Optical encryption system is generally vulnerable to attacks based on phase retrieval algorithm. In this paper, an improved encryption scheme is proposed based on the coherent 4-f system and complementary masks. This pair of irregular shaped complementary masks are introduced to cut the ciphertext and regroup them. The stitched ciphertext has high immunity to ciphertext attacks based on phase retrieval algorithms. We have done numerically simulation to demonstrate the feasibility and validity of the proposed technique.
Absolute testing is an important means of measuring the surface deviation with high precision. A novel method is proposed to approach solutions of the absolute surface 3-D distributions that based on the two-flat method. Measurement
data are separated into even and odd part and the rotation averaging method is used to calculate the rotation variant part. The performance of this new method is evaluated by compared with the method in the literature. The maximum
difference of peak to valley (PV) and root mean square (RMS) between the two methods are 2.3nm and 0.4nm, respectively. The advantage of this method is that it can obtain the surface information of the low and mid-spatial
frequency. The repeatability error propagation of the proposed method is discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.