CN103292743B - The detection method of axial cone mirror cone angle - Google Patents

Abstract

A detection device and detection method for the cone angle of an axicon mirror. The device is composed of a laser, a beam expander lens group, a focusing lens and an image sensor. A beam mirror group, a focusing lens and an image sensor, the socket of the axicon to be measured is arranged between the beam expander mirror group and the focusing lens. The invention has the advantages of simple structure, easy realization of the measurement of any axicon cone angle and the like.

Description

Method for detecting cone angle of axicon mirror

technical field

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

technical background

As a rotationally symmetrical pyramid optical element, the axicon lens can provide a long focal depth for the optical system. Due to this advantage, it is widely used in many fields, such as laser beam shaping, laser drilling technology, optical inspection, Laser resonators, generation of non-diffraction beams, etc., and the use of axicon mirrors in lithography illumination systems can achieve ring illumination modes. 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.deAngelis, S.DeNicola, P.Ferraro, etal. "Testofaconical lenses using a two-beamshearing interferometer", OptLaserEng.39:155-163 (2003).) Utilize two-beam shearing interference technology to detect the diffraction cone Lens, used to measure the angle formed by the plane and the tapered 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] (JunMa, ChristofPruss, Matthias, etal. "Systematic analysis of the measurement of cone angles using highline density computer-generated holograms", Optical Engineering. 50 (5): 05580-1-05880-9 (2011).), provides the experimental study of cone angle measurement Law. This method first needs to make a high linear density computational hologram, and then calibrates the interferometer, and also needs to move the axicon mirror to be measured axially and circularly.

Contents of the invention

The object of the present invention is to provide a detection device and detection method for the cone angle of an axicon mirror. The device and method have the advantages of simple structure, easy realization of the measurement of any axicon cone angle, and the like.

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 laser, a beam expander lens group, a focusing lens and an image sensor. A beam mirror group, a focusing lens and an image sensor, the socket of the axicon to be measured is arranged between the beam expander mirror group and the focusing lens.

Utilize the detection device of above-mentioned axicon cone angle to carry out the detection method of axicon cone angle, it is characterized in that this detection method comprises the following steps:

① Insert the axicon lens to be measured into the socket of the axicon lens to be measured between the beam expander lens group and the focusing lens in the direction of the laser beam output beam, and the plane of the axicon lens to be measured faces the light output direction of the laser ;

②Adjust the optical path: adjust the central axis of the beam expander group to coincide with the central axis of the outgoing beam of the laser; adjust the plane of the axicon to be measured to be perpendicular to the outgoing beam of the laser, while ensuring that the The central axis of the axicon mirror to be measured coincides with the central axis of the laser output beam; adjust the focus lens to be perpendicular to the laser output beam, and at the same time ensure that the optical axis of the focus lens is in the center of the laser output beam Axis coincidence; adjust the plane of the image sensor to be perpendicular to the optical axis of the laser output beam;

③ The beam emitted by the laser is expanded by the beam expander lens group, and the expanded beam passes through the axicon lens to be measured and enters the focusing lens, and the beam passing through the focusing lens is converging onto the image sensor;

④ Adjust the distance between the focusing lens and the image sensor, so that the image sensor is placed on the focal plane of the image side of the focusing lens, so that the obtained light spot can be detected by the image sensor , thereby solving the cone angle of the axicon mirror to be measured.

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

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}<span\; class="notranslate">\; ]</span>$

Wherein, n is the refractive index of the axicon lens to be measured, D is the size of the light spot received by the image sensor, and f represents the focal length of the focusing lens.

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.

Description of drawings

Fig. 1 is the schematic diagram of measuring the convex axicon by the axicon cone angle detection device of the present invention

Fig. 2 is the optical path 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

Fig. 4 is the optical path diagram of measuring the 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. 3 first. FIG. 1 and FIG. 3 are schematic diagrams of implementation examples of the axicon cone angle detection device of the present invention. As can be seen from the figure, the detection device of the axicon cone angle of the present invention is composed of a laser 1, a beam expander lens group 2, a focusing lens 4 and an image sensor 5, and its positional relationship is: along the direction of the outgoing light beam of the laser 1 The beam expander group 2 , the focusing lens 4 and the image sensor 5 are in sequence, and the socket of the axicon 3 to be measured is arranged between the beam expander group 2 and the focusing lens 4 .

