基于子孔径拼接干涉法的非球面测量技术
78 浏览量
更新于2024-08-28
收藏 943KB PDF 举报
"基于子孔径拼接干涉法的非球面表面测量技术"
在光学行业中，非球面表面的精确测量对于制造高质量的光学元件至关重要，尤其是那些在高精度光学系统中使用的元件。传统的全口径干涉法在测量复杂形状的非球面时可能会遇到挑战，因为它通常需要使用昂贵且复杂的零级校准光学器件。为了克服这一问题，"基于子孔径拼接干涉法（Sub-aperture Stitching Interferometry，SSI）"的新型测量方法被提出，它能够无需额外的null optics辅助就能对凸非球面表面进行测试。
该方法的核心是将大的测量区域划分为多个小的子孔径，每个子孔径通过干涉仪分别进行测量。子孔径拼接干涉法的理论基础在于光的波前重建和干涉原理，通过在不同子孔径之间进行精确的拼接，可以重建整个非球面表面的形状。具体实现中，研究者采用了合成优化拼接模式，结合同质坐标变换和同步最小二乘拟合算法，确保了各子孔径测量数据的有效融合。
文章中提到，SSI的软件被设计开发，以支持这种复杂的测量流程。此外，还设计并研制了一款原型设备，用于通过SSI技术测试大型非球面。实验部分，他们使用五个子孔径对一个凸非球面进行了实际测量，验证了该方法的有效性和实用性。
子孔径拼接干涉法的优势在于其灵活性和适应性，它能处理大尺寸和复杂形状的非球面，同时降低了对昂贵零级光学器件的依赖。这种方法对于提升光学制造的精度和效率具有重要意义，特别是在需要大量生产非球面元件的现代光学工业中。
"基于子孔径拼接干涉法的非球面表面测量技术"是一种创新的非球面测量解决方案，它利用了干涉测量的精度和子孔径拼接的灵活性，为非球面光学元件的精密制造提供了新的工具。这项技术的成熟和应用将进一步推动光学技术的发展，尤其是在航空航天、通信、医疗和科学研究等领域。
COL 11(Supp.), S21201(2013) CHINESE OPTICS LETTERS September 30, 2013
Aspheric surface measurement based on sub-aperture
stitching interferometry
Xiaokun Wang (
%%%
)
Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute
of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
∗
Corresponding author: jimwxk@sohu.com
Received January 19, 2013; accepted March 5, 2013; posted online July 17, 2013
In order to test convex aspheric surfaces without the aid of other null optics, a novel method combined
sub-aperture stitching and interferometry called SSI (sub-aperture stitching interferometry) is introduced.
In this letter, the theory, basic principle, and flow chart of SSI are researched. A synthetical optimization
stitching mode and an effective stitching algorithm are established based on homogeneous coordinate’s
transformation and simultaneous least-squares fitting. The software of SSI is devised, and the prototype
for testing of large aspheres by SSI is designed and developed. The experiment is carried out with five sub-
apertures for a convex silicon carbide (SIC) aspheric mirror with a clear aperture of 130 mm. The peak-to-
valley (PV) and root-mean- square (RMS) error are 0.186 λ and 0.019 λ, respectively. For the comparison
and validation, the TMA system which contained the convex asphere is t ested by interferometry. The
wavefront error of th e central field of the optical system is 0.068 λ RMS which approaches to diffraction
limitation. The results conclude that this technique is feasible and accurate. It enables the non-null testing
of aspheric surfaces especially for convex aspheres.
OCIS codes: 120.6650, 120.0120, 240.0240.
doi: 10.3788/COL201311.S21201.
Aspheric surfaces have great ability on correcting aber-
rations, improving ima ge quality and reducing the size
and weight of the system
[1,2]
. So they are extr e mely
impo rtant in optical sy stems and have been applied in
various kinds of fields. As the us e of aspheres in optical
systems becomes more and more prevalent, the need for
precise and efficient metrology grows. One of the most
promising measurements is interferometry. Because of
its high resolution, high sensitivity and reproducibility,
this technology has become the standard tool for testing
optical sur faces and wavefronts. However, when tes ting
the aspheric surfaces with large aperture, steep and large
departure, many interference fringes are formed on the
detection device and proper analysis are difficult to per -
form, so we will fall back on auxiliary optics such as null
corrector or c omputer generated hologra m (CGH). The
auxiliary elements must have been specially designed
and customized which co sts much more time and cost.
What is more it bring s other errors including both man-
ufacturing errors and some unavoidable misalignment
errors. The cost of making and verifying the null ele-
ments conspires to keep aspheres away from practical
optical designs.
Sub-aperture stitching interfer ometry (SSI) can ex-
pand both the longitudinal and lateral dynamic ranges
of the interferometer itself, and broaden the scope of
measurement significantly
[3−6]
. The basic idea of sub-
aperture testing method was first proposed by Kim in
1982
[7]
. It can test la rge optical system by an array of
smaller optical flats without large reference flat, which
substantially reduces the cost and complexity. The sec-
ond milestone is the discrete phase method developed
by Stuhlinger
[8]
. Then the le ast-squares method to fit
the relative piston and tilt by the datum of overlapping
regions was introduced by Otsubo et al.
[4,9]
. The men-
tioned stitching methods are effective for testing large
flats, but they cannot be used to measure large spheres
or aspheric surfaces.
The last significant progress of SSI is the automated
subaperture stitching interferometer workstation pro-
duced by QED(Queues Enforth Development, Inc.)
Technologies
[10−12]
. It is a pplicable not only to plano
optics, but also to spherical and moderate aspheric sur-
faces with the aperture smaller than 200 mm. But the
mathematic model and stitching algorithm have not been
described in detail by QED.
Recently we have proposed a synthetical optimization
stitching algorithm for testing large aspheric surfaces by
SSI
[13,14]
. In this letter, a prototype for testing of larg e
aspheres with the stitching method is developed. We
fabricate a convex silicon carbide (SIC) mirror by com-
puter c ontrolled optical surfacing (CCOS) and measured
it by SSI. It shows that SSI can be used to test as phere
especially for convex asphere at high resolution, low cost,
and high efficiency without a ny null optics.
The s ketch of s e tup for testing convex asphere by
SSI is shown in Fig. 1, and the elaborate flow chart
is given in Fig. 2. Firstly, we define the surface to
be measured, in particular its nominal aperture and ra-
dius of the curvature. The prop e r transmission sphere
is selected correctly, and then the s iz e and number of
the sub-aperture are determined by the surface diam-
eter and the relative aperture
[15]
. The second step is
to control the interferometer and the tested asphere
precisely. The first null is located at the ce nter of
the surface and the curvature of the spher ical wave-
front is consistent with the measured region. The
phase distribution of this region will be recorded. Next,
when we align the interferometer or the asphere again
and again, let the slope of the spherical wavefront
1671-7694/2013/S21201(4) S21201-1
c
2013 Chinese Optics Letters
下载后可阅读完整内容，剩余3页未读，立即下载
2021-02-09 上传
2021-02-04 上传
2021-02-11 上传
2021-02-10 上传
2021-02-22 上传
2021-02-09 上传
2021-02-04 上传
2021-02-23 上传
2021-02-10 上传
