We present a standardized procedure to measure the amount of speckle in laser based projection systems. The parameters of the measurement procedure are chosen such that the measured speckle contrast values are in correspondence with the subjective speckle perception of a human observer, independent of the particularities of the laser projector's illumination configuration. The resulting measurement configuration consists of a single digital image sensor in combination with a camera lens of which the settings are related to the human eye. In addition, a standardized measurement procedure and speckle pattern analysis method are suggested. Finally, the speckle measurement set-up is applied to a laser projection system and corresponding subjective speckle perception results of a large test public are discussed.

We study the perception of speckle by human observers in a laser projector based on a 40 persons survey. The speckle contrast is first objectively measured making use of a well-defined speckle measurement method. We statistically analyse the results of the user quality scores, revealing that the speckle perception is not only influenced by the speckle contrast settings of the projector, but it is also strongly influenced by the type of image shown. Based on the survey, we derive a speckle contrast threshold for which speckle can be seen, and separately we investigate a speckle disturbance limit that is tolerated by the majority of test persons.

Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/05/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspxAbstract. Secondary optics that allow for the integration of a light-emitting diode (LED)-based luminescent light source into various étendue-limited applications-such as projection systems-are investigated. Using both simulations and experiments, we have shown that the optical efficacy of the luminescent light source can be increased using a collimator. A thorough analysis of the influence of the collimator's refractive index on the optical outcoupling and luminance is investigated and it is shown that it is most optimal to use a refractive index of 1.5. The optimal shape of the collimator is equal to that of a compound parabolic concentrator. Experimental results show that by using a collimator, we can improve the amount of outcoupled light with a factor of 1.8 up to 2.1 depending on the used optical configuration of the LED-based luminescent light source.

In a multi-disciplinary effort, we investigate the level of speckle that can be tolerated in a laser cinema projector based on a quality of experience experiment with movie clips shown to a test audience in a real-life movie theatre setting. We identify a speckle disturbance threshold by statistically analyzing the observers’ responses for different values of the amount of speckle, which was monitored using a well-defined speckle measurement method. The analysis shows that the speckle perception of a human observer is not only dependent on the objectively measured amount of speckle, but it is also strongly influenced by the image content. The speckle disturbance limit for movies turns out to be substantially larger than that for still images, and hence is easier to attain.

In this work we present a prototype multiview projection display that combines high-spatial and high-angular resolution with low complexity, compact form factor and potentially low-cost design. The system consists of a single projector and an image steering projection screen. It is based on beam steering using decentered microlens arrays in the projection screen and time-sequential rear-projection of the view images. The prototype has a 25 in. screen, a total of 27 viewing zones with XGA resolution and a horizontal field of view of 30°.