6-10 Optical Filters and Their Properties Quiz

Optical Filters

• Bandpass filters transmit wavelengths in a narrow range around a specified wavelength.
• The primary function of optical filters is to selectively transmit or block specific wavelengths of light.
• Long-pass filters transmit wavelengths above a designated cut-on wavelength.

Filter Composition

• Interference filters, such as dichroic, dielectric, and reflective filters, consist of multiple thin layers of materials that create interference effects to selectively transmit light.
• Absorbance filters, like color glass filters, function by absorbing certain wavelengths and allowing others to pass.

Properties of Light in Medicine

• Refraction occurs due to the change in speed of light when it meets a new material at an angle other than perpendicular.
• In medicine, the detection of porphyria utilizes the property of light absorption in biological samples.
• Chemical changes in molecules due to absorbed photon energy demonstrate the property of light related to energy transfer.

Medical Use of Light

• Visible light helps obtain visual information about a patient's skin and detect abnormal structures.
• The heating of tissues in medical applications is attributed to the property of light absorption.

NIR Photons and Light Emission

• Cells in the human body are most sensitive to a specific range of near-infrared (NIR) photons.
• LED, OLED, and CFL lighting and displays are referred to as 'Visible Only' emitters as they primarily emit visible light without significant infrared or ultraviolet components.
• Comparing the spectrum of 'Visible Only' emitters to natural sunlight based solely on the spectrum of the Sun is misleading, as natural sunlight also comprises infrared and ultraviolet light.

Human Body Response to Light

• Studies suggest that the human body responds differently to UV and high-energy visible (HEV) photons, noting sensitivity in areas like the retina.
• Fetus and young child cells are exposed to larger amounts of NIR photons compared to adult cells, which receive around 60% of NIR exposure.

Circadian Rhythms and Melatonin

• The primary function of optical filters in relation to sunlight exposure is to alter the body's response to light, helping regulate biological rhythms.
• Chronobiologists assert that specific properties of the solar spectrum, particularly blue light, stimulate the pineal gland to secrete circulating melatonin.
• Modern Visible Only lighting systems play a role during the day in managing light exposure, potentially influencing circadian rhythms.
• Exposure to wavelengths that correspond to the blue of the sky can affect circadian rhythms by promoting wakefulness and alertness.

Sunlight Exposure Effects

• Circulating melatonin levels are significant in their regulatory role on existing circadian rhythms, influencing sleep patterns and overall health in response to light exposure.

Test your knowledge about optical filters and their properties with this quiz. Learn about how filters transmit, absorb, and reflect light of different wavelengths, and their various applications in optical systems.