TABLE 3.
List of symbols and definitions pertaining to the first biophysical function
| Symbol | Definition |
| Φ | Total light flux (photons s−1) |
| Φo, Φz | Value of Φ at z = 0 and at distance z from base |
| A | Cross-sectional area of outer segment, assumed to be equal with the surface area of a transverse membrane, referred to as a lamella (Eckmiller, 1987). One rod disk, also called flattened saccule, has the surface of two lamellae |
| Ao, Az | Value of A at the base and at distance z from it |
| A┴, A║ | Outer segment absorbance for transversely and axially polarized light |
| Jo | Incident flux density (photons s−1 μm−2); Jo = Φo/Ao |
| Jz | Transmitted flux density through level z from base; Jz = Φz/Az |
| R | Dichroic ratio: absorbance ratio at two orthogonal polarizations; R = A┴/A║ |
| S┴ | Specific absorbance at transverse polarization; S┴ = A┴/d |
| d | Outer segment diameter (mean) |
| do, dz | Outer segment diameter at base and at a distance z from the base |
| c | Concentration of visual pigment in appropriate units |
| α | Molecular extinction coefficient (µm2 per molecule; Eqs. 7 and 9) |
| ε | Molar extinction coefficient (liter mole−1 cm−1; Eqs. 8 and 9) |
| λmax | Wavelength of peak extinction |
| k | Anisotropy factor: ratio of anisotropic to isotropic absorbance |
| a | Absorption coefficient (usually in cm−1; Eq. 3) |
| a−1 | Characteristic length (reciprocal of a) expressed in μm (signifies the distance at which Φz reduces to 36.8% of Φo) |
| ah1 | Absorption coefficient required for invariance of light flux along the outer segment, as by Eq. 6 |
| ah1−1 | Characteristic length, based on invariance of light flux along an outer segment (μm) |
| az′ | Absorption coefficient obtained by Eq. 10 |
| az′′ | Absorption coefficient obtained by Eq. 16 |
| az′−1, az′′−1 | Characteristic lengths (μm) obtained from az′ and az′′ |
| τ | Taper, as defined by Eq. 17 |
| Θ | Angle of incidence with respect to cell axis |
| Θc | Critical angle of Θ, defined as Θc = 90° − ϕc |
| ϕc | Critical angle with respect to normal of boundary (Eq. 19) |
| ϕi, ϕo | Angles of incidence and refraction to normal of boundary |
| n1, n2 | Refractive indices of two optical media forming a boundary |
| z | Axial distance within outer segments (μm), with z = 0 at the base |