Portable test paper counting device and method based on single photon detector

A test paper counting method based on a single photon detector by using a portable test paper counting device based on a single photon detector,

• the portable test paper counting device based on a single photon detector comprising a box-shaped housing, two guide rail pairs, two hanger rods, a laser, a reflecting mirror, a single photon detector, a power supply, and a PC computer, wherein a rectangular operating hole penetrating from left to right is formed in a lower edge of a right side wall of the box-shaped housing, and a lower hole wall of the rectangular operating hole is jointed to an inner bottom wall of the box-shaped housing;
• a right part of the inner bottom wall of the box-shaped housing is provided with an assembly hole penetrating from up to down;
• a left side wall of the box-shaped housing is provided with a threading hole penetrating from left to right;
• a guide rail of the first guide rail pair is longitudinally fixed to a left part of an inner top wall of the box-shaped housing;
• a guide rail of the second guide rail pair is longitudinally fixed to a right part of the inner top wall of the box-shaped housing;
• sliders of the first guide rail pairs and the second guide rail pairs both face downwards;
• a first hanger rod is vertically fixed to a lower surface of a slider of the first rail pair;
• a second hanger rod is vertically fixed to a lower surface of a slider of the second rail pair;
• the laser is fixed to a lower end of the first hanger rod, and an emitting end of the laser faces rightwards;
• the reflecting mirror is fixed to a lower end of the second hanger rod, and a mirror surface of the reflecting mirror is inclined leftwards;
• an incident end of the reflecting mirror directly faces the emitting end of the laser;
• the single photon detector is fixedly embedded in the assembly hole, and the single photon detector is lower than the inner bottom wall of the box-shaped housing;
• an incident end of the single photon detector faces upwards and directly faces an emitting end of the reflecting mirror;
• the power supply is located outside the box-shaped housing, and an output end of the power supply passes through the threading hole and is connected to a power supply end of the laser;
• and the PC computer is located outside the box-shaped housing, and an input end of the PC computer is connected to an output end of the single photon detector;
• the method comprising following steps:
• putting step, configured for putting a stack of test papers to be counted horizontally into the box-shaped housing through the rectangular operating hole, such that a left edge of the stack of test papers is located between the incident end of the single photon detector and the emitting end of the reflecting mirror;
• starting step, configured for starting the laser, wherein a beam emitted by the laser is incident upon the left edge of the stack of test papers via the reflecting mirror, partial photons in the beam is absorbed by the stack of test papers, the remaining photons pass through the stack of test papers and are incident upon the single photon detector, and the single photon detector detects a number N of the remaining photons, and sends a detection result to the PC computer;
• calculating step, configured for calculating by the PC computer, an luminous intensity I of the beam after passing through the stack of test papers according to the number N of the remaining photons first, then calculating a thickness d of the stack of test papers according to the luminous intensity I of the beam after passing through the stack of test papers, and then calculating a number m of the test papers according to the thickness d of the stack of test papers, thereby completing the counting of the stack of test papers, wherein specific calculation expressions are as follows:
• I=Nhν (1)
• I=I0e−αa(λ)d (2)
• m=d/d0 (3)
• wherein h denotes a Planck constant;
• v denotes an output frequency of the laser;
• I0 denotes an output luminous intensity of the laser;
• αa(λ) denotes an absorption coefficient of a single test paper;
• d0 denotes a thickness of a single test paper;
• and h, v, I0, αa(λ), and d0 are all known parameters.