CN210982890U - F-theta objective lens - Google Patents
F-theta objective lens Download PDFInfo
- Publication number
- CN210982890U CN210982890U CN201922263000.1U CN201922263000U CN210982890U CN 210982890 U CN210982890 U CN 210982890U CN 201922263000 U CN201922263000 U CN 201922263000U CN 210982890 U CN210982890 U CN 210982890U
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- lens
- focal length
- theta objective
- concave
- einzel
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/0005—Optical objectives specially designed for the purposes specified below having F-Theta characteristic
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/021—Mountings, adjusting means, or light-tight connections, for optical elements for lenses for more than one lens
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
Abstract
An F-theta objective lens comprising a singlet lens having: as a concave-concave lens having a focal length f1First einzel lens L1As a concave-convex lens having a focal length f2Second einzel lens L2As a concave-convex lens L3Has a focal length f3Third einzel lens L3And as a convex-convex lens having a focal length f4Fourth einzel lens L4And the total focal length F of the F-theta objective lens, wherein the focal lengths F1‑f4The ratio to the total focal length f satisfies the following condition: -1.80 < f1/f＜‑1.20‑3.20＜f2/f＜‑2.10+1.20＜f3/f＜+1.8+1.10＜f4/f＜+1.70。
Description
Technical Field
The present invention relates to a focused F-theta objective for high power lasers, which can be used for example in scanning devices for laser material processing.
Background
The F-theta objective focuses the laser beam scanningly hitting within a scanning angle range of +/-theta with respect to the optical axis of the F-theta objective into a planar imaging region, wherein within this scanning angle range the ratio of the scanning angle to the distance of the hitting point of the laser beam in the imaging region from the optical axis follows a linear function. I.e. a laser beam scanned at a constant angular velocity produces a focal spot in the imaging area, which moves at a constant velocity. Here, the size of the focal point should be constant at each position in the imaging region. The size of the focal spot is determined depending on the purpose of the laser material processing, such as marking, delaminating or cutting.
Due to the wavelength-dependent refraction of the laser beam when passing through the F-theta objective, the F-theta objective corrects the wavelength of the processing laser beam used in order to achieve a high focus quality, i.e. the objective is calculated as follows: within the permissible temperature tolerance range for the predetermined wavelength and the predetermined laser beam diameter, the objective lens has no or only very small optical imaging distortions for an imaging region of a predetermined size, which result in a significant size change of the focal point. The F-theta objective has a large imaging area and a large total focal length, especially for use in laser material processing.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a F-theta objective for high power laser instrument, it has 532 nm's wavelength and 92mm to 138 mm's total focal length, and this F-theta objective can realize the formation of image of no back reflection of laser beam. This object is achieved by the following solution.
An F-theta objective lens comprising a singlet lens having: as a concave-concave lens having a focal length f1First einzel lens L1As a concave-convex lens having a focal length f2Second einzel lens L2As a concave-convex lens L3Has a focal length f3Third einzel lens L3And as a convex-convex lens having a focal length f4Fourth einzel lens L4And the total focal length F of the F-theta objective lens, wherein the focal lengths F1-f4And the total focal lengthThe ratio of f satisfies the following condition:
-1.80＜f1/f＜-1.20
-3.20＜f2/f＜-2.10
+1.20＜f3/f＜+1.8
+1.10＜f4/f＜+1.70。
according to a preferred embodiment of the present invention, f1/f＝-1.52、f2/f＝-2.66、f3F +1.49, and4/f＝+1.43。
according to another preferred embodiment of the invention, the entrance pupil EP of the F-theta objective is spaced at a distance d of 27mm1Is positioned on the first single lens L1Before.
Drawings
The invention shall be explained in detail below with the aid of the drawings. In the drawings:
fig. 1 shows a geometrical optical representation of an objective according to the invention with a representation of the beam course along the optical axis a and at the maximum scanning angle.
List of reference numerals
d1 EP-L1Distance d 7L4-L4Of (2) is
d2 L1Thickness d 8L4Thickness of
d3 L1-L2Distance d 9L4Spacing of protective glass
d4 L2Thickness d10 thickness of cover glass
d5 L2-L3Distance d11 Protect glass-imaging plane distance
d6 L3Thickness of
Detailed Description
The F-theta objective according to the invention has a spaced-apart entrance pupil EP arranged in front of the F-theta objective, which entrance pupil can be arranged in a plane in which one scanner mirror is located, or a substitute plane calculated therefor when two scanner mirrors are usedThe face lying in this plane, and the objective lens comprising four einzel lenses L arranged on a common optical axis A1-L4The four einzel lenses L1-L4The configuration is such that the singlet lenses form a "negative-positive" lens sequence, i.e., the first and second singlet lenses L1And L2Having a negative focal length, and two other einzel lenses L3And L4Having a positive focal length.
The first lens L1Is a concave-concave lens (biconcave lens), and the second lens L2The third lens L being a concave-convex lens3Also a concave-convex lens and the fourth lens L4Is a convex-convex lens (biconvex lens).
The focal lengths of the four single lenses meet the following requirements:
the first lens L1Focal length f of1The focal length ratio to the total focal length f is: -1.80 < f1/f＜-1.20。
The second lens L2Focal length f of2The focal length ratio to the total focal length f is: -3.20 < f2/f＜-2.10。
The third lens L3Focal length f of3The focal length ratio to the total focal length f is: 1.20 < f3/f＜1.80。
The fourth lens L4Focal length f of4The focal length ratio to the total focal length f is: 1.10 < f4/f＜1.70。
Can be arranged at the four single lenses L1-L4A cover glass SG is arranged behind.
