System for psychophysical measurements of two-photon vision

Two-photon absorption occurring in photoreceptors of human eye is responsible for perception of pulsed infrared laser beams. Color of perceived light corresponds to about half of wavelength of stimulating beam. This recently discovered phenomenon is called two-photon vision. However it is yet not clear how such phenomena could impact an ophthalmic diagnosis and therefore further studies are required. In this paper we present the system that enables future psychophysical experiments to extend knowledge about two-photon vision and its diagnostic value by identifying differences between two-photon and single-photon vision. Full Text: PDF ReferencesD. A. Atchison, G. Smith, Optics of the human eye (Butterworth-Heinemann 2000) CrossRef G. Palczewska et al. "Human infrared vision is triggered by two-photon chromophore isomerization", Proceedings of the National Academy of Sciences 111, 1428 (2014). CrossRef P. Artal, S. Manzanera, K. Komar, A. Gambín-Regadera, M. Wojtkowski, "Visual acuity in two-photon infrared vision", Optica 4, 1488 (2017). CrossRef K. Komar et al. "Posterior Eye Shape Measurement With Retinal OCT Compared to MRI", Investigative Ophthalmology & Visual Science 57, 196 (2016). CrossRef K. Komar et al. "Two-photon visual sensitivity of human cones - a psychophysical study", Investigative Ophthalmology & Visual Science 59, 4049 (2018). DirectLink S. A. Burns,R.H. Webb, Handbook of optics 28 (New York, McGraw Hill 1994) DirectLink R. W. Nygaard, T. E. Frumkes, "Calibration of the retinal illuminance provided by maxwellian views", Vision Research (1982) CrossRef P. Melillo et al. "Pupillometric analysis for assessment of gene therapy in Leber Congenital Amaurosis patients", Biomedical engineering online 11, 40 (2012) CrossRef P. A. Stanley, A. K. Davies, "The effect of field of view size on steady-state pupil diameter", Ophthalmic and Physiological Optics, 15, 601 (1995) CrossRef S. Mathôt, "Pupil mimicry is the result of brightness perception of the iris and pupil" Journal of Cognition 1 (2018) CrossRef M. M. Thomas, T. D. Lamb, "Light adaptation and dark adaptation of human rod photoreceptors measured from the a‐wave of the electroretinogram", The Journal of physiology 518, 479 (1999) CrossRef

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Determination of 4H-SiC Ionization Rates Using OBIC Based on Two-Photon Absorption

Materials Science Forum ◽

10.4028/www.scientific.net/msf.858.245 ◽

2016 ◽

Vol 858 ◽

pp. 245-248 ◽

Cited By ~ 2

Author(s):

Hassan Hamad ◽

Christophe Raynaud ◽

Pascal Bevilacqua ◽

Sigo Scharnholz ◽

Bertrand Vergne ◽

...

Keyword(s):

Single Photon ◽

Green Laser ◽

Photon Absorption ◽

Absorption Process ◽

Field Range ◽

Two Photon Absorption ◽

Two Photon ◽

Avalanche Diodes ◽

Single Photon Absorption ◽

Ionization Rates

Optical Beam Induced Current (OBIC) measurements are performed on 4H-SiC avalanche diodes with a very thin and a highly doped active region. A pulsed green laser, with a wavelength of 532 nm, illuminates a reverse biased diode leading to generate electron-hole pairs in the space charge region. Comparison between the 4H-SiC bandgap and the incident photon energy shows that single photon absorption process can be neglected and two-photon absorption process dominates in this case. Ionization rates are then extracted from multiplication curve in a high electric field range (3 to 5 MV.cm–1). Results are in good agreement with previous ones obtained on the same diodes using single photon absorption process.

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Measurements of two-photon and single-photon absorption cross sections and picosecond relaxation times in organic dyes

IEEE Journal of Quantum Electronics ◽

10.1109/jqe.1972.1077018 ◽

1972 ◽

Vol 8 (6) ◽

pp. 530-531

Author(s):

D. Bradley ◽

M. Hutchinson ◽

H. Koetser ◽

T. Morrow ◽

G. New

Keyword(s):

Cross Sections ◽

Organic Dyes ◽

Single Photon ◽

Relaxation Times ◽

Photon Absorption ◽

Absorption Cross ◽

Two Photon ◽

Single Photon Absorption

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Fabrication Technology of Involute Micro Gear Based on Two-Photon of Femtosecond Laser

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.44-47.670 ◽

2010 ◽

Vol 44-47 ◽

pp. 670-674 ◽

Cited By ~ 1

Author(s):

Shu Feng Sun

Keyword(s):

Femtosecond Laser ◽

Light Source ◽

Single Photon ◽

Three Dimensional ◽

Photon Absorption ◽

Micro Electro Mechanical Systems ◽

Excitation Light ◽

Two Photon ◽

Machining System ◽

Set Up

Microfabrication is a kind of critical technology for the development of Micro Electro-Mechanical Systems (MEMS). The frequently-used microfabrication technologies are electric discharge machining, photoetching, LIGA and laser fabrication, et al. Micro structures may be fabricated by these technologies. The polymerization principle of two-photon of femtosecond laser is different from that of single-photon. Photoinitiator of photosensing material absorbs two photons simultaneously to accomplish energy level transition and to induce the material to occur photochemical reaction. For the material absorbing two photons, the energy of each photon is equivalent to half of the energy that needed by the material transiting from ground state to excited state. It is also equal to half of the energy needed by the material occurring single-photon absorption. Therefore, the photonic frequency of two-photon excitation light source is half of the single-photon light source. According to two-photon fabrication principle, machining system of two-photon of femtosecond laser is set up. Which includes light path transmission equipment, three dimensional micro displacement scanning stage and control software, et al. Involute micro gear is fabricated by two-photon of femtosecond laser generated by the system.

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Transient and steady-state behavior of single and two-photon absorption by microwave driven field

Canadian Journal of Physics ◽

10.1139/cjp-2013-0480 ◽

2014 ◽

Vol 92 (4) ◽

pp. 284-288

Author(s):

Seyyed Hossein Asadpour ◽

H. Rahimpour Soleimani

Keyword(s):

Steady State ◽

Microwave Field ◽

Single Photon ◽

Photon Absorption ◽

State Behavior ◽

Two Photon Absorption ◽

Two Photon ◽

Probe Gain ◽

The One ◽

Transient And Steady State

In this paper, the effect of microwave field on the transient and steady state response of the four-level inverted Y-type atomic system is investigated. It is found that the properties of transient and steady processes can be affected by microwave field. It is found that the absorption spectrum behaves differentially for single-photon absorption and two-photon absorption. Also it is observed that in the one-photon absorption, the microwave field can lead to the probe gain and for two-photon absorption case, the strong microwave can enhance the absorption.

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