CN103884295B - Axial cone mirror cone angle detecting device and detection method thereof - Google Patents

Abstract

An axicon mirror cone angle detection device and detection method thereof, the device is composed of a collimator, a focusing lens and an image sensor, and its positional relationship is: along the direction of the outgoing light beam of the collimator, the focusing lens is sequentially and the image sensor, the socket of the axicon to be measured is set between the collimator and the focusing lens. The device has the advantages of simple structure, easy realization of the measurement of the axicon at any angle, and the ability to measure the cone angles at different positions of the axicon and the like.

Description

Axicon mirror cone angle detection device and detection method

technical field

The invention relates to the field of optical detection, in particular to an axicon cone angle detection device and a detection method thereof.

technical background

The axicon is a rotationally symmetrical pyramidal optical element whose focal line is along the optical axis. Because it can provide a long focal depth for the optical system, it is used in laser beam shaping, laser drilling technology, optical detection, laser resonators, Aspects such as the generation of non-diffraction beams are widely used, and the use of axicon mirrors in lithography illumination systems can achieve ring illumination patterns. This puts forward strict requirements on the manufacturing accuracy of the tapered surface, and the measurement of the cone angle of the axicon mirror needs an accurate method to realize.

Prior Art [1] (M.de Angelis, S.De Nicola, P.Ferraro, et al. "Test of a conical lensusing a two-beam shearing interferometer", Opt Laser Eng.39:155-163(2003) .) Diffractive cone lenses are inspected using a two-beam shearing interferometry technique for measuring the angle formed by the plane and the conical face of the lens. This technology is an off-axis interference detection method that realizes the wavefront transmission of two coherent surfaces through the tapered lens to be tested. This method is ineffective for the measurement of large-angle axicons.

Prior art [2] (Jun Ma, Christof Pruss, Matthias, et al. "Systematic analysis of themeasurement of cone angles using high line density computer-generated holograms", Optical Engineering.50(5):05580-1-05880- 9(2011).), gave the experimental research method of cone angle measurement. This method firstly needs to make a computational hologram with high linear density, and secondly needs to calibrate the interferometer.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, the present invention proposes an axicon cone angle detection device and a detection method thereof. Advantages such as cone angle at the position.

Technical solution of the present invention is as follows:

A detection device for the cone angle of an axicon mirror, which is characterized in that the device is composed of a collimator, a focusing lens and an image sensor, and its positional relationship is: along the direction of the outgoing light beam of the collimator, the focusing lens is sequentially and the image sensor, the socket of the axicon to be measured is set between the collimator and the focusing lens.

Utilize above-mentioned axicon cone angle detection device to the detection method of axicon cone angle, this detection method comprises the following steps:

① Insert an optical wedge whose wedge angle is the same or close to that of the axicon in the socket of the axicon to be measured between the collimator and the focusing lens, and place the plane of the axicon Facing the light output direction of the collimator, adjusting the plane of the optical wedge to be perpendicular to the output beam of the collimator;

②Adjust the central axis of the focusing lens to coincide with the central axis of the wedge exit light; the photosensitive surface of the image sensor coincides with the focal plane of the image side of the focusing lens;

③ The light beam emitted by the collimator converges to the photosensitive surface of the image sensor for imaging through the optical wedge and focusing lens, and records the position of the image;

④ replace the optical wedge with the axicon to be measured, and adjust the plane of the axicon to be measured to be perpendicular to the outgoing light beam of the collimator; The centerline in one direction coincides with the centerline in the corresponding direction of the cross-section of the exit beam of the collimator, and the cross-section of the exit beam of the collimator does not intersect with the centerline in the other direction of the plane of the axicon mirror to be measured;

5. the light beam emitted by the collimator passes through the axicon to be measured and the focusing lens to converge on the photosensitive surface of the image sensor for imaging, and records the position of the image;

⑥Measure the position deviation Δx of the image on the photosensitive surface of the image sensor after the light beam emitted by the collimator passes through the optical wedge or the transmitted light of the axicon lens to be measured is focused by the focusing lens, and calculates the position deviation Δx of the image to be measured by using the following formula: Axicon cone angle θ:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;x</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;x</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span>$

In the formula, n is the refractive index of the axicon to be measured, f is the focal length of the focusing lens, α is the wedge angle of the optical wedge, and θ1 is obtained;

