CN205940763U - Distribution photometry system based on lock -in amplifier - Google Patents

Abstract

The utility model relates to a distribution photometry system based on lock -in amplifier. The purpose is that the measurement system who provides that provides still has simple structure, characteristics that the practicality is strong. Technical scheme is: distribution photometry system based on lock -in amplifier is including the distribution photometer host computer that has two free revolving stages and diaphragm, be used for the computer that detects the photoelectric detector of light signal and go on handling to the detected signal, its characterized in that photoelectric detector's front end is furnished with the chopper to the light signal modulate of distribution photometer host computer reflection, and the chopper is connected to the modulator, the system still disposes lock -in amplifier, and the signal input part of chopper is connected to lock -in amplifier's benchmark reference signal end, and the signal output part of modulator is connected to lock -in amplifier's benchmark reference signal end, and the signal after the lock -in amplifier operation is carried to the computer.

Description

Distributed luminosity measuring system based on lock-in amplifier

Technical field

This utility model is related to a kind of measuring system, especially distributed luminosity measuring system.

Background technology

Distribution photometer is to test various light fixtures, the capital equipment of light source intensity distribution.This equipment passes through swing arm and sample Synchronous axial system, is received the luminous intensity of measured light different directions, is calculated light intensity spatial distribution by photodetector pointwise Data.But existing distribution photometer is when measuring light intensity data, the photodetector of use is to the linear response of light intensity Defect；Especially when micrometer weak light source, the rapid switching of strong and weak light and noise jamming, uncertainty of measurement is very big, light intensity Data easily generation system error.This is the key factor affecting luminous intensity distribution measurement accuracy at present.

Utility model content

The purpose of this utility model is to overcome the shortcomings of above-mentioned background technology, provides a kind of distribution based on lock-in amplifier Photometric measure system；The measuring system being provided also has the characteristics that structure is simple, practical.

This utility model provide technical scheme be：

Based on the distributed luminosity measuring system of lock-in amplifier, including the distribution photometer with double free turntables and diaphragm Main frame, for detecting the photodetector of optical signal and the computer that detection signal is processed；It is characterized in that it is described The front end of photodetector is furnished with the chopper that the optical signal to the reflection of distribution photometer main frame is modulated, and chopper is connected to Manipulator, described system is also configured with lock-in amplifier, and the reference signal end of lock-in amplifier connects the signal of chopper Input, the reference signal end of lock-in amplifier connects the signal output part of manipulator, the letter after lock-in amplifier computing Number it is delivered to computer.

Described photodetector and chopper are installed in detector carriage.

The beneficial effects of the utility model are：

The measuring system that this utility model provides, only increased lock-in amplifier and chopper on the basis of existing equipment, Thus structure is simple, practical, it is particularly suitable for the detection of faint light.

Brief description

Fig. 1 is the attachment structure schematic diagram of distributed luminosity test system involved by this utility model embodiment.

Fig. 2 is the measurement procedure schematic diagram of this utility model embodiment.

In figure has：Distribution photometer main frame 1, double freedom turntable 2, sample 3, power supply 4, diaphragm 5, light electrical resistivity survey Survey device 6, chopper 7, manipulator 8, lock-in amplifier 9, optical path 10, computer 11, detector carriage 12.

Specific embodiment

Further illustrate below in conjunction with embodiment shown in the drawings.

Lock-in amplifier is the small-signal phase-sensitive detection device based on correlation detection technology.Coherent detection is frequency-region signal Arrowband processing method, be a kind of measurement of correlation of integral process.It utilizes correlation properties between signal and external signal, picks Except the noise signal interference of non-correlation, reach accurately to pick up in noise signal and detect faint measured signal purpose.

Distributed luminosity test system using lock-in amplifier includes following part：

Distribution photometer main frame carries double free turntables and diaphragm 5, and photodetector is used for detecting optical signal, computer 11 For processing to detection signal；These are all similar with existing distributed luminosity test system.

Improvement of the present utility model, one is to be furnished with the chopping the light that the optical signal to the reflection of distribution photometer main frame is modulated Device, this chopper is arranged on the front end of described photodetector；Described photodetector and chopper are mounted on detector and prop up On frame.Two is that described system configuration has lock-in amplifier, and the reference signal end of this lock-in amplifier connects chopper and tune Device processed, the input of lock-in amplifier connects the outfan of photodetector, and the signal after lock-in amplifier computing is delivered to meter Calculation machine.

