Tables of the Modulation Transfer Function of a Defocused Perfect Lens

Levi, Leo; Austing, Richard H.

doi:10.1364/ao.7.000967

Cited by 20 publications

(4 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We take the total refracting power of the eye to be 66.6 D. 26 Hopkins's equations cannot be solved analytically, but numerical values have been tabulated by Levi and Austing. 27 They express W 20 in units of the Rayleigh criterion and call it A:…”

Section: Ideal-lens Calculationsmentioning

confidence: 99%

Tolerance to visual defocus

et al. 1987

View full text Add to dashboard Cite

Low-resolution optical systems are more tolerant to defocus than are high-resolution systems. We wished to determine whether this principle applies to human vision. We used psychophysical methods to measure the effects of defocus in normal eyes under low-resolution conditions. Modulation transfer of sine-wave gratings was measured as a function of dioptric defocus at low and medium spatial frequencies. We defined the depth of focus at a given spatial frequency to be the dioptric range for which the modulation transfer exceeds 50% of its peak value. For dilated pupils, depth of focus increased from about 2.5 diopters (D) at 3.5 cycles/deg to about 17 D at 0.25 cycles/deg. From our results we predicted that tasks requiring only low spatial frequencies will be more tolerant to defocus than tasks requiring higher spatial frequencies. This prediction was confirmed in a letter-recognition experiment. The increasing tolerance to defocus at low spatial frequencies also implies that individuals with low acuity will be more tolerant to defocus than people with normal vision. We confirmed this prediction by measuring tolerance to defocus in 30 low-vision eyes.

show abstract

Section: Ideal-lens Calculationsmentioning

confidence: 99%

Tolerance to visual defocus

et al. 1987

View full text Add to dashboard Cite

show abstract

“…The contrast is computed by making use of equations (1) through (6). Different values of IX (a = 0.1, 0.25, 0.5, 0.75) have been used for two values of obscuration ratio E = 0.4 and 0.6.…”

Section: Resultsmentioning

confidence: 99%

Effect of Defocusing on the Rectangular Wave Response of an Annular Aperture

Maggo

Singh

1971

Annalen der Physik

View full text Add to dashboard Cite

show abstract

“…6 show how image contrast is reduced as defocus is introduced. They are derived from the Tables of Levi & Austig (1968), and are calculated for a grating of 1-47 cycles/deg (our standard grating of bar width 3 units in the '3, 5, 7' experiment) and a pupil of 06 mm. One conclusion is that contrast falls little within the range of the primary lobes.…”

Section: Methodsmentioning

confidence: 99%

“…tracing of local irradiance shift as a function of defocus, for parameters as for upper panel, but for pupil aperture = 0-6 mm. The crosses show how contrast is reduced as a function of defocus, from Tables ofLevi & Austig (1968).…”

mentioning

confidence: 99%

Electrophysiological optometry using Scheiner's principle in the pigeon eye.

Fitzke¹,

Hayes²,

Hodos³

et al. 1985

The Journal of Physiology

View full text Add to dashboard Cite

SUMMARY1. A new electrophysiological optometer has been developed, based on Scheiner's principle. Using two light-emitting diodes driven in counterphase, and grating stimuli in Maxwellian view, the system has been used to refract the photoreceptor plane of the pigeon eye.2. When a grating is conjugate with the photoreceptors, the electroretinographic response (e.r.g.) is minimal, and the image is stationary. As defocus is introduced, so image shift occurs, and the e.r.g. rises on each side of the refractive minimum.3. Two experiments were devised to test whether a derived minimum point is primary, by using gratings of bar width 3, 5 and 7 units, and by using random checkerboard stimuli.4. Ray tracing was used to compute the lobe width of dioptric profiles for gratings of spatial frequency 1-47, 0-88 and 0-63 cycles/deg. The computed lobe widths agree well with experimentally determined e.r.g. profiles.5. Examination of the lateral visual field, on the horizon, shows that the pigeon eye is emmetropic, and well corrected for astigmatism.

show abstract

Tables of the Modulation Transfer Function of a Defocused Perfect Lens

Cited by 20 publications

References 4 publications

Tolerance to visual defocus

Tolerance to visual defocus

Effect of Defocusing on the Rectangular Wave Response of an Annular Aperture

Electrophysiological optometry using Scheiner's principle in the pigeon eye.

Contact Info

Product

Resources

About