⑦ After ensuring that the outgoing beam of the collimator is perpendicular to the plane of the axicon to be measured, the midline of a certain direction of the plane of the axicon to be measured coincides with the midline of the corresponding direction of the cross section of the outgoing beam of the collimator , and the cross-section of the beam emitted by the collimator does not intersect the midline of the axicon plane in another direction, move the axicon to be measured, repeat steps ⑤ and ⑥, and obtain θ2;

8. Ensure that the outgoing beam of the collimator is perpendicular to the plane of the axicon to be measured, and the midline of a certain direction of the plane of the axicon to be measured coincides with the midline of the corresponding direction of the cross section of the outgoing beam of the collimator , and the cross-section of the beam emitted by the collimator does not intersect the midline of the plane of the axicon to be measured, rotate the axicon to be measured, and repeat steps ⑤ and ⑥ to obtain θ3;

⑨The average cone angle θ of the axicon lens to be measured calculated in steps ⑥, ⑦, and ⑧=(θ1+θ2+θ3)/3 is the cone angle θ of the axicon lens to be measured.

The axicon to be measured is a convex axicon or a concave axicon.

Compared with prior art, technical effect of the present invention is as follows:

1. The present invention can realize the cone angle measurement of any angle axicon;

2. The device of the present invention has a simple structure and is easy to realize the detection operation;

3. The present invention can not only measure the cone angle, but also measure the distribution of cone angles at different positions, and the result is more accurate.

Description of drawings

Fig. 1 is the schematic diagram of determining the position of the light wedge transmitted light on the image sensor by the axicon mirror cone angle detection device of the present invention

Fig. 2 is the schematic diagram of measuring the convex axicon by the axicon cone angle detection device of the present invention

Fig. 3 is the schematic diagram of measuring concave axicon by the axicon cone angle detection device of the present invention

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and implementation examples, but the protection scope of the present invention should not be limited thereby.

Please refer to FIG. 1 and FIG. 2 first. FIG. 1 and FIG. 2 are schematic diagrams of the axicon cone angle detection device of the present invention. As can be seen from the figure, the axicon cone angle detection device of the present invention is composed of a collimator 1, a focusing lens 3 and an image sensor 4. image sensor4. An optical wedge or the socket of the axicon to be measured is placed between the collimator 1 and the focusing lens 3 .

Using the above-mentioned axicon cone angle detection device to detect the axicon cone angle, the detection method comprises the following steps:

①In the socket of the axicon to be tested between the collimator 1 and the focusing lens 3, insert the optical wedge 2 with the same processing cone angle as the axicon, and the plane of the optical wedge 2 faces the light output direction of the collimator 1; adjust The plane of the optical wedge 2 is perpendicular to the outgoing beam of the collimator 1;

②Adjust the central axis of the focusing lens 3 to coincide with the central axis of the outgoing light of the optical wedge 2; the position of the image sensor 4 coincides with the focal plane of the image side of the focusing lens 3;

③ The light beam emitted by the collimator 1 passes through the optical wedge 2 and enters the focusing lens 3, and the focusing lens 3 converges the light beam onto the image sensor 4, and records the position of the image on the image sensor 4.

④ Replace the optical wedge 2 with the axicon 5 to be tested, and adjust the plane of the axicon 5 to be tested to be perpendicular to the outgoing beam of the collimator 1; The cross-section corresponding to the centerline of the direction coincides, and the cross-section of the outgoing light beam of the collimator 1 does not intersect with the centerline of the other direction of the plane of the axicon 5 to be measured;

⑤ The light beam emitted by the collimator 1 passes through the axicon lens 5 to be measured and enters the focusing lens 3, and the focusing lens 3 converges the light beam onto the image sensor 4, and records the position of the image on the image sensor 4. The cone angle of the axicon 5 to be measured can be calculated by comparing the positions of the light transmitted by the optical wedge 2 and the axicon 5 to be measured on the image sensor 4 after being focused by the focusing lens 3 .

The cone angle θ of the axicon 5 to be measured can be expressed as:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;x</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;x</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span>$

In the formula, n is the refractive index of the axicon 5 to be measured, f is the focal length of the focusing lens 3, α is the angle of the optical wedge 2, and Δx is the light transmitted by the optical wedge 2 and the axicon 5 to be measured after being focused by the focusing lens 3 Positional deviation on image sensor 4 .

⑥ After ensuring that the outgoing beam of the collimator 1 is perpendicular to the plane of the axicon 5 to be measured, the midline in a certain direction of the plane of the axicon 5 to be measured coincides with the midline in a certain direction of the cross-section of the outgoing beam of the collimator 1, and the parallel light Move the axicon 5 to be measured under the condition that the cross-section of the beam emitted by the tube 1 does not intersect the midline of the plane of the axicon 5 to be measured in another direction, and repeat step ⑤.