The measuring method that this utility model provides comprises the following steps (referring to Fig. 2)：

1st, place chopper in photodetector front end, chopper connects manipulator, manipulator reconnects lock-in amplifier. Wherein manipulator, according to test needs, adjusts the operating frequency controlling chopper, and as frequency signal, inputs to lock and mutually put The reference signal end of big device；

2nd, photodetector outfan is connected to the test signal input of lock-in amplifier, lock-in amplifier is exported Measured signal；

3rd, the signal output part of lock-in amplifier is connected on computer, for receiving light intensity data；

4th, sample (light fixture or light source) is placed in distribution photometer station to be measured to fix, and connects power line；

5th, switch on power to package unit, that is, give computer, distribution photometer host supplying power, light measured light；To light Electric explorer, lock-in amplifier, chopper are powered, and make equipment enter working condition；

The light that measured light a direction sends is reflected by the 6th, distribution photometer main axis by photometric reflecting mirror Accept to be received by photodetector again after modulation to chopper, then export as measured signal；Lock-in amplifier receives simultaneously To the reference frequency signal coming from chopper and manipulator, and as lock-in amplifier computing reference signal；Reference signal and Measured signal is input simultaneously in lock-in amplifier, and computer is obtained and the photoelectricity after computing by software collection lock-in amplifier Signal simultaneously records.

7th, lock-in amplifier uses Theory of correlation detection, by carrying out to reference signal x (t), measured signal y (t) Multiplication Integral Processing, the noise of suppression detector, so that faint optical signal is detected from noise；I.e.：

X (t)=Vs (t)+n₁(t)

Y (t)=Vr (t)+n₂(t)

$\begin{array}{c}Rxy\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{2T}{\∫}_{-T}^{T}x\left(t\right)y(t-\mathrm{\τ})dt\\ =R_{Sr}\left(\mathrm{\τ}\right)+R_{S2}\left(\mathrm{\τ}\right)+R_{r1}\left(\mathrm{\τ}\right)+R_{12}\left(\mathrm{\τ}\right)\end{array}$

$Rxy\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{2T}{\∫}_{-T}^{T}Vs\left(t\right)*Vr(t-\mathrm{\τ})dt$

8th, because photometer passes through to control turntable real-time motion, the light that light source different directions are sent constantly delivers to spy Survey in device, it is different luminous that the continuous light intensity signal I (θ, φ) that lock-in amplifier obtains is measured light difference luminous flat Light distribution on angle；

9th, the signal processing system in computer adopts following luminosity computing formula (conventional public to obtained light intensity data Formula) calculate：

Thus calculating by the luminous flux of light-metering, realizing the accurate measurement to distribution of light sources luminosity, especially the low light level being distributed The high-acruracy survey of luminosity.

Test specific example

Choose the standard LED straight tube light source of a low light level.Its luminous flux is by certificate of measurement and weight it is known that being 14.02lm.

With this sample of conventional distributed photometer retest 3 times, record luminous flux respectively：

14.93lm, 13.56lm, 14.45lm；

Thus illustrate, in weak light source maximum conditions measurement case, record the linearity of luminous flux array and concordance relatively Difference, the data such as luminous flux, light distribution all cannot ensure accurate reliability.

The distributed luminosity test system based on lock-in amplifier being provided using this utility model, retest 3 times, record Luminous flux is respectively：14.20lm, 14.26lm, 14.21lm.Compared with sample standard value, deviation<2%, prove repeated measure number According to having high concordance.

Claims (2)

1. the distributed luminosity measuring system based on lock-in amplifier, including the distribution photometer master with double free turntables and diaphragm Machine (1), be used for the photodetector (6) detecting optical signal and the computer (11) that detection signal is processed；Its feature It is that the front end of described photodetector is furnished with the chopper (7) that the optical signal to the reflection of distribution photometer main frame is modulated； Chopper is connected to manipulator (8), and described system is also configured with lock-in amplifier (9), the reference signal of lock-in amplifier End connects the signal output part of manipulator, and the input of lock-in amplifier connects the outfan of photodetector, lock-in amplifier Signal after computing is delivered to computer.

2. the distributed luminosity measuring system based on lock-in amplifier according to claim 1 it is characterised in that：Described photoelectricity Detector and chopper are installed in detector carriage (12).