Increasing the sensitivity of laser triangulation systems using structured optical surfaces

Patrick Kienle; Michael H. Köhler; Kun Wang; Martin Jakobi; Alexander W. Koch

doi:10.1117/12.2566094

20 August 2020 Increasing the sensitivity of laser triangulation systems using structured optical surfaces

Patrick Kienle, Michael H. Köhler, Kun Wang, Martin Jakobi, Alexander W. Koch

Proceedings Volume 11500, ODS 2020: Industrial Optical Devices and Systems; 115000J (2020) https://doi.org/10.1117/12.2566094
Event: SPIE Optical Engineering + Applications, 2020, Online Only

Abstract

Laser triangulation is an optical method for measuring distances to an object. A laser beam is directed towards a measurement surface, and the diffusely reflected light is collected by an imaging system onto a detector. The absolute distance can be obtained by using known geometric relations of the system and the position of the laser spot on the detector. Therefore, a change in the measurement distance results in a corresponding movement of the imaged laser spot, defining the sensitivity of the system in pixels per millimeter. This value depends on the geometrical and optical design of the laser triangulation setup, especially the base distance between the laser and the imaging lens, as well as its focal length. As those parameters also influence the geometric dimensions and the possible measurement range of the device, the sensitivity cannot be increased arbitrarily. Thus, the sensitivity of a standard laser triangulation system is limited to a certain value. In this contribution, structured optical surfaces are applied onto the measurement surface to further increase the sensitivity. Through the spatial modulation of the imaged laser spot intensity distribution, the calculated laser spot displacement is larger than its actual geometrical displacement. This effect is examined through simulations with a bar structure, which leads to an improvement of the sensitivity by a factor of up to 5.7 at a distance of 1 m and a measurement range of 2 mm. Eventually, the concept is proven in measurements and feasible implementations of such a structure are considered.

Conference Presentation

Citation Download Citation

Patrick Kienle, Michael H. Köhler, Kun Wang, Martin Jakobi, and Alexander W. Koch "Increasing the sensitivity of laser triangulation systems using structured optical surfaces", Proc. SPIE 11500, ODS 2020: Industrial Optical Devices and Systems, 115000J (20 August 2020); https://doi.org/10.1117/12.2566094

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