Optical design of an ultrashort throw ratio projector with two freeform mirrors

Yunfeng Nie; Rubén Mohedano; Pablo Benítez; Julio Chaves; Juan C. Miñano; Hugo Thienpont; Fabian Duerr

doi:10.1117/12.2236613

28 September 2016 Optical design of an ultrashort throw ratio projector with two freeform mirrors

Yunfeng Nie, Rubén Mohedano, Pablo Benítez, Julio Chaves, Juan C. Miñano, Hugo Thienpont, Fabian Duerr

Proceedings Volume 9947, Current Developments in Lens Design and Optical Engineering XVII; 99470C (2016) https://doi.org/10.1117/12.2236613
Event: SPIE Optical Engineering + Applications, 2016, San Diego, California, United States

Abstract

In this work, an optical design approach is presented to design an ultrashort throw distance projection system by combination of an off-the-shelf refractive lens and two off-axis freeform mirrors. These two freeform mirrors are used to greatly shorten the projection distance by more than three times compared to conventional (rotationally symmetric) systems, while still maintaining a good imaging quality. Firstly, a direct design method that enables the simultaneous calculation of two off-axis freeform-profile mirrors by partially coupling more than three fields is introduced. The specifications of the conventional refractive lens are taken into account during this procedure. The pupil matching principle is applied to ensure good performance between the two sub-systems. The calculated mirrors then serve as a good starting point for optimization using commercial optical design software. To step from freeform profiles to freeform surfaces, the calculated two profiles are fitted into odd polynomials to evaluate the image quality and then re-fitted into XY polynomials for further optimization. Finally, the polynomial coefficients of the two freeform mirrors are imported into the optical design program. The merit function is built from RMS spot radii over the full field, and additional constraints are made for correcting distortion. After optimization, the calculated initial design quickly converges to a well performing imaging system. As an example, an ultrashort throw distance projection lens with a large 80-inch diagonal image at 400mm throw distance is designed, analyzed and compared with literature data. The values of MTF are over 0.6 at 0.5 lp/mm and the distortion is less than 1.5%: showing a very good and well balanced imaging performance over the entire field of view.

Citation Download Citation

Yunfeng Nie, Rubén Mohedano, Pablo Benítez, Julio Chaves, Juan C. Miñano, Hugo Thienpont, and Fabian Duerr "Optical design of an ultrashort throw ratio projector with two freeform mirrors", Proc. SPIE 9947, Current Developments in Lens Design and Optical Engineering XVII, 99470C (28 September 2016); https://doi.org/10.1117/12.2236613

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

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.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available