激光对焦

最新推荐文章于 2025-10-28 16:49:40 发布

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本文详细介绍了激光对焦技术在透明或反射性强的物体测距过程中遇到的问题及解决策略。通过使用STMVL6180进行红外激光测距，并结合特定算法计算物距，实现精准的对焦。文章还讨论了在不同距离范围内的对焦方式选择，以及如何通过线程接收测距信息，调整镜头位置以保持在景深范围内。

之前预研过激光对焦,demo已经做好了,对焦速度和准确度都还不错,但因为激光测距对矿泉水瓶等透明或反射性强的物体容易测距不准,再加上其他一些因素最终未能量产到项目,在此简单记录一下,以备查询.

主要是利用stmvl6180来红外激光测距(<40mm)并定时input上报给系统,建立一个线程接收测距,每帧图像都会对比当前镜头位置是否在景深范围内,如果在则镜头不动,如果不在则利用基本的光学公式1/u + 1/v = 1/f 和景深计算公式调整镜头位置,再就是,如果测距在40mm以内就用激光对焦方式,如果在40mm以外就用普通反差式对焦(40mm以内基本覆盖了马达的80%动作距离).

int LaserEvents::PreLaserAFCode(int Laserdist)
{//Laserdist ( mm )

//int Laserdist = LaserRanging() - 10;
if ((Laserdist > 400)/*||(Laserdist<70)*/){
MY_LOG("maleijie out of range\n");
Laserdist = 1000000;
return -1;
}
CalcDepth(&d_front,&d_back,Laserdist);
if(!((d_front>pre_back)||(d_back<pre_front))){//说明在原景深范围内
MY_LOG("maleijie PreLaserAF pre_code:%...\n",pre_code);
return pre_code;
}
Laserdist=Laserdist*100;
//计算物距
long iamge_laser_dist = EFL*Laserdist/(Laserdist - EFL);
//计算直线方程
long A_Code = A_CODE;//150 code
long A_Obj_Dist = A_OBJ_DIST*100;//5000mm
long A_Distance = EFL*A_Obj_Dist/(A_Obj_Dist - EFL);
long B_Code = B_CODE;//850 code
long B_Obj_Dist = B_OBJ_DIST*100;//70mm
long B_Distance = EFL*B_Obj_Dist/(B_Obj_Dist - EFL);
ALOGE("maleijie PreLaserAF Laserdist %d,iamge_laser_dist %d,A_Code %d,A_Obj_Dist %d,A_Distance %d,B_Code %d,B_Obj_Dist %d,B_Distance %d\n",
Laserdist,iamge_laser_dist,A_Code,A_Obj_Dist,A_Distance,B_Code,B_Obj_Dist,B_Distance);
//long k = (A_Distance - B_Distance) / (A_Code - B_Code);
//long b = A_Distance - A_Code*(A_Distance - B_Distance)/(A_Code - B_Code);//A_Distance - k*A_Code;
//long y = (iamge_laser_dist - b)*(A_Code - B_Code)/(A_Distance - B_Distance);//(iamge_laser_dist - b)/k;

long y=((iamge_laser_dist-A_Distance)*(B_Code-A_Code))/(B_Distance-A_Distance)+A_Code;

MY_LOG("maleijie PreLaserAF Laser Focus Code %d\n", y);
//y=y/100;
pre_front=d_front; pre_back=d_back; pre_code=y;//
return y;//lens code
}
int LaserEvents::CalcDepth(int* before,int* after,int laserdist){
long front,back;
front=(FNO*DEL*laserdist*laserdist)/(EFL*EFL*100+FNO*DEL*laserdist);//分子分母都*1000000
back=(FNO*DEL*laserdist*laserdist)/(EFL*EFL*100-FNO*DEL*laserdist);//or ~ , 分子分母都*1000000
MY_LOG("maleijie CalcDepth before:%d,after:%d\n",(laserdist-front),(laserdist+back));
*before=laserdist-front;
*after=laserdist+back;// or ~
return 0;
}