Utilize the detection device of above-mentioned axicon cone angle to carry out the detection method of axicon cone angle, it is characterized in that this detection method comprises the following steps:

① An axicon lens 3 to be measured is placed between the beam expander lens group 2 and the focusing lens 4 in the direction of the beam output of the laser 1, and the plane of the axicon lens 3 to be measured faces the light output direction of the laser 1;

②Adjust the optical path: adjust the central axis of the beam expander group) to coincide with the central axis of the outgoing beam of the laser 1; adjust the plane of the axicon 3 to be measured to be perpendicular to the outgoing beam of the laser 1 , while ensuring that the central axis of the axicon 3 to be measured coincides with the central axis of the laser 1 outgoing beam; adjust the focusing lens 4 to be perpendicular to the outgoing beam of the laser 1, while ensuring that the focusing lens 4 The optical axis of the laser device 1 is coincident with the central axis of the outgoing beam of the laser device; the plane of the image sensor 5 is adjusted to be perpendicular to the optical axis of the outgoing beam of the laser device 1;

③ The beam emitted by the laser 1 is expanded by the beam expander group 2, and the expanded beam passes through the axicon lens 3 to be measured and enters the focusing lens 4, and passes through the Focusing lens 4 beams are converged onto the image sensor 5;

④ adjust the distance between the focus lens 4 and the image sensor 5, so that the image sensor 5 is placed on the focal plane of the image side of the focus lens 4, so that the image can be used The sensor 5 detects the size of the obtained light spot, so as to obtain the cone angle of the axicon 3 to be measured.

The cone angle θ of described axicon mirror 3 to be measured can be expressed as:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}<span\; class="notranslate">\; ]</span>$

Wherein, n is the refractive index of the axicon lens 3 to be measured, D is the size of the light spot received by the image sensor 5 , and f represents the focal length of the focusing lens 4 .

Example 1

Fig. 2 is the optical path diagram of measuring the convex axicon by the axicon cone angle detection device of the present invention, as can be seen from the figure, the axicon 3 to be measured in embodiment 1 of the present invention is a convex axicon, which measures the cone angle of the convex axicon The steps are as follows:

① An axicon lens 3 to be measured is placed between the beam expander lens group 2 and the focusing lens 4 in the direction of the beam output of the laser 1, and the plane of the axicon lens 3 to be measured faces the light output direction of the laser 1;

②Adjust the optical path: adjust the central axis of the beam expander group 2 to coincide with the central axis of the outgoing beam of the laser 1; adjust the plane of the axicon 3 to be measured to be perpendicular to the outgoing beam of the laser 1 , while ensuring that the central axis of the axicon 3 to be measured coincides with the central axis of the laser 1 outgoing beam; adjust the focusing lens 4 to be perpendicular to the outgoing beam of the laser 1, while ensuring that the focusing lens 4 ) the optical axis coincides with the central axis of the outgoing beam of the laser 1; adjust the plane of the image sensor 5 to be perpendicular to the optical axis of the outgoing beam of the laser 1;

③ The beam emitted by the laser 1 is expanded by the beam expander group 2, and the expanded beam passes through the axicon lens 3 to be measured and enters the focusing lens 4, and passes through the Focusing lens 4 beams are converged onto the image sensor 5;

④ adjust the distance between the focus lens 4 and the image sensor 5, so that the image sensor 5 is placed on the focal plane of the image side of the focus lens 4, so that the image can be used The sensor 5 detects the size of the obtained light spot, so as to obtain the cone angle of the axicon 3 to be measured.

The cone angle and the refractive index of the axicon 3 to be measured are respectively θ, n, and the refraction angle β of the light beam through the axicon 3 to be measured can be expressed as:

β = arcsin(nsinθ)(1)

The angle ρ between the refracted ray and the optical axis through the axicon 3 to be measured is expressed as:

ρ=β-θ(2)

$\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Wherein, D is the aperture of the light spot detected by the image sensor 5 , and f is the focal length of the focusing lens 4 .

