Liquid crystal display as spatial light modulator for diffractive optical elements and the reconstruction of digital holograms

Wernicke, Guenther K.G.; Krueger, Sven; Gruber, Hartmut; Demoli, Nazif; Duerr, Matthias; Stephan, T.

doi:10.1117/12.447341

Cited by 13 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A dynamic phase modulating system opens here new possibilities for non-destructive testing devices based on interferometry. This new approach is really the biggest challenge for SLMs, but the obtained results are more than just a feasibility study [10,12,13].…”

Section: Applications In Diffractive Opticsmentioning

confidence: 91%

See 1 more Smart Citation

Spatial light modulator system as dynamic diffractive element

et al. 2003

Self Cite

View full text Add to dashboard Cite

A new spatial light modulator system based on a high-resolution LCOS micro-display is presented. The parameters like pixel size and number as well as the fill factor and especially the phase modulation properties open up many application in coherent optical applications. The light efficiency of this system can compete with other static optical solutions. A major application field, diffractive optics, will be illustrated and performance and perspectives of this system will be discussed.Investigations were done mostly on the addressing of the 2.3 Mega pixel device. The effect of ghost images and cross talk due to the addressing scheme will be discussed concerning the influence of the optical performance. General optical measurements like complex modulation is presented, particularly focused on the phase modulation properties. Furthermore, possibilities of adapting the modulation by the use of "Gamma-correction" curves are shown. Various experiments, which illustrate different application fields the modulator system, are presented.

show abstract

Section: Applications In Diffractive Opticsmentioning

confidence: 91%

“…The result is again the realization of both optical functions, what is the same that happens with double exposure techniques in interferometry, fringes are visible. The addition of two digital phase masks leads in reconstruction to interference [10,12,13].…”

Section: Applications In Diffractive Opticsmentioning

confidence: 99%

Spatial light modulator system as dynamic diffractive element

et al. 2003

Self Cite

View full text Add to dashboard Cite

show abstract

“…For information input (SLM1) transmissive amplitude LC SLM HoloEye LC2002 [12][13][14] with 800×600 pixels and 32×32 µm 2 pixel size was used. To image encryption DOE (SLM2) reflective phase LC SLM HoloEye PLUTO VIS [15][16][17] with 1920×1080 pixels and 8×8 µm 2 was used.…”

Section: Optical Encryption In Spatially-incoherent Monochromatic Ligmentioning

confidence: 99%

Optical encryption in spatially-incoherent light using two LC SLMs for both information input and encryption element imaging

et al. 2014

View full text Add to dashboard Cite

At present time methods of optical encryption are actively developed. The majority of existing methods of optical encryption use not only light intensity distribution, easily registered with photosensors, but also its phase distribution which require application of complex holographic schemes in conjunction with spatially coherent monochromatic illumination. This leads to complex optical schemes and low decryption quality. To eliminate these disadvantages it is possible to implement optical encryption using spatially incoherent monochromatic illumination which requires registration of light intensity distribution only.Encryption is accomplished by means of optical convolution of image of scene to be encrypted and encryption diffractive optical element (DOE) point spread function (PSF) which serves as encryption key. Encryption process is described as follows. Scene is illuminated with spatially-incoherent monochromatic light. In the absence of encryption DOE lens forms image of scene in photosensor plane. DOE serves as encryption element, its PSF -encryption key. Light passing through DOE forms convolution of object image and DOE PSF. Registered by photosensor convolution is encrypted image. Decryption was conducted numerically on computer by means of inverse filtration with regularization. Kinoforms were used as encryption DOE because they have single diffraction order. Two liquid crystal (LC) spatial light modulators (SLM) were used to implement dynamic digital information input and dynamic encryption key change. As input scene amplitude LC SLM HoloEye LC2002 with 800×600 pixels 32×32 μm 2 and 256 gray levels was used. To image synthesized encryption kinoforms phase LC SLM HoloEye PLUTO VIS with 1920×1080 pixels 8×8 μm 2 and 256 phase levels was used. Set of test images was successfully optically encrypted and then numerically decrypted. Encrypted images contents are hidden. Decrypted images despite quite high noise levels are positively recognizable. Results of optical encryption and numerical decryption are presented.

show abstract

“…An improvement in the SNR of the fringe pattern can be obtained by limiting either the variance (range of values) of the modulation intensity M I or of the random speckle phase sp ϕ , or both. When using liquid crystal arrays whose pixels are matched to the CCD-camera [13], phase and amplitude of the transmitted wave can be independently controlled pixel by pixel. An experimental set-up is illustrated in Fig.2.…”

Section: Speckle Noise Reduction Before Image Capturementioning

confidence: 99%

Improvement of speckle correlation fringes by adaptive correction using twisted nematic LCD

Hack

Gundu

2006

SPIE Proceedings

View full text Add to dashboard Cite

Subtraction correlation fringes in Digital Speckle Pattern Interferometry are described as a smoothly varying intensity distribution multiplied with high-frequency noise that is due to the random distribution of speckle intensity and speckle phase across the image plane. Although intensity modulation and speckle phase can be eliminated by phase stepping or other phase retrieval methods, noise is not eliminated completely due to the limited dynamic range of image processing, given by the saturation level of the camera, the digitisation depth and the electronic noise. Digital image processing techniques have been developed to reduce the speckle noise from the fringe pattern, but in most cases the fringes are not restored completely. In this paper the speckle noise is reduced before image digitisation by reducing the range of either the modulation intensity values or the speckle phase values, or both, in the interference pattern. This is done adaptively by using programmable twisted nematic LCDs. Since the manipulation is performed for each pixel independently in the reference beam, the imaging quality is retained and no blurring occurs. We quantitatively discuss the improvement and limitation of the method. The experimental verification is performed using an amplitude-only or phase-only spatial light modulator in a conventional ESPI setup.

show abstract

Liquid crystal display as spatial light modulator for diffractive optical elements and the reconstruction of digital holograms

Cited by 13 publications

References 8 publications

Spatial light modulator system as dynamic diffractive element

Spatial light modulator system as dynamic diffractive element

Optical encryption in spatially-incoherent light using two LC SLMs for both information input and encryption element imaging

Improvement of speckle correlation fringes by adaptive correction using twisted nematic LCD

Contact Info

Product

Resources

About