Introduction

  The human eyes cannot perceive objects that are smaller than a certain size. Also, they cannot recognize light whose intensity is lower than an inherent threshold. We take these limitations into account to determine the number of fluorescent proteins that must accumulate before we can notice any fluorescence, and establish the minimum circular area required for us to perceive any fluorescence.

  Objective

  Investigate concentration required for an amount of fluorescent protein in the E.coli that makes light from E.coli be visible for human.

  Background

  Human has the limits in vision. For our objective, we have to know about the limit of recognizing size of objects in human vision. This limit is called the ‘Minimum visible acuity’. The exact definition of minimum visible acuity is the minimum size of object that the human eyes can discern. In the table 1 Types of visual acuity(reference 1), the value of detection acuity(red box), ~1.0 arc second, is the minimum visible acuity that we take.

  Table : Types of visual acuity ¹

  We assume that the E. coli is in a darkroom for discovering the minimum number of fluorescent protein. In this reason, we use 0.1 lx, the minimum intensity of light that cone cells in human can perceive. ² In fig1 (a), There is a brief picture for minimum visible acuity. We choose that 1 second is the basic time scale, so have to know the number of fluorescent protein per 1 second. By our research, The range of the photon emitted time is wide, from to