⑦ After ensuring that the outgoing beam of the collimator 1 is perpendicular to the plane of the axicon 5 to be measured, the midline in a certain direction of the plane of the axicon 5 to be measured coincides with the midline in a certain direction of the cross-section of the outgoing beam of the collimator 1, and the parallel light When the cross-section of the beam emitted by the tube 1 does not intersect the midline of the plane of the axicon 5 to be measured in another direction, rotate the axicon 5 to be measured and repeat step ⑤.

⑧ The average cone angle of the axicon 5 to be measured can be obtained by averaging the measured angles at each position.

Fig. 3 is the schematic diagram of measuring the concave axicon by the axicon cone angle detection device of the present invention, as can be seen from the figure, the axicon 5 to be measured in embodiment 2 of the present invention is a concave axicon, and measures the cone angle of the concave axicon The procedure for measuring the cone angle of a convex axicon is the same.

Claims (3)

1. A detection device for an axicon cone angle, characterized in that the device is made up of a collimator, a focusing lens and an image sensor, and its positional relationship is: along the direction of the outgoing light beam of the collimator is described successively Focusing lens and image sensor, the socket of the axicon lens to be measured is set between the collimator and the focusing lens; the wedge angle is inserted into the socket of the axicon lens to be measured to be the same or close to the cone angle of the axicon lens an optical wedge, the plane of the optical wedge faces the light output direction of the collimator, and the plane of the optical wedge is perpendicular to the outgoing light beam of the collimator. 2. utilize the axicon cone angle detecting device described in claim 1 to the detection method of axicon cone angle, it is characterized in that this detection method comprises the following steps: ① Insert an optical wedge whose wedge angle is the same or close to that of the axicon in the socket of the axicon to be measured between the collimator and the focusing lens, and place the plane of the axicon Facing the light output direction of the collimator, adjusting the plane of the optical wedge to be perpendicular to the output beam of the collimator; ②Adjust the central axis of the focusing lens to coincide with the central axis of the wedge exit light; the photosensitive surface of the image sensor coincides with the focal plane of the image side of the focusing lens; ③ The light beam emitted by the collimator converges to the photosensitive surface of the image sensor for imaging through the optical wedge and focusing lens, and records the position of the image; ④ replace the optical wedge with the axicon to be measured, and adjust the plane of the axicon to be measured to be perpendicular to the outgoing light beam of the collimator; The centerline in one direction coincides with the centerline in the corresponding direction of the cross-section of the exit beam of the collimator, and the cross-section of the exit beam of the collimator does not intersect with the centerline in the other direction of the plane of the axicon mirror to be measured; 5. the light beam emitted by the collimator passes through the axicon to be measured and the focusing lens to converge on the photosensitive surface of the image sensor for imaging, and records the position of the image; ⑥Measure the position deviation Δx of the image on the photosensitive surface of the image sensor after the light beam emitted by the collimator passes through the optical wedge or the transmitted light of the axicon lens to be measured is focused by the focusing lens, and calculates the position deviation Δx of the image to be measured by using the following formula: Axicon cone angle θ: $\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span>$ In the formula, n is the refractive index of the axicon to be measured, f is the focal length of the focusing lens, α is the wedge angle of the optical wedge, and θ1 is obtained; ⑦ After ensuring that the outgoing beam of the collimator is perpendicular to the plane of the axicon to be measured, the midline of a certain direction of the plane of the axicon to be measured coincides with the midline of the corresponding direction of the cross section of the outgoing beam of the collimator , and the cross-section of the beam emitted by the collimator does not intersect the midline of the axicon plane in another direction, move the axicon to be measured, repeat steps ⑤ and ⑥, and obtain θ2; 8. Ensure that the outgoing beam of the collimator is perpendicular to the plane of the axicon to be measured, and the midline of a certain direction of the plane of the axicon to be measured coincides with the midline of the corresponding direction of the cross section of the outgoing beam of the collimator , and the cross-section of the beam emitted by the collimator does not intersect the midline of the plane of the axicon to be measured, rotate the axicon to be measured, and repeat steps ⑤ and ⑥ to obtain θ3; ⑨The average cone angle θ=(θ1+θ2+θ3)/3 calculated in steps ⑥, ⑦, and ⑧ of the axicon to be measured is the cone angle θ of the axicon to be measured. 3. The detection method according to claim 2, characterized in that the axicon to be tested is a convex axicon or a concave axicon.