telescope around this drift angle back turn over (180 °-A); Get back to a side of beam projecting; Observe whether aim at dioptric image this moment through telescope, do not aim at, rotate telescope again and make it aim at dioptric image if.So repeated multiple times just can make prism appearance piece be in exactly on the monochromatic angle of minimum deviation position of being thrown light on; 4) through the angular instrument circle reading, obtain the pairing angle of minimum deviation value of this drift angle δ _MinA5) then according to said method, test the pairing angle of minimum deviation value of two other drift angle δ respectively _MinBAnd δ _MinC

According to three pairing angle of minimum deviation of drift angle of the above-mentioned prism appearance piece that records, can calculate the refractive index n of the optical material of this prism appearance piece then according to formula, this derivation of equation is following:

(1) adopt the basic calculating formula of angle of minimum deviation measuring optical material refractive index to be:

$n=\frac{\sin \frac{{\mathrm{\δ}}_{\min A}+A}{2}}{\sin \frac{A}{2}}...\left(1\right)$

According to the trigonometric function relation, formula (1) can be rewritten as:

$n=\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}\cos \frac{A}{2}+\sin \frac{A}{2}\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}{\sin \frac{A}{2}}...\left(2\right)$

Can get according to formula (2): $\mathrm{Tan}\frac{A}{2}=\frac{\mathrm{Sin}\frac{{\mathrm{\δ}}_{\mathrm{Min}A}}{2}}{n-\mathrm{Cos}\frac{{\mathrm{\δ}}_{\mathrm{Min}A}}{2}}...\left(3\right)$

For two other drift angle of prism appearance piece, above-mentioned same relation is arranged also.

Because an Atria interior angle A+B+C=180 °, so

According to formula (3) and (4), can obtain first kind of computing formula through three angle of minimum deviation values of appearance piece calculating optical material refractive index:

(2) derive as follows through second kind of computing formula of three angle of minimum deviation values of appearance piece calculating optical material refractive index:

According to triangle interior angle funtcional relationship:

tanA+tanB+tanC=tanA×tanB×tanC...................................（6）

Because $\mathrm{Tan}A=\frac{2\mathrm{Tan}\frac{A}{2}}{1-{\mathrm{Tan}}^2\frac{A}{2}}...\left(7\right)$

Convolution (3), (6) and (7), can derive following second kind of computing formula:

$\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}\right)}^2}+\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}\right)}^2}+\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}\right)}^2}=\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}\right)}^2}\×\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}\right)}^2}\×\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}\right)}^2}$

.........................................................................................................................（8）

。

Claims (2)

1. the method for testing of prism angle of minimum deviation, it is characterized in that: this method may further comprise the steps:

1) behind the angle value A of certain the drift angle A that measures prism appearance piece; Side at this drift angle beam projecting; After utilizing the telescope of angular instrument to search out corresponding angle of minimum deviation position and aiming at dioptric image, with telescope around this drift angle direction turn over (180 °-A); 2) observe through telescope,, just explain that prism appearance piece has been on the monochromatic angle of minimum deviation position of being thrown light on if just in time aim at reflection image; 3) if observe through telescope, not to aim at reflection image, then rotate telescope and make it aim at reflection image; And then telescope back turned over (180 °-A), get back to a side of beam projecting are observed whether to aim at dioptric image this moment through telescope around this drift angle; Do not aim at if; Rotate telescope again and make it aim at dioptric image, so repeated multiple times just can make prism appearance piece be in exactly on the monochromatic angle of minimum deviation position of being thrown light on; 4) through the angular instrument circle reading, obtain the pairing angle of minimum deviation value of this drift angle δ _MinA5) then according to said method, test the pairing angle of minimum deviation value of two other drift angle δ respectively _MinBAnd δ _MinC

2. the method for testing of optical material refractive index, method according to claim 1 records three pairing angle of minimum deviation δ of drift angle of prism appearance piece _MinA, δ _MinBAnd δ _MinC, can calculate the refractive index n of the optical material of this prism appearance piece then according to formula, this formula is:

Or

$\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}\right)}^2}+\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}\right)}^2}+\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}\right)}^2}=\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min A}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min A}}{2}}\right)}^2}\×\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min B}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min B}}{2}}\right)}^2}\×\frac{2\×\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}}{1-{\left(\frac{\sin \frac{{\mathrm{\δ}}_{\min C}}{2}}{n-\cos \frac{{\mathrm{\δ}}_{\min C}}{2}}\right)}^2}.$

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