Post on 03-Jan-2016
نور :آشكارساز
آشكارسازي امواج الكترومغناطيسي دررنج طيفي گويند.LIGHT DETECTORازفرابنفش تامادون قرمزرا
ازنقطه نظرپايداري براي طراح سنسور،جذب فوتون موادناشي ازپاسخ يكي ازدوموضوع SENSINGبوسيله quantum وthermal.است
به دوگروه اصلي كوانتومي light detectorsبنابراين همه وگرمائي تقسيم ميشوند.
Quantum Efficiency The efficiency in single photon detection
Gain Multiplication of the initial signal
Sensitivity Minimum # of photons required for output signal
High – Voltage Supply Timing and Positioning
Capability of providing time and position information of the incoming photon
Noise Dark current Nuclear counter effect Experimental Conditions B-field, Temperature, Radiation Levels, Particle Rate, etc.
Complexity of construction Physical Shapes of Detectors Price
Main Characteristics of Light Detectors
Photodiodes
فوتوديودهانيمه هادي هائي هستندكه به نورحساس هستند.
ها رامي توان light detector عملكردكلي اين درشكل صفحه بعدديدكه يك ديودبه صورت
معكوس باياس شده ومي توان ديد كه جريان معكوس بانورتابيده شه به ان افزايش چشمگيري
مي كندكه نتيجه افزايش حامل هاي اقليت دردوسوي پيونداست.
Operation Modes
Photovoltaic mode: like a solar cell, the illuminated photodiode generates a voltage which can be measured. However, the dependence of this voltage on the light power is nonlinear, and the dynamic range is fairly small. Also, the maximum speed is not achieved.
Photoconductive mode: here, a reverse voltage is applied to the diode (i.e., a voltage in the direction where the diode is not conducting without incident light) and measures the resulting photocurrent. (It may also suffice to keep the applied voltage close to zero.)
Phototransistor
از نظرعملكردشبيه فتوديود فتوترانزيستور است بعالوه اينكه گين جريان را فراهم مي كند واز حساسيت بيشتري برخوردار است.
applications
Automatic lighting control
Burglar alarm systemsBurglar alarm systems
Street light controlStreet light control
Photocopy machinesPhotocopy machines
colorimetric test equipmentcolorimetric test equipment