The advantageous effect achieved with the F-theta objective according to the invention is that four einzel lenses L consisting of quartz glass are used1-L4Producing an F-theta objective lens corrected for 532nm wavelength suitable for high power lasers with an overall focal length of 115mm, the F-theta objective lens being configured with its parameters at the lenses L1-L4And, where appropriate, the back reflections produced at the protective glass SG are not focused on the lenses L1-L4On the surface of or around the entrance pupil EPThe above. The F-theta objective has no back reflection in the material of the lens. No back reflection occurs on the optical surface and no back reflection occurs at the proposed scanner position. The specific structure and parameters of one embodiment of such an F-theta objective lens are described below.
The entrance pupil EP of the F-theta objective lens is at a distance d1Is located on the first lens L1Before the anterior apex, the first lens has a thickness d2A concave-concave lens or a biconcave lens of which the front surface has a radius r1And its rear surface has a radius r2The second lens L2At an air distance d3Follows the first lens L1The second lens has a thickness d4The front surface of which has a radius r3And its rear surface has a radius r4。
The third lens L3At an air distance d5Following, the third lens is of thickness d6The front surface of which has a radius r5And its rear surface has a radius r6The fourth lens L4At an air distance d7Following, the fourth lens is of thickness d8A convex-convex lens or a biconvex lens of which the front surface has a radius r7And its rear surface has a radius r8. One has a thickness d10Of protective glass SG parallel to the plane with an air gap d9And (6) following. The imaging region BE is spaced at a distance d from the cover glass SG11As material, all the single lenses L1-L4And the protective glass SG is quartz glass having a refractive index n.
These singlet lenses L are given in the table below1-L4Its thickness and its spacing d.
TABLE 1
The pitch and thickness are likewise denoted d and are continuous in their order along the optical axis A of the F-theta objective in the beam passage directionNumbered and shown as d in FIG. 11-d11. The description of the "front" and "back" surfaces refers to the direction of light beam passage. These radii r1-r10Reference may be made to the lens L involved1-L4This is unambiguously associated with the cover glass SG and is therefore not shown in fig. 1 for good clarity.
Relying on these einzel lenses L1-L4Depending on the refractive index n of the material, these einzel lenses L1-L4Thickness d of2、d4、d6、d8Radius of curvature r of the einzel lens1-r8The individual lenses L are respectively determined in association with each other1-L4Focal length f of1-f4. The focal length f is not given in fig. 11-f4These focal lengths describe the einzel lens L, respectively1-L4Because the einzel lenses L are not labeled for good clarity1-L4Of the main plane of the plate. Again, no overall focal length F is given, which describes the distance of the imaging region BE from an alternative principal plane for the F-theta objective.
For an F-theta objective having the parameters given herein, it is derived for the first lens L1Focal length f1A ratio to the total focal length f of-1.5, for the second lens L2Focal length f2A ratio to the total focal length of-2.7, and a third lens L for the third lens3Focal length f3A ratio to the total focal length f of +1.5, and for the fourth lens L4Focal length f4The ratio to the total focal length f is + 1.4.
By these lenses L1-L4Are arranged behind one another and have an air spacing d of3、d5、d7In connection therewith, this total focal length f is 115 mm. The F-theta objective lens is corrected for a wavelength of 532 nm.
Claims (3)
1. An F-theta objective lens comprising a single lens, characterized in that: as a concave-concave lens having a focal length f1First einzel lens L1Tool as concave-convex lensHaving a focal length f2Second einzel lens L2As a concave-convex lens L3Has a focal length f3Third einzel lens L3And as a convex-convex lens having a focal length f4Fourth einzel lens L4And the total focal length F of the F-theta objective lens, wherein the focal lengths F1-f4The ratio to the total focal length f satisfies the following condition:
-1.80＜f1/f＜-1.20
-3.20＜f2/f＜-2.10
+1.20＜f3/f＜+1.8
+1.10＜f4/f＜+1.70。
2. the F-theta objective lens as set forth in claim 1, wherein:
f1/f＝-1.52、f2/f＝-2.66、f3f +1.49, and4/f＝+1.43。
3. the F-theta objective lens as set forth in claim 2, wherein: the entrance pupil EP of the F-theta objective lens is spaced at a distance d of 27mm1Is positioned on the first single lens L1Before.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE202019100168.2U DE202019100168U1 (en) | 2019-01-14 | 2019-01-14 | F-Theta lens |
| DE202019100168.2 | 2019-01-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210982890U true CN210982890U (en) | 2020-07-10 |
Family
ID=65441571
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201922263000.1U Active CN210982890U (en) | 2019-01-14 | 2019-12-16 | F-theta objective lens |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR20200001645U (en) |
| CN (1) | CN210982890U (en) |
| DE (1) | DE202019100168U1 (en) |
-
2019
- 2019-01-14 DE DE202019100168.2U patent/DE202019100168U1/en active Active
- 2019-12-16 CN CN201922263000.1U patent/CN210982890U/en active Active
- 2019-12-23 KR KR2020190005220U patent/KR20200001645U/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE202019100168U1 (en) | 2019-02-06 |
| KR20200001645U (en) | 2020-07-23 |
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