According to the above formula, the cone angle of the axicon 3 to be measured can be expressed as:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In this way, the cone angle of the axicon 3 to be measured can be solved.

Example 2

Fig. 4 is the optical path 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 3 to be measured in embodiment 2 of the present invention is a concave axicon, and the concave axicon cone angle is measured The steps are as follows:

① An axicon lens 3 to be measured is placed between the beam expander lens group 2 and the focusing lens 4 in the direction of the beam output of the laser 1, and the plane of the axicon lens 3 to be measured faces the light output direction of the laser 1;

②Adjust the optical path: adjust the central axis of the beam expander group 2 to coincide with the central axis of the outgoing beam of the laser 1; adjust the plane of the axicon 3 to be measured to be perpendicular to the outgoing beam of the laser 1 , while ensuring that the central axis of the axicon 3 to be measured coincides with the central axis of the laser 1 outgoing beam; adjust the focusing lens 4 to be perpendicular to the outgoing beam of the laser 1, while ensuring that the focusing lens 4 The optical axis of the laser device 1 is coincident with the central axis of the outgoing beam of the laser device; the plane of the image sensor 5 is adjusted to be perpendicular to the optical axis of the outgoing beam of the laser device 1;

③ The beam emitted by the laser 1 is expanded by the beam expander group 2, and the expanded beam passes through the axicon lens 3 to be measured and enters the focusing lens 4, and passes through the Focusing lens 4 beams are converged onto the image sensor 5;

④ adjust the distance between the focus lens 4 and the image sensor 5, so that the image sensor 5 is placed on the focal plane of the image side of the focus lens 4, so that the image can be used The sensor 5 detects the size of the obtained light spot, so as to obtain the cone angle of the axicon 3 to be measured.

In this way, the size of the light spot detected by the image sensor 5 can be used to solve the cone angle of the axicon 3 to be measured.

Claims (1)

1. A detection method of an axicon cone angle, the detection device adopted in the method is made up of a laser (1), a beam expander group (2), a focusing lens (4) and an image sensor (5), and its positional relationship is : along the outgoing beam direction of the laser (1) are the beam expander lens group (2), the focusing lens (4) and the image sensor (5) successively, and the beam expander lens group (2) and the focusing The socket of the axicon (3) to be measured is set between the lenses (4), it is characterized in that the method comprises the following steps: ① Place the axicon lens (3) to be measured between the beam expander lens group (2) and the focusing lens (4) in the direction of the laser (1) output beam, and the plane of the axicon lens (3) to be measured faces The light emitting direction of the laser (1); ②Adjust the optical path: adjust the central axis of the beam expander group (2) to coincide with the central axis of the outgoing beam of the laser (1); adjust the plane of the axicon lens (3) to be measured to coincide with the The outgoing beam of the laser (1) is vertical, while ensuring that the central axis of the axicon (3) to be measured coincides with the central axis of the outgoing beam of the laser (1); adjust the focusing lens (4) and the The outgoing beam of the laser (1) is vertical, while ensuring that the optical axis of the focusing lens (4) coincides with the central axis of the outgoing beam of the laser (1); adjust the plane of the image sensor (5) and the laser ( 1) The optical axis of the outgoing beam is vertical; ③ The beam emitted by the laser (1) is expanded by the beam expander group (2), and the expanded beam passes through the axicon lens (3) to be measured and enters the focusing lens (4), the light beam is converged onto the image sensor (5) through the focusing lens (4); ④ adjust the distance between the focus lens (4) and the image sensor (5), so that the image sensor (5) is placed on the image side focal plane of the focus lens (4), Like this just can utilize described image sensor (5) to detect the size of gained spot, thereby solve the cone angle of described axicon lens (3) to be measured; The cone angle θ of the described axicon (3) to be measured is: $\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&lsqb;</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}<span\; class="notranslate">\; \&rsqb;</span>$ Wherein, n is the refractive index of the axicon lens (3) to be measured, D is the size of the light spot received by the image sensor (5), and f represents the focal length of the focusing